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Societatea Geologică a României - www.geo.edu.ro/sgr
GEO-2002 – Sesiunea ştiinţifică anuală, 24-25 mai
Abstract Volume
The Romanian Geological Society
a possible link to the future
Prof.univ.dr. Nicolae Anastasiu
ass.Member of the Romanian Academy- RGS president
At the beginning of a millenium where science progresses crossed several borders, and where man
is already exploring for some time the space and the oceans depth, when the states controlling the
high technique take samples from the moon space, a glance to a distant past brings us into the world
of those who searched and discovered, systematically, materials that we are calling today raw
materials: iron, aluminum, coal, lead, silica, oil, gold …and many others. Over the last two hundred
years, the geologists stood behind these discoveries, those men who, by their love and
understanding for nature, drew up hypothesis and issued concepts regarding the evolution and
structure of the earth crust-this fragile cover which protects the earth coat and accumulates, for
billions and hundreds of millions of years, mineral riches conserved and kept hidden. We should not
forget that, for the last centuries and, moreover, nowadays, we were given the access thanks to the
effort made in order to know and understand the mineral, vegetal and animal world, the processes
which generated over long periods of time, permanent interactions between the lithosphere, the
atmosphere, the hydrosphere and the biosphere and the formation of resources with an extremely
variety of properties.
From the beginning, the Geology gathered a community of specialists with complex background,
trained for approaching, by physical, physical-chemical, optical, radiometric and geo-physical
continuously improved methods, the concentration places of the energetic and mineral substances,
geological bodies shape where they are localized, the depth at which they are found, and, but not
last, the economic reserves and their qualities.
If we do not neglect all these aspects-which define only a fragment of what Geology and the
geological activities mean- then we do realize a part of the importance or of the role played by this
field of the geological sciences foe the human society and its evolution, as well as the role which
was and is still played by this science in the human civilization history.
The observation facts that allowed it to define itself and to impose itself or to clearly create its own
investigation methods and instruments gathered slowly, with big efforts and, many times, with
many disputes…always specific to a scientific community in progress.
The institutions which were and are in charge of the GEOLOGY, in the strict sense of the word,
appeared late, but they developed fast. I would dare to compare this system with the computers
universe…The traditional countries established, in the high education first, Geology Departments at
the beginning and at the middle of the XIXth century (….) and much more later they established
governmental institutions licensed to manage “the geologic fund”. Whether they were called
Research Institutes, Geological Survey or Agencies for the regulation and the evolution of the
resources and reserves potential, once they appeared, they diversified a lot its specialization, they
created its specialists and they developed. Nowadays they exist in all developed countries,
European or non-European, not from a moral obligation to those who created them, but from an
important necessity: that of a interdisciplinary integration which is the base for the globalization
profits and strategies.
In March 1930, prof.L. Mrazec also proposes the establishment of a geological Society “established
on the demand of and for the geologists and the geology friends from the country, disregarding the
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Societatea Geologică a României - www.geo.edu.ro/sgr
GEO-2002 – Sesiunea ştiinţifică anuală, 24-25 mai
place where they develop their activity”; in this way, it was established a non-governmental
institution, with its own rules and generous projects, opened to the civil society and to those spirits
which have something to say about “the formation and evolution of the earth crust, about its riches,
about the phenomena which keep it alive- the earthquakes and the volcanism evolution-, about the
oil and salt origin…”
Looking further, we foresee new zones and new priorities where the geological knowledge is a
must. In this way, the globalization imposes us a fast adaptation to the new rules required by the
environmental protection, the lasting development, the soils fertilization, the fight with the natural
disasters, the water need in the desert zones and not only, the climate predilections…Starting with
the hammer and the microscope, the utility airplanes (for gravimetry, radiometry, magnetometry ),
the electronic wells and performance computers gather information necessary for the statistics and
the strategic decisions: data banks are a reality, and the geological drawers must be full.
Today’s Romanian Geological Society-by charter, a non-profit and non-governmental organization
– with its septuagenarian tradition and with the chance of having had as members and leaders
important personalities, looks further remembering that: ”the spirit of free scientific thinking and
harmony always dominated inside the Society… This spirit can grow only in the framework of a
free education, namely in the framework of that atmosphere which guarantees the liberty of
searching, thinking and scientifically speaking, leaving free initiative to the researcher. These are
the essential conditions for following undisturbed to find the truth which is the thinking and
research supreme scope”. (said L.Mrazec in 1934)
May be it is high time to intuit what RGS desires to become:
-
a place for as many as possible;
an institution opened to the civil society which it can inform about the life of the Planet;
an active association, where the geologists and the geologist students can debate, in a
regular way, their problems and where they have the opportunity to become famous;
a professional society which can keep in touch with many profile societies from the country
and abroad (AAPG, for example) and which would be represented by its most important
members at the national and international scientific events;
a “club” for pupils and students where they can find information about the jobs and the
professional orientations;
a window towards geological sites from other continents;
a space where it can be found motivations or where one can rediscover the campaigns
world..
All these facts can be a message and a few clues we are bearing in our minds; it can be others, too,
but no matter how many of them are added, we need as many as possible, so that our experiences,
our passions and our knowledge-all gathered together- would gain strength and would enforce the
prestige and the life of the Society whose members we are. On their behalf, we send our greeting to
the partners interested in cooperating with us, and we wish luck to the RAPG scientific session.
Societatea Geologică – nevoia de comunicare
Prof.univ. dr. Nicolae Anastasiu
m.c. al Academiei Române – preşedinte SGR
La începutul unui mileniu în care progresele ştiinţei au trecut numeroase frontiere, iar omul explorează de mult spaţiile
extraterestre şi fundurile oceanelor, când statele care controlează tehnica de vârf exploatează probe din spaţiul lunar, o
privire într-un trecut îndepărtat ne fixează în lumea celor ce au căutat şi au descoperit, metodic, substanţe utile pe care
astăzi le denumim materii prime: fier, aluminiu, cărbune, cupru, silice, petrol, aur...şi câte altele.În spatele lor, în
ultimii două sute de ani, au stat geologii, cei care, iubind şi înţelegând natura , au elaborat ipoteze şi au emis concepte
despre structura şi evoluţia scoarţei terestre – acest fragil înveliş ce protejează mantaua pământului şi acumulează, de
miliarde şi sute de milioane de ani, bogăţii minerale pe care le conservă şi le ţine ascunse. Nu ar trebui să uităm că în
ultimele secole şi, cu atât mai mult, astăzi, accesul la ele a fost şi este posibil graţie unui efort de cunoaştere şi
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înţelegere a lumii minerale, vegetale şi animale, a proceselor care au generat, în lungi perioade de timp, interacţiuni
permanente între litosferă, atmosferă, hidrosferă şi biosferă şi au generat resurse purtătoare de proprietăţi de o extremă
diversitate.
De la început, Geologia a grupat o comunitate de specialişti cu formaţie complexă, pregătiţi pentru a aborda, prin
metode mereu avansate - fizice, fizico-chimice, optice, radiometrice, geofizice - locurile de concentrare a substanţelor
minerale şi energetice, forma corpurilor geologice în care sunt localizate, adâncimea la care se găsesc şi, nu în ultimul
rând, rezervele economice şi calităţile lor.
Dacă nu neglijăm toate aceste aspecte – care definesc, însă, doar un mic segment din ce înseamnă Geologia şi
activităţile geologice – atunci realizăm o parte din importanţa sau rolul pe care acest domeniu al ştiinţelor geonomice îl
are pentru societatea omenească şi pentru dezvoltarea sa , precum şi din rolul pe care această ştiinţă l-a jucat şi îl joacă
în istoria civilzaţiei pământene.
Faptele de observaţie care i-au permis să se autodefinească şi să se autoimpună sau să-şi creeze, în mod evident,
propriile metode şi instrumente de investigaţie s-au adunat încet, cu mari eforturi şi, nu de puţine ori, cu multe
dispute...mereu proprii unei comunităţi ştiinţifice în progres.
Instituţiile care s-au ocupat şi se ocupă de GEOLOGIE, în sens strict, au apărut târziu, dar
s-au dezvoltat rapid. Aş compara sistemul cu universul computerelor....Ţările cu tradiţie au fiinţat, iniţial în
învăţământul superior, Catedre de Geologie la începutul şi mijlocul secolului XIX (....) şi mult mai târziu instituţii
guvernamentale acreditate să administreze „fondul geologic”,. Fie că s-au numit Institute de cercetări, Geological
Survey, sau Agenţii de reglementare şi evaluare a potenţialului de resurse şi rezerve, odată apărute, ele şi-au diversificat
mult specializările , şi-au creat specialişti şi s-au dezvoltat. Astăzi ele există în toate ţările dezvoltate, europene şi
extraeuropene, nu dintr-o obligaţie morală pentru cei ce le-au creat, ci dintr-o necesitate stringentă: aceea a unei
integrări interdisciplinare ce fundamentează strategiile şi beneficiile globalizării. Lumea ştie peste tot de ele, iar cei
dintre noi care au pus bazele instituţiilor fundamentale din învăţământ, cercetare şi industrie au făcut eforturi mari să ne
facă cunoscuţi.
În martie 1930, prof. L. Mrazec a propuns constituirea unei Societăţi Geologice “înfiinţată la cererea şi pentru
geologii şi prietenii geologiei din ţară, indiferent de locul în care îşi desfăşoară activitatea” ; se statua, astfel, apariţia
unei instituţii neguvernamentale, cu reguli proprii şi proiecte generoase, deschisă spre societatea civilă şi spre acele
spirite care aveau ceva de spus despre „formarea şi evoluţia scoarţei terestre, despre bogăţiile ei, despre fenomenele care
o ţin în viaţă – cutremurele şi vulcanismul- , despre originea petrolului şi a sării...
Privind înainte , întrezărim noi zone şi noi priorităţi în care aplicarea cunoştinţelor geologice este iminentă. Astfel,
globalizarea ne impune o adaptare rapidă la noile reguli cerute de protecţia mediului, de dezvoltarea durabilă, de
fertilizarea solurilor, de lupta cu hazardele naturale, de nevoia de apă în zonele deşertice şi nu numai, de predicţiile
climatice…Pornind de la ciocan şi microscop, avioanele utilitare (pentru gravimetrie, radiometrioe, magnetometrie)
sondele electronice şi computerele performante culeg informaţii utile pentru statistici şi decizii strategice: băncile de
date sunt o realitate, iar sertarele geologice se cer pline.
Societatea Geologică a României de astăzi - prin statut, o organizaţie neguvernamentală şi non-profit – cu tradiţia sa
septuagenară şi cu şansa de a fi avut ca membri şi conducători personalităţi marcante – după L. Mrazec, pe Ion
Simionescu, Gh. Macovei, I.Popescu-Voiteşti, D.M.Preda, Al.Codarcea, George Murgeanu, Dan Rădulescu, Mircea
Săndulescu - , priveşte înainte aducându-şi aminte că : „spiritul de cugetare ştiinţifică liberă şi de armonie a dominat
întotdeauna în sânul Societăţii..Acest spirit nu se poate desvolta decât în cadrul libertăţii învăţământului , şi anume în
acea atmosferă ce garantează libertatea de a cerceta, de a gândi şi de a grăi ştiinţificeşte, lăsând iniţiativă liberă
cercetătorului ( L.Mrazec, 1934).
In noua sa formă organizatorică SGR grupează geologi din numeroase domenii - mineralogie, petrologie, metalogenie,
geochimie,paleontologie, stratigrafie, sedimentologie, geologie marină, geologie structurală, geologie economică,
geologie ambientală - dispuşi să comunice şi să interacţioneze în proiecte generoase ştiinţific şi profitabile economic.
Colocviile lunare care s-au derulat în primul semestru al anului 2002 au umplut amfiteatrul de la Universitate şi au
prefigurat certitudinea că o motivaţie pentru dialog interdisciplinar exista şi o punte între generaţii, se schiţează.
Organizarea Sesiunii ştiinţifice GEO 2002 ne-a apărut ca o provocare, iar cele 60 de lucrări a căror rezumate le grupăm
în acest volum sunt expresia nevoii de comunicare.
Autorii lor, în mare măsură membrii ai Societăţii Geologice a României, sunt cercetători cu experienţă, profesori de
prestigiu şi, alături de ei, studenţi şi geologi de la diverse companii.
Poate este momentul să intuim ceea ce SGR poate şi doreşte să devină:
 un loc pentru cât mai mulţi;
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

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o instituţie deschisă spre societatea civilă, pe care să o informeze despre viaţa Planetei;
o asociaţie activă, în care geologii şi studenţii din aria geologiei să-şi poată dezbate, regulat, problemele de care se
ocupă şi în care să se facă cunoscuţi;
o societate profesională, care să ţină legătura cu multe alte societăţi de profil din ţară şi din străinătate (AAPG-ul
,de exemplu) şi care să fie prezentă la reuninunile ştiinţifice naţionale şi internaţionale, prin membrii săi de elită;
un “club” pentru elevi şi studenţi în care să poată găsi informaţii despre job-uri şi orientări profesionale;
o fereastră spre sit-uri geologice din alte continente,
un spaţiu, în care să se găsească motivaţii sau să se redescopere lumea campaniilor de teren..
Pot constitui toate acestea un mesaj şi câteva repere pe care le purtăm în gând; pot fi şi altele, dar oricâte s-ar adăuga,
este nevoie de cât mai mulţi, pentru ca experienţele, pasiunile şi cunoştinţele noastre – puse alături – să capete forţă
şi să întărească prestigiul şi viaţa Societăţii ai cărei membri suntem .
mai 2002
DIAGENETICAL EFFECTS ON THE NEOCOMIAN LIMESTONES
FROM THE CENTRAL AREA OF MOESIAN PLATFORM
– RELATIONS TO THE HYDROCARBONS DYNAMICS
Nicolae ANASTASIU, Relu-Dumitru ROBAN
Universitatea Bucureşti, [email protected]
Cuvinte cheie: Moesian Platform, Neocomian, diagenesis, dolomitisation, stylolite, hydrocarbon reservoir
A sedimentological analysis has been performed in order to point out the postdepositional
(diagenetic) evolution of the reservoir architectures component of Videle, Blejesti, Serdanu and
Ungureni structures. For this several methods – i.e. grain- size & shape analyses, microstructures
examination, cathodoluminiscence and U.V. fluorescence studies - have been applied.
Specific postdepositional processes – physical, chemical and biochemical in character – that acted
differently - spatially and temporally - have been identified, as follows: differential compaction and
illuviation of matrix, sindepositional bioturbations, micritizations, vadose- and submarine
cementations, polymorphic transformations, recrystallizations (by aggradation), authigeneses of
calcite, dolomite and pyrite, pressure solutions, and joints/ fractures.
Recrystallizations (by aggradation), are the most frequently, selective, and affect the matrix,
peloides, intraclasts and bioclasts . The process is never complete, not symmetrical. Microstylolites
are effect of pressure solution, and cover the boundaries between the litons. Sometimes it cut
pelloides , and that is a prove for water roll in the process. Dolomitization it was a recurrent
processes, in telogenesis, and mesogenesis stages. We can see a cover effect.
The effective and total porosity of the studied reservoirs is directly subject to this processes, that
specifically controlled modifications of "grain- support" and pore space as well, within three
diagenetic stages: incipient burial (eogenesis), uplifting (telogenesis) and, respectively, progressive
burial (mesogenesis).
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The hydrocarbons dynamic – either from source to reservoir bodies or inside reservoirs – could be
considered as a complex process, mainly controlled by pore space configuration and by the
relationship between the time of hydrocarbon maturation and the evolution of each process
modifying pore space.
The prediction of hydrocarbons in dolomitic reservoirs – which hosted a large void, should
be connected with depositional model. Intercrystalline pores, and dissolution voids are the most
frequent in the reservoirs.
EVOLUTION OF ORGANIC MATTER IN PALEOZOIC FORMATIONS
LYING TO THE EAST OF BUCHAREST MERIDIAN
Stefania ARSENE, Nina BARBULICEANU
C.C.P.E.G. Toamnei Ave.,nr.103, sect.2,Bucharest, e-mail: [email protected] ; [email protected]
To the east of Bucharest meridian, the Paleozoic penetrated by the drillings carried out in the
area consists of sedimentary series that have been divided in three major Formations: Tandarei,
Calarasi and Vlasin.
Throughout these formations, pelitic sequences have been identified, where in both the
organic matter content and the chemical composition classify them within the category of
hydrocarbon source rocks.
The laboratory analyses performed on the organic matter taken out from these formations
made it possible to remark on the type of initial organic matter, transformation degree and its actual
state.
The available data suggest that the organic matter deposited in Tandarei and Calarasi
Formations is of a marine origin and gave rise to kerogen type II and the one deposited in Vlasin
Formation has a highly terrestrial input resulting in the formation of mixed kerogen. These
formations are actually at the end of the oil window.
The genetic relationship between these source rocks and the oils occuring within the
relevant area's accumulations could not be established mainly due to the advanced oil degradation
level.
DIAGENETIC EVOLUTION OF THE CARBONATE DEPOSITS
NEAR THE JURASSIC-CRETACEOUS BOUNDARY FROM LESPEZI QUARRY
Victor BARBU
University of Bucharest, Faculty of Geology and Geophysics, Department of Geology & Paleontology
1 Nicolae Balcescu Ave, sect. 1, RO-70111 Bucharest, ROMANIA
e-mail: [email protected]
Keywords: limestone, diagenesis, staining, cathodoluminescence, Jurassic/Cretaceous boundary, Lespezi quarry.
Lespezi quarry was selected for studying diagenetic evolution of the carbonate deposits near
the Jurassic-Cretaceous boundary from the Southern Carpathians. This quarry localized in the
southern part of the Bucegi Mts. represent a key outcrop for understanding geological evolution of
the narrow carbonate platforms attached to the extensional continental margins during the Upper
Jurassic.
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GEO-2002 – Sesiunea ştiinţifică anuală, 24-25 mai
Several specific techniques for analyses of the diagenetic features have been applied in the
laboratory: staining with Alizarin Red and K Ferricyanide for carbonate mineral identification
(Dickson, 1966), optical petrography and cathodoluminescence for deciphering the growth zones of
the cements inside the pores.
These analyses helped to establishing the diagenetic environments, fluid flows and temporal
evolution of these carbonate deposits. Based on these analyses it was for the first time recorded a
subaerian exposure surface and several phases of drowning within the post-depositional evolution
of this small carbonate platform.
SEDIMENTOLOGICAL ANALYSIS OF THE NEOCOMIAN LIMESTONES FROM LESPEZI QUARRY
(SOUTHERN BUCEGI MOUNTAINS)
Victor BARBU1, Cristina E. PANAIOTU2, Cristian PANAIOTU2,
1
University of Bucharest, Faculty of Geology and Geophysics, e-mail: [email protected]
2
University of Bucharest, Paleomagnetism Laboratory, e-mail: [email protected]
Keywords: calcimetry, rock-magnetism, Neocomian limestone, Lespezi quarry, Bucegi Mountains.
Sedimentologic and rock-magnetic investigations have been done on 12 samples collected from
Neocomian limestones in Lespezi quarry (southern part of the Bucegi Mts.). Sampling was
systematically done from each bed for a total thickness of 3 m. Sedimentary structures and lithology
changes were registered on a detailed log in the field.
In the laboratory, we applied several specific techniques: optical petrography, calcimetry, rockmagnetic proprieties (κn – magnetic susceptibility, ARM – anhisteric remanent magnetization, IRM
– isothermal remanent magnetization) to identify the variability of siliciclastic input versus
carbonate accumulation. Total carbonate content (calcimetry) is an estimation of the planktonic
productivity, while magnetic susceptibility may give information about fine grained clastic input
and/or syndepositional bacterial activity.
From these parameters which correlate very well each other, high resolution pattern of
sedimentation can be identified and correlated with variation in climate and depositional
environment. These deposits represent the cap of the Upper Jurassic tectonically drowned carbonate
platform accumulated in a deep-water basin evolving in extensional regime.
CONDIŢII DE FORMARE ŞI EXPLOATARE A ACUMULĂRILOR DE HIDROCARBURI
PE STRUCTURA SÂNIOB, BAZINUL PANONIAN
Mihai Valentin BATISTATU
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Universitatea Petrol-Gaze Ploieşti, Facultatea de Foraj, Catedra Geologie-Geofizică, B-dul Bucureşti nr. 39, Ploieşti,
e-mail: [email protected]şti.ro
Key words: well logs, model, acumulations, depositional enviroment.
The upper Miocene of the Chişlaz – Sâniob zone is caracterized by the existence of some
hydrocarbons bearing zone. The present paper tries to provide a model for these acumulations, to
explain the existence of different zones with different productivity by means of depositional
enviroment. These considerations are based mainly on the well logs production data corelated with
geological features of the area.
CONSIDERATIONS ON THE SPREAD OF PROBOSCIDIAN FOSSILS
IN PRAHOVA COUNTY AND NEARBY AREA
Victor BACARAN, Dumitru FRUNZESCU
283, Bvd. Republicii, bl. 3 B1, ap. 9, Ploiesti, 2000, Prahova
University of Petroleum-Gas of Ploiesti, Faculty of Drilling, Geology-Geophysics Section
39, Bvd. Bucuresti, 2000, Ploiesti, Prahova e-mail: [email protected]
Key words: proboscidian fossils, Prahova County, biometric measurements, distribution.
The paper presents several fossil proboscidian fragments which have been recently found in
Prahova County. Taking into account the biometric measurements, a species diagnosis was made
and several considerations on the distribution of proboscidian fossil forms were made.
STAGES OF THE GERMINATION PROCESS OF FOSSIL FUNGI SPORES.
A CASE-HISTORY ON DOFTANA MOLASSE MIOCENE
FROM DRAJNA SYNCLINE
Victor BACARAN, Dumitru FRUNZESCU
283, Bvd. Republicii, bl. 3 B1, ap. 9, Ploiesti, 2000, Prahova
University of Petroleum-Gas of Ploiesti, Faculty of Drilling, Geology-Geophysics Section
39, Bvd. Bucuresti, 2000, Ploiesti, Prahova e-mail: [email protected]
Key words: Miocene, Doftana Molasse, fungi spores germination, conservation.
The study of palinomorphes distribution from Doftana Molasse Miocene offers examples of
fungi spores, which are found in different germination stages: from primordial stages of
germination hifes to the stage of spores which are released by hifes. The different germination
stages are constituted in premises of different degrees of conservation of fossil material.
REACŢII METASOMATICE ŞI GENEZA SKARNELOR
DIN VALEA LUI STAN (M-ţii Făgăraş)
Alecsandru BĂRBULESCU, Dragoş POPESCU, Liliana POPA (anul III)
Îndrumători: Lect. Dr. Ing.Gelu COSTIN, Asist. Peter LUFFI
Lucrarea descrie pentru prima dată o ocurenţă de skarne asociate metamorfismului regional
din versantul sudic al Munţilor Făgăraş (Valea lui Stan).
Sunt prezentate mineralogia, stadiile paragenetice şi geneza posibilă a skarnelor precum şi a
rocilor de tranziţie derivate prin reactii metasomatice.
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Mineralogia skarnelor este reprezentată de asociaţia calcit, granat (grossular 80- almandin 20
), hedembergit, epidot, sfen, cuarţ. Iar în rocile de tranziţie au fost identificaţi amfiboli , plagioclazi
relicţi (anortit 40), clorit magnezian în asociaţie cu talc alaturi de actinot, cuarţ, epidot şi sfen .
Aceste minerale în rocile vecine skarnelor se asociază în benzi bi, tri sau poliminerale .
Benzile de compoziţie diferită precum şi gradul de idiomorfism al mineralelor sugerează o
zonalitate de tip metasomatic.
Considerăm că geneza skarnelor şi a rocilor de tranziţie este legată de reacţii metasomatice
pe un protolit gabbroic în prezenţa unei faze fluide cu compozitie variabilă locală (actiunea C02
>acţiunea H2O în skarne şi acţiunea C02 <acţiunea H2O pe masură ce ne depărtăm de skarne).
Relaţiile de teren precum şi imaginile microscopice arată deformări intense ale asociaţiilor
minerale pe zonele de tranziţie skarne – şisturi gazdă (gnaise oculare , gnaise plagioclazice,
amfibolite). Această deformare ductilă intensă (în regim decrosant) asociată cu temperaturi relativ
ridicate (cute ptigmatice în rocile gazdă) şi influxul de CO2 sugerează o geneză metasomatică a
skarnelor în condiţii sincinematice, asociată probabil unei zone de forfecare profundă . Sursa CO2
ar putea fi asociată prezenţei unor “slice-uri” tectonice de natură corbonatică în profunzime (grupul
de Făgăraş încălecat de grupul Cumpăna) .
La adâncimi mari, carbonaţii din astfel de roci carbonatice , tectonic supraîncălzite , se pot
disocia eliberând CO2. Fluidul metasomatic astfel produs localizează strainul generând o zonă de
forfecare de-a lungul căreia CO2 alături de H2O poate migra ascendent , producând pe parcurs
reacţii metasomatice ca cele descrise în lucrarea de faţă.
GEOMAGNETIC EXPRESSION OF AN ANCIENT PLATE BOUNDARY SOUTHERN
SOUTH CARPATHIANS, ROMANIA. TRANS-GETICA FAULT
Lucian BEŞUŢIU
Institute for Geodynamics of the Romanian Academy, Solid Earth Dynamics Department
70201 Bucharest, 19-21 Jean Louis Calderon Str., sector 2, e-mail: [email protected]
Key words: geomagnetic map, complex interpretation, crustal fault, plate tectonics, South Carpathians, Moesian Plate
The reconstruction of the national ground geomagnetic map of Romania, after removing the
secular variation effect, provided the opportunity to take into consideration and appropriate
interpreting some previously hidden or distorted large-scale peculiarities of the vertical component
geomagnetic anomaly. By appropriate filtering the newly achieved images, a large discordance in
the geomagnetic anomaly pattern southern South Carpathians occurred. It was associated to the
presence of a large-scale discontinuity affecting the crust at least down to the crystalline basement.
It has been named Trans-Getica Fault (TGF) and seems to be the northern boundary of the Moesian
microplate (MoP), playing a major role in the tectonics of the area. Additional information provided
by magnetotelluric soundings (MTS) and deep seismic soundings (DSS) data on the western sector
evidenced for its trans-crustal features. Actually, the trans-crustal Tg. Jiu-Călimăneşti fault
(Visarion et al, 1994) appears as the western segment of TGF. Divergent Wiese vectors (Soare,
1989) along the geomagnetic revealed fault path mark the presence of a high electrical conductive
element in the lower crust, which seems to correspond to the contact between MoP and the IntraAlpine microplate (IaP). Normal seismicity recorded along TGF advocate for both its deep and
actual active nature.
The contact area can be easily followed eastward up to a meridian where it seems to met
another major geotectonic discontinuity, Peceneaga-Camena fault (PCF). Active seismicity along its
track fully supports the idea of a plate contact. Several evidence, such as the geomagnetic pattern
within the neighboring compartments, and the repartition of the regional stress within MoP, as
inferred from the analysis of the normal earthquake mechanism (Zugrăvescu and Polonic, 1997),
advocate for its transform features.
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It is very hard to interpret the TGF age. Taking into account the almost unfolded Palaeozoic
deposits within South Carpathians, except for their westernmost bending segment (Pavelescu and
Niţu, 1977), it is likely that in a primary geodynamic stage, probably during the Late PalaeozoicEarly Triassic, an important block of East European Plate was shifted westward along TGF.
Thereafter, it acted by distorting the shape of the Carpathians geosyncline, and tightly folding
Palaeozoic deposits located in front of it. Similarities between the basement of the Walachian sector
of the Moesian Platform (with Archaean granite to diorite rocks, and Lower Triassic large volumes
of basic effusives), and the basement of the SW margin of East European Platform, as revealed by
deep drillings support the idea. Consequently, it seems that Tornquist-Teisseyre Zone was broken
somewhere in the Vrancea active seismic area, and shifted westward hundreds of kilometers, in the
Serb Banat area. Europe gravity images seem to support the idea. Present active dynamics along
TGF are evidenced by intense normal seismicity and stress distribution within South Carpathians
area.
Selected references:
Pavelescu, L., Niţu, Gh. (1977) Le probléme de l’Arc Carpato-Balcanique; An. Univ. Bucuresti,
Geologie, An. XXIV, 19-35
Soare, A. (1989) Preliminary results of some tectonomagnetic researches at the Surlari Geophysical
Observatory; Rev. roum. géol. géophys. géogr., Géophys., 33, 43-47
Visarion, M., Stănică, D., Stănică, M.(1984) Deep-structure of the region between the Motru valley
and Argeş valley, Romania, as shown by the results of geophysical surveys; Acta Geodaet.,
Geophys. et Montanist. Hung. Volume 19,1-2, 173-184
Zugrăvescu, D., Polonic, G. (1997) Geodynamic compartments and present-day stress state on the
Romanian territory; Rev. Roum. Géophys., 41, 3-24
MIGRATION OF THE VRANCEA INTERMEDIATE-DEPTH SEISMICITY:
REALITY OR MATHEMATICAL FICTION?
Lucian BEŞUŢIU and Nicoleta CADICHEANU
Institute for Geodynamics “Sabba S. Ştefănescu” of the Romanian Academy, Solid Earth Dynamics Department
RO-70201 Bucharest 37, 19-21, Jean Louis Calderon Str., sector 2, e-mail: [email protected]
Key words: intermediate-depth seismicity, geodynamics, space-time migration
General considerations
Vrancea intermediate-depth seismicity stands for a long time as a challenge to geoscientists
all over the world. Many efforts have been made during the years to decipher the strange
mechanism generating strong intermediate-depth earthquakes in a rather confined area located in
the East Carpathians bending region. The special geometry of the epicentral zone, with its strong
NE-SW elongation suggested to some authors the presence of a rectangular fragment of an assumed
sinking slab in the area.
Paper aim
Unlike previous works, the present paper is intended to demonstrate, based on a statistical
analysis of the seismic event occurrence, that the elongated shape of the epicenter region is at least
partly due to a space-time migration of the intermediate-depth seismicity developed within a
smaller, more isometric active seismic zone moving towards SW.
Data
The statistics has been performed on a data set provided by the ROMPLUS catalogue
(Oncescu et al, 1998), which has been completed with more recent events as provided by the website of the National Institute for Earth Physics. The time span after the major event of November
1940 was considered. To study the intermediate-depth seismicity, earthquake hypocenters located
beneath 60 km depth were considered only. Besides, several deep events located far outside
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Vrancea geotectonic area were also excluded. All in all, more than 2100 seismic events were taken
into consideration, which represent, in our opinion, a significant statistical database.
The approach
Basic idea in developing the carried out research was that an eventual migration of the
seismic activity should be the result of two components: (i) a random occurrence of the earthquakes
within an inhomogeneous seismic body, and (ii) a systematic (deterministic) trend generated by an
assumed displacement of sub-crustal masses under the influence of convective currents in the upper
mantle. To avoid, or at least to attenuate the stochastic component, seismic activity within Vrancea
area was integrated along time intervals between major seismic events (of distinct moment
magnitude): 1940 (Mw = 7.7), 1977 (Mw = 7.4), 1986 (Mw=7.1), and 1990 (Mw = 6.9). Among
them, several sub-intervals, related to the solar activity cycle were inserted, where the case. Both
simple and weighted averages have been used for determining the centers of the seismic activity
within each interval.
Main results
By performing the above-mentioned analysis an obvious migration of the intermediate-depth
seismicity in the Vrancea area was pointed out. Generally, the seismic activity seems to move SW,
by gently dipping, except for the moment around the major earthquake of March 4, 1977, when the
trend reversed. Unlike previous and following intervals, during the 1970-1977 the seismic activity
center fallen down at about 140 km depth, to come back on the trend within 1977-1986 interval.
After the 1977 catastrophic earthquake, the westward displacement was also reversed, the seismic
activity moving eastward during the next interval.
Selected references
Oncescu, M.C., Mârza, V.I., Rizescu, M., Popa, M., 1998. The Romanian earthquake catalogue
between 984-1997: In Vrancea Earthquakes: Tectonics, Hazard and Risk Mitigation.
Wenzel, F., Lungu, D. (Editors) and Novak, O. (co-Editor)). Kluwer Acad. Publ.,
Dordrecht/Boston/London, 43-48
ASPECTE PRIVIND INFLUENŢA METODELOR EOR ASUPRA
ROCILOR COLECTOARE
Gheorghe Adrian BRĂNOIU
Universitatea Petrol-Gaze Ploieşti, Facultatea de Forajul Sondelor şi Exploatarea Zăcămintelor,
Catedra Geologie-Geofizică, B-dul Bucureşti nr. 39
KEY WORDS: EOR methods. Mineralogical changes. Modified physical properties of rocks.
The purpose of this paper is to analyse the some aspects of the influence of EOR (Enhanced
Oil Recovery) methods on reservoir rocks. Getting to know this influence which consists in
mineralogical changes, the modification of the physical properties of rocks (porosity, permeability)
is useful in reservoir engineering helping in choosing the most efficient EOR methods.
CATEVA DATE NOI ASUPRA CALCARELOR DE LA POIANA AIUDULUI
Ioan I. BUCUR, Emanoil SÃSÃRAN, Endre PAP.
Universitatea Babeş-Bolyai, Departamentul de Geologie-paleontologie, Str. M. Kogălniceanu nr.1, 3400 Cl;uj-Napoca.
E-mail: [email protected]
Cariera de calcar de la Poiana Aiudului este deschisă în versantul sud-vestic al Dealului
Mare, într-un olistolit de dimensiuni considerabile, prins în depozitele terigene ale flişului cretacic
superior ce aflorează atât în baza căt şi în partea superioară a succesiunii calcaroase. Grosimea
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totală a calcarului depăşeşte 125 m, fiind însă greu de făcut o estimare foarte exactă datorită faptului
că nu se poate urmări un profil continuu pe întreaga deschidere.
Analiza secţiunilor subţiri efectuate prin eşantioanele recoltate a pus în evidentţă o gamă
largă de microfaciesuri, de la bioclastite de pantă a platformei carbonatice până la calcare fenestrale
şi laminite intertidale. Au fost recunoscute de asemenea suprafeţe de discontinuitate marcate de
fenomene de carstificare.
Asociaţiile micropaleontologice determinate au pus în evidenţă două pachete distincte ca vârstă:
unul Berriasian?-Valanginian (în partea inferioară a succesiunii) şi altul Barremian-Apţian inferior
(în partea superioară). Limita dintre cele două pachete nu a putut fi practic observată în teren.
Calcarele berriasian?-valanginiene conţin o asociaţie cu : Actinoporella podolica,
Salpingoporella annulata, Salpingoporella pygmaea, Salpingoporella circassa, Seliporella
neocomiensis, Andersenolina alpina, Andersenolina aff. elongata, Protopeneroplis banatica,
Haplophragmoides joukowskyi şi Meandrospira favrei. Asociaţia din calcarele barremian-apţiene
cuprinde: Neomeris cretacea, Triploporella cf. marsicana, “Coptocampylodon” fontis,
Palorbitolina ? sp. şi Paleodictyoconus arabicus. Din această asociaţie se remarcă prezenţa
orbitolinidului Paleodictyoconus arabicus, întâlnit cel mai frecvent în depozite situate la limita
Barremian-Apţian.
Dacă vârsta valanginiană a calcarelor de la Poiana Aiudului era deja de mult cunoscută (e.g.
BEDELEAN, 1966), prezenţa depozitelor Barremian-Apţiene în partea superioară a succesiunii
deschise în carieră reprezintă o noutate notabilă.
SECVENŢE EVAPORITICE ÎN MOLASA MIOCENĂ A CARPAŢILOR ORIENTALI DE
CURBURĂ – SEMNIFICAŢII PALEOAMBIENTALE
Marius BULBUC (anul IV), Răzvan ARGHIR (anul II), Dragoş PORUMB (anul II)
Centrul de Sedimentologie, Universitatea din Bucureşti/ Facultatea de Geologie şi Geofizică
Îndrumător: Lector Dr. Marius POPA
Prezentul studiu este o abordare sedimentologică preliminară asupra secvenţelor evaporitice
"molasice" miocene ale Carpaţilor Orientali (zona de curbură), ce aflorează în lungul profilelor
deschise de V. Teleajen şi Prahova, în scopul reconstituirii mediilor de sedimentare specifice.
Metodologic, analiza sedimentologică efectuată a urmărit identificarea faciesurilor
evaporitice (sulfatice) în succesiune litologică (ca tip petrografic; morfologii şi microstructuri
specifice; structuri depoziţionale/ postdepoziţionale, definitorii si asociate) şi caracterizarea
secvenţelor evaporitice (petrografic; succesiuni; limite).
În secţiunile stratigrafice analizate au fost determinate 14 faciesuri evaporitice sulfatice,
depoziţionale şi postdepoziţionale, asociate în secvenţe de două ordine de mărime. Din punct de
vedere depoziţional, microsecvenţele separate (mm- cm în grosime) constituie de fapt microritmuri
rezultate în urma unor variaţii ciclice, pe termen scurt, ale gradului de salinitate (ex. gips- argilă/
marnă, gips- mat cianobacterial) şi/ sau al tipului sedimentării (ex. gips clastic- marnă/ argilă).
Asocierea acestora defineşte mai multe tipuri de mezosecvenţe – în grosimi dm- m – care au fost
încadrate ambiental. Astfel, pe baza faciesurilor diagnostic, a tranziţiilor în succesiune şi a
caracterului suprafeţelor de discontinuitate (interne şi limită), mezosecvenţele analizate sugerează
depuneri în ambianţe marine costiere şi adiacente, reprezentate în principal de plaje evaporitice
("coastal sabkha"), lagune saline ("lagoon"), lacuri/ bazinete marginale sărate ("saline pan") şi
ambianţe litorale. Controlul acestor mezosecvenţe a fost în principal climatic, dar şi tectonic (fapt
demonstrat de prezenţa în anumite secvenţe a unor parabrecii sulfatice de resedimentare
gravitaţională şi a structurilor de injecţie hidroplastică).
Procesele diagenetice (postdepoziţionale) au avut un rol important în modificarea
trăsăturilor faciale primare.
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MAGMATITELE ACIDE ŞI SKARNELE ASOCIATE DIN CRISTALINUL MUNŢILOR
SEBEŞ: MINERALOGIE ŞI PETROGENEZĂ
Mihai CIOCÎRDEL (masterand)
Îndrumători: Lect. Dr. Gelu COSTIN, Prof. Dr. Marin ŞECLĂMAN
Magmatite acide, porfirice, afanitice, holocristaline (de compoziţie granodioritică) aflorează
sub formă de corpuri miciţ izolate în cristalinul M-ţilor Sebeş.
Lucrarea prezintă mineralogia corpurilor granodioritice, succesiunea de cristalizare
magmatică precum şi evoluţia compoziţiei topiturii ca urmare a cristalizării şi contaminării
magmatice. Sunt de asemenea prezentate şi skarnele asociate genetic acestor corpuri.
Distribuţia areală relativ liniamentară a corpurilor magmatice (asociate spaţial cu zona de
forfecare Răşinari – Stelea, 1996) precum şi lipsa deformărilor ductile penetrative, sugerează o
origine post- sau tarde-colizională a acestor magmatite.
Geneza magmelor granodioritice o considerăm a fi legată de o anatexie parţială a crustei
continentale asociată formării zonei de forfecare Răşinari (Cărpiniş-Căpâlna) în regim decroşant.
Magmele astfel generate au putut asimila diferite tipuri de şisturi cristaline, modificându-şi
chimismul şi succesiunea de cristalizare.
Mineralogia skarnelor, relaţiile de teren, şi prezenţa unor zonalităţi de tip metasomatic arată
că skarnele se formează prin reacţii metasomatice în prezenţa unor volatile bogate în CO2.
AN ACTIVE LANDSLIDE INVESTIGATION
CASE STUDY: EASTERN CARPATHIAN MOUNTAINS, ROMANIA
Horatiu V. CORBEANU1, Tom H. BRIKOWSKI2, Carlos V. AIKEN2
1
- SC COGES GRUP SRL - Campina, 2150, Prahova, Romania, [email protected]
- Geosciences Department, University of Texas at Dallas, Richardson, 75083, USA
2
Keywords: landslide, failure mechanisms, GPS, VES, Romania
The areal density of destructive landslides in the oilfields of the Eastern Carpathian
Mountains is one of the highest in Romania. Detailed study of one rainfall-triggered landslide
reveals a complex kinematic history. A variety of investigative tools were used to evaluate this
history and determine the landslide characteristics. Detailed global-positioning surveys (GPS) of
landslide movement uncovered the mechanisms of deformation, and demonstrated the relationships
between the triggering factors and the dynamics of the movement. Geotechnical and vertical
electrical sounding investigations were carried out to determine the quantitative stability conditions
of the slope and the geometry of the failure surface. All this information was combined to generate
a failure-prediction model, which can be used to define prevention measures for the mitigation of
slide effects, and reduce the loss of human lives and assets.
The model illustrates the complex process leading to recurrent landsliding at the site. The
upper part of the landslide moves and loads continuously onto the lower part, which in turn fails
critically and episodically. The landslide, characterized mostly as a translation slide, presents
multiple failure surfaces at depths 2, 8 and 13 m. The whole landslide developed in four stages:
accumulation of colluvial deposits at the upper part, creep sliding, rotational failure at the lower
part, and finally massive translational failure.
Analysis of this slide and development of a failure model required application and
integration of a diverse set of methods (GPS, boreholes and geophysical methods). Complete
analysis of most active landslides can be expected to require a similarly diverse approach.
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AN ATTEMPT TO USE THE OLIGOCENE-LOWERMOST MIOCENE ICHTHYOFAUNA
(TELEOSTEI) IN THE RECONSTRUCTION OF SOME ANCIENT ENVIRONMENTS
FACTORS FROM EASTERN CARPATHIANS FLYSCH ZONE
(CENTRAL-SOUTH AREA)
Paul CONSTANTIN
Geological Institute of Romania, 1 Caransebes street, 78344 Bucharest; E-mail: [email protected]
Key words: ichthyofauna, Teleostei, Oligocene, Lowermost Miocene, Eastern Carpathians, paleoenvironment factors, mass mortality.
In the lack of other groups of organisms, classical for paleoecological reconstructions, the
study of fossil fishes has been possible as an alternative in order to determine some
paleoenvironment factors. Thus, an example can be offered by the rich Oligocene - Lowermost
Miocene ichthyofauna, which has been known for a long time from the formations developed in the
bituminous facies in the carpathic flysch area, generally lacking other fossil organisms. The above
mentioned ichthyofauna represented the goal of our latest studies in the Central and South area of
the Eastern Carpathians. The fossil fish-fauna (71 teleostean species belonging to 39 genera and 30
families) which has been revealed so far due to the field research, completed with museal collections
investigation or published data examination, was generally provided by fine pelitic, bituminous
shales, laminitic limestones or bituminous marls, found on different stratigraphic levels in the
Oligocene - Lowermost Miocene, being predominant in its lower part (Rupelian) among all the 34
localities indentified in our studies. The bearing fossil fish-fauna formations belong as well to all the
Oligocene - Lowermost Miocene lithofacies known in the Romanian Eastern Carpathians: Valea
Caselor Facies (Inner Bituminous Facies), Fusaru-Pucioasa Facies, Slon Facies, Mixed Facies, and
Bituminous Facies with Kliwa Sandstone (Outer Bituminous Facies).
In order to use the fossil fish-fauna to establish some paleoecological factors, the fosiliferous
material nature was taken into account. The taphonomic aspects showed that the ichthyofauna was
generally represented by "in situ" specimens, preserved under favourable fossilization conditions
(anaerobic environment, lack of streams, very fine sedimentary material, etc.). Only for the
ichthyofauna borne in the formations belonging to the Valea Caselor lithofacies, the mass mortality
could be recognized, due to some catastrophic conditions (changes in the depth where H2S was
borne, under some temperature and pression conditions)
As fishes are mainly nectonic organisms, characterized by a great mobility, the whole
association was taken into account, as much as possible, in the interpretation of the environment
significance, trying to detect the predominant (autochtonous) species from those which were
accidentally present in the association, due to the migrations.
Comparing the fossil ichthyofauna with the Recent one (taking into account the limits
imposed by this approach) or using the fossil species morpho-functional studies, a paleotemperature
reconstruction was tried (subtropical climate for Rupelian, with a possible cooling during
Lowermost Miocene), a paleosalinity one (marine basin, with normal salinity during Rupelian, but
with possible brackish waters during Lowermost Miocene, at least in areas closely to the shore,
within perilitoral basins, temporary closed), and the sedimentation basin paleobathymetry as well,
basin corresponding to the Oligocene -Lowermost Miocene formations from the South of the Trotus
Valley (the sedimentation basin reached different depths, according to the place and the period
analysed).
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ULTRASTRUCTURE AND CHEMISTRY OF ZOOPHYCOS PELETS MASSALONGO
1855 (PRELIMINARY CONSIDERATIONS)
Constantin COSTEA*, Titus BRUSTUR**
* Institutul Geologic al României, str. Caransebes 1, 78344, Bucuresti 32
** Institutul National de Geologie si Geoecologie Marinã, str. D. Onciul 23-25, P.O. Box 34-51, Bucuresti
Zoophycos ichnogenus represents an interesting biogenic sedimentary structure. Its origin is
still controversial. The simple to complex “spreite” type morphology is the result of a detritus–
feeding vermiform organism living in transitional sublittoral–bathial marine areas. We present some
preliminary data on the Zoophycos pelets ultrastructure and chemistry in the Hangu Formation from
the Bucovina Eastern Carpathians Outer Flysch.
MINERALOGICAL AND MICROSTRUCTURAL PROPERTIES OF KLIWA
SANDSTONE FROM THE CORNER OF THE EAST CARPATHIANS
– ON THE ROLE FOR A RESERVOIR QUALITY
Eduard V. DRĂGAN, Nicolae ANASTASIU, Lidia NUTU
Bucharest University, Faculty of Geology and Geophysics
Keyword: East Carpathian, Kliwa sandstone, diagenesis, cathodoluminescence, UV fluorescence, reservoir quality
One of the famous reservoir in the Carpathians, Kliwa Sandstone (Oligocene –early Miocene age) was
documented, using raffined technics (textural analysis, optical microscopy, cathodoluminescence, UV fluorescence) in
mineralogical and microstructural aspects of grains and intergrains framework, on the samples both from wells (5003500m depth) and outcrops.
Quartz, the main component of arenites, is monocrystalline (80-85%), or polycrystalline. Quartz is present also
as detrital grains (<10-20 microns) concentrated in lens and laminaes in interbeded dysodilic shales and slates. Others
component are feldspars, ortoclase, microcline and plagioclase, rock fragments, dominantly wackes, micrograywackes,
phyllites, mud clasts. Micas are represented by muscovite and biotite, and heavy minerals common are epidote zircon,
apatite, ilmenite, magnetite, rutile, tourmaline, sillimanite, monazite, sphene. Glauconite is pelletes and, less common
authigen. Skeletal fragments are, generally, bioclasts of radiloari, sponge spicules, foraminiferas. Optical porosity show
a mean value of 6%, with a maximum of 25% in the Runcu site.
The compaction was active in the whole sedimantary sequence; in this reason microfaults are very common,
also ductile deffects. Deformed mica grains in thin sections observations evidence mechanical compaction and physical
readjustment to the overburden load in the sandstones. Floating grains is very common, other type of grain contacts are
long, point, concav-convex. Sutured contacts and pressure solutions are very rare. Particularly, in some samples floating
grains are the result of corrosion of detrital grain and modification of textural parameters by cementing.
Diagenetic silica is a very common mineral phase. Porosity leaves an open system, and following compaction,
diagenetic modifications are mainly related to changes in the pore-water chemistry. Large existence of the metastabile
silica cement, amorphous silica and calcedony, suggest that cement does not precipitate for kinetic reasons. Quartz
overgrowths are not common, and some samples show evidence of reworking quartz grain with overgrowths. Secundary
porosity (up to 10% in some cases) developed in depth over 2500m was caused by a large chemical activtiy of pore
fluids. Replacement processes were responsible for dissolution and leaching of feldspar grains, precipitation of calcite
as mosaic cement, disintegration of unstable ferromagnesian minerals, release of iron oxides and formating of infiltrated
clay in the interparticle pore spaces.
Reservoir quality of the analysed interval is medium, due by secundary porosity as a result of partial clast
dissolution and microfaulting processes. Microfaults, in our case, have a dual role: as high permeability pathways and
as seals (constrain fluid flow and generate permeability barriers). However, partially, microfaults developed are later by
oil emplacement. Argilaceous minerals, as matrix, is a negativ factor during production process.
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DEEP GEOTECTONICS OF THE NORTHWESTERN BLACK SEA
CONTINENTAL MARGIN BY GRAVITY AND MAGNETIC DATA
Radu G. DIMITRIU
GeoEcoMar, 23-25, Dimitrie Onciu Street, 70318 Bucharest, Romania, [email protected]
The northwestern continental margin of the Black Sea basin consists of the following main
geotectonic units: the Scythian Platform (SP), the North Dobrogea Orogen (NDO) and the
dobrogean sector of the Moesian Platform (MP), separated by crustal-scale faults. These major
geotectonic units both extend onshore and offshore, where they are dipping and concealed by the
Albian to Quaternary sediments of the Black Sea basin. All gravity and magnetic data available
both onshore and offshore have been re-processed in order to obtain the gravity and magnetic
anomalies maps of the Romanian sector of the western Black Sea continental margin and integrated
with information resulted from newest geological investigation and seismic prospecting.
Geological interpretation of geophysical data suggests a shear-type model for the western
Black Sea continental margin, developed through: (a) rifting processes, initiated in the Early
Cretaceous on a quasi-normal direction compared to the nowadays margin and developed until the
end of the Cretaceous or Paleocene; (b) southward migration of the rift axis and development of a
N-S trending active transform boundary and (c) formation of a passive margin along an inactive
fracture zone that separates continental from oceanic crust. The first consequence of the described
process and one major feature of the shear margin is the presence of a relatively narrow transition
sector. This transition sector is 50 to 80 km wide and separates the continental and oceanic crust,
along which the thickness of the consolidated crust decreases from 30-35 km to only 5-12 km. This
process is partly compensated offshore by the important thickening of the Black Sea sedimentary
cover to values exceeding 10-12 km. A greater continental crust thickness, exceeding 40-45 km,
appears in the onshore sector of the NDO and SP. The large, vertical displacements occurring along
Peceneaga-Camena Fault (2-3 km offshore to 8-10 km onshore), affecting both Conrad and Moho
discontinuities, prove its crustal scale.
Some of the main geotectonic features of the continental margin, pointed out by geophysical
data interpretation and modeling performed, are as follow: [1] Two half-grabens and three subbasins, whose infill is represented by bimodal volcanics and continental clastics, resulted during
Late Permian-Early Triassic rifting, have been recognized within the SP; [2] The relativelly shallow
emplacement of several intrusives within the crystalline basement and Paleozoic deposits of the SP
has been pointed out; [3] Several tectono-magmatic alignments, showing different ages and
structural significance, have been recognized within the sector corresponding to NDO. Calcalkaline Hercynian intrusives outcropping onshore in the northwestern Dobrogea lie at 3-5 km
depth in the littoral area and at 8-10 km further seaward; [4] The tectonic block bordered by the Sf.
Gheorghe and Văcăreni-Agighiol Faults, mainly consisting of turbiditic and pelagic Early Paleozoic
sediments, devoid of calc-alkaline magmatites, represents a remnant of the accretionary wedge
formed during the South directed Late Paleozoic subduction of the Rheic oceanic crust; [5] A
limited side extension and oblique trend of the former Early Triassic intracontinental rift axis, have
been observed in the central part of NDO; [6] Late Jurassic effusive rocks occur both onshore and
offshore in the footwall of the Peceneaga-Camena Fault; [7] A great structural importance for the
regional architecture of the moesian crystalline basement have been played, both within the
continental and marine domains, by the oldest (Neo-Proterozoic) tectonic element of Dobrogea
which is the Palazu overthrust line; [8] A major structural significance also play the highly
magnetized metamorphic rocks of Palazu Group, which act as a genuine magnetic marker for the
whole Moesian realm; [9] The presence of two main fault systems in the investigated area is
obvious: the older, Paleozoic to Cretaceous fault system, gathers mainly NW-SE trending faults
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(e.g. Sf. Gheorghe, Peceneaga-Camena, Capidava-Ovidiu, Intramoesian, etc.), which are both
normal and reverse; the younger, NE-SW trending fault system, includes normal and strike-slip
faults (e.g. Constanţa-Dunavăţ, Lacu Roşu, West Midia, etc.). The most important structures
resulted from the interaction between these two fault systems are: Sărata-Tuzla and Sulina Grabens,
separated by the Chilia-Snakes Island High in the SP, the Histria Depression on the NDO offshore,
between the Sacalin and the Central Highs, the Corbu, Constanţa and Delfin Depressions, separated
by Constanţa Horst and the uplifted Midia Block on the Moesian offshore; [10] During syn- and
post-rift times, a major structural significance was played by the marginal ridge, that includes the
Central and Midia Blocks on the Romanian offshore, as well as the Tulenovo and Nanevo Blocks
on the Bulgarian offshore.
SOME QUESTIONS REGARDING THE GEOTECTONIC STRUCTURE OF THE SOUTH
APUSENI MOUNTAINS (ROMANIA)
Dorin Gheorghe DORDEA, Viorel SPRANCEANA
Prospectiuni S.A., 1 Caransebes st., 78.344-Bucharest, Romania, Phone: +401-224.18.85, Fax: +401-224 35 56, E-mail: [email protected]
Key words: South Apuseni Mountains, Midd Ocean Ridge Basalts -ophiolites, Island Arc Volcanics, nappe structure, suture slide structure
The Mesozoic igneous rocks of South Apuseni Mountain (SAM) are composed by J – K1 Ntype Midd Ocean Ridge Basalts (MORB) sequences of ultramafic-mafic isotropic cumulates of
gabbros and diorites / sheeted dykes / pillow lava forming an ophiolitic complex and volcanic island
arc rocks (IAV) of J3 and K1 age. The geologic setting of SAM is completed by a variety of J - K
sedimentary deposits which compose, together with the Mesozoic magmatic suites, the nappe
structure. Different interpretations of this nappe structure have been advanced.
A lot of unclear issues still persist on nappe postulate because:
- There is no detailed mapping to discriminate MORB, IAV and the Mesozoic sedimentary
deposits (generally covered with soil and vegetation);
- No systematical detailed photogeological mapping was performed untill now;
- Widespread ophiolitic tectonic breccias occurring within Capalnas-Techereu unit
has been considered cartographically as “pyroclasics”;
- Breccias-type of the limestone olistolithes is entirely ignored;
- The olistolith elongation and straight alignement of few kilometers, despite the
narrow width, of hundreds of meters, is also ignored;
- The obvious recurrence of some discordant stratigraphic successions (the Fenes
unit) are interpreted as successive faulting;
- The presence of crystalline rocks in the ophiolitic Capalnas-Techereu unit still
remains exotic, unaccountable in a unitary remnant of ocean floor crust.
The photogeological interpretation reveals the development of some long, imbricate slides
on the entire Transilvanides area. The slides are formed exclusively of Mesozoic rocks. Successive
slides of ophiolites, limestone and flysch rocks, as well as successive ophiolitic and island arc
volcanic rocks may develop. Only the thickness of the limestone slides may exceed 200-300 m.
Within the ophiolitic slides, the typical succession of an ophiolitic complex
(peridotite/gabbro/sheeted dikes/pillow lava) cannot be distinguished, though the specific ophiolitic
types have been randomly described all over the Transilvanide area. However, the basaltic pillowlavas prevail, though frequently transformed into tectonic breccias. Both the carbonatic and the
carbonatic - ophiolitic “olistolithes” develop linearly as continuous or discontinuous slides.
Within the alignments of regional maximum gravity, associated mainly to the ophiolitic
piles, the subsequent detailed measurements (upon the Valisoara – Luncoiul de Jos area) have
revealed a succession of gravity maximum and minimum relative parallel to the main direction
(WSW - ENE) of the ophiolites. The relative gravity minimum may be associated either to the
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presence of IAV, or to sedimentary rocks. This alternation is better reflected by the horizontal
gravity gradient (detailed), which suggests a possible suture slides structure.
The entire SAM area represents a suture mélange formed by slides of oceanic crust (equally
composed by MORB, IAV and sedimentary rocks), which randomly solders to the continental
margins. The design of the majority of the nappes forehead, represented cartographically, may
constitute a structural local reality, but the real nature of the nappes, as a whole, represents in fact, a
recurrence in an uncountable number of such slides.
A DETAILED MAGNETOTELLURIC SURVEY
FOR DEEP GAS STRUCTURE FRASIN, ROMANIA
C.DAVID1, G.IOAN1, L.IONESCU2, Beatrice LACATUSU2
1
S.C.Prospectiuni S.A.,Bucharest, 2ROMGAZ,Medias, Romania
Even the seismic in the external flysch zone of the Eastern Carpathians is the main
geophysical method used for oil and gas exploration, due to increased costs in areas with complex
geological structures (such as flysch zone) and rough topography, non-seismic methods were
applied in order to retrieve the deep structures. The V5-2000 MT satellite synchronized system
(Phoenix-Geophysics, Canada) working in remote reference mode was used to collect data in an
area of Frasin gas accumulations, northern Romania (see fig.1). More than 250 MT soundings were
recorded in an almost regular net (0.25x0.25 km) covering about 12km2 area.
Two-dimensional inversion of the transverse magnetic (TM) data along 20 lines allowed to
point out the major geological structure, characterized by the presence of NNW to SSE up lifted
block situated in the basement of the flysch nappes, at depths exceeding 4000m. This structure is
governed by the existence of the complex system of faults, directional and senestral strike-slip
faults at the level under thrust platform.
The study area is situated near Moldova Valley, in the external flysch zone of the Eastern
Carpathians. Lithological units present in the area belong to Moldavides (Tarcau, Marginal Folds
and Subcarpathian Nappes). From east to west they comprise the following units:
a)
Subcarpathian unit is mainly made up of Lower and Middle Miocene, mostly
molassic sediments; in this area occur two subunits, Valea Mare and Pietricica.
b)
The Marginal Folds, detached from their substratum in the Cretaceous black
shale level, usually form two or three superimposed duplexes. They have been thoroughly
investigated by exploration wells, and their Oligocene sandstone reservoirs (Kliwa
sandstone) have constituted the main objective of Carpathian petroleum exploration since its
early days.
c)
The Tarcau Nappe, which has entirely overthrust the Marginal Folds and
locally directly overlies the Subcarpathian domain, still comprise both Cretaceous and
Paleogene flysch sequences; in this area three subunits occur: Vama, Frasin-Tazlau and
Voronet
The MT survey was conducted for studying its possibility to outline deep buried structures
beneath the flysch units, at depth exceeding 4000m. Several wells in Frasin area are productive but
there are also several with bad results.
The feasibility of MT method is based upon the resistivity contrasts between different
geological formations of the flysch units. These contrasts came as a result of thorough examination
of numerous resistivity well logs. Lithological units of Moldavidian Nappes may have different
properties. For instance, low resistivity values are typical for Black Shales Formation (Lower
Cretaceous) or for salt formation (lower Miocene). On contrary, high values of resistivity are
characteristic for sandy or calcareous flysch deposits. A very strong contrast appears between
sedimentary cover and the crystalline basement of the platform.
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Data processing was performed using Phoenix programs. The data analysis, 1D
interpretation and 2D inversion were made using Winglink software. The results show that the
impedance strike direction is N to N200 and it remains about the same from the lower to the highest
frequencies. Some significant distortions of sounding curves, at high frequencies, appear in the
middle part of the delimited area where two directional faults determine outcrops of formations with
high contrast of resistivity.
2D inversion model shows three elements:
a)
crystalline basement, at depth exceeding 5000m, with an up-lifted zone in the
central part of the section; this one represents a very important structure which is explored
for gas accumulations;
b)
platform cover, including Paleozoic up to Badenian deposits, having the
same trend as the basement; a high resistivity contrast is reflected between Badenian
Formation (few hundred meters thick, consisting in anhydrite and sandstone able to be
reservoirs) and formation and the Neogene upper deposits;
c) flysch deposits, characterized by a very complicate structure and a lot of contrasts but
suggesting eastward overthrust of the units.
GEOLOGICAL EVOLUTION OF THE SOUTH-WESTERN PART OF THE MOESIAN
PLATFORM DURING THE PLIOCENE-QUATERNARY TIME
Petru ENCIU 1, Mariana ENCIU 2
1.
Institute of Geography, Romanian Academy, e-mail: [email protected]
2.
INCERTRANS Research Institute, e-mail: [email protected]
Key words: river-dominated delta, braided river system, Pliocene, Pleistocene
In the Late Miocene (Pontian), the under-Carpathians slipping of the western panel of the
Moesian Plate was roughly stopped. Subsequently, the slow descending motion of the Vanju Mare –
Prunisor, Lom-Bailesti-Filiasi and Giurgita-Valea Stanciului buried Depressions, and the
prevalently upward movement of the inserted Strehaia-Calafat, Balsi-Leu-Teasc and Gura Vaii
Jiului Uplifts, are the driving force for the filling process of the south-western corner of the Central
Paratethys (Dacian Basin).
As result of the general cooling (around of 5.5 million years BP) the level of the Central
Paratethys decreased and the Danube river-dominated delta plane extended in the Turnu Severin –
Vanju Mare – Prunisor portion, 160 m thick of sandy pile. (Enciu, 1995) In the Bailesti sector (150
m thick of sandy distributary Lom channel) and in the Macesu de Jos area (110 m thickness of
sandy littoral sheet), the Berbesti formation developed, too.
On the main Lom-Bailesti-Filiasi and Gura Vaii Jiului Uplifts, the mixted lacustrine-river
dominated delta plain environments are partially kept up (25-40 thick of sands, the Berbesti
formation, Lower Dacian in age). Then, during the Upper Dacian- Middle Romanian, the
constructive deltaic phase was succeeded by the upper delta plain and flood plain phases (the JiuMotru Formation). Its lower part consists of several distributaries-fill in the main mud-filled area
(0-115 sequences with sands, silts, clays, gleic paleosoils or 2-9 coal seams). The middle and upper
part of the Jiu-Motru formation preserved ca 0-125 m of river channels multistoried infill,
interstratified with compacting fine-grained rocks.
Generally, from the western and south edges of the Dacian Basin to the axis (FiliasiTurceni-Bibesti line), during the Middle Romanian substage, the Jiu-Motru formation passed from
proximal braided river stage, including alluvial fans (Poroina Mare, Caraula, Maracinele, Podari
etc.) to the meandering river stage.
In the Upper Romanian – first part of the Lower Pleistocene, as result of the progressive
cooling of the climate, of the uplift of the Carpathians Realm, the feeding with alluvia and fresh
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water of the westernmost part of the Dacian Basin was intensified. In the present Serbia-Romania
territory, the Danube built the Alluvial Fan (Lower Member of the Danube Formation, Enciu,
1998). On the southern edge of the Getic Piedmont, an increasing W-E elongated strip (5-20 km
wide, over 75 km long) representing the lateral north edge of the Lower Member, preserves.
The axial part of the Lower Member of the Danube formation was self-evacuated in the
Middle-Upper Pleistocene (when it deposited the frontal load in the north-easternmost part of the
Dacic Basin).
Starting with the second part of the Lower Pleistocene, the Danube cut the actual profile of
the valley. As a result, the higher relief of the Oltenia Plain, ensured repeated down-cutting of the
stairway-like seven terraces sequence and the actual alluvia of the meadow (the Upper Member of
the Danube Formation).
FLUID INCLUSIONS IN NEPHELINE: THE ROLE OF THE FLUIDS
IN THE PETROLOGIC EVOLUTION OF THE NEPHELINE SYENITES
OF THE DITRĂU ALKALINE MASSIF
András FALL1, Csaba SZABÓ2
1
Univesity of Bucharest, Faculty of Geology & Geophysics, 1, N. Balcescu Ave., sect.1, RO-70111, Bucharest, e-mail: [email protected]
2
Eötvös University, Department of Petrology and Geochemisrty, 1/C, Pázmány Péter Ave., 1117 Budapest, e-mail: [email protected]
Keywords: fluid inclusions, nepheline, Ditrău Alkaline Massif
The Ditrău Alkaline Massif is one of the best-studied and most complicated geological formation
in Romania. Many works and publications are addressed to the mineralogy, petrology, structure, genesis,
age and economic potential of the rocks of the Massif. The complex geological built up, the specific
rocktypes and their variable occurrence in the Massif led to numerous unequivocal theories about the
genesis of the Alkaline Massif. However, several questions about the petrogenesis of the Massif still
persist.
The nepheline syenite is the most abundant rock type in the Massif. The rock is composed of
pertitic feldspars, nepheline, biotite, amphibole, pyroxene, cancrinite, sodalite and calcite. This rock type
occurs in the central and eastern part of the complex and represents the youngest intrusion of the
complex. We observed fluid inclusions in nepheline during the petrographic examination of nepheline
syenite samples from Ditrău. The inclusions are two-phase (liquid and 2-8 % vapor) or three-phase
(liquid, 2-8 % vapor, 5-15 % solid), with elongated, negative crystal shapes and sizes between 2-40 µm.
In as much as the inclusions have primary character they preserve the original geochemical environment
during the crystallization of the nepheline and the formation of the nepheline syenites, respectively
(ROEDDER 1984).
The examinations of the fluid inclusions were carried out by microthermometric methods, with a
Fluid Inc. USGS type heating-cooling stage. The results of the microthermometric studies show that the
composition of the majority of the inclusions can be modeled as simple H2O-NaCl solutions, with an
average salinity of 21.2 wt% NaCl. However, a few phase-changing temperatures suggest more complex
composition of the fluids, with ions of Na+, Cl-, K+, Ca2+, Mg2+, SO42-, CO32-, OH-, H+ in them. The
homogenization temperatures vary between 172.5 and 305.0 °C. This variation could be in relation with
the long formation period of the nepheline and the cooling history of the nepheline syenites.
Microthermometric results made possible the valuation of the pressure and temperature conditions during
the trapping of fluid inclusions in the nepheline. These conditions are between 400-700 °C and 2.5-5
kbar.
Knowing the composition of the fluids and the significance of these elements in the formation and
evolution of the whole massif, mentioned also by the literature (IANOVICI 1938, STRECKEISEN şi
HUNZIKER 1974, KRÄUTNER şi BINDEA 1998, MOROGAN et al. 2000), we can point out that the chemical
elements present in the fluids had played a significant role in formation of the nepheline-postdated
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cancrinite, sodalite, analcite and maybe scapolite to.
REFERENCES:
IANOVICI, V. (1938): C. R. Acad. Sci. Roum. 2., 689-694.
KRÄUTNER, H. G., BINDEA, G. (1998): Slovak Geol. Mag., 4, 213-223.
MOROGAN, V. et al. (2000): Min. and Petr. 69, 227-265.
ROEDDER, E. (1984): Rev. In Min., Vol 12., 646 p.
STRECKEISEN, A., HUNZIKER, J. C. (1974): Min. und Petr. Mitt., LIV, 59-74.
TYPES OF SEQUENCES AND LITHOLOGIC SUCCESSIONS IN THE TUFF AND
GYPSUM SUBFORMATION OF THE LOWER BADENIAN FROM PIATRA VERDE,
SLANIC-TEISANI
Dumitru FRUNZESCU
University of Petroleum-Gas of Ploiesti, Faculty of Drilling, Geology-Geophysics Section
39, Bvd. Bucuresti, 2000, Ploiesti, Prahova e-mail: [email protected]
Key words: Miocene, Slanic sycline, evaporitic megasequences, Paleoenvironments
The paper presents details on the succession of Badenian sulphatic evaporitic deposits from
Piatra Verde, concerning the presentation of various, special evaporitic facies, with their specific
structures which allow the diagnosis of primary genetic environments. Their cyclicity is used in the
integrated interpretation of the basinal evolution from Miocene.
THE SEDIMENTOLOGICAL ANALYSIS OF SULPHATIC EVAPORITIC
LITHOFACIES BELONGING TO SALT BRECCIA FORMATION
FROM VALEA REA, ISTRITA HILL
Dumitru FRUNZESCU
University of Petroleum-Gas of Ploiesti, Faculty of Drilling, Geology-Geophysics Section
39, Bvd. Bucuresti, 2000, Ploiesti, Prahova e-mail: [email protected]
Key words: Miocene, East Carphatian Folded Area, sulphatic evaporites, sedimentological analysis
The paper presents details concerning petrographic structural varieties of the sulphatic
evaporites from the Badenian salt breccia formation which appears on Istrita Hill. These varieties
are known as Valea Rea selenite. The varieties, unique in Romania, which are met, are described
and genetically interpreted as characterizing salt lake environments, with a prolonged residence of
salinity. Data concerning the evaporitic sequences which were registered are similar to the ones in
Sub-Carpathian Ucraine and Poland and allow the elucidation of some aspects of Miocene
evolution of the Carphatian Foredeep Basin.
THE SEDIMENTOLOGICAL INTERPRETATION OF THE PALINOMORPHES
DISTRIBUTION BELONGING TO THE LOWER TUFF AND GYPSUM
SUBFORMATION FROM PIATRA-VERDE, SLANIC-TEISANI
Dumitru FRUNZESCU, Victor BACARAN
University of Petroleum-Gas of Ploiesti, Faculty of Drilling, Geology-Geophysics Section
39, Bvd. Bucuresti, 2000, Ploiesti, Prahova e-mail: [email protected]
283, Bvd. Republicii, bl. 3 B1, ap. 9, Ploiesti, 2000, Prahova
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Key words: Miocence, Slanic syncline, palinomorphes, sedimentological analysis
The paper presents the palinomorphes distribution belonging to the lithological sucession of
the lower tuff and gypsum subformation from Piatra-Verde (Slanic-Teisani). The frequence which
was registered in different lithons strenghtens the sedimentological conclusions which were
petrographically deduced: the great diversity of taxons and the great frequence of heavy
palinomophes are indicators of some stages of lowstand systems tract and the reduced diversity and
the great frequence of light palinomorphes suggest the dillution in highstand systems tract stages.
TRANSPORT AND EMPLACEMENT MECHANISMS OF IGNIMBRITES FROM GUTAI
MTS., EASTERN CARPATHIANS, ROMANIA
Alexandrina FULOP
North University, 62A, V. Babes street, Baia Mare, e-mail:[email protected]
Key words: Gutai Mts, rhyolitic ignimbrites, sedimentary structures, flow regime, transport and emplacement mechanisms
The 15.4 Ma rhyolitic ignimbrites were the first volcanic products from Gutai Mts. They
covered the south-western border of Gutai Mts. on 20 km length and 10 km width. Their thickness
decreases from 350 m in west to 30 m in east. Tens of boreholes and large outcrops offer an control
on the ignimbrites spreading and allow a detailed study. The focus on the sedimentary structures of
the ignimbrites show what kind of mechanisms were essential for the transport and emplacement
and which processes developed in those conditions. They bring us in the field of conceptual models
related to sustained suspension currents and their rheological extremes: dense and dilute flow
regimes, subcritical and supercritical styles of flowing.
The ignimbrites form a thick stratified deposit composed of multiple units. Each unit
develops a massive structure showing a weak reverse coarse-tail grading of the pumice clasts.
Deposits, as a whole, show the normal coarse-tail grading of the large, mainly sedimentary
xenoliths. These primary sedimentary structures are indicators of the parental flows regime
suggesting highly concentrated laminar flows or dilute, subcritical flows, both emplaced by
progressive aggradation.
The secondary sedimentary structures bring information about the eruptive style, flow
rheology, volatiles and temperature regime. The columnar jointings assess the hot-state deposition
of the ignimbrites as a highly cohesive deposits.The eutaxitic texture is present on the whole
thickness, showing the general high degree of welding. It is compatible with a gas-retention regime
preserving high temperatures and explains the scarce lack of welding by local increase of cooling
rate. Welding, preserved on 20 km length, excludes the dense laminar parental flow that would
cause a massive, near source aggradation. The cooling textures, such as spherulitic and perlitic
textures, bring informations about the cooling history and the gas-escape regime. Spherulites show
high eruption temperatures and slowly cooling rates. Perlites suggest syn-emplacement contraction
or post-emplacement hydration processes. Very scarse gas-escape pipes are compatible with
volatile-retention regime and indicate a weak degree of fluidization. The data are compatible with a
steady, maintained, dilute turbulent pyroclastic current, moving on a surface of constant slope and
roughness.
The primary and secondary structures suggest mass flows in subcritical regime which
allowed the areal development of welding. The subcritical flow is slow and deep, have a relatively
small amount of kinetic energy and cannot entrain significant quantities of air as they propagate.
That explains the long run-off, enhanced by the spreading along a confined channel. This lowfluidized flow regime preserved the high temperature up to 20 km away from the source because of
the volatile-retention regime. According to the stratified suspension current behaviour, the
ignimbrites were emplaced from the basal, dense part of the dilute suspension current, by
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progressive aggradation processes. Multiple units were rapidly emplaced, cooling together as a
single cooling unit.
LONG PERIOD SEISMOELECTRIC SIGNAL
Valentin Constantin FURNICA
Romanian Academy-Institute of Geodynamics
19-21, Jean-Louis Calderon St., R-70201, Bucharest, sector 2, Romania, e-mail:[email protected]
Keywords: earthquake, seismoelectric precursor
Modern research regarding the ultra-low frequency (ULF, <10Hz) natural electric and
electromagnetic fields, for the identification of anomalies with earthquakes precursory
characteristics, allowed to classify them in seismoelectric signals (SES) of short (few minutes to
many hours), medium (half a day to several days) and long period (half a month to six month).
Starting from the assumption that between the seismic source and a point in the epicentral
area there is an energetic transfer by means of the ULF electromagnetic field, and observing the
Kirchhoff’s law, we made a sensor which works like an electric micropile, in similar conditions
with those which are specific for electrochemical corrosion phenomena in stationary weak solution
of sodium chloride.
The V variation (in mV) between November 2000 and April 2002 is presented. Its main
anomaly, bipolar, could be classified in the long period seismoelectric signals category. During this
anomaly, the seismic activity on the Earth, of magnitude M5, has been controlled by a
phenomenon which had a strong influence on the Earth’s electrical activity, earthquakes greater
than 7 degrees not being recorded by any international seismological network. In the Vrancea
seismic area, two earthquakes are coincident with anomaly morphological features, which could
become important geodynamic indicators.
There are evident causal links with astronomical events (equinox, lunar and solar eclipses)
and with the strongest earthquake (M=8.4) which occurred on Earth during 2001.
ALTERATION PROCESSES OF THE HYDROCARBON ROCK MAGAZINES FROM
THE FISSURED CRYSTALLINE BASEMENT. A CASE STUDY - CHEŢ STRUCTURE PANNONIAN BASIN
Octavian GEORGESCU
University "Petrol-Gaze" Ploieşti, Departement of Geology and Geophysics, Bd. Bucureşti 39, 2000 Ploieşti,
[email protected]
Key words: alteration, fissuration, crystalline basement, rock magazine.
The paper proposes the use of the physical methods of mineralogical analysis for the
determination of the alteration degree of the rocks from the crystalline basement.
Correlating the degree of alteration with the degree of fissuration the rocks capable to
become hydrocarbon rock magasines can be identified.
This aspect is demonstrated on the Cheţ Structure from the northern part of the romanian
sector of the Pannonian Depression.
STRUCTURI SEDIMENTARE MECANICE ÎN DEPOZITELE VULCANOCLASTICE
ALE CARPAŢILOR ORIENTALI DE CURBURĂ – PROCESE SPECIFICE
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Monica GHENCIU (anul IV), Maria ANDRONE (anul III)
Centrul de Sedimentologie, Universitatea din Bucureşti/ Facultatea de Geologie şi Geofizică
Îndrumător: Marius POPA
Lucrarea de faţă este un studiu sedimentologic preliminar asupra structofaciesurilor
mecanice ale depozitelor vulcanoclastice din alcătuirea "Tufului de Slănic". Aceste depozite apar în
structura formaţiunilor "molasice" acumulate în unitatea Pânzei de Tarcău, şi sunt bine dezvoltate în
zona de curbură a Carpaţilor Orientali. În acest scop s-au urmărit secţiunile stratigrafice ce aflorează
în Dl. Piatra Verde (loc. Slănic- Prahova) şi în profilele deschise de V. Teleajenului şi Lupa.
Algoritmul de analiză aplicat a urmărit identificarea şi caracterizarea faciesurilor
vulcanoclastice în succesiuni (secvenţe) şi detalierea structurilor mecanice - din punct de vedere al
poziţiei în cadrul litonilor (intern/ la suprafaţă), a elementelor dimensionale şi morfologice, a
categoriilor granulometrice, a structurilor asociate (în extindere laterală şi succesiune) – în scopul
identificării proceselor care le-au controlat.
Au fost puse astfel în evidenţă mai multe categorii de structuri construcţionale (masive,
stratificate/ laminate paralel, granoclasate normal, oblic- tabulare şi concoide, lenticulare, ondulate),
erozionale (scour marks, flute casts) şi deformaţionale (load casts, dish- and- pillar), legate genetic
de procese mecanice distincte. Interpretările elementelor descriptive ale acestora au evidenţiat că
procesele de sedimentare ale unităţilor vulcanoclastice au avut la origine procese de transport
controlate de mecanisme individuale – prin suspensii în general turbulente, fluide, uneori cu
capacitate erozională ridicată - şi în masă – prin curgeri gravitaţionale de diverse tipuri (între care sau recunoscut şi produse ale curenţilor de turbiditate). În aceste condiţii depunerea s-a făcut prin
mecanisme variate (agradare, progradare, îngheţare) în ambianţe marine de apă puţin adâncă
(litorale şi de şelf, ce evoluau în proximitate cu sisteme deltaice), situate într-un cadru geotectonic
activ – aşa cum este indicat de modul de asociere al structurilor şi de prezenţa unor structuri
diagnostic.
THE SOLAR SYSTEM FORMING AS SUMERIANS HAVE KNOWN
Teofil GRIDAN
S.C. PROSPECTIUNI S.A., 1 Caransebes st., 78344-Bucharest, Romania, Phone: 6845306
The modern man and more than him the scientist is tented to clasify the myth, legends and
epics somewere in the literature domain. He is wrong obviously, because he ignores the “scientific”
mesage, ciphered conveyed by long time ago extincted cultures and civilizations.
The epic Enuma Elis was puzzled from sumerian tells writen on 7 broken slates, descovered
by archeologists in the suposed Asurbanipal’s Library from Ninive. The epic related “The Creation
Story”, in fact, the sumerians concept about the solar system genesis.
The present paper trys, following the epic verses, tablet by tablet, to descipher “the scientific
mesage” which reveal an amazing advanced knowledge of sumerian civilization, in Mesopotania
teritory, statued 4000 years before Jesus Christ. The sumerians have known all the plates of the
solar system, including the asteroids belt and have had credible explanations for ther genesis. Their
knowledge remained coverd under the Ninive ruins. And who to belive them, because only in the
XIXth century there were (re)descovered the last three planets of the solar system: Uranus, Neptun
and Pluto?
As well as in the other science domains, in cosmogeology, the roots are long time ago
seeded and we are only continueing the sumerian knowledge.
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LIMITA JURASIC MEDIU-JURASIC SUPERIOR IN CADRUL OLISTOLITULUI DE PE
VALEA PELESULUI (MASIVUL BUCEGI)
Ioana HOBLE (anul IV)
Îndrumător: Prof. Dr. Ovidiu DRAGASTAN
Versantul estic al Masivului Bucegi este caracterizat prin prezenta unui contact tectonic
peste zona flisului marcat de olistolite calcaroase Triasic-Cretacic inferior. Caracteristic pentru
succesiunea depozitelor Jurasicului superior de pe flancul estic al Masivului Bucegi este Olistolitul
A de pe Valea Pelesului.
Depzitele incep prin o succesiune de gresii cu intercalatii de marne si sisturi argiloase
marnoase Bathovian superior-Callovian inferior, probabil mediu, peste care se dispun transgresiv si
discordant radiolaritele si calcarele cenusii-albicioase de varsta Oxfordian-Tithonian. Limita
Oxfordian-Kimmeridgian se poate trasa atat litologic, prin trecerea de la radiolarite rosii la calcare
cenusii; cat si paleontologic. Varsta Oxfordian este data de asociatia de radiolari si foraminifere ca
Globuligerina oxfordiana. Urmeaza in Kimmeridgian-Tithonian faciesul dominat de foraminifere
bentonice cu Lenticulinide si Nodosarii, iar in Kimmeridgian-Tithonian intalnim micrite si
pelsparite cu Saccocome, Globochaete alpina si Mercierella dacica (Dragastan).
Asociatia de microfosile indica un domeniu de sedimentare din zona slope-ului superior, la
marginea platformei carbonatate, respectiv selful extern.
ON SOME GEOLOGICAL AND GEO-MECHANIC ASPECTS OF THE COAL AND
ADJACENT SOFT ROCKS IN JILT MINING FIELD - GORJ COUNTRY - ROMANIA
Radu Virgil HOBINCU, Florica STROIA, Ion STOICAN
Key words: coal-oriented samples; variogramme; hyperbolic model; nugget-effect.
The Jilt coalfield belongs to Getic Depression, i.e. southern part of the Carpathian foredeep,
characterized by presence of molasse sediments, continental association variety [Anastasiu, 1998].
Formed in late Laramic diastrophism, stratigraphical succession begins from low Eocene
and end at upper Pliocene. Some scientists consider that here, the low Pleistocene in present like a
continuation of the Pliocene sedimentary process. In the Jilt mining field are exploited in this
moment, especially the layers numbered VI-VII, VIII, and X and, in a few places XI and XII. The
coal is a light brown coal (lignite), cantonal soft rocks being clays, silt-clays, marl-clays and sands
of different compositions and textures. In underground is exploited X coal seam by the longwall
method, the others being exploited in quarries. Like in others fields in Oltenia coal basin, the
mining works design was based on the hypothesis of a simple tectonic structure of the coal deposits
and an isotropy of the rocks themselves. The researches developed especially in the last fifteen
years shown that the tectonic structure is more complicated in rapport with the initial model and
also that nor coal seam, neither the other rocks are isotropic.
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The heterotropy of entire structure is demonstrated at small and large scale too. The main
results of the researches consist in the elaboration of a new macro-tectonic and micro-tectonic
model based on the field investigation, identification of the structural and mechanical anisotropy
elements and geostatistical characterization of some of these properties.
Structural researches in field has proof a more complicate tectonic than previously was
considerate; the structure is not a "monocline" but a southern side of an anticline, containing also
secondary folds. This plicate structure has an approximate strike E-W. It is affected by disjunctive
major elements consisting in direct faults occurring especially in the inflexion synclinal - anticline
sides introducing a significant displacement of the coal seams. The microtectonic is present by
dilation tension joints, mainly observed in the coal. Was measured (using the dip / dip-direction
method) two joints directions, the main set being parallel and the co-set orthogonal in rapport with
the principal tectonic axis. All the joins are quasi-perpendicular on coal bedding.
The results of the laboratory mechanic test, realized on coal-oriented samples, show that the coal
resistance has different values in different directions, i.e. the coal is a natural anisotropic material,
concordant to general structure.
The geostatistical data analysis demonstrates that many of the layer properties (like
whiteness, calorific power and other) are regionalized variables. The most part of the variogramme
can be modeled through the spherical Matheron model or the hyperbolic model. In the both cases
appears a strong nugget-effect interpreted by the authors in an own new manner. Two geostatistical
methods (variogramme and absolute dispersion) demonstrate that influence radius for the most of
layer parameters is greater than the specific dimension of the exploration boreholes network.
Consequent of these results, some natural and techniques phenomena can be explained. To this
category belong the fossil landslips and a part of the stability problems appearing in mining practice
in underground mine and also in quarries. The link existing between natural peculiarities and the
mining activity conduce to many environmental effects, like topical landslips and soil surface
degradation. The results can be used equally in layer exploration, mining activity and also in
environmental
geologic
problems,
like
risk
map
elaboration.
THE SOUTH CARPATHIANS, FAGARAS AND LEAOTA-IEZER MOUNTAINS.
Viorica IANCU1, Valerica AXENTE2, Henri MALUSKI3
1
Geological Institute of Romania, 1, Caransebes Street, sect. 1, RO-78344, Bucharest, e-mail: [email protected]
2
Univesity of Bucharest, Faculty of Geology & Geophysics, 1, N. Balcescu Ave., sect.1, RO-70111, Bucharest, e-mail: [email protected]
3
Laboratoire de Geochronologie, UMR 5567, Universite Montpellier 2 Place Eugene Bataillon 34095, Montpellier, Cedex 05, e-mail:
[email protected]
The pre-Mesozoic rock assemblages and litho-tectonic units in the South Carpathians are
well preserved in the Alpine Getic and Supragetic basement napes, especially in the eastern part of
the Fagaras and Leaota-Iezer Mountains.
The sedimentary cover sealing the pre-Alpine nappe stacks (Iancu et al., 1998) in Fagaras
and Iezer-Leaota Mountains begin with lower Jurassic. 40Ar/39Ar ages of 309-320 Ma (Dallmeyer
et al., 1996) support a thermal activity related to the Late Variscan orogeny.
The basement of the Fagaras-Iezer-Leaota Mountains includes:
- Gneissic terranes (Fagaras, Cumpana and Sebes pre-Alpine units cf. Iancu & Maruntiu,
1994); they partly correspond to metamorphic series described by Balintoni et al., 1986 and
Gheuca, 1988). The protoliths ages are not known but Upper Proterozoic to Lower Paleozoic could
be accounted.
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- Low to medium grade metamorphic terranes; the Calusu and Leaota units, (greenschist to
epidote-amphibolite facies, cf. Iancu, 1998) are assigned to the Paleozoic (Dimitrescu et al., 1990)
sedimentary and geotectonic cycle.
New Ar/Ar age data of 354-331 Ma (Maluski, unpublished results) and Sm/Nd of 358-323
Ma (Dragusanu, Tanaka, 1999) are good proofs for the Variscan ss. timing of the final regional
metamorphic evolution and nappe stacking in the area; the inherited metamorphic terranes are so of
Variscan affinities.
A polystage nappe stacking evolution related to the Variscan collision, following the oceantype and continental subduction processes, can be recognized in the Fagaras and Iezer-Leaota
Mountains. Complex normal to strike-slip faulting activity was subsequently followed by extension
and up-lift processes. Shear zones correspond to the main tectonic boundaries of thrust-overthrust
and strike-slip type (Iancu, Maruntiu, 1994; Iancu, 1998). They are strongly diversified depending
on the physical conditions and rheological properties.
Detailed analysis of the mylonitic and pre-mylonitic paragenesis and the reconstitution of
the blastesis-deformation progressive history deciphered the dynamic metamorphism. Retrograded
and folded mylonites suggest a complex tectonic history.
There are distinguished:
- Low to medium-grade mylonites; they are generally connected to tectonic boundaries
cropping out at upper crust level; biotite-garnet-muscovite-chlorite-epidote (greenschist to epidoteamphibolite facies) neoblasts overprint different types of protoliths and pre-mylonitic metamorphic
rocks whose porphyroclasts are passively rotated and recrystallized in a S-C-C’ type matrix.
- Medium to high-grade mylonites; the kyanite-sillimanite-garnet-biotite and omphacitepyrop-amphibole-kyanite-phengite-rutile bearing mylonites are the best examples from Fagaras and
respectively Iezer-Leaota Mountains. Their almost complete re-equilibration in the amphibolite
(M2) to greenschist facies conditions is related to Late Variscan evolution. Bodies of magmatic
protoliths (coronitic metagranites of Albesti type) and eclogite facies mylonites are well preserved
in the Bughea tectonic zone; these bodies can be interpreted as exhumed subduction-related HP
rocks lately incorporated into an epidote-amphibolite facies matrix.
First 40Ar/39Ar data in the Iezer-Leaota Mountains are: 354+/-4Ma and 342.6+/-3Ma on
amphibole and phengite from the retrograded eclogite of the Bughea shear zone; 346+/-3Ma on
muscovite from mica-chlorite schist belonging to Calusu Unit; 331.3+/-4Ma on biotite from biotitegarnet-epidote-bearing mylonites on Cumpana type rocks. These Ar/Ar data argue for a Late
Variscan tectono-metamorphic evolution in the Lower Carboniferous (pre-Westphalian) time.
GEOLOGICAL CONDITIONS OF EXPLOITING HIDROCARBON
RESERVOIRS THROUGH MINING WORKS
Mircea N. IONESCU
„Petroleum-Gas” University of Ploiesti
Key words: bituminous sands, petroleum sands, mining works.
The practice of putting in value de petroleum reservoirs for a century and a half indicated an
increase of the world production. The process was first slow in the first century of exploatation and
it was followed by a high rhythm in the second half of the twentieth century. In the last decade a
period of stabilisation took place.
Starting from the second and third decades of the latest century, the prognoses indicate a
decline. This evolution is the consequence of the fact that these natural resources were exhausted
and it is due to the physical limits of the used technologies. A good part of the prognosed resources
cannot be recovered from resources through classical methods. Under such circumstances new
methods of exploiting the reservoirs are imposed.
The author analyses the possibility of putting in value the hidrocarbon resources, by means of
mining works and shallow, underground or mixed mining-drilling works.
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The new technologies become interesting under several circumstances concerning price
evolutions. Therefore some petroleum sands, bituminous scistes, and shallow depleted petroleum
sands under 300-500 metres can be efficiently valued.
RECONSTRUCTING A LOWER ROMANIAN FLUVIAL BELT
IN THE COAL BEARING DEPOSITS, MĂTĂSARI-ROVINARI AREA
Dan C. JIPA1, Marian PALCU, Corina FURTUNA1
1
National Institute for marine Geology and Geoecology- GeoEcoMar
23-25 Dimitrie Onciul St., Bucharest, e-mail: [email protected]
Key words: fluvial paleomorphology, point bar, longitudinal bar
The Upper Dacian - Pleistocene deposits in the Dacian Basin display a rather wide variety of
fluvial features. Observed in outcrops or interpreted from subsurface information, the fluvial features
appear practically always in vertical intersects, with restricted extenuation.
Taking advantage of the dense well exploration network in the study area, isopach map
information led to the partial reconstruction of a fluvial belt. The investigated fluvial sequence, of Lower
Romanian age, is bounded by the coal layers VII and VIII. Information concerning the fluvial
sedimentary process have been derived from sedimentological investigations in open mines.
Extending for 18 km, in between Jiltz and Rovinari coal pits, the reconstructed fluvial belt
segment is 1,5 km to more than 3 km wide. A meandered river was flowing along this belt, with a
general flow directed from south-west towards north-east.
The river water depth was significant, as the thickness of the fluvial sand filling is sometime
amounting to more than 20 m. Tabular cross laminated units indicate the existence of longitudinal
fluvial bars on the river channel floor.
A large point bar developed in the Jiltz section of the fluvial belt. The Jiltz point bar registered a
lateral development of about 1 km. Inclined bedding of the bar is made obvious by thin clay drapes.
Tributary channels have been outlined on the both sides of the main fluvial belt. The largest
tributary is up to 1.5 km wide and can be traced on a 6 km length. Compared with the main river
channel, the sandy fluvial load of this important tributary channel is finer grained, as indicated by
observations in the Rosia de Jiu quarry.
UPPER NEOGENE SEDIMENTATION OF THE DACIAN BASIN UNDER THE
INFLUENCE OF GLOBAL FACTORS: STATE-OF-THE-ART.
Dan C. JIPA
National Institute of Marine Geology and Geoecology – GeoEcoMar, 23-25 Dimitrie Onciul St., 70318 Bucharest, e-mail: [email protected]
Key words: sediment fan, source-area, paleoenvironment, global factor
Located in between the Carpathian chain and the Euxinic area, the Pliocene Dacian Basin
acted as a moderator in between the sediment source-area and the final deep-sea sediment
accumulation area. In the same time the Basin evolved under the influence of the global factors
represented by the two (mountainous and marine) major neighboring areas.
The analysis of the sediment thickness distribution reveales that within the Dacian Basin
two independent sediment accumulation areas co-existed. The eastern, most extensive Dacian
sedimentation area appears as a large sediment fan. The more restricted, western sedimentation area
seems to accommodate a space centered on a possible local subsidence zone.
The Eastern Dacian Fan shows an active western progradation, while aggradation is
dominant over its central and northern parts. In contrast, the western sedimentary area of the Dacian
Basin has a distinct retrogradation character.
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Based on surface (outcrops) and subsurface (well) data, the paleo-environmental analysis
pointed out three main types of sedimentary environments: lacustrine, littoral lacustrine (deltaic
and shoreline) and fluvial (in the channel, near the channel and out of channel).
The three paleo-environments occur within three distinct genetic intervals. The succession
of these genetic sediment intervals points out the environmental evolution of the Dacian Basin
during the Pliocene time. The lacustrine phase of the Dacian Basin corresponds to the Pontian time.
Coarsening upward sediments (sometime with wave ripples or hummocky sedimentary structures)
point out the shallow water, prograding, littoral-lacustrine phase of the Dacian Basin during the
Lower Dacian.
The littoral genetic interval represents the final episode of the Dacian Basin lacustrine
development. Since the upper part of the Dacian time to the modern time the fluvial sedimentation
was strongly dominant over the area of the Dacian basin. This fact outlines the possibility that an
early feature of the Lower Danube River could have acted even from the Upper Dacian.
The three major paleo-environmental intervals (lacustrine, littoral, fluvial) also represent
stratigraphic units, with a potential use for an integrated both genetic and stratigraphic framework of
the Dacian Basin.
A dominantly one-side sediment supply coming from the Carpathian area indicates that the
Dacian Basin sedimentation was strictly controlled by the tectonic factor.
The governing role of the eustatic factor over the basin evolution seems to be indicated by a
correlated occurrence of coarser sediments in the Dacian Basin and the Black Sea area.
SEDIMENTOLOGY OF PANNONIAN (S.STR.) DEPOSITS IN THE NIRAJ VALLEY AREA
(EASTERN TRANSYLVANIAN BASIN)
Csaba KRÉZSEK
University of Babeş-Bolyai, Faculty of Biology & Geology, Dep. Geology
1., M. Kogălniceanu, RO-3400, Cluj-Napoca, e-mail:[email protected]
Keywords: sedimentology, submarine fan, Pannonian, Transylvanian Basin
The Transylvanian Basin is an Upper Neogene strike-slip basin, located in the inner belt of
the Carpathian Mountains, Romania. The uppermost basin-fill sediments are represented by
Pannonian (s.str.) deposits.
The studied Pannonian sedimentary succession comprises an epiclastic sequence of
conglomerate, sandstone and mudstone. The entire sequence can be represented by 9 distinctive
sedimentary facies organized into 3 facies associations (A, B, C).
Facies association A is characterized by thick, coarse, sometimes gravelly sandstone and a
minor amount of conglomerates interbedded with thin sandstones and mudstones. These were
interpreted as products of coarse-grained or sandy debris-flows deposited in proximal fan areas.
Facies association B consists of massive, stratified or laminated sandstone and mudstone
which form graded bedding. This association represents turbidites and fine grained sandy debrisflows deposited in medial fan area.
Facies association C are represented by laminated mudstones occasionally interlayered with
thin horizontally or ripple-laminated fine-grained sandstones. This facies association was deposited
in the lower fan area, representing distal lobe fringes.
The sedimentary units are components of deep water siliciclastic fans, fed by coarse grained
braid-plain- and fan-deltas, which fills the Eastern Transylvanian Basin during the Slavonian. In the
studied area, the uppermost Pannonian (s.str.) sediments deposited in shallow water or continental
setting were eroded during the strong Pliocene-Quaternary uplift of the Transylvanian Basin.
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SOME EXQUISITIVELY PRESERVED, RARE FOSSILS FROM THE MIDDLE
JURASSIC DEPOSITS OF THE BUCEGI MOUNTAINS
Iuliana LAZĂR, Victor BARBU, Csiki ZOLTAN
University of Bucharest, Faculty of Geology and Geophysics, Laboratory of Palaeontology
1, N. Balcescu Ave., 70111,Bucharest, ROMANIA.
e-mail: [email protected]; [email protected]; [email protected]
Key words: corals, nautiloids, arthropods, echinoids, fish teeth, Middle Jurassic, Bucegi, Romania.
The Middle Jurassic deposits, outcropping on the western flank of the Bucegi Mountains,
are known in the literature mainly by the richness of the bivalve and brachiopod assemblages.
Many of the Jurassic macrofaunal associations from this area, dominated by bivalves, also
contain other groups such as corals, gastropods, nautiloids, belemnites, serpulids, arthropods,
bryozoans, crinoids, echinoids and fish teeth. These groups both show a reduced diversity and are
represented by few specimens in the Middle Jurassic associations from Bucegi.
The preservation pattern of the faunas is variable, being influenced by shell or skeletal
morphology, the size of each taxon, their mode of life, the type of the sediment, as well as the
taphonomic processes that affected these assemblages.
From the rich fossil faunas that we collected from these deposits, in the present paper we
introduce only some examples showing a high degree of preservation. The taxa belong to the
following groups: solitary corals (Montlivaltia sp.), gastropods (Pleurotomaria monilifera
DEFRANCE, Pyrgotrochus elongatus (SOWERBY)), nautiloids (Paracenoceras cf. hexagonum
(SOWERBY), Eutrephoceras sp.), chelipod fragments belonging to some arthropods, bryozoans
(Berenicea sp.), echinoids (Pygaster patelliformis (AGASSIZ), Pygaster sp.), as well as
chondrichthian (Asteracanthus sp., ?”Orthacodus sp.”) and holostean (Lepidotus sp.) teeth.
The presence of these groups or taxa was already reported in several previous papers, but
none of them was figured or properly described.
On the synthetic log recorded for the research area, the following marker levels are
indicated: “Isognomoids Bed”, “Brachiopods Bed”, “Montlivaltia and Nerineids Bed”,
“Cephalopods Bed”; the provenance of the above mentioned species is also marked. The systematic
study and the detailed description of these taxa will be published in forthcoming papers.
THE ORIGIN OF AMPHIBOLES OCCURRING IN MAFIC AND ULTRAMAFIC ROCKS
OF THE DITRĂU ALKALINE MASSIF (EASTERN CARPATHIANS)
István MÁRTON1 , Csaba SZABÓ2 , Elemér PÁL-MOLNÁR3
1
2
Univesity of Bucharest, Faculty of Geology & Geophysics, 1, N. Balcescu Ave., sect.1, RO-70111, Bucharest, e-mail: [email protected]
Eötvös University, Department of Petrology and Geochemisrty 1/C, Pázmány Péter Ave., HU-1117 Budapest, e-mail: [email protected]
3
Univesity of Szeged, Department of Petrology, Geochemisrty and Mineralogy P.O. Box 651, HU-6701, Szeged, e-mail: [email protected]
Keywords: alkaline magmatic body, ultramafic rocks, and amphibole metasomatism
The Ditrău Alkaline Massif, Middle Triassic to Lower Cretaceous in age (PÁL MOLNÁR and
ÁRVA-SÓS 1995, DALLMEYER et al. 1997; KRÄUTNER and BINDEA 1998, STRECKEISEN and
HUNZIKER 1974), intruded into the pre-Alpine metamorphic rocks of the Bucovina Nappe in several
phases. This series is related to the Alpine extensional tectonism, which began with the detachment
of the Getic-Bucovinian microplate from the margin of the Eurasian platform (KRÄUTNER and
BINDEA 1998).
The mafic and ultramafic rocks of the Massif occur in a well-defined area (Tarnica
Complex), interdigited, with gradual transitions or forming intercalations (PÁL MOLNÁR 2000).
Their genesis is different from those of the other rock types in the Massif. MOROGAN et al. (2000)
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suggest that the ultramafic rocks (clinopyroxenites and olivine-clinopyroxenites) are cumulates of
mantle origin and they have been carried to higher crustal levels by the first intrusion of dioriticgabbroic magmas (KRÄUTNER and BINDEA 1998).
The goal of our study is to describe samples from the ultramafic and mafic rocks, using
detailed petrographic observations and mineral chemistry analyses, trying to express the
characteristics of different rock types, focusing mostly on the genesis of the most abundant rockforming component, the amphibole.
Detailed petrographic study shows that the occurrence of amphiboles varies in the different
rock types. In alkaline diorites and hornblendites, with shape-preferred orientation, their habit is
euhedral, prismatic indicating their primary magmatic origin. Textural analysis of the hornblendites
show numerous deformation features in these rocks (kink bands in biotites and deformation
twinning in amphiboles). Amphiboles in clinopyroxenites and olivine clinopyroxenites display
typical textural features: 1) small, oriented crystals along clinopiroxen cleavages; 2) replacing and
enclosing clinopyroxenes which cause poikilitic-like textures; and 3) large amphiboles containing
tiny relicts of clinopyroxene. These textural features from type 1 to type 3 suggest a pro-grading
amphibole metasomatism.
Amphiboles are pargasites, kaersutites, ferro-kaersutites and magnesium-hastingsites.
Amphiboles differ in their compositions with respect to their occurrence in different rock types
(MOROGAN et al., 2000). The formation temperature of amphiboles is estimated to be in the interval
of 1030-820oC (MOROGAN et al., 2000). Amphiboles in the hornblendites, with shape-preferred
orientation, display strong chemical zonation, with high Si, Ti, Fe, K enrichment and Al, Mg, Na
depletion at the rims.
Compositional profiles through clinopyroxenes from clinopyroxenites suggest that
amphiboles were formed by infiltrated Na-Fe-K-Ti enriched fluids reacting along with
clinopyroxene cleavages. It is typical for clinopyroxenes in contact with amphiboles, that directly
next to the amphibole they suddenly get depleted in mobile elements such as Na, Fe, K and Ti,
which may be related to the metasomatic “front effect”.
The experimental results of SEN and DUNN (1994) for modal metasomatism were applied to
constrain the amphibole forming reactions. The reaction equation indicates that an infiltrating
alkaline/syenitic metasomatic melts gives rise to continuous change in the composition of the origin
ultramafic rocks, and that the production of amphiboles was controlled by the original
clinopyroxene-olivine modal ratio.
SOME ASPECTS CONCERNING THE DETERMINATION OF POROSITY VALUES
FROM ACOUSTIC AND DENSITY LOGS
Ion Mălureanu
University "Petrol - Gaze" Ploieşti, Department of Geology and Geophysics, Bd. Bucureşti 39, 2000 Ploieşti
Key words: porosity, borehole compensated log, density log
The paper treats the problem of determining the porosity from the combination borehole
compensated log - density log.
For determining the porosity were established formulas for clean formations and for clayey
formations on the basis of the acoustic impedance. The results obtained comparatively to the
porosity determined by singular methods from the borehole compensated log and from the density
log, as well as from the neutronic log are analysed.
GEOLOGY OF FRASIN REGION (EAST CARPATHIANS FLYSCH ZONE)
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Mihai - Codru MICU
S.C. Prospectiuni S.A., 1 Caransebes st., 78344-Bucharest, E-mail:prospec 1 @ sunu.rnc.ro.
Key words: East Carpathians, Flysch Zone, Moldavides, Carpathian Foredeep, underthrusted platform, strike-slip faults, Neogene tectonics.
Very detailed geological mapping carried out since 1997 within the Tarcau Nappe croppingout in the Moldova Valley Basin have led to a supply of new lithostratigraphic and structural data
regarding the deposits of the Cretaceous - Paleogene Flysch Zone developed immediately westward
of Gura Humorului.
Among the previous geological researches concerning the above mentioned area it is worth
mentioning those due to Bancila & Agheorghiesei (1964), Ionesi (1971), Dicea (1974), Sandulescu
et al. (1987) and Micu (1997 - 2001 - unpublished reports).
Following lithofacial and structural criteria we recognized in the study area two duplexes
belonging to the Tarcau Nappe, Frasin Duplex and Voronet Duplex, separated by Obcina Mare
Fault. The main lithological differences between these subunits are especially recorded at the level
of Eocene deposits (Ciumarna Beds vs. Sucevita Beds and Pasieczna Limestone, Plopu Beds s. str.
vs. Plopu and Bisericani Beds).
Both Frasin and Voronet duplexes are made up by a series of unequally developed scales
that overlap west - eastwards. In the area a series of transverse senestral strike - slip faults were for
the first time pointed out too. These latter affect alike the entire pile of deposits belonging to the
outer Moldavides (Tarcau, Marginal Folds and Subcarpathian Nappes), Carpathian Foredeep and
the underthrusted platform as far as its crystalline basement. The youngest reactivation of these
transverse faults was probably during intra - Bessarabian compressional events.
MICROFAUNA DEPOZITELOR CRETACICULUI INFERIOR DE PE VALEA MUIERII,
BAZINUL DAMBOVICIOARA
Liliana MIHAILESCU (anul IV)
Indrumator: Lector Marius STOICA
In prezenta lucrare sunt descrise asociatiile microfaunistice (Foraminifere si Ostracode) din
probele micropaleontologice recoltate de pe Valea Muierii, Bazinul Dambovicioara. Depozitele care
afloreaza in acest profil sunt incadrate in Formatiune de Valea Muierii de varsta Barremian-Aptian
inferior si sunt reprezentate in special printr-o alternanta de marnocalcare si calcare detritice cu
intercalatii de marne moi.
Microfauna recoltata, in special din nivelel marnoase, este foarte bogata in specii de
foraminifere care pot fi incadrate la Biozona cu Lingulogavelinella sigmoicosta si L. barremiana
(Barremian-Aptian bazal) si respectiv Biozona cu Epistomina spinulifera (Aptian inferior).
Ostracodele identificate sunt tipice pentru intervalul Barremian Aptian fiind reprezentate pin specii
ale genurilor Cytherella, Cytherelloidea, Cythereis, Protocythere, Schuleridea etc.
Se fac referiri de natura paleoecologica, considerandu-se ca aceasta microfauna s-a dezvoltat
in condiile unor ape relativ calde cu salinitate normala si adancimmi de pana la 200 m caracteristice
shelfului distal. In baza Aptianului exista cateva nivele calcaroase cu orbitoline, ceea ce
demonstreaza ca adancime bazinului putea sa fie si mai scazuta in acest interval.
LA PRESENCE ET LA SIGNIFICATION DES SCHISTES A PHYLLOSILICATES
PAUVRES EN QUARTZ DANS LA PILE EPIMETAMORPHIQUE DU GROUPE
TULGHES – ORDOVICIEN INFERIEUR (CARPATES ORIENTALES)
Mircea MUREŞAN
Institutul Geologic al Romaniei – str. Caransebes 1, Sector 1, 78.344 Bucuresti 32, Romania
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Le Groupe Tulgheş (Tg), logé dans la Zone cristallino-mesozoïque (ZCM) des Carpates
Orientales, renferme une pile formée pendant l’Ordovicien inférieur, puis épimetamorphisée
régionalement à la fin du celui-ci (Mureşan, 2000 a), sous un régime barrovien (Kräutner et al.,
1975). Le Tg a quatre formations lithostratigraphiques : Tg 1, Tg 2, Tg 3, Tg 4 (Bercia et al., 1976;
Vodă, 1980; Kräutner et al., 1992).
Étudiant les nombreux forages (plus de 70), effectués (par GEOLEX S. A. – Miercurea
Ciuc) dans la région Tulgheş-Hagota-Vallée Belcina-Gherpotoc- Pângărati (située dans la partie
méridionale de la ZCM), nous avons découvert, dans la pile du Tg (logée dans le socle
métamorphique de la Nappe alpine bucovinienne (établie par Săndulescu, 1967, 1975, 1976), des
intervalles constitués seulement par de roches terrigènes riches en phyllosilicates et pauvres en
quartz (le quartz < 10 %, souvent, < 5% ): des schistes sériciteux pauvres en quartz (SSePQu) et des
schistes sériciteux- chloriteux pauvres en quartz - SSeClPQu (dans ces poches, presque toujours, la
séricite prédomine vis-à-vis de chlorite) ; le dernier type est moins repandu. Nous mentionnons que
la plupart des roches terrigènes de la pile du Tg ont des pourcentages plus élevés de Qu (30-60 %,
dans les SSeCl; plus que 60 %, dans les schistes quartzeuses).
Les schistes à phyllosilicates pauvres en quartz n’ont pas été décrits dans la littérature
concernant les épimétamorphites du Tg. Ces roches nous les avons trouvées presque exclusivement
dans la Tg 4 et, sporadiquement, dans la Tg 3, étant mises en évidence, par exemple, dans les
forages: 43 Vallée Baratu Mare (le plus grand intervalle de SSePQu, trouvé dans le Tg 4: 370-532
m; des SSeClPQu: 370-394 m); 24 Vallée Balaj (des SSePQu dans la Tg 4: 377-434 m); 53 au N de
Vallée Bălaj (dans la Tg 4: 192-213 m); 42 Vallée Baratu Mare (dans la Tg 4: 84-99 m); 22 Vallée
Putna (dans la Tg 4: 70-81 m; 93-97 m); 44 au sud de Vallée Bălaj (dans la Tg 4: 453-472 m); 8
Vallee Baratu mic (dans la Tg 3: 86-92 m; dans la Tg 4: 369-376 m).
Les principaux traits de toutes ces roches phylliteuses pauvres en quartz sont: 1) la
prédominance nette des phyllosilicates (Se ± Cl plus de 90 %) sur le Qu ± Fld (felspath – albite); 2)
comme d’habitude, chaque intervalle renferme un seul type de roches pauvres en quartz: soit
sériciteux, soit sériciteux-chloriteux; 3) le Qu est toujours présent, tandis que le Fld peut manquer;
4) le Qu et le Fld sont toujours disséminés uniformement dans la masse phylliteuse, sous forme de
petits granules (autour de 0,5 mm) bien arrondies, de mêmes dimensions; 5) dans tous les cas, les
granules de Fld sont tournés avec 40-90° vis-à-vis de la schistosité principale (S 1 synmétamorphique), fait demontré par les paillettes de Se renfermées dans les grains de Fld; donc,
cette rotation du Fld s’est produit après la recristallisation de la Se, dans une phase tardécinematique
vis-à-vis de S 1; 6) presque dans tous les cas, ces roches renferment des pseudomorphoses
titaniferes (dans lesquelles l’ilmenite a ete remplace, comme d’habitude, par rutile) lamellaires et
granulaires et, rarement des aiguilles de Ru; frequemment, dans ces roches, les pseudomorphoses
titaniferes lamellaires se disposent habituellement parallelement ou quasi-parallelement vis-à-vis de
S 1; parfois, ces lamelles ont été derangées partiellement ultérieurement, étant tansposées au long
de la schistosité de clivage axial S 2.
Les schistes phylliteux pauvres en quartz représentent l’aspect métamorphique des
matériaux argileux, très faiblement impurifiés avec des éléments sableux (Qu, Fld et Ilm), signifiant
des épisodes de sédimentation pélitiques, installés quand la puissance de transport des courants
marines s’est diminuée sensiblement. L’abondance de la Se dans les roches examinées signifie des
apports primaires massifs illitiques; la chlorite suppose des apports montmorillonitoorthochloritiques. Initialement, ces minéraux argileux primaires se sont formés dans une écorce
d’altération continentale, sur un socle métamorphique, situé vers l’Est vis-à-vis de bassin (de type
« back arc ») où s’est formée la pile primaire du Tg. Ce socle était constitué tant par de roches
riches en Fld et Qu, que par de roches basiques (Muresan, 2002).
EVOLUŢIA SUBSOLIDUS A GRANITELOR DE ALBESTI
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Mihaela NĂSTASE (anul IV)
Îndrumător: Lector Dr. Gelu COSTIN
Lucrarea urmăreşte să elucideze evoluţia subsolidus a granitelor de Albeşti (M-ţii IezerLeaota) din două ocurenţe: Râul Târgului, amonte de localitatea Lereşti şi valea Bughiţa de Sus
(jud. Argeş). Sunt abordate: mineralogia cantitativă de detaliu a granitelor, studiul paragenetic,
identificarea reacţiilor minerale, precum şi estimarea preliminară a condiţiilor PT de echilibrare a
diverselor parageneze.
Majoritatea reacţiilor minerale identificate (formarea granatului coronitic în jurul biotitului,
pseudomorfozele complexe pe seama feldspaţilor magmatici şi eventual cordierit) demonstrează
faptul că reacţiile se desfăşoară în condiţii allochimice în prezenţa unei faze fluide. Se încearcă o
corelaţie între apariţia sau intensitatea unor reacţii minerale şi gradientul de strain.
MARKERI DIAGENETICI IN FORMATIUNEA GRESIEI DE KLIWA
- IMPLICATII IN DINAMICA HIDROCARBURILOR Lidia NUTU (anul IV), Florin STOICAN (anul II)
Centrul de Sedimentologie, Universitatea din Bucuresti, Catedra de Mineralorgie
Îndrumător: Profesor Dr. Nicolae ANASTASIU
Rezervor celebru in zona Flisului Extern din Carpatii Orientali, Formatiunea Gresiei de
Kliwa (Oligocen-Miocen inf.), nu este inca documentata din punct de vedere al inter-relatiilor
variabilelor diagenetice si implicatiilor acestora in calitatea de rezervor de hidrocarburi. Studiul
efectuat, pe probe din aflorimente deschise de V.Buzăului si V.Teleajen si pe carote din forajele din
zona (500-3500m), se vrea o analiza pertinenta, prin metode de abordare specifice – microscopie
optica, catodoluminescenta, fluorescenta UV – a produselor diagenetice, interpretarea acestora in
termeni factori-procese si integrarea acestora intr-un model diagenetic, cu scop aplicativ in geologia
petrolului.
Analiza probelor, din punct de vedere diagenetic, arata o evolutie postdepozitionala
complexa, marcata de procese de tasare, rearanjari mecanice, disolutii partiale, recristalizari,
cimentari episodice, uneori dizolvari sub presiune, pentru un model imaginat incadrat in regimuri
diagenetice hidrogeologice meteorice si compactationale (Galloway, 1984) cu recurente
compozitionale.
Porozitatea optica totala (Ehrenberg, 1995) arata valori medii 7% (primara si secundara), iar
coroborarea acesteia cu date de petrofizica (porozitate medie 9,33%) indica o calitate a rezervorului
medie (Zimmerle, 1995) in zona studiata. Procesele de porogeneza-poronecroza, pentru etapele
diagenetice de eo-, mezo- si telogeneza in modelul imaginat, permit atat interpretarea migrarii,
degradarii si acumularii hidrocarburilor cu diferite grade de participare, cat si modelari ale
geometriilor corpurilor, omogene/heterogene-anizotrope/izotrope.
BLACK SEA ROMANIAN SHELF: RECENT SEDIMENTARY PROCESSES
AND SEDIMENT GEOCHEMISTRY
Gheorghe OAIE, Dan SECRIERU
National Institute for Marine Geology and Geoecology, Bucharest, 23-25, Dimitrie Onciul Str., sect. 1, RO – 703181 CP 34 – 51,
[email protected], [email protected]
Keywords: Black Sea, sediment fluxes, whether pollutants, coccolithic ooze
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The North-Western Black Sea shelf, characterised by important sedimentation rates (1.19 –
2.19 m/ka), preserves great quantities of sediments and associated pollutants. Sediment fluxes,
originating from the important rivers (e.g. Danube, Dniestr, Dniepr), are distributed over a very
large shelf area with a high retention degree. The average sediment discharge of the main
contributor, the Danube River, is 30 – 40 million t/year. Total sediment fluxes (56.85Mt/yr) consist
mainly of fine suspended sediment (mud, silty-mud, silt), with a small amount of coarser fraction
(sandy silt, silty sand, fine sand). Sediments are transported sub-parallel to the Romanian –
Bulgarian coast, being deposited to the south under the influence of the main longshore current.
Controlling factors led to the formation of several sedimentary units (Danube delta front, Danube
prodelta). Detailed sedimentological observations and X-ray photographs interpretations were made
on superficial bottom sediments. According to grain size analyses, bottom sediments of the Black
Sea shelf area are dominantly fine (silt, mud, muddy silt, silty mud). For the deeper part of the basin
(water depth  200 m), silty clay, clayey silt and mud compose the Upper Holocene coccolithic
ooze and Middle Holocene sapropelic mud. Sandy clayey silt and clayey silty sand form thin
intercalations. Burrows, gas structures and, sometime, wood fragments and plant roots occur. The
analysis of sediment cores helped identify whether pollutants (nutrients, heavy metals, organic
matter, radionuclides, etc.) are transported by natural processes.
Major, minor and trace components, including some of the heavy metals with the greatest
toxicity (Cd, Pb, Cu, Zn) were analyzed. Chemical components are characterized by large variation
ranges, with coefficients of variation (Cv) usually greater than 50%. Zr is the only component with a
more homogenous distribution (Cv<30%), due to its presence exclusively as zircon and its ensuing
independence. The chemical composition corresponds to sediments varying from purely terrigenous
(<10% CaCO3 in the nearshore coarse sediments and 10-20% CaCO3 in terrigenous muds from the
area under Danube influence), to carbonated ones (up to 80% CaCO3 in shelly sediments from the
sediment starving shelf and the Upper Holocene coccolithic ooze). The TOC contents, reflecting the
participation of organic matter in sediment constitution, vary from <0.5% in coarser, welloxygenated sediments, to 2-3% in finer shelf sediments and 3-5% in the abyssal zones (coccolithic
ooze), with maximal values (>5% and up to 10%) in the sapropelic mud. The sequentially vertical
sampling revealed a general manganese post-depositional mobilization and re-deposition at
sediment-water interface. Owing to favorable conditions (vertical distribution of Eh, sediment
permeability, etc.), the process is extremely active in the sediment starving continental shelf and
oxygenated shelf break areas, leading to MnO concentrations in the superficial layer up to 1.6%,
with the possibility to formation small manganese nodules. Statistical graphical and mathematical
analyses of chemical data show abnormally high concentrations of most heavy metals at some
stations. The upper 25-30 cm of sediment were measurably enriched in all of the considered heavy
metals, excepting Cr and V, with a strong increasing tendency of metal excesses toward the
sediment-water interface. The Danube prodelta is one of the most heavy metal polluted area,
showing positive heavy metal excesses. The second heavily polluted area, the sediment starving
continental shelf, was related to off-shore drilling activities, as determined by intensive Ba
contamination. As sediments are normally poor in terrigenous components, the contamination
degree can be higher than in the Danube Delta front.
THE POLYMETALLIC MINERALIZATION GENESES IN SCRIND – RACHITELE –
POIANA HOREA REGION, VLADEASA MOUNTAINS
Mihai PANAITE, Ioana PANAIT
S.C.ProspectiuniS.A.,Caransebes st.1, 78344, Bucuresti, e-mail [email protected]
Key words:precambrian syngenetic strata bound; remobilized mineralizations;laramide veins.
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The polymetallic mineralizations in Scrind-Rachitele-Poiana Horea region belong to the
folowing genetic types:
1. Stratiform, volcano-sedimentary-metamorphosed mineralization, of Kuroko type,
interlayed in uper part of acid metatuff (Zn-Pb-Ag-Au), or in over layin muscovite-biotite
micaschists (Cu-Au)
2. Hydrothermal metamorphosed veins, also associated to calco-alcaline volcanism, usualy
localized near the fisrt ones;
3. Hydrothermal sulfide mineralizations, as veins, or mineralized column (stockwerk),
mobilized from precambrian syngenetic mineralizations, in hercinian and alpine cycles
4. Hydrothermal laramide sulphide mineralization, as veins, at the boundary of the Somes
series with Vladeasa volcano-plutonic structure.
The syngenetic, stratiform, volcano-sedimentary mineralizations comprises the following
types: massive, complex (Zn-Pb-Ag-Au), developed in Alunis valley; iron banded ore and massive diseminated Cu-Au ore, which outcrop in Gingineasa valley, Negru brook and Golumbat brook.
The complex ore made up of pyrite, arsenopyrite, pyrothite, sphalerite, galena, chalcopyrite,
freibergite, siderite, quartz and muscovite is developed as strata bound in acid metatuff and it
passes in marginal zones to diseminated type, where only pyrite and arsenopyrite are present. This
type of ore is equivalent with Burloaia central facies (East Carpathians). In the massive pyrite ore
(Negru brook, Gingineasa valley), consisting mainly of pyrite and arsenopyrite (equivalent with the
marginal facies, East Carpathians) and in the hydrothermal metamorphosed veins are sporadically
pyrothite nests with pyrite relics, as a consequence of the aynmetamorphic origin. The massive,
polymetallic ore was deposited near hydrotherms, while the massive iron ore and the massive and
diseminated Cu-Au formation took place at the end of the volcanic period, distal to hydrotherms.
The hydrothermal metamorphosed veins, highly brecciated as footwall and highwall
metamorphics, consisting of siderite, pyrite, arsenopyrite, chalcopyrite, pyrothite and quartz, were
formed in the same time with the stratiform polymetallic ore, on the fractures, near the main fault
controlling hydroterms.
The Somes metamorphics and syngenetic interlayed mineralizations were highly affected by
the hercinian and alpine deformation movements, which caused minor mobilizations of the soft
sulphide, remobilized as small discordant veins, but complex remobilizations, consisting of
sphalertite vein, or small stockwork, made up of cloritized breccia mineralized with sphalerite,
pyrothite, pyrite, arsenopyrite and galena. The ore consists of sphalerite and pyrothite ground mass,
where recristalized pyrite, arsenopyrite and galena with tetraedrite exolutions are developed. The
ore breccia is twice up to four times richer in Zn and Pb and tens times poorer in Ag and Au than
massive syngenetic, polymetallic ore.
In nothern side of the area, a low temperature hydrothermal mineralization, of sulphide and
native gold, associated to laramide metalogeneses, outcrops. The vein mineralization is made up of
pyrite, marcasite (which are sometime epitaxial intergrowed), sphalerite, galena, chalcopyrite and
quartz. Its presence shows a possible influence of the laramide metalogeneses on the precambrian
syngenetic, stratiform and hydrothermal metamorphosed mineralizations.
COMBINED MAGNETIC, SEDIMENTOLOGIC AND ASTRONOMICAL CYCLICITIES
FOR SOME ROMANIAN LOESS-PALEOSOL SEQUENCES
Cristina PANAIOTU1, Cristian PANAIOTU1, Adrian GRAMA1, Cristian NECULA1
University of Bucharest, Paleomagnetism Laboratory ([email protected])
key words: loess, cyclic processes, orbital tunning, age model, Romania
Loess deposits act as a key archive in the study of palaeoclimatic change. Investigation of
loess sequences, mainly from Northern China, has led to the development of a number of
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continuous palaeoclimatic records using physical parameters (magnetic properties, grain size,
calcimetry) which demonstrated to be accurate proxies for climatic variations over the past 2.6 Myr.
A number of studies have demonstrated a close correspondence in the susceptibility variations
within loess sequences to signatures of past global climatic change derived from other archives, e.g.
oceanic and ice-core δ18O profiles. The cyclic nature of the oceanic δ18 O signal allowed climatic
variations to be calibrated in time via the association of identified isotopic oscillations to orbitally
controlled changes in insolation. Orbital tuning has been utilized in the production of highresolution astrochronologies for both oceanic sediments and loess-paleosol sequences. Detailed
rock magnetic profiles were measured recently on two loess-paleosol sequences: Mostiştea Lake
(southeastern part of the Romanian Plane) and Costineşti (Dobrogea). All magnetic properties are
similar with those recorded in the loess deposits of China. On the basis of this similarity, an age
model was developed for the Romanian sequences by tuning the magnetic susceptibility record to
time-series of insolation and to the orbitally tuned ODP677 δ18O records. To ensure that a
consistent relationship between the proxyclimate record and the chosen target curves was
maintained throughout the tuning procedure, a number of correlation criteria were imposed.
Palaeosols were related to regional maxima in insolation, maxima in eccentricity and odd numbered
marine oxygen isotope stages (MIS), whilst loess units were consistently assigned to insolation
minima and evenly numbered MIS. The two susceptibility profiles from Mostiştea and Costineşti
were tuned independently. Spectral analysis of obtained time-series of susceptibility was performed
to determine whether coherent orbitally frequencies have successfully been introduced into
palaeoclimatic time series during a tuning procedure. This analysis was performed using two
different statistical algorithms specially designed for unevenly spaced time series: SPECTRUM and
MC-CLEAN. We found that the susceptibility signal is dominated by the 100 ka eccentricity period,
followed by the 41 ka period of obliquity and a very weak spectral peak corresponding to the 23 ka
period of precession. Such a spectral composition dominated by the 100 ka period, is typical for
paleoclimatic series younger than 1 Ma and demonstrates that the tuning of susceptibility profiles is
reliable. The age model based on magnetic susceptibility was transfer to the calcimetry profiles
measured at Mostiştea and Costineşti and to the grain size profile measured at Costineşti. Spectral
analyses show that these time series have the same power spectrum dominated by Milankovitch
periods. All these results demonstrate that an orbitally tuned palaeoclimatic timescale provides a
robust, high-resolution chronological solution for the Romanian loess sequences. According to our
age model the onset of loess accumulation started in Costineşti around 630 ka and in Mostiştea
around 416 ka.
HOW CONTINUOUS WAS THE ROTATION OF CARPATHIANS AROUND MOESIAN
PLATFORM: PRELIMINARY PALEOMAGNETIC DATA FROM ROMANIAN AND
SERBIAN BANAT
Cristian PANAIOTU1, Cristina PANAIOTU1, Tudor BERZA2 and Dragan MILOVANOVIĆ3
1
University of Bucharest, Paleomagnetism Laboratory; 2 Geological Institute of Romania, Bucharest; 3 Faculty of Mining and Geology, Belgrade
key words: paleomagnetism, jurassic limstones, banatites, Banat
The aim of this paper is to use new paleomagnetic data for clarifying the mechanism of
clockwise rotation of the Southern Carpathians around Moesian platform during the Tertiary.
Previous paleomagnetic results from Romania showed that large areas from the Transylvanian
Basin, the Apuseni Mountains and the Southern Carpathians were affected by a large clockwise
rotation during Tertiary. To extend the area with paleomagnetic data further to the south, we
sampled five sites in the Danube Valley on the Romanian territory and 6 sites in the Timok area
from Eastern Serbia. From Romania, 4 sections in Middle Jurassic red limestones (Danubian Unit)
were sampled along the Danube Valley and 1 site in the Upper Cretaceous magmatites from the
Lilieci Valley (Getic Unit). From Eastern Serbia we sampled 5 sites in the Upper Cretaceous
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volcanics and intrusions (1 site in Krepoljin and 4 sites in Bor area all in Getic Unit) and 1 site in
Middle Jurassic red limestones from Tîrnaica, only 20 km south of the Danube (Danubian unit).
The structure of the natural remanent magnetization was examined by progressive thermal
and alternating field demagnetizations in the Paleomagnetism Laboratory of Bucharest University.
All red limestones from the left bank of the Danube Valley are completely remagnetized and fold
test was negative. Declination of this remagnetization, around 70º - 80º, is similar with the primary
direction of the Upper Cretaceous magmatic rocks from the Lilieci Valley. In the Bor area one of
the sites has reversed polarity and others have normal polarity, so the magnetization of these Upper
Cretaceous magmatic rocks is primary. Declination of the mean direction is around 30º. A similar
declination was also obtained from the remagnetized Middle Jurassic limestones from Tîrnaica. The
new results from the left bank of the Danube Valley demonstrate that the area with large clockwise
rotation extend about 330 km, from northern part of the Apuseni Mountains and Transylvanian
Basin, until the Danube Valley. The transition to the less rotated Timok (Bor) area, with a Tertiary
clockwise rotation around 30º, seems to be very sharp, in less than 20 km (Tîrnaica) Moreover, the
amplitude of rotation measured in Bor area is similar with the post-Middle Eocene rotation
observed in the western Balkan Mountains from northwestern Bulgaria. These preliminary data
show that the Tertiary tectonic history cannot be modeled as a simple progressive rotation around
the corner of the Moesian platform, but some other mechanism must be involved to explain this
sharp transition from 30º to 80º clockwise rotation, in only a couple of tens of kilometers.
CHANGES IN FLUID INCLUSIONS AFTER TRAPPING IN MINERALS
Vasile POMÂRLEANU
Geological Institut of Romania Caransebes, 4, 78344, Bucharest
In this paper, some transformations of fluid inclusions subsequent their born, are presented.
These to refere at physical and chemical changes. The physical changes comprehend:
cristalization on the walls, necking down, shrinkage and imiscibilly, reversible and ireversible
volume. Also migrations of fluid inclusions in a termal gradient have been exposed.
Chemical changes consist turn up fluid daughter phases (daughter minerals) decrepitation
and refilling phenomena.
All fluid inclusions changes to pointed out various rocks and are deposita from Romanian
territory.
The transformations of fluid inclusions presented some genetic and practice significances.
PHYSICAL STRUCTURES AND PECULIAR DEPOSITIONAL MECHANISMS AND
ENVIRONMENTS IN THE MIOCENE SILICICLASTIC SEQUENCES FROM
SOUTHERN EAST CARPATHIAN "MOLASSE", ROMANIA
Marius POPA
Bucharest University, Faculty of Geology & Geophysics, Mineralogy Dept.
e-mail: [email protected]
The study focused on Miocene Molassic clastic sequences of "Brebu Conglomerates" and
"Doftana Formation" units, component of the East Carpathian system (southern part). Facies/
sequence analysis methodology has been applied on four stratigraphic sections in order to interpret
peculiar aspects of different physical structures, as revealed by the depositional units separated
within sequences.
In our opinion, the examination of a physical structure of a depositional unit should be
performed more accurately by taking into account all the facies features that could characterize the
spatial distribution of the component clasts. This could be very important especially in the case of
"heterogeneous" units (e.g. that ones which display lateral/ internal variations in aspects related to
clast distribution) and associations (sequences) - as we have found in the studied deposits – or when
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comparative analyses between the same structural types is intended. Accordingly, we have tried to
describe physical structures by considering: textural (grain- size related) characteristics&
heterogeneities (Popa& Anastasiu, 1997); main& associated (physical) structures (laterally&
vertically); 3D aspects.
The main structural types recognized have been grouped in four textural (grain- size related)
categories, as follows: gravelly- massive, imbricated, normally-/ inversely- graded, cross- stratified,
plane- stratified; sandy - massive, parallel (even or wavy) laminated, cross- stratified, hummocky
stratified, rippled; heterolithic (sandy/muddy associations)- flaser-, lenticular or wavy- stratified;
muddy- massive or laminated (Popa, 2000). By integrating the above- mentioned characteristics we
have recognized peculiar depositional processes, controlled by different clast- supporting
mechanisms (cohesive/ cohesionless, characterized by matrix strenght/ disperssive pressure forces/
collissional forces/ turbulence) and depositional mechanisms (en- masse freezing/ frictional
freezing/ progressive freezing/ suspension settling), developed in (fan)- delta (in subaerial or
subaequeous) areas and shallow- water (shoreface, offshore) settings, wave- and tide- influenced,
tectonically- active.
It is also to note that a good understanding on transport/ depositional mechanisms allows
the recognition of the dynamic variability of the processes involved. This is particularly important
in the case of gravity- flow products, where lateral and vertical facies variations may develop due to
this reason.
SILICICLASTIC SEQUENCES AND RELATED ARCHITECTURES IN THE MIOCENE
DEPOSITS OF SOUTHERN- EAST CARPATHIANS, ROMANIA
Marius POPA, Nicolae ANASTASIU
Bucharest University, Faculty of Geology & Geophysics, Mineralogy Dept.
e-mail: [email protected]
The studied stratigraphic succession (700- 800 m in thickness) is the main part of the
Miocene Molasse component of the East Carpathian system (southern sector), being a clastic
sequence comprising "Brebu Conglomerates" and "Doftana Formation" units. By using sequence
analysis on four stratigraphic sections different facies types, sequences types/ orders– and related
3D architectures - have been described.
Several sequence types, of different orders, have been identified – here called micro-, mesoand macrosequences - the data set for each separated sequence specifically including: component
facies-/ lower- order sequence types; bounding surfaces (at the base, top and internally);
paleocurrent data; 3D architecture; lateral/ vertical transitions (Popa, 2000).
The microsequences - up to 1 m in thickness - are the result of different small-scale
processes that led to the deposition of distinctive small- scale facies associations.
Lower- order mesosequences (up to 5- 8 m in thickness) correspond to laminated sand
sheets (LS), channels (CH), gravity flow deposits (SG), gravelly bars (GB), sandy bars (SB), levees
(LV), hummocky cross-stratified sandstone bodies (HCS). The bounding- surfaces genetically
correspond to erosional/ nonerosional (at base) and bioturbated (at top) surfaces. These sequences
were deposited in (fan)- delta (in subaerial or subaequeous) areas and shallow- water (shoreface,
offshore) settings, wave- and/or tide- influenced.
Higher- order mesosequences (up to 60 m) are subaerial gravity flow lobes (GFL); alluvial
braidplain sheets (ABS); fan- delta plain sheets (FDP); (fan)- delta front lobes/ bars (FDFL); (fan)delta front nearshore bars (FDFB); (fan)- delta front subaequeous gravity- flow lobes (FDFS);
interdistributary bay- fills/ (fan)- delta fringe (IBF/FDF); shoreface- offshore wedges (SOW). Their
stacking pattern is mainly progradational or progradational- aggradational. These have been
interpreted as constructive or destructive phases in the evolution of (fan)- delta systems
development, strongly controlled by sediment supply and tectonic regime (proximally) and by
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wave- and/or tide- activity of the adjacent shoreface systems (distally). The quality and stacking –
pattern of proximal (continental) mesosequences allowed us to recognize the equivalents of
dispersion- entrenchment – trench backfilling stages (s. DeCelles et al., 1991) in the evolution of the
alluvial systems involved. The subaequeous architectures are very often bioturbated at the top and
display a basinward shift in facies. These features indicate them as being parasequences, but their
sedimentation have been influenced also by an active tectonic regime, as suggested by welldeveloped diagnostic physical structures. The proximal – “alluvial” equivalents have been separated
– when possible - by changes in alluvial architecture.
The association of the above- mentioned mesosequences allowed the separation of 3 IIIrd
(IV th ?) order macrosequences (parasequences sets). Their stacking pattern was the effect of
variations in accomodation space/ sediment supply ratio, with climatic and tectonic control.
INTEGRATED INTERPRETATION AND REPRESENTATION OF WELL LOGS
Cristian POPA
University of Bucharest, Faculty of Geology and Geophysics, email: [email protected]
Key words: well logs, integrated interpretation, formation evaluation.
In the complex process of formation evaluation the need of high-level integration derives
from the multitude of data that are available. The integration is not required only in formation
analysis process, but also in the ways the available and calculated data are represented.
This paper presents a formation evaluation study, a study that was made using well logs data
from three boreholes from Eremieni field. The studied interval is approximately 1000 meters,
between 1500 – 2500 meters depth and for this were used all geophysical data available.
The evaluation was made using the Petrophysics module from GeoFrame 4.02 software and
the final scope was to obtain the distribution of physical properties in the studied interval.
CRETACEOUS CONIFERS OF ROMANIA
Mihai E. POPA1 and David L. DILCHER2
1
University of Bucharest, Faculty of Geology and Geophysics, Laboratory of Palaeontology, 1, N. Balcescu Ave., 70111, Bucharest, ROMANIA. Email: [email protected]
2
University of Florida, Florida Museum of Natural History, Palaeobotany Laboratory, Dickinson Hall, PO Box 117800,
Gainesville FL 32611-7800, USA. E-mail: [email protected]
Cretaceous conifer material from Romania is known since the XIXth century, collected
mainly from the South Carpathians, as well as from other occurrences. This paper deals with an
overview of Romanian Cretaceous conifers, discussing them as a whole, from all known
occurrences, with their systematic affinities and nomenclatorial aspects. The oldest Cretaceous sure
conifer fossils were reported from Dobrogea, where they are Aptian in age, from Cernavoda,
preserved as permineralizations, with Cupressacean affinities. Cenomanian remains were recorded
from Rucar, as well preserved compressions, belonging to Cupressaceae (Taxodiaceae). Turonian
conifers were described from Babadag Basin, Dobrogea, also in compressive state, and they belong
to Cupressaceae (Taxodiaceae) and Incertae sedis (the case of Brachyphyllum).
HYDROTHERMAL ALTERATION AT FANCEL LAPUSNA VOLCANIC EDIFICE
(EASTERN CARPATHIAN MOUNTAINS, ROMANIA) AND ITS SIGNIFICANCE IN
EXPLORATION FOCUS
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Tiberius POPA, Silvia POPA, Erika MATSCH, Iulian SEBA
S. C. Prospectiuni S. A., 1 Caransebes Street, Sector 1, Bucuresti-32, Romania; e-mail: [email protected]; [email protected]
Key words: andesites, propylitisation, potassic alteration, intermediate argillisation, advanced argillisation, factor analysis
The volcanic edifice Fancel-Lapusna (FL) is included in the volcanic neogene CalimaniGurghiu- Harghita chain of the Romanian Eastern Carpathian Mountains.
FL is a caldera type structure that dominates the northern part of the Gurghiu Mountains.
The edifice is an around semicircular depression with an E-W diameter of almost 10-km The
caldera has shaped as a result of a bulky explosive eruption, which interrupted the growth of a large
complex cone. During the cone edifice stage, there were evolved two units: a volcanoclastic one
and a stratovolcanic one. The second unit consists in intrusive bodies, lava flows, domes, breccia
bodies and pyroclastic products. Field mapping corroborated with microscope study led us to
confine zoned hydrothermal alterations (propylitic, potassic, intermediate argillisation and advanced
argillisation). For geochemical study we used factor analysis method. The earlier intrusive stage
(andesitc-dioritic) was propylitisation. In the latest postcaldera stage of the intrusions, the
hydrothermal solutions developed complex alteration zonality: potassic alteration in the depth,
enveloped in the upper part by argilisation. In the apical part of this system, it has developed a
convective system, where ascended magmatic volatiles have been absorbed by meteoric water. It is
present at the surface with a high grade advanced argillic alterations with vuggy silica.
Propylitic alteration transforms partial or totals the phenocrysts of maphic minerals
(pyroxenes and green and brown hornblendes) and they are replaced by neominerals, like as
chlorite ± epidote ± carbonate ± leucoxene ± actinot. Factor analysis shows an arrangement of
chemical elements related with the rock petrogenesis and a weak mineralisation in the main and
second factors.
Intermediate argillic alteration conserves the structure of the andesites. The rock is
distinguished by neoformation assemblages: illite + sericite + montmorillonite/ chlorite ± pyrite and
Fe oxides ± calcite. The factor analysis of an intermediate argilic rocks unit shows the pathfinder
elements for gold mineralisation (As, Sb, Hg).
Potassic alteration was observed in andesite bodies, mainly. This alteration is produced in
the end of the magmatic activity and it modifies partially the rocks. Factor analysis of potassic rock
samples unit indicates in the main factor the association Cu-K-Na-Ag-Zn-Mn. It is characteristic for
porphyry copper mineralization, and in the second factor Au has a good correlation with As and Ag,
which is characteristic for epithermal gold mineralisation.
Advanced argillic alteration is associated with the process of forming vuggy silica. The
neominerals assemblages are quartz, alunite, pyrite, diaspor, rutile and amorphous clays. In the
inner of the advanced argillic alteration zone there is vuggy silica, which results by destruction of
all primary rock-forming minerals except quartz. Vuggy silica is composed of quartz, pyrite, and
minor rutile and has coarse voids structure. A second variety of nearly pure quartz rocks are
mineralogical similar to the vuggy silica but lacks large void spaces. Vuggy silica alteration occurs
like big boulders inside the advanced argilic alterated rocks.The main factor of the factor analysis
displays a connection between alteration and an epithermal gold mineralization, notify the good
correlation between Sb-Au-As-Hg-Ag.
GIS APPLICATION IN COMPLEX GEOLOGICAL, GEOCHEMICAL AND
GEOPHYSICAL DATA PROCESSING AND INTEGRATED INTERPRETATION
Dragoş Găbudeanu RĂDULESCU
S.C. Prospectiuni S.A., 1 Caransebes st., 78344-Bucharest, Romania, E-mail [email protected]
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Geological, geochemical and geophysical data management and interpretation may become
very easy when they are performed in an integrated environment like GIS.
Using GIS can be particularly efficient when large amounts of data resulted from long term,
complex surveys, performed on large areas, are processed. In these cases, serious problems of
synchronization in the data management may occur and integrated interpretation can be rather
difficult to perform.
The poster illustrates the procedures to follow, in GIS environment, in order to manage and
correlate the data provided by the different surveying methods and to obtain an geological image of
the area as close as possible to the field reality.
The case study presents a complex survey on an area of about 400 sq.km, 1:5000 scale,
using the following investigation methods:
Geological survey - 20000 observation points;
Geochemical survey - 12000 samples;
Gravity survey - 7000 stations;
Magnetic survey - 95000 stations;
Electric survey - 3600 stations.
All the field observations were introduced in Access'97 database. Geophysical interpretation
was performed using Oasis Montage. The graphical database was accomplished using MapInfo 6.5
software.
MapInfo 6.5 and MapBasic 6.5 software are very practical solutions in geological data
processing and interpretation, taking in account their low price and the fact that MapBasic allows to
customize GIS environment as a geological work environment by writing personal adequate
applications.
CLAY MINERALOGY AND GEOCHEMISTRY OF THE COAL BEARING DEPOSITS:
DACIC BASIN
Silviu RÃDAN
National Institute of Marine Geology and Geo-ecology (GeoEcoMar)
23-25, Dimitrie Onciul St., sect. 2, RO-70318 Bucharest, e-mail: [email protected]
Key words: clay minerals, coal, geochemistry, paleo-environment, Pliocene, Dacic Basin (Romania).
Pelitic rocks associated with Dacic Basin coals are characterized by a large diversity of clay
mineral assemblages and a variable chemical composition. Any clear correlation was observed
between the stratigraphic succession of the coal bearing deposits and the vertical evolvement of
their clay mineralogy and chemistry. However, the paleo-environmental and the lithologic control
are very certain.
So, the clays included within the detrital sequences encompassed between the main coal
beds and from the coal roof are dominated by illite (Lupoaia quarry) and/or smectite (Husnicioara
quarry), followed by kaolinite, and containing low percentage of chlorite. Clayey interbeds
intimately associated with coals contain a kaolinite-rich fraction with little illite and smectite, and
the underclays are characterized by abundant smectite with subordinate illite and chlorite. Fine
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fractions separated from the thick sandy sequence of Husnicioara quarry show a ternary clay
mineral assemblage with comparable percentages of kaolinite, illite and smectite.
Geochemical studies revealed a clear transition from clays richer in alkalies and alkaline
earths, characterized by low maturity index, to more aluminous rocks, with higher maturity index.
The sequence is started by the clays included within the detrital units separating the coal beds,
continues with coal roof clays, followed by underclays, and is closed by the clayey
interstratifications contained by the coal seams. This succession corresponds, as was pointed out by
Englund and Jorgensen (1973), to a transition from immature rocks, rich in feldspars, illite and
chlorite, to more and more weathered clays, enriched in smectite and kaolinite.
The wide mineralogical spectrum is the result of participation of three well-known
mechanisms: inheritance (reworking), transformation and neoformation. These genetic processes
interfered with variable intensity and extent in the course of time, controlled or influenced by local
and regional changes of sedimentary conditions. Clay mineral assemblages included within the
main detrital sequences resulted principally from reworking of clayey materials provided by a
northern and north-western source area – the South Carpathians; for smectite-rich underclays, a
substantial contribution of transformation and neoformation processes could be admitted, and for
the kaolinitic clays included inside of coals, the neoformation (authigenesis) represents the main
mechanism. Illite and chlorite are practically exclusively reworked, but for kaolinite and smectite,
other additional mechanisms could be superposed. Thus, kaolinite was generated by neoformation
processes, especially within the clays included in coals and sometimes in underclays (diagenetic)
and within the sands (epigenetic). Smectite minerals can be reworked from older formations and/or
neoformed at expense of volcanic ash provided by erosion of some Miocene tuff levels. As regards
the high smectite concentration in underclays, diagenetic transformation of illite (and perhaps
chlorite), typical for vertisols and underclays, should be taken into consideration. Differential
transport and sedimentation processes could be also invoked.
Smectite “invasion” evidenced in the whole sedimentary sequence cropping out in
Husnicioara quarry suggests the interference of a second source area, richer in volcanogenic
material, such as Badenian deposits, well represented westward and even southward (Timoc Valley
zone).
A peculiar case of mineralogical changes supported by clays is represented by the baked
rocks (porcelanites and clinkers), generated in consequence of natural burning of the coal beds:
primary clay and non-clay minerals are progressively replaced with hematite, cristobalite, mullite,
spinel, tridimite, -cuartz, cordierite and magnetite.
TRACE FOSSIL ASSEMBLAGES FROM SIRIU VALLEY TURBIDITES THE
EASTERN CARPATHIAN FLYSCH
Relu D. Roban 1, Bogdan L. Varban2, Nicolae Anastasiu1
1) University of Bucharest, 2) University of Western Ontario, Canada,
Keywords: Ichnofacies, Turbidites, Carpathians
The Tarcau Sandstone outcropping in the southern East Carpathians (Buzau Valley) consists of
turbidite sequences of Eoceneage. Based on texture and physical sedimentary structures eight (F1F8) facies have been identified: non-organized rudites,amalgamated clast-supported rudites, matrixsupported arenite-rudites, grading stratified arenites, massive (non-organized)arenites, paralel
stratified fine arenites, sand-mud couples, mudstones/limestones couples. In the 400 m of measured
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section we separated two first order sequences (called here turbidite systems) consisting of different
facies associations. The tracefossils described from each facies associations represent 18
ichnogenera and 23 ichnospecies (s. Ksiazkiewicz, 1970), belonging to different ethological classes
(domichnia, fodinichnia, pascichnia, repichnia, agrichnia) (Pemberton , MacEachen1992).
Ichnogenus Circulichnis and a fodinichnia graphogliptid are new occurrences in the Tarcau
Sandstone and are described herein. The most common association is represented by
predepositional suites (such as Paleodictyon, Spiroplycus, Spiroraphe, Megagrapton), and
postdepositional suites (Ophiomorpha, Granularia, Scolicia, Planolites, Sabularia, Palaeophycos )
(Kern1980). Based on the distribution of species and species associations two recurrent ichnofacies
were identified: Nereites and Zoophycos. The Zoophycos traces are mostly preserved in what we
interpreted as turbidite channel environments, whereas the Nereites is very common in lobe and
basin plain environments. These ichnofacies are conspicuous similar in both first order
turbidite sequences (systems). There is no any clear indication of major water depth change, and we
interpret the trace fossils distribution being primary related to local energy conditions (nutrient
supply and oxygenation).
PRODUCTION AND LOSS OF HIGH-DENSITY BATHOLITHIC ROOT - SOUTHERN
SIERRA NEVADA, CALIFORNIA
SALEEBY, J.* DUCEA, M. CLEMENS-KNOTT, D.
Division of Geological and Planetary Sciences, California Institute of Technology, Mail Stop
100-23, Pasadena, CA 91125
Department of Geosciences, University of Arizona, 1040 E. Fourth St., Tucson, AZ 85721
Department of Geological Sciences, California State University, Fullerton, CA 92634
*Email: [email protected]
Experimental studies show that when hydrous mafic to intermediate composition
assemblages are melted in excess of 10 kb liquids typical of Cretaceous Sierra Nevada batholith
granitoids are generated and garnet+clinopyroxene dominate the residue assemblage. Upper
mantle-lower crustal xenolith suites that were entrained in mid-Miocene volcanic centers erupted
through the central Sierra Nevada batholith are dominated by garnet clinopyroxenites which are
shown by geochemical data to be petrogenetically related to the overlying batholith as its residue
assemblage. The xenolith data in conjunction with an exposed oblique crustal section in the
southernmost Sierra, as well as seismic data, form the basis for the synthesis of a primary
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lithospheric column for the Sierra Nevada batholith. Critical aspects of this column are the
dominance of felsic batholithic rocks to between 35 and 45 km depths, a thick (~ 35 km)
underlying garnet clinopyroxenite residue sequence, and underlying garnet peridotite lithospheric
mantle to ~ 125 km depths. The peridotite section appears to be the remnants of the mantle
wedge from beneath the Sierran arc. The principal source for the batholith was a polygenetic
hydrous mafic to intermediate lower crust dominated by mantle wedge derived mafic intrusions.
Genesis of the composite batholith over an ~ 50 m.y. time interval entailed the complete
reconstitution of the Sierran lithosphere.
Sierra Nevada batholith magmatism ended by ~ 80 Ma in conjunction with the onset of
conductive geotherm from beneath by flat slab subduction. Disruption of the cornerflow
circulation of asthenosphere into the wedge environment by the Laramide slab is suggested to
have been the prime factor in the termination of magma genesis. In the southernmost Sierranorthern
Mojave Desert region the sub-batholithic mantle lithosphere, including the garnet
clinopyroxenite residue sequence, was mechanically delaminated by a shallow segment of the
Laramide slab, and was replaced by underthrust oceanic assemblages. These relations record a
segmentation of the Laramide slab beneath the southernmost Sierra, similar to that observed
beneath the modern Andes.
Despite these Laramide events the greater Sierra Nevada mantle lithosphere for the most
part remained intact throughout much of Cenozoic time. A pronounced change in xenolith suites
sampled by Pliocene-Quaternary lavas to garnet absent, spinel and plagioclase peridotites, whose
thermobarometry define an asthenosphere adiabat, as well as seismic data indicate that much of
the remaining sub-Sierran lithosphere was removed in Mio-Pliocene time. Such removal is
suggested to have arisen from a convective instability related to high-magnitude extension in the
adjacent Basin and Range province, and to have worked in conjunction with the recent phase of
Sierran uplift and a change in regional volcanism to more primitive compositions. In both the
Mio-Pliocene and Late Cretaceous lithosphere removal events the base of the felsic batholith
was the preferred locus of separation. This is suggested to have resulted from the sharp
rheological contrast between weak quartzofeldspathic deep batholithic rocks, and the stronger
and much denser residue sequence. Such phenomena may be of global importance in continent
edge arcs, and responsible for the common Moho depths of 30 to 40 km observed in the
derivative batholithic belts. This is also suggested to help fractionate and isolate the Earth's
felsic crust in the long term.
THE OCEAN FLOOR METAMORPHISM AND THE GENESIS OF SPILITES IN THE
MURES ZONE, ROMANIA
Haralambie SAVU
Geological Institute of Romania, 78344 Bucharest 32, 1 Caransebeş St.; E-mail : geol@igr. ro
Key words: Ocean floor metamorphism; Spilitization; Spilites; Mineral assemblages; Chemical composition.
The ocean floor metamorphism of the Mures Zone ophiolites resulted from the incandescent
lava/salt-water reaction1. It manifested itself at temperatures of up to 4oo0 C, and its characteristic
mineral assemblage is: albite-chlorite-epidote-quartz-hematite. It is associated with the spilitization
process, a reason for witch it was marked as the spilitic facies of metamorphism. Due to the high
temperature, the ocean floor salt-water passed into very hot steam, that penetrated into basaltic
lavas, which cooled as pillow lava and got steam-vesicles. At the same time, superheated steam and
salt-water infiltrated the previously cooled lavas, altering their magmatic minerals, as follows:
plagioclase was albitized; augite passed into pseudomorphoses of chlorite  epidote  iron oxides.
1
Savu, H. Metamorphic and metasomatic processes in the Alpine ophiolites from the Mureş Zone, Romania. Proc.
Rom. Acad. Series B, vol 4 (in press)
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These minerals, together with calcite, zeolite, and quartz, infilled the vesicles, too, it resulting in the
amygdaloidal structure of spilites. The substances in excess have been antrained by the ocean floor
salt-waters and released as limestone and red argillite beds and eventually iron deposits occurring
now as intercalations among the spilite flows.
WHAT IS CCZN-ARMALCOLITE? –
A CRYSTAL-CHEMICAL DISCUSSION AND A PREDICTION
Gavril SĂBĂU
Geological Institute of Romania
1, Caransebeş St., sect. 1, RO-78344 Bucharest 32, e-mail: [email protected]
Key Words: CCZN-armalcolite, crichtonite, close-packed oxides, CCP
The term CCZN-armalcolite was created to encompass titanate phases very close in composition to
minerals of the armalcolite-pseudobrookite series (Mg, Fe2+,Fe3+)(Ti,Fe3+)2O5, but containing essential Cr,
Ca, Zr or Nb. Such compounds were initially identified in lunar samples (Levy et. al., 1972; Brown et
al.,1972), but have subsequently been found also in a number of terrestrial occurrences, typically mantle
rocks or mantle-derived igneous products. Though contents in small cations like Cr and Nb are considered
important in distinguishing “CCZN-armalcolite” from normal armalcolites (Haggerty, 1973), it appears that
the most significant difference is given by large cations as Ca (also K in the Argyle “K,Cr-armalcolites” Jaques et al., 1990), contained in proportions which rise the question of compatibility with the armalcolite
lattice. Because small grain size prevented so far structural studies on “CCZN-armalcolites”, they are
traditionally distinguished from chemically similar compounds on account of their relatively high TiO 2
contents, matching those of armalcolites. On the other hand, there are reports of titanates with CCZNarmalcolite composition, but which represent XRD-documented high-Ti loveringite, a mineral of the
crichtonite group (Lorand et al., 1987;Wang et al., 1999).
Normalising published analyses of “CCZN-armalcolites” and Ti-rich loveringites to A=1, according
to the general formula AMxOy, where A represent large cations and M small ones, one obtains a consistent
array placed at higher M/O ratios than armalcolite in the M vs. O plot. The plot is not essentially influenced
by the Fe valence considered. This would result in even higher (A+M)/O ratios and proves inconsistency of
“CCZN-armalcolite” compositions with an armalcolite formula. As compared to armalcolites, “CCZNarmalcolites” either display a denser overall metal coordination, or a certain degree of AO_ substitution, or
both. Along the mentioned array, the plotted analyses tend to concentrate in well-defined clusters, extending
over a wide range of A/M (or A/O) ratios, thus indicating that “CCZN-armalcolite” rather represents an
artificial heading under which several different mineral phases have been inadvertently packed. High-Ti
loveringites proven by diffraction plot well along the array, either in the cluster around the theoretical
AM21O38 crichtonite point, or in a cluster immediately adjacent to it. The cluster containing the largest
number of analyses plots, however, around the AM16O30 point.
Considering that mantle titanates basically display three structural types, namely a pyrochlore-type
lattice, channelled close-packed structures related to hollandite, and close packed ones with large cations
substituting in some anion positions, the A/M ratio would indicate the last mentioned type for a compound
with formula AM16O30. By analogy with similar groups like magnetoplumbites and crichtonites, the basic
modules of the lattice would consist of: (a) layers with a large cation site similar to that in perovskite (CCP)
or to that in BaTiO3 (HCP), surrounded by ternary bracelets (Moore, 1973) of octahedral clusters with
trigonal symmetry, close packed with (b) structurally matching octahedral-tetrahedral layers which do not
contain large cations. The best fit for the formula is given by a structure consisting of double layers which
contain perovskite-type A sites surrounded by clusters consisting of three octahedra, joined by an additional
octahedron (AM8O14), that alternate with double layers containing the same octahedral pattern, joined by
tetrahedra (M8O16). The corresponding unit cell has a trigonal symmetry R(-3), is based entirely on a CCP
stacking and contains 16 close-packed octahedral layers. Considering a layer thickness of ca. 2.3 Å, the
resulting cell parameters are approximately ahex=5.98 Å, chex=36.8 Å.
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EVIDENCE FOR A NEOPROTEROZOIC FORELAND BASIN
AT THE SOUTH-WESTERN MARGIN OF BALTICA
Antoneta SEGHEDI1, Gheorghe OAIE2, Magdalena IORDAN1 & Marioara VAIDA1
1
2
Geological Institute of Romania, 1 Caransebes st., RO-78344, Bucharest 32 Romania (e-mail: [email protected])
National Institute of Marine Geology and Geoecology, 23-25 Dimitrie Onciul St, RO-70318, Bucharest, Romaina
Key Words: Foreland basin, Turbidites, Moesian Platform, Pre-Dobrogea Depression, Moldavian Platform, Vendian.
Midfan and distal turbidites of Histria Formation (HF) exposed in an uplifted block of the
Moesian Platform accumulated in the inner part of a foreland basin (Oaie 1999), as suggested by
following evidence: deposition as deep water turbiditic fans in a basin floored by continental crust;
location north of the northward vergent Neoproterozoic thrust wedge, preserved in the subsurface of
South Dobrogea; a southerly located source area, indicated by paleoflow directions; great thickness
of the succession (5000 m, as estimated from geological and geophysical data); overall upward
coarsening facies association suggesting northward progradation of the source area; coarse member
composition indicating both older continental crust, as well as volcanic arc input (such source area
composition characterise continental margins dominated by active volcanic arcs); mixed sandstone
petrofacies, suggesting sediment recycling (due to secondary, intrabasinal sources, represented by
submarine highs related to thrust fronts); longitudinal sediment transport, frequent in foreland
basins; deformation of the basin fill at 570 Ma (K-Ar WR) in very-low grade metamorphic
conditions by northward verging, E-W trending open folds.
Geological and geophysical data suggest that the depositional basin was floored by
heterogeneous continental crust, made up of Middle Proterozoic metamorphic rocks (Altin Tepe
Group) and by the Palazu Mare BIF. The southerly located active continental margin was probably
the northern coast of Vendia with its Cadomian volcanic arc. The former was composed of gneisses
and BIF, similar to those involved in thrusting. This is in good agreement with zircon provenance
data that indicate an older, Svecofennian Baltican and Grenvillian age of the source area (1.5 Ga
and 1.0-1.2 Ga, Zelazniewicz et al. 2001). The Late Proterozoic-Early Cambrian age of sediments is
documented by palynological assemblages, as well as by a medusoid imprints (Nemiana simplex
Palij) identified in the fine grained members of HF. Considering the HF the oldest, proximal
member of a foreland basin succession, its shallow water counterparts should be found in areas
located to the north.
Along the southern margin of the EEP and overlying a Proterozoic basement (granitoids and
diorites), a 2000 m thick Vendian succession is known from boreholes in the subsurface of the PreDobrogea Depression (PDD). Its Vendian age is indicated by the presence of Vendotaenia antiqua
Grujilov. The Avdarma Series represents an upward coarsening and shallowing sequence of finegrained marine sediments, which grade upwards into continental red clastics (Neaga & Moroz
1987). Black shales rich in phosphate nodules are common.
West of the Ukrainian Shield, in the Moldavian Platform, the Vendian succession dated on
Nemiana simplex Palij directly overlies the Upper Riphean Cosauti Sandstone. In boreholes, the
Vendian succession (about 350 m thick) contains Vendotaenia antiqua Grujilov. The Vendian is an
upward coarsening sequence of red and purple mudstones and fine-grained sandstones-siltstones,
topped by sandstones. Similar to the PDD, black shales with phosphate nodules are interbedded,
indicative of shallow water depth and cold currents.
Various evidence suggest that the Vendian successions from the margins of Moesia and East
European Platform might represent distinct parts of the same large foreland basin, located in cold
climate at aproximately 60o south latitude and floored by Baltican crust. The northward decrease in
basin depth is acompanied by development of upward coarsening and shallowing sequences in the
external parts of the basin and by decrease in intensity of deformation. Various parts of the basin
were subsequently displaced along large-scale crustal faults during translations related to the
formation of the Alpine belts.
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NEW INVESTIGATION METHOD OF NATURAL SLIDING RISK
IN MATASARI AREA - JILT COAL BASIN
Florica STROIA1, Ion STOICAN2, Dumitru ION1, Marius MOCUTA1
1
University of Bucharest, Faculty of Geology & Geophysics,1,N.Balcescu Ave.,sect.1,RO-70111,Bucharest, e-mail:[email protected]
2
Diplomat Engineer in Geology, National company for Lignite "OLTENIA"
Key words: fine loose sediments; coal's mechanical stiffness; sliding risk map.
The hills "Dragotesti" and "La Rupturi" are contiguous to Matasari town, located to the half
distance between Motru and Tg.Jiu and there are belonging to Getic Plateau relief.
Geologic ages of the sediments are Dacian, Romanian and Quaternar. There are fine loose
sediments: clays with sand and coal intercalation. The geological structure consist on a succession
of anticlines and sinklines with small flanks bending angles: 2-3 0 to maximum 50.
The first step to evaluation of natural sliding risk was a total estimation considering the
slope equilibrium in context of simultaneous action of divers features: lithologic, geomorphologic,
structural, hydrographic and climatic, hydrogeologic, seismic, anthropic.
Starting from the potential and probability of sliding risk it was computed a global
coefficient (Marghidanu,1998) whose value is 0,40. That means a medium towards high sliding
probability.
Map with equal slope surface zoning, made by computer from the whole area was another
possibility to evaluate the sliding risk. Surfaces are representing in different colors, each of them
corresponding to a certain slop angel associate to the suitable risk.
In the sedimentary unconsolidation rocks succession, with sliding vulnerability, the lignite
levels are in contrast because they're high stiffness. A main set and a cosset of fissures affected
coals, bought with quasyvertically joint surfaces. As a result the thin coal layers are ease to carry
away in slope sliding even on rainless seasons. We define as "minimum resistance surface" the
surface make through joining the points in there drills are encountered the first lignite layer.
There did make, by computer, tridimensional images with the topographic surface;
isobathic map on minimum resistance surface; isopahite map with the sediments resting above those
surface; map with slope tendencies. Finally by superposing all those it was made the sliding risk
map. All of them are concerning with field elevation and drilling data made before coal exploitation
is developed. The prognosis result is confirmed by recent field investigation.
RECENT MICROFAUNA OF THE DANUBE DELTA SEDIMENTS
- PALEOENVIRONMENTAL SIGNIFICANCE Marius STOICA
University of Bucharest, Faculty of Geology & Geophysics,
1, N.Balcescu Ave., sect.1, RO-70111, Bucharest,
e-mail: [email protected]
Key words: Recent, fresh and brackish water, Ostracoda, Paleoecology.
These paper present for the first time a micropaleontological association from recent
sediments of Danube Delta. The material came from short cores extracted from main lakes of
Danube Delta and samples from surface sediments of deltaic and littoral systems.
The microfaunistical assemblage is dominated by ostracods that are the best microfossil for
reconstruction of fresh and brackish paleoenvironments. In the studied samples ostracods are
associated sometimes with foraminifers, gastropods, bivalves, bryozoa, fish tees and bones, otoliths
and characea oogons.
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The micropaleontological analysis allows us to separate two types of faunas that are
dependent of palaeoenvironment, the salinity being the most important factor: a fresh water fauna in
the upper part of sediments and a brackish fauna in lower part. The fresh water fauna is dominated
by Cypridacean ostracods that belong to Candona, Cypridopsis, Hetrocypris, Eucypris, Cypria,
Cyclocypris, Ilyocypris and Darwinula genus. In the brackish fauna the Cytheracean ostracods with
species of Cyprideis, Leptocythere, Heterocythereis, Loxoconcha, Xestoleberis, Pontocythere and
Paracytherois genus are dominant.
Based of facies fossils we can restore with great precision the salinity of the sedimentary
paleonvironment that permitted us to reconstruct the evolution of deltaic system.
ELECTROGRAPHY: A NON-DESTRUCTIVE METHOD TO INVESTIGATE
THE RELATIONSHIPS BETWEEN MINERALS, ROCKS AND FLUIDS
Dan SVORONOS1, Aneta BALABAN2, Adrian NICOLESCU1
1. Geological Institute of Romania, 78344 Bucharest, 1 Caransebeş st, E-mail: [email protected]
2. Prospectiuni S.A., 78344 Bucharest, 1 Caransebes nr. 1
Key Words: Electrographic images, Electoluminescence, Electrical structures, Water, Pores morphology
Introduction
Electrography is one of the most adequate non- destructive technique for the investigation
of the internal structure/ texture of a large category of samples (biological , mineral, rock).
The aim of this paper is to present basic data regarding the problems of interpreting the
bright manifestations of the minerals and rocks in relation with water or other liquids, investigated
by this method.
Short presentation of the method
The device (Petroelectrograph II) is the monoimpulses electric generator, with values of the
tension between 8 and 55 kV, 2500 Hz ( the reference frequency) and 0.2 ms duration of the
obtained impulse. The impulse (mono) is applied on a capacitor, created between the rock sample
and the electrode. The electrode can have a positive or negative charge. As a result, in our system a
positive or negative impulses can be used to produce corresponding positive or negative outputs and
images.
The working device of this technique consists in putting a special film, AZOIX-RXR-2, blue
sensitive, on a dielectric surface (glass) in direct contact with the under bottom of the analyzed
sample and placing this “sandwich” in electrical circuit of the device.
Electrography principle
Our research with many types of minerals (micas, granular and fibrous large gypsum,
quartz), rocks in geometrically cut forms or modeled clays, in relations with different fluids (pure or
mineralized water, oil) has partially emphasized a very spectacular aspect, similar to the images
with “the Kirlian aura ”( the images by special technique, of the radio- frequency electric fields).
The recorded effects are the result of some complex phenomena .The image analysis carried was
out using the computer. The luminescent impressions (the samples aura) express the characteristics
of the pore morphology and the mineral/rock-fluid relationship in connection with very fine
chemical peculiarity and volume of fluids.
The images (anode / cathode electric discharge – graphic images) can be ranked in the
following way; from the viewpoint of “luminescent aura amplitude” and streamers’ morphology
for each group of minerals or rocks, characterized by an ionic conductivity.
Summary of the results and conclusions
The outlined streamer patterns mainly reflect the energetic equilibrium ratio between the samples and the surrounding environment.
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The investigations point out the following aspects: mineral/rock-water-air relation in the
process of infiltration/ex-filtration; laminar flow in porous media; quality of a collector for fluids;
quality of water solution in minerals and rocks.
We may add the following conclusions:
 The electrography for rocks (petroelectrography) does not imply the destruction of
the rock samples;
 The petroelectrographic images are related to the free water (or various fluids)
content and to the physically weak linked water in the rock pores.
