Kinematic model for the Main Central thrust in Nepal
... duplex (i.e., within the Ramgarh thrust sheet) to ;6–8 kbar. Thus, imbrication and horizontal shortening would have juxtaposed rocks that were subjected to peak pressures ranging from ;3 kbar in the southern part of the duplex to ;8 kbar in its northern part. This predicted pattern matches the press ...
... duplex (i.e., within the Ramgarh thrust sheet) to ;6–8 kbar. Thus, imbrication and horizontal shortening would have juxtaposed rocks that were subjected to peak pressures ranging from ;3 kbar in the southern part of the duplex to ;8 kbar in its northern part. This predicted pattern matches the press ...
The north Pyrenean Front and related foreland basin along the Bay
... tectonic structures grew during the Mesozoic opening of the Bay of Biscay and were squeezed during the deposition of the uppermost Cretaceous to lower Miocene synorogenic deposits which are folded upon these structures. Close to the southern boundary of the basin, the MARCONI-3 profile also shows th ...
... tectonic structures grew during the Mesozoic opening of the Bay of Biscay and were squeezed during the deposition of the uppermost Cretaceous to lower Miocene synorogenic deposits which are folded upon these structures. Close to the southern boundary of the basin, the MARCONI-3 profile also shows th ...
Tectonic Setting and Regional Geology of the KSZ
... This study integrates petrological, structural, geochemical, geochronological and isotopic investigations of the geodynamic evolution of the Neoproterozoic Keraf Shear Zone (KSZ) in NE Sudan. It is a ~500 km long, thrust-bounded and wedge-shaped belt, that is narrower (∼30 km) in the S and wider (∼1 ...
... This study integrates petrological, structural, geochemical, geochronological and isotopic investigations of the geodynamic evolution of the Neoproterozoic Keraf Shear Zone (KSZ) in NE Sudan. It is a ~500 km long, thrust-bounded and wedge-shaped belt, that is narrower (∼30 km) in the S and wider (∼1 ...
Chapter 4 Intrusive Igneous Rocks
... Compositional classification is based on Le Maitre (1989) (Figure 7). The major intrusions are divided into medium-, flne- to medium-, and fme-grained lithologies. On the basis of geochemical and minera logical studies, the granites may be further divided into separateplutons or intrusive units. Th ...
... Compositional classification is based on Le Maitre (1989) (Figure 7). The major intrusions are divided into medium-, flne- to medium-, and fme-grained lithologies. On the basis of geochemical and minera logical studies, the granites may be further divided into separateplutons or intrusive units. Th ...
Comparison of the Central Metamorphic Belt and Trinity terrane of
... Several observationsstrongly suggestthat metamorphism of the Central Metamorphic Belt took place concurrent with emplacement of the Ce.n~ralMetamorphic Belt beneath!he Trinity terrane along the Tnmty thrust: (1) peak metamorphIc temperatures and grain sizegenerally increasestructurally upward toward ...
... Several observationsstrongly suggestthat metamorphism of the Central Metamorphic Belt took place concurrent with emplacement of the Ce.n~ralMetamorphic Belt beneath!he Trinity terrane along the Tnmty thrust: (1) peak metamorphIc temperatures and grain sizegenerally increasestructurally upward toward ...
Barrovian metamorