A reassessment of the timing of early Archaean crustal
... of similar gabbroic samples yield an isochron age of 3677 ± 37 Ma, and (3) a volcanogenic Akilia Association schist was dated at 3685 ± 8 Ma with the U-Pb ion-probe method. The combined age of c. 3.67–3.68 Ga is in direct conflict with the interpretation of U-Pb zircon age spectra of younger, cross- ...
... of similar gabbroic samples yield an isochron age of 3677 ± 37 Ma, and (3) a volcanogenic Akilia Association schist was dated at 3685 ± 8 Ma with the U-Pb ion-probe method. The combined age of c. 3.67–3.68 Ga is in direct conflict with the interpretation of U-Pb zircon age spectra of younger, cross- ...
Qal Alluvium - Deposits of sand and gravel with lesser...
... Interlayered mafic and felsic gneiss - Northern unit. White to very light gray, medium to finely crystalline felsic gneiss with serate texture. Felsic gneiss composed of feldspar, quartz, and muscovite. Mafic gneiss is dark greenish-gray to greenish-blaccomposed of hornblende and feldspar. Correlati ...
... Interlayered mafic and felsic gneiss - Northern unit. White to very light gray, medium to finely crystalline felsic gneiss with serate texture. Felsic gneiss composed of feldspar, quartz, and muscovite. Mafic gneiss is dark greenish-gray to greenish-blaccomposed of hornblende and feldspar. Correlati ...
orogenesis and ore deposits
... frequently with narrower, sharper downwarpingsunder load, hencemore frequent deformation and lesslofty mountains. Observations of sediments in the Precambrian shields indicate that break-down of rocks under weathering was less complete than in later times. Deformation and igneousactivity within orog ...
... frequently with narrower, sharper downwarpingsunder load, hencemore frequent deformation and lesslofty mountains. Observations of sediments in the Precambrian shields indicate that break-down of rocks under weathering was less complete than in later times. Deformation and igneousactivity within orog ...
No Slide Title
... Precambrian Earth and Life History—The Hadean and Archean -platforms and shield areas= together make craton -early planet: volcanic, toxic gases (CO2), -Hadean geology: rare rocks preserved!! -Archaen geology: v little evidence, greenstone belts-volcanics and sedimentary rocks. -atmosphere and ocean ...
... Precambrian Earth and Life History—The Hadean and Archean -platforms and shield areas= together make craton -early planet: volcanic, toxic gases (CO2), -Hadean geology: rare rocks preserved!! -Archaen geology: v little evidence, greenstone belts-volcanics and sedimentary rocks. -atmosphere and ocean ...
Cratons, mobile belts, alkaline rocks and
... Fig. 4. Idealized sections for a frontal collision of Himalayan-type between a craton and an active margin. Relations between rigidity of the plates and depth are represented left and right of the sections respectively for the craton and the active margin at the vertical of the numbered arrows. (A) ...
... Fig. 4. Idealized sections for a frontal collision of Himalayan-type between a craton and an active margin. Relations between rigidity of the plates and depth are represented left and right of the sections respectively for the craton and the active margin at the vertical of the numbered arrows. (A) ...
3.1. GENERAL Rocks of the study area mainly belong to the
... quartzites. This rock occurs as dark coloured mass with light yellow color bands. E. Micaceous quartzite & banded hematite quartzite Micaceous quartzite occurs within the hill of Guda, Wawadi, Konchya, Chowkadi, Wawadi and Luni. Muscovite and sericite make the quartzite fissile. These phyllosilicate ...
... quartzites. This rock occurs as dark coloured mass with light yellow color bands. E. Micaceous quartzite & banded hematite quartzite Micaceous quartzite occurs within the hill of Guda, Wawadi, Konchya, Chowkadi, Wawadi and Luni. Muscovite and sericite make the quartzite fissile. These phyllosilicate ...
1551903 b853 - Institutionen för geovetenskaper
... two diamond mines in Kimberley, South Africa. It is also to find out the protolith and the age of the greenstone‐schists and amphibolites that were found in the mines. To answer that, five weeks of mapping and sampling in the Bultfontein and Dutoitspan mines owned by Petra Diamonds was performed. ...
... two diamond mines in Kimberley, South Africa. It is also to find out the protolith and the age of the greenstone‐schists and amphibolites that were found in the mines. To answer that, five weeks of mapping and sampling in the Bultfontein and Dutoitspan mines owned by Petra Diamonds was performed. ...
1 Accretion of terranes and growth of continental crust along the
... orogenic contraction and terrane accretion within the Ouachita embayment at ~309 Ma (Nicholas and Waddell, 1989). The orthogonal intersection of the northwest-striking Alabama-Oklahoma transform fault with the northeast-striking southern segment of the Blue Ridge rift outline the Alabama promontory ...
... orogenic contraction and terrane accretion within the Ouachita embayment at ~309 Ma (Nicholas and Waddell, 1989). The orthogonal intersection of the northwest-striking Alabama-Oklahoma transform fault with the northeast-striking southern segment of the Blue Ridge rift outline the Alabama promontory ...
Crustal-scale shear zones and their significance to Archaean gold
... adjacent to shallowly dipping faults or shear zones (e.g. Oroya Shoot, Kalgoorlie). More than one style may be present in a single mine/deposit. Where a stratigraphic succession has been well established (e.g. Kalgoorlie-Kambalda area), there is also a tendency for large gold deposits to be located ...
... adjacent to shallowly dipping faults or shear zones (e.g. Oroya Shoot, Kalgoorlie). More than one style may be present in a single mine/deposit. Where a stratigraphic succession has been well established (e.g. Kalgoorlie-Kambalda area), there is also a tendency for large gold deposits to be located ...
Supercontinent cycles and the distribution of metal
... between 1.3 and 1.0 Ga, but there is relatively little known associated mineralization. However, most Late Proterozoic gold mineralization is from the - 6 9 0 Ma Telfer deposits (Goelnicht et al., 1989) in the Paterson orogen in Western Australia. Other important metallogenic events are recorded in ...
... between 1.3 and 1.0 Ga, but there is relatively little known associated mineralization. However, most Late Proterozoic gold mineralization is from the - 6 9 0 Ma Telfer deposits (Goelnicht et al., 1989) in the Paterson orogen in Western Australia. Other important metallogenic events are recorded in ...
IOCG and Porphyry-Cu deposits in Northern
... Anatectic granites were formed during 1.82–1.79 Ga, during another major stage of deformation and metamorphism. Large-scale migration of fluids of variable salinity during the many stages of igneous activity, metamorphism and deformation is expressed by regional scapolitisation, albitisation and alb ...
... Anatectic granites were formed during 1.82–1.79 Ga, during another major stage of deformation and metamorphism. Large-scale migration of fluids of variable salinity during the many stages of igneous activity, metamorphism and deformation is expressed by regional scapolitisation, albitisation and alb ...
the passira anorthositic complex and associated granites
... multicrystal U-Pb zircon age of 1.70+0.02 Ga was obtained for the anorthosite (Accioly, 2000), which is interpreted as the age of crystallization. The associated granitic orthogneisses can be divided into two groups as below defined. 2.1 - Metaluminous alkalic (Sipuá Hill) granite type This type occ ...
... multicrystal U-Pb zircon age of 1.70+0.02 Ga was obtained for the anorthosite (Accioly, 2000), which is interpreted as the age of crystallization. The associated granitic orthogneisses can be divided into two groups as below defined. 2.1 - Metaluminous alkalic (Sipuá Hill) granite type This type occ ...
The Geology of Antarctica
... The Vestfold Hills (V, Fig. 2) is an orthogneiss-dominated granulite terrain that experienced its main magmatic accretion events and crust formation in the time interval 2520-2480 Ma (Black et al., 1991). An older (2520-2000 Ma) group of tonalitic orthogneisses and pyroxene granulites, and supracrus ...
... The Vestfold Hills (V, Fig. 2) is an orthogneiss-dominated granulite terrain that experienced its main magmatic accretion events and crust formation in the time interval 2520-2480 Ma (Black et al., 1991). An older (2520-2000 Ma) group of tonalitic orthogneisses and pyroxene granulites, and supracrus ...
The Precambrian rift-related metamagmatic rocks of the Southern
... We have studied mainly mafic-ultramafic sequence and partly their wall-rocks. REE abundances of these rocks are listed in Table 1. The strongly altered mafic-ultramafic rocks on the REE patterns normalized to average ordinary chondrite exhibit well-pronounced negative Eu anomaly and other characteri ...
... We have studied mainly mafic-ultramafic sequence and partly their wall-rocks. REE abundances of these rocks are listed in Table 1. The strongly altered mafic-ultramafic rocks on the REE patterns normalized to average ordinary chondrite exhibit well-pronounced negative Eu anomaly and other characteri ...
No Slide Title
... Greenstone Belts • An ideal greenstone belt has 3 major rock units – volcanic rocks are most common – in the lower and middle units – the upper units are mostly sedimentary ...
... Greenstone Belts • An ideal greenstone belt has 3 major rock units – volcanic rocks are most common – in the lower and middle units – the upper units are mostly sedimentary ...
Cratons and Fold Belts of India - ReadingSample - Beck-Shop
... Early studies on the Dharwar craton were ambiguous and controversial in regard to the status of gneisses and schistose (greenstone belts) rocks of “Dharwar System” (see review in M.S. Krishnan, 1982). In the early nineteenth century, Bruce Foote stated that crystalline granitoid gneiss was Fundament ...
... Early studies on the Dharwar craton were ambiguous and controversial in regard to the status of gneisses and schistose (greenstone belts) rocks of “Dharwar System” (see review in M.S. Krishnan, 1982). In the early nineteenth century, Bruce Foote stated that crystalline granitoid gneiss was Fundament ...
Fluid evolution within Eastern Rhodopian sedimentary rock
... minerals. Metamorphic basement rocks are generally barren, but are variably altered to sericite, chlorite, clay minerals, and pyrite-hematite assemblages in a ductile-brittle transition zone, below the detachment. However, at one of the prospects, i.e. Surnak, this transition zone is displaced to de ...
... minerals. Metamorphic basement rocks are generally barren, but are variably altered to sericite, chlorite, clay minerals, and pyrite-hematite assemblages in a ductile-brittle transition zone, below the detachment. However, at one of the prospects, i.e. Surnak, this transition zone is displaced to de ...
Cratons of the Indian Shield
... Early studies on the Dharwar craton were ambiguous and controversial in regard to the status of gneisses and schistose (greenstone belts) rocks of “Dharwar System” (see review in M.S. Krishnan, 1982). In the early nineteenth century, Bruce Foote stated that crystalline granitoid gneiss was Fundament ...
... Early studies on the Dharwar craton were ambiguous and controversial in regard to the status of gneisses and schistose (greenstone belts) rocks of “Dharwar System” (see review in M.S. Krishnan, 1982). In the early nineteenth century, Bruce Foote stated that crystalline granitoid gneiss was Fundament ...
Three‐dimensional field perspective on deformation, flow, and
... Chitradurga greenstone belt; CSZ, Chitradurga shear zone; KGB, Kolar greenstone belt; K, Kabbaldurga. ...
... Chitradurga greenstone belt; CSZ, Chitradurga shear zone; KGB, Kolar greenstone belt; K, Kabbaldurga. ...
I. Archaean specificities
... - The Acasta gneisses in the Slave province are just big enclaves in much younger rocks; - The oldest coherent Archaean block: SW Greenland (Isua Greenstone belt, Amitsoq gneisses) - Pilbara (NW Australia) and Kaapvaal (Barberton) cratons formed between 3.5 and 3.2 Ga, they are probably the next old ...
... - The Acasta gneisses in the Slave province are just big enclaves in much younger rocks; - The oldest coherent Archaean block: SW Greenland (Isua Greenstone belt, Amitsoq gneisses) - Pilbara (NW Australia) and Kaapvaal (Barberton) cratons formed between 3.5 and 3.2 Ga, they are probably the next old ...
Crustal Scale Interpretation
... Schematic Cross Section of the South American Margin (29º-33ºS) during Carboniferous to Early Triassic ...
... Schematic Cross Section of the South American Margin (29º-33ºS) during Carboniferous to Early Triassic ...
SEDIMENTARY BASINS - AN INTRODUCTION Definition of a
... Definition of a sedimentary basin: A sedimentary basin is an area in which sediments have accumulated during a particular time period at a significantly greater rate and to a significantly greater thickness than surrounding areas. (Compare with physiographic basin - a depression in the surface of th ...
... Definition of a sedimentary basin: A sedimentary basin is an area in which sediments have accumulated during a particular time period at a significantly greater rate and to a significantly greater thickness than surrounding areas. (Compare with physiographic basin - a depression in the surface of th ...
Yilgarn Craton
The Yilgarn Craton is a large craton that constitutes the bulk of the Western Australian land mass. It is bounded by a mixture of sedimentary basins and Proterozoic fold and thrust belts. Zircon grains in the Jack Hills, Narryer Terrane have been dated at ~4.27 Ga, with one detrital zircon dated as old as 4.4 Ga.