GYPSUM IN RELATIONSHIPS WITH FLUIDS: ELECTROGRAPHIC IMAGES
Dan SVORONOS 1, Aneta BALABAN2, Adrian NICOLESCU1
Geological Institute of Romania, 78344 Bucharest, 1 Caransebeş st., E-mail: [email protected]
2
Prospectiuni S.A.,78344 Bucharest,1Caransebes st.
1
Key Words: Electrographic images, Electoluminescence, Electrical structures, Water, Pores morphology
Introduction
The variable porosity of the gypsum samples are considered the best to spotlight the
relationship between rocks and fluids.
Our contribution to prove this process is based on the electrographic technique – a nonconventional analysis method.
Technical aspects of the experimental investigation
Laboratory standard conditions: temperature 25020 C; temperature of solution l8020 C;
atmospheric pressure: 76o mm Hg.
The samples typology:
 granular gypsum: mono-mineral rock ;
 fibrous gypsum : mono-mineral rock;
 gypsum-powder: mineral association – gypsum-anhydrite-quartz-argillaceous
minerals-chlorite; chemical specific of sample CaSO42H2O–
95,15 %; SiO2 – 1,02 %; Al2O3 – 0,45%.
The solution used was de-ionized water, and sometimes another fluids (NaOH, HCl, in
various concentrations).
The device used (Petroelectrograph) is mono-impulses generator characterized by variable
tension varying 8-55 kV, the reference frequency 2500 Hz and 0,2 ms duration of impulse.
Results
Electrographic images recorded on the film (AZOIX-RXR-2) suggest a clear relationship
between the rock structure/texture and contained fluids.
The dried samples showed not streamers “aura”. A presence in images of a very large
streamers “aura” is equivalent to a strong saturation in fluids and a significant porosity. The
morphology of the streamers is dependent on the pores morphology and the geochemical feature of
the used rocks and fluids. The perturbation in the obtained images, dried samples or fluids saturated,
represent the migration velocity of the fluids, a process dependent on many parameters. There have
been obtained by each experiment two images: positive and negative (values of the electric field).
Usually, the positive images are analyzed by color-trace-mode (with linear or arbitrary color
variation). With help of a computer, such as in our own methodology, many unseen details have
been revealed. The difficulty in interpreting the electrographic images taken into account is
represented by the control of the quantity of received/given water by the rock during the
experiment.
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Conclusions
In this study we presented the migration of the fluids in rocks using the method operating in
the image domain. The following aspects have been investigated:
 the process of infiltration of fluids in gypsum;
 the relationship between samples and acid/basic fluids.
Our method is based on the special non-conventional technique.
A PROPOSAL FOR A GEOCHIMICAL MAP OF ROMANIA
Constantin SUCIU, Ion IONEL, Dorina IONEL, Adrian BIŢA
S.C. PROSPECŢIUNI S.A., 1 Caransebeş St., 78344 Bucharest, Romania
E-mail: prospec1 sunu.rnc.ro
These days pollution problems national priorities in the world, as well as the necessity of
base metal contens knowledge in environment, determined many countries or international
organizations to promote regional geochemical mapping programs.
These maps illustrate the distribution in surface, in different sampling targets, of different
metals with economic concentration or environmental value very useful in the following domains:
 petrogenetical districts limitation, with low elementary variability, from
metallogenetical districts with high natural variability;
 rich content heavy metals values zones limitation caused by pollution;
 useful base data for epidemic statistic studies conceming some degenerative human,
animals or crops diseases.
 In the last decade the envinmental protection and rational utilization concept, as a
fundamental component of development projects, was determined on a national and international
level. Thus, to adopt the scientfic fundamental measures for lithosphere and hydrosphere protection,
UNESCO and UNEP promoted two interdisciplinary projects:
 The protection of lithosphere as an envinment component (1979-1984)
 Geology
and
environment
(1984).
The major conclusion of the projects is that the environment utilization has to control the
geological atlases and maps on various scales (Austria, Finland, Norway, Germany, United
Kingdom, Sweden etc.). Unitary projected, those reserches followed many elements or components
in differet targets (rocks, soils, superficial and underground waters, stream sediments from riovers
and lakes, or vegetation), at sampling scales to cover largest part or entire teritory of a country.
Generally, the regional geochemical maps elaboration was coordinated in the last decade
by the European Geological Reserch Forum (FOREGS), by a special domain works froup (RGM).
This group elaborated a three-year (1988-1990) project for drawning up regional geochemical maps
by using a low density of collecting samples. This program objectives were to prepare elaboration
of a regional geochemical maps set for the whole Westwrn Europe and to establish the limits of
using only the samples from sediments to working out these maps.
Although our program for drawning up regional geochemical maps, is not yet integrated in
the European institutions, the achievements are, at least, noteworthy. During six years, there were
collected from an about 5,800 sq. km area a number of 23,500 soil samples, 8.750 roks samples,
3,852 samples from the fine fraction of the present sediments, 3,250 plant samples and 1,340
samples from springs and active water flows.
All the samples were analyzed for 20 elements by spectral methods (in emission,
absorbtion or plasm I.C.P.), and the data were interpretated according to apllied geochemistry
criteria. Using heavy metals values, the maps of their distribution in the sample media were drawn
up.
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The field working methods were based on the recomandations of Lowering et al. (1950),
Rope, Howks and Weeb (1981), garrett and Nichol (1967), Grigorion and Bens (1967), Morozov
and Sokilov (1981), concering sampling representativity and reproductibility aspects. The data
obtained as a result of heavy metals distribution processing and comparison on sampled areas are
extremely suggestive and important for the further regional geochemical maps drawning up
programs.
Thus, the following were established:
- the main mineralized and potentially mineralized areas were delimited, using
lithogeochemical, pedogeochemical and stream-sediments samples;
- the contaminated areas were outlined, mainly by mising work, using stream-sediment and
water samples;
- the plants biogeochemical changes, due to theexcessive presence of some heavy metals,
were performed;
- the plants biogeochemical migration aspects, in different media, of some noxious metals
(Pb, Cd, As) could be compared;
- an optimal, strict and efficient methodology for elaboration of a geochemical maps atlas for the
whole Romanian territory was estabilished.
MINERAL REACTIONS ON KYANITE IN ECLOGITES
FROM THE PORTILE DE FIER UNIT
Marin ŞECLĂMAN, Gelu COSTIN, Anca LUCA, Péter LUFFI
University of Bucharest, Faculty of Geology & Geophysics
1. Bălcescu Blvd., sect.1, RO-70111, Bucharest, e-mail: [email protected]
Keywords: eclogite, kyanite, symplectite, coronitic texture, metasomatic reaction, melt, incongruent crystallization, Portile de Fier Unit
Kyanite crystals from the eclogites of Porţile de Fier Unit are frequently replaced by various
mineral phases forming coronitic textures. Substitutions have been realized by capturing of ionic
groups by the kyanite according to the following reaction:
Kyanite + Mn+ + n(OH)-  B  H2O,
where Mn+ = Ca2+, Mg2+, Fe2+, Na+, K+, Si4+ and B symbolize the phases formed on the kyanite.
Water formed by this reaction may be preserved as inclusions in the B phases or expelled. The most
important reactions are:
2Kyanite + Ca2+ + 2(OH)-  Anorthite + Corundum + H2O
(1)
Kyanite + Ca2+ + Si4+ + 6(OH)-  Anorthite + 3H2O
(2)
2+
2+
2+
2Kyanite + Ca + (Mg , Fe ) + 4(OH)  Anorthite + Spinel + 2H2O
(3)
+
4+
Kyanite + 2Na + 5Si + 12(OH)  2Albite + 6H2O
(4)
Kyanite + 2K+ + 5Si4+ + 12(OH)-  2Kspar +
(5)
+
4+
3Kyanite + 2K + 3Si + 14(OH)  2Muscovite + 5H2O
(6)
+
6Kyanite + 2K + 2(OH)  2Muscovite + Corundum
(7)
3Kyanite + 2K+ + 6(Mg2+, Fe2+) + 14(OH)-  2Biotite + 2Corundum + 5H2O
(8)
+
2+
2+
3Kyanite + 2K + (6+n)(Mg , Fe ) + (8+n)(OH) 
 2Biotite + Spinel + (n)Corundum +(4+n)H2O (9)
Kyanite + K+ + 3(Mg2+, Fe2+) + 2Si4+ + 14(OH)-  Biotite + 6H2O
(10)
The assemblage anorthite+corundum±spinel+H2O is certainly formed at high temperatures.
In some cases reaction (1) may be coupled with the zoisite breakdown reaction:
2Zoisite + 2Kyanite  Anorthite + Corundum + H2O
The equilibrium of this reaction has a positive slope in the P-T field, above an invariant
point at 700°C and ~9Kbars. By cooling, the assemblage anorthite+corundum+H2O should break
down to margarite. However, in absence of the necessary water this reaction occurs rarely.
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At crystal-scale, all the above-described reactions are metasomatic, implying a ~30% volume
increase for their solid terms. The source of the ions involved in the reactions (2) to (10) is very
likely a hydrous silicate melt. These reactions are believed to describe an incongruent crystallization
from a hydrous liquid: Liquid(1) + Solid(1)  Liquid(2) + Solid(2), with Vr=0.
The final crystallization leaded to the forming of an amphibole-plagioclase symplectite, reducing
significantly the activity of water. Therefore the metastable preservation of the assemblage kyanitefeldspars-corundum-spinel became possible.
GRANITOIDE INTRUSE ÎN COMPLEXUL BAZIC DIN VALEA CUMPĂNA
MINERALOGIE ŞI POSIBILE SEMNIFICAŢII GENETICE
Mircea TOPÂRCEANU (anul III)
Îndrumător: Lect. Dr. Gelu COSTIN
Corpul granitoidic (granite, granodoirite), cu aspect pofiroid, apar intruse în rocile
metamorfice bazice (amfibolite cu granat, meta-gabbrouri) din bazinul Văii Cumpăna (M-ţii
Făgăraş).
Lucrarea prezintă date preliminare privind mineralogia acestor granitoide, succesiunea
posibilă de cristalizare magmatică precum şi tipurile de transformări subsolidus.
Deformarea penetrativă a acestor corpuri (dezvoltarea unui fabric liniar – planar) precum şi
tipurile de transformări subsolidus, arată o punere în loc a granitoidelor în condiţii PT de stabilitate
a granatului, apoi o evoluţie post răcire şi depresurizare (biotit crescut pe granat, pertite de exsoluţie
controlate de deformare, pertite de substituţie, myrmekite). Evoluţia asociată depresurizării estimăm
că este comună cu cea a complexului bazic.
Geneza magmelor granitoidice este presupusă a fi legată de procesele sincolizionale
hercinice.
THE ESSENTIAL ROLE OF THE VALACH CLIMATIC CYCLE (4,1 M.Y.)
IN THE OCCURRENCE AND DEVELOPMENT OF THE SENONIAN AND
CAINOZOIC COAL FACIES IN ROMANIA
Mircea TICLEANU1, Nicolae TICLEANU2, Paul CONSTANTIN1,
Simon PAULIUC1, Florian MARINESCU2
1 - Geological Institute of Romania, 1 Caransebes street, 78344 Bucharest; E-mail: [email protected]
2 - Faculty of Geology and Geophysics, Bucharest University1 Blvd. N. Balcescu, 70111 Bucharest; E-mail: [email protected]
Key words: Valach climatic cycle, coal facies, generating coal stages, Quaternary glaciation, Senonian, Cainozoic, Romania.
The detailed study of Pliocene coal facies from the western side of the Dacic Basin leaded to
the idea of a climatic cycle ("The Valach Cycle" - nom. nov., Praga, 1998, M. Ticleanu et al.), with a
period of about 4,1 m.y., responsible for the Neogene coal complexes occurrence. The warm periods
of this climatic cycle, due to the same possible pulsations of the Solar system (named "Valach
pulsations") leaded to the appearance of the coal facies. The cool periods were not favourable for
these, the last cool period of the Valach cycle practical corresponding to the Quaternary glaciation.
The analyses of coal bearing Palaeogene formations from Romania allowed to distinguish
other three distinct generating coal stages. Thus, from Uppermost Eocene to Pliocene one can notice
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the following generating coal stages: 1) Priabonian-Lowermost Rupelian; 2) Middle Rupelian; 3)
Lower Chattian; 4) Uppermost Chattian; 5) Middle Burdigalian; 6) Badenian; 7) Middle Sarmatian;
8) Middle Pontian; 9) Pliocene (Upper Dacian- Lower and Middle Romanian). All these can be
illustrated by the coal deposits from Romania.
Considering the Thanetian generating coal stage (Uppermost Palaeocene from Paris and
Pannonic basins), we could approximate the stratigrafical levels of the other four Eocene generating
coal stages (illustrated by the coals from Western Europe and Russian platform): Ypresian, Lower
Lutetian, Upper Lutetian and Bartonian. The characteristic features of the first two generating coal
stages (Ypresian and Lower Lutetian) are the great thickness of the coal layers but their smaller
extension and, for the last two stages (Upper Lutetian and Bartonian) are the coal layers with smaller
thickness but a large extension.
The period of the Valach cycle is confirmed by the stratigraphical position of the Senonian
generating coal stages from Rusca Montana, Rosia and Vad-Borod basins. We could notice only
one generating coal stage (Santonian developed in Vad-Borod Basin) versus two generating coal
stages (Lower and Middle Maastrichtian developed in Rusca Monta and Rosia basins). Other
Campanian generating coal stages are known from the Rhone Basin. Three stratigrafical levels
between Middle Maastrichtian and Thanetian might be illustrated by generating coal stages (Upper
Maastrichtian, Lower Danian and Selandian) but these seem to be hidden by the superposition of a
strong cool period of another cycle, superior in order one (the Galactic Cycle).
This data permitted us to appreciate that the Valach cycle can be justifed, through the
alternance of coal facies with cool periods, on a span of time of about at least 86 m. y.
ASOCIATIA DE SPONGIERI JURASICI
DIN VALEA CHECHIRGEA (DOBROGEA CENTRALA)
Daniel UNGUREANU (anul III), Eugen BARBU (anul IV)
Îndrumător: Prof. Dr. Aurelia Barbulescu
Lucrarea de fata este o continuarea a studiului nostru realizat in Valea Chechirgea si
prezentat cu ocazia celui de-al III – lea Simpozion National al Studentilor, Iasi 18 – 20 aprilie 2002.
Vom urmari aceleasi criterii de analizare a distributiei spongierilor:
a) criteriul dimensional, morfometric – studiu static pe exemplare complete (observatii in situ si pe
material colectat) si fragmente recuperate – rezultatele studiului bazate acest criteriu vor fi
exemplificate prin material ilustrat;
b) criteriu taxonomic – statistic;
Vor fi prezentate rezultate obtinute cu ocazia ultimei deplasari de pe teren; continuarea
studiului din punctul ramas pina la Valea Scrofeni, Valea Cumpana;
Vom evidentia trecerea de la faciesul de spongieri la faciesul de corali, cu urmarirea
genurilor si modului in care se face aceasta trecere.
De asemenea, vom incerca elaborarea unui model matematic de incadrare sistematica luind
in calcul diversi parametri cum ar fi: densitatea porilor, dimensiunile exemplarelor complete
(inaltime, dimeniunea osculului, grosimea peretelui) etc.
Localizarea pe afloriment prin realizarea unei schite cit se poate de complete in punctele in
care abundenta spongierilor sau diverse relatii paleoecologice sint mai evidente.
Completarea graficului de distributie a genurilor de porifere si a tabloului sistematic.
CLAY FRACTION OF ARGILLIC BROWN SOILS
FROM THE PIŞCHIA AREA, TIMIŞ COUNTY
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Stela URUIOC
Banatului University, Timişoara
This paper presents a study concerning the mineralogical composition of argillic brown soils
clay fraction from the Pişchia area. The soil horizons samples were analysed in the polarising
transmission microscopy, electron transmission microscopy, infrared absorption spectroscopy, and
X-ray diffractommetry. The clay minerals identified in the clay fraction of these soils were smectite
(montmorillonite), illite and kaolinite. The quantitative variations of the clay minerals (illite,
illite/smectite, smectite, illite/chlorite, chlorite/smectite, kaolinite) along the entire profile may have
been caused by the initial non-uniformity of the parental material and by pedogenetic processes, as
well.
STRUCTURA DEPOZITELOR PALEOGENE SI MIOCEN INFERIOARE DIN NORDUL
BAZINULUI TRANSILVANIEI DEDUSA DIN DATE SEISMICE
Iuliana VASILIEV (masterand)
Acest studiu isi propune interpretarea geometriei depozitelor paleogene si miocen inferioare
din cadrul Bazinului Transilvaniei. Au fost folosite 24 de sectiuni seismice de reflexie si date din 23
de sonde sapate in zona studiata.
Datorita calitatii exceptionale a sectiunilor seismice a fost posbila separarea diferitelor
formatiuni din cadrul intervalelor de timp studiate. Pentru Eocen au putut fi separate Formatiunea
de Jibou, Formatiunea de Racoti, Formatiunea de Turbuta. In cadrul Oligocenului au fost urmarite
Formatiunea de Ileanda si de Valea Carelor. Miocenul se distinge prin Formatiunea de Hida si
Formatiunea Tufului de Dej.
Din interpretarea sectiunilor seismice reiese faptul ca, in Bazinul Transilvaniei, exista
structuri si discordante importante la toate nivelele stratigrafice. Aceste structuri si discordante sunt
concomitente cu structurile si discordantele din intreaga arie carpatica. Acestea au influentat
morfologia bazinului, natura depozitelor sedimentare si extinderea lor.
Acestea sunt concluziile preliminare ale unui studiu mai amplu care se va materializa in
realizarea lucrarii de dizertatie.
TRANSFORMARILE MINERALOGICE OBSERVATE IN SONDA K 8,
IN PROCESUL COMBUSTIEI SUBTERANE
A HIDROCARBURILOR, SUPLACU DE BARCAU
Viorel - Eugen VASILIU
Oil and gas University of Ploiesti, 28 Bucuresti Ave., ro-2000.
The paper reviews the main mineralogical transformations that could be detected by optical
microscope analyses, X-ray analyses, electronic microscopy and spectral analyses. It could be thus
noticed, by a parallelism with the data obtained from the cores taken of well 474, a pronunced
diminishing of the calcite content, argillization processes of the feldspars, the creation of a real
fracturing system, aragonite disappearance, montmorillonite transformation in illite and micas as
well the occurence of new minerals as wollastonite, wairakite and scapolite in K 8 well.
It must be also mention the organo-minerals presence, the thread-shaped "semi-coke" forms.
STRIKE-SLIP FAULT SISTEMS IN THE CRYSTALLINE-MESOZOIC ZONE EAST CARPATHIANS (ROMANIA)
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Societatea Geologică a României - www.geo.edu.ro/sgr
GEO-2002 – Sesiunea ştiinţifică anuală, 24-25 mai
Alexandru VODA
PROSPECTIUNI S.A., 78.344-Bucharest, 1 Caransebes st., E-mail: [email protected]
The Crystalline-Mesozoic Zone (East Carpathians) is limited at south by a very important
strike-slip fault – the South Transylvanian Fault, which opposes the Garbovei crystalline rocks
from Persani Mountains and the crystalline rocks from North-East Fagaras Mountains. The
Garbovei crystalline rocks form the basement of a frontal ramification of the Bucovinic Nappe
and the eastern edge of the Fagaras Mountains contains Austrian and Mediterranean structural
units from South Carpathians.
The Crystalline-Mesozoic Zone of Eastern Carpathians is crossed from Vladeni gorge up
to the northern border of Romania, by lots of strike-slip faults as follows (named from north to
south): Vaser Fault, Dragos Voda Fault, Crucea-Zugreni Fault, Darmoxa-Grinties Fault, North
Persani Fault, Garbova Fault.
A geotectonic analysis including evidence from the western side, under the post-tectonic
sedimentary deposits of the Transylvanian Basin, offers an interpretative model in which the
mentioned faults form two systems of strike-slip faults:
a) the senestral strike-slip fault system connected to Dragos Voda Fault
b) the dextral strike-slip fault system formed by the Persani Mts. faults connected to the
South Transylvanian Fault.
The Vaser Fault limits the Vaser crystalline at SSE, the Miocene retro-overlapping from the
Maramures Mts. north and Southwards of Black Flysch from the Crystalline-Mesozoic Zone border.
South-westwards it is connected with Dragos Voda Fault and is senestral.
The Dragos Voda Fault is an EW one and continues the transcrustal Bogdan Voda Fault,
limiting southwards the Rodnei Mountains elevation. Eastwards of Carlibaba is difficult to be
marked. The moderate effects of strike slip between Carlibaba, Tatarca and Breaza suggest its
continuity south eastwards of Ciocanesti, then on direction of Crucea-Zugreni Fault up to
Brosteni.
The Crucea-Zugreni senestral Fault, followed northwards of Lesul Ursului Mining Field,
divides tectonic entities with different compositions and structures. Its correlation with BogdanDragos Voda Fault gives sense to the Rodnei Mountains and Bistritei Mountains structure.
The Darmoxa-Grinties Fault and its possible prolongation southwards of Rodnei Montains
to Preluca Mountains, limited, northwards up to Dragos Voda - Bogdan Voda – Borsteni Fault, the
tectonic compartment of Rodnei Mountains and the southern side of Bistritei Mountains, striked
eastwards.
The North Persani Fault is deduced as the northern limit of an area covered by a upper
Aptian post-tectonic cover. By geophysical data it continues westwards under the sedimentary
deposits of thr Transylvanian Basin, marking the magnetic anaomaly decreasing southwards of
Tarnava Mare River.
The North Garbova Fault, in southern part of Persani Mountains, put in contact Garbova
ramification of Bucovinic Nappe with Transylvanian Nappes from Persani Mts., by eastwards
movement of the northern compartment.
STRUCTURAL FEATURES USED IN THE MAPPING OF METALLOGENIC FIELDS
FROM CRYSTALINE-MESOZOIC ZONE OF EAST CARPATHIANS (ROMANIA)
Alexandru VODA
PROSPECTIUNI S.A., 1 Caransebes st.,78.344-Bucharest, E-mail: [email protected]
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Societatea Geologică a României - www.geo.edu.ro/sgr
GEO-2002 – Sesiunea ştiinţifică anuală, 24-25 mai
The metallogenic studies on large scale impose as obligatory the analysis of geotectonic
context from major structural unit, where the mineral ores exist. Taking into account the main
elements which define the metallogenic frame –mineralization type, mineralogical definition,
geochemistry, deposition type, place and timing – is difficult to correlate global metallogenic
provinces.
The synthesis of Crystalline-Mesozoic zone from East Carpathians evidenced that the
structural elements which bound singenetic pre-alpine ores on major scale are: (a) in deep – nappe
surface , (b) in length – strike sleeping faults. The major strike sleeping faults explain the
interruption of Balan, Lesu Ursului and Fundu Moldovei metallogenic fields. The connection
between the mineralized zoned areas and their ultimate geotectonic evolution is evident for alpine
epigenetic ores (barite, base metal, uranium etc.). The barite ore (Ostra type) and the uranium ore
(Crucea type), in opposite geotectonic context, but in the same external side (eastern) of protoBucovinic Realm – the generator of the Bucovinic Nappe frontal ramifications, offer the best
example.
The correlations between some ores from the Crystalline-Mesozoic zone of the Eastern
Carpathians and similar ones from the South Carpathians are suggestive. For example, the base
metal ores from Muncelu Mic of crystalline Pades Group could be correlated with the ones from
Lesu Ursului if the pre-alpine Putna unit would be accepted as a correspondent of Gladna unit from
Poiana Rusca Mountains and the Rodna unit would correspond with Hunedoara Nappe (in
limestones from Fagaras Group from Fagaras mountains lead-zinc mineralizations Blaznei type
exist).
The base metal ores from the East Carpathian Crystalline-Mesozoic zone Tulghes Group
could be correlated with the Gemerides East Carpathians Smolnic ones, each ones in opposite
structural position on the Major Tethysian suture. This correlation suggests that the Transylvanian
Tethys spreading crosscut some pre-alpine metallogenic unitary zones.
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