Tinos, Cyclades
... ancient ocean crust preserved in ophiolites have provided important insight into the processes of hydrothermal seawater^rock interaction occurring at oceanic spreading centers [1^4]. Typically, it is found that gabbros have N18 O values lower than that of unaltered MORB (5.7 þ 0.2x) [5,6] as a resul ...
... ancient ocean crust preserved in ophiolites have provided important insight into the processes of hydrothermal seawater^rock interaction occurring at oceanic spreading centers [1^4]. Typically, it is found that gabbros have N18 O values lower than that of unaltered MORB (5.7 þ 0.2x) [5,6] as a resul ...
Precambrian Rocks of the Southeastern Llano
... Within the Valley Spring lie discordant bodies of poorly foliated granitic rock that are intrusive into the gneiss. ...
... Within the Valley Spring lie discordant bodies of poorly foliated granitic rock that are intrusive into the gneiss. ...
zeolites in eocene basaltic pillow lavas
... rhombohedra), laumontite, and amethystine quartz. Common three-mineral assemblages are: natroliteanalcime-sfilbite, stilbite-heulandite-chabazite, stilbite-apophylli~e-chabazite, and natrolite-mesolite-laumontite. Alteration of basaltic glass, which was initially abundant, appears to have been an im ...
... rhombohedra), laumontite, and amethystine quartz. Common three-mineral assemblages are: natroliteanalcime-sfilbite, stilbite-heulandite-chabazite, stilbite-apophylli~e-chabazite, and natrolite-mesolite-laumontite. Alteration of basaltic glass, which was initially abundant, appears to have been an im ...
Chapter 3
... • Color and appearance are two obvious clues that can be used to identify minerals. • Some other properties to study include how hard a mineral is, how it breaks, and its color when crushed into a ...
... • Color and appearance are two obvious clues that can be used to identify minerals. • Some other properties to study include how hard a mineral is, how it breaks, and its color when crushed into a ...
Review of the behavior of plagioclase under metamorphic
... the jadeite-glaucophane type only albite seems to exist. He mentionedthat the relation betweengarnet and the discontinuityin plagioclasecomposition is not clear; there is an implication that reactions involving garnet and other Ca-rich phases may or may not be important in this connection.Sen (1963) ...
... the jadeite-glaucophane type only albite seems to exist. He mentionedthat the relation betweengarnet and the discontinuityin plagioclasecomposition is not clear; there is an implication that reactions involving garnet and other Ca-rich phases may or may not be important in this connection.Sen (1963) ...
Heterogeneous material distribution, an important reason for generation of
... In southern HMB, metamorphic and intrusive rocks were laid under the condition of amphibolite facies at the peak metamorphic stage (Fig. 4, Shimura et al., 1997). Mylonitic deformation occurred under lower green schist facies condition (300 to 400◦ C) based on the microscopic observations that felds ...
... In southern HMB, metamorphic and intrusive rocks were laid under the condition of amphibolite facies at the peak metamorphic stage (Fig. 4, Shimura et al., 1997). Mylonitic deformation occurred under lower green schist facies condition (300 to 400◦ C) based on the microscopic observations that felds ...
Geology and paragenesis of the Boseto copper deposits, Kalahari
... ABSTRACT Detailed lithostratigraphic, structural, and petrographic studies coupled with fluid inclusion and stable isotopic analyses and geochronological studies indicate that the Boseto copper deposits formed initially during diagenesis as metalliferous brines ascended along basin faults and moved ...
... ABSTRACT Detailed lithostratigraphic, structural, and petrographic studies coupled with fluid inclusion and stable isotopic analyses and geochronological studies indicate that the Boseto copper deposits formed initially during diagenesis as metalliferous brines ascended along basin faults and moved ...
Formation of Igneous Layering in Granodiorite by Gravity Flow: a
... Previous studies on the layered structures in felsic plutons have proposed mechanisms and processes that are primarily based on field observations and, in some cases, whole-rock compositions. At present very little is known about the microstructure; that is, the arrangement (distribution, orientatio ...
... Previous studies on the layered structures in felsic plutons have proposed mechanisms and processes that are primarily based on field observations and, in some cases, whole-rock compositions. At present very little is known about the microstructure; that is, the arrangement (distribution, orientatio ...
GEOLOGY OF THE RAINBOW MOUNTAIN
... 3 percent rhyodacitic pyroclastics (compositions based on mineralogy). These volcanic rocks are interbedded with feldspathic and lithic sandstones and conglomerates, all of which were derived from volcanic sources. Silicified siltstones, claystones, and fossiliferous limestones also are present. The ...
... 3 percent rhyodacitic pyroclastics (compositions based on mineralogy). These volcanic rocks are interbedded with feldspathic and lithic sandstones and conglomerates, all of which were derived from volcanic sources. Silicified siltstones, claystones, and fossiliferous limestones also are present. The ...
Genesis of platinum-group minerals in the Las Aguilas mafic
... yellowish-brown ferri-tschermakitic amphibole. The olivine-rich ultrama®c rocks (dunites, harzburgites, lherzolites) are partly altered to serpentine and secondary magnetite. Textural observations of dunite and pyroxenite reveal that fresh to partially serpentinised olivine, orthopyroxene and chromi ...
... yellowish-brown ferri-tschermakitic amphibole. The olivine-rich ultrama®c rocks (dunites, harzburgites, lherzolites) are partly altered to serpentine and secondary magnetite. Textural observations of dunite and pyroxenite reveal that fresh to partially serpentinised olivine, orthopyroxene and chromi ...
New Approaches to Evaluation of Chemical Weathering
... Abstract: - The chemical weathering of rock proceeds by water-rock interaction. Through weathering geochemically mobile elements, alkali and alkali-earth elements are easily leached from rocks. On the other hand, the residual elements with components from the atmosphere form new minerals. The princi ...
... Abstract: - The chemical weathering of rock proceeds by water-rock interaction. Through weathering geochemically mobile elements, alkali and alkali-earth elements are easily leached from rocks. On the other hand, the residual elements with components from the atmosphere form new minerals. The princi ...
Sedimentology and Reservoir Geology of the Middle
... positively and negatively by several diagenetic processes. These processes include: mechanical compaction factors (grain slippage and crushing of the ductile grains), quartz overgrowths, precipitation of siderite and calcite, feldspar and clay mineral authigenesis, dissolution of carbonate and of th ...
... positively and negatively by several diagenetic processes. These processes include: mechanical compaction factors (grain slippage and crushing of the ductile grains), quartz overgrowths, precipitation of siderite and calcite, feldspar and clay mineral authigenesis, dissolution of carbonate and of th ...
Geology of Greenland Bulletin 185, 12-24
... Moorbath et al. 1973), which occurs in the Isukasia area at the head of Godthåbsfjord (Nuup Kangerlua) in West Greenland (Fig. 4), is the most extensive occurrence of early Archaean supracrustal rocks known on earth. It forms a zone up to 4 km wide and up to c. 35 km long and has been investigated i ...
... Moorbath et al. 1973), which occurs in the Isukasia area at the head of Godthåbsfjord (Nuup Kangerlua) in West Greenland (Fig. 4), is the most extensive occurrence of early Archaean supracrustal rocks known on earth. It forms a zone up to 4 km wide and up to c. 35 km long and has been investigated i ...
Stratigraphy and geological structure of the
... Talus deposits mainly consisting of gravel bed are distributed along rivers and in the valley with slightly higher surface than recent river bed. Fault with large displacement cuts these strata except talus deposits from northwest to southeast. There are many folds with northeast-directing fold ...
... Talus deposits mainly consisting of gravel bed are distributed along rivers and in the valley with slightly higher surface than recent river bed. Fault with large displacement cuts these strata except talus deposits from northwest to southeast. There are many folds with northeast-directing fold ...
HIGH-LEVEL METAMORPHISM OF PELITIC ROCKS IN
... these assemblagesimply bulk rock compositions that are not highly aluminous. Figure 2 shows the probable successiveequilibrium configurations ("mineral facies," Thompson, 1957)of the projection from the biotite zoneinto the sillimanite zone,as inferred from petrographic study in this area. Becauseof ...
... these assemblagesimply bulk rock compositions that are not highly aluminous. Figure 2 shows the probable successiveequilibrium configurations ("mineral facies," Thompson, 1957)of the projection from the biotite zoneinto the sillimanite zone,as inferred from petrographic study in this area. Becauseof ...
CELSIAN, (Ba,K)-FELDSPAR AND CYMRITE FROM
... 3) The host-rocks consist of interbedded chert, siliceous and black shale, limestone, metavolcanic rocks, greywacke and feldspathic quartzite. Chert and shale are the most important rock-types. According to geochemical data (Moro et al. 1994), the host rocks may well have formed in a marine continen ...
... 3) The host-rocks consist of interbedded chert, siliceous and black shale, limestone, metavolcanic rocks, greywacke and feldspathic quartzite. Chert and shale are the most important rock-types. According to geochemical data (Moro et al. 1994), the host rocks may well have formed in a marine continen ...
- Mineralogical Society of America
... we conceptualize it, the conversion of low-permeability bedrock to regolith generally begins due to the transport of meteoric water into protolith through the large-scale fractures that are present as a result of regional tectonic factors or exhumation (Wyrick and Borchers 1981; Molnar et al. 2007). ...
... we conceptualize it, the conversion of low-permeability bedrock to regolith generally begins due to the transport of meteoric water into protolith through the large-scale fractures that are present as a result of regional tectonic factors or exhumation (Wyrick and Borchers 1981; Molnar et al. 2007). ...
CONTACT METAMORPHISM and INTRUSIVE RELATIONS
... Complex, Croton Falls Complex, Rosetown Pluton, Torment Hill and Stony Point Plutons have been recognized by various workers. ...
... Complex, Croton Falls Complex, Rosetown Pluton, Torment Hill and Stony Point Plutons have been recognized by various workers. ...
Types of Metamorphism
... View over the Race Track valley to the quartz-monzonitic Ubehebe Peak intrusion and its contact aureole. Ubehebe Peak belongs to a series of alkaline intrusions which formed the Hunter Mountain Batholith. The field area is located in the Death Valley National Park, CA (USA). ...
... View over the Race Track valley to the quartz-monzonitic Ubehebe Peak intrusion and its contact aureole. Ubehebe Peak belongs to a series of alkaline intrusions which formed the Hunter Mountain Batholith. The field area is located in the Death Valley National Park, CA (USA). ...
Title of paper - Subterra-ing
... However, tests such as ethylene-glycol in conjunction with Atterberg limits, among others, can allow early detection of overpressure magnitude in order to design and optimize lining in accordance to the problems associated with these phenomena. Therefore, the main hypothesis states that swelling cla ...
... However, tests such as ethylene-glycol in conjunction with Atterberg limits, among others, can allow early detection of overpressure magnitude in order to design and optimize lining in accordance to the problems associated with these phenomena. Therefore, the main hypothesis states that swelling cla ...
Muscovite
... and the third octahedron is vacant. However, in most micas, the number of octahedra is not always exactly 2.0 or 3.0 Substitutions: For K: Na, Rb, Cs, Ca, Ba For octahedral Al: Mg, Fe2+, Fe3+, Mn, Li, Cr, Ti, V For OH: F, Cl ...
... and the third octahedron is vacant. However, in most micas, the number of octahedra is not always exactly 2.0 or 3.0 Substitutions: For K: Na, Rb, Cs, Ca, Ba For octahedral Al: Mg, Fe2+, Fe3+, Mn, Li, Cr, Ti, V For OH: F, Cl ...
Provenance of plutonic detritus in cover sandstones of Nicoya
... subophitic textures. Monocrystalline grains include plagioclase, quartz, and pyroxene. Both plagioclase and quartz grains are, however, difficult to interpret, because in many cases they do not exhibit diagnostic petrographic features of a plutonic or volcanic origin. The most important mafic minera ...
... subophitic textures. Monocrystalline grains include plagioclase, quartz, and pyroxene. Both plagioclase and quartz grains are, however, difficult to interpret, because in many cases they do not exhibit diagnostic petrographic features of a plutonic or volcanic origin. The most important mafic minera ...
The Lamington Conglomerate: further evidence for an ophiolitic
... (Floyd 1982). The Lamington Conglomerate may be up to 300 m thick and crops out as a lenticular mass 1300 m in length, between [NS 990 312] and [NT 001 321] (Figure 1). At Crow Craigs [NS 991 313], hillside exposures reveal a mostly matrix-supported, poorly-sorted conglomerate with sub-rounded to we ...
... (Floyd 1982). The Lamington Conglomerate may be up to 300 m thick and crops out as a lenticular mass 1300 m in length, between [NS 990 312] and [NT 001 321] (Figure 1). At Crow Craigs [NS 991 313], hillside exposures reveal a mostly matrix-supported, poorly-sorted conglomerate with sub-rounded to we ...
20 Crystallization, Fractionation and Solidification of Co
... from the magma are denser than the magma and buoyancy forces lead to gravity settling the crystals. In some rare and denser iron-rich or carbonatite magmas, feldspar crystals may float. The viscosity of silicate magma generally increases with a decrease in the temperature - with decreases in dissolv ...
... from the magma are denser than the magma and buoyancy forces lead to gravity settling the crystals. In some rare and denser iron-rich or carbonatite magmas, feldspar crystals may float. The viscosity of silicate magma generally increases with a decrease in the temperature - with decreases in dissolv ...
Tertiary volcanic rocks from the Halmahera Arc, Eastern Indonesia
... ranges from 0.3 to 4.5 mm. Piagioclase phenocrysts and microphenocrysts can be subdivided on the basis of their textures, inclusions and zoning patterns. They include grains which are inclusion-free, and others which have resorption and growth textures (Morrice and Gill 1986). Zoned grains include t ...
... ranges from 0.3 to 4.5 mm. Piagioclase phenocrysts and microphenocrysts can be subdivided on the basis of their textures, inclusions and zoning patterns. They include grains which are inclusion-free, and others which have resorption and growth textures (Morrice and Gill 1986). Zoned grains include t ...
Sedimentary rock
Sedimentary rocks are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles (detritus) to settle and accumulate or minerals to precipitate from a solution. Particles that form a sedimentary rock by accumulating are called sediment. Before being deposited, sediment was formed by weathering and erosion in a source area, and then transported to the place of deposition by water, wind, ice, mass movement or glaciers which are called agents of denudation.The sedimentary rock cover of the continents of the Earth's crust is extensive, but the total contribution of sedimentary rocks is estimated to be only 8% of the total volume of the crust. Sedimentary rocks are only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, forming a structure called bedding. The study of sedimentary rocks and rock strata provides information about the subsurface that is useful for civil engineering, for example in the construction of roads, houses, tunnels, canals or other structures. Sedimentary rocks are also important sources of natural resources like coal, fossil fuels, drinking water or ores.The study of the sequence of sedimentary rock strata is the main source for scientific knowledge about the Earth's history, including palaeogeography, paleoclimatology and the history of life. The scientific discipline that studies the properties and origin of sedimentary rocks is called sedimentology. Sedimentology is part of both geology and physical geography and overlaps partly with other disciplines in the Earth sciences, such as pedology, geomorphology, geochemistry and structural geology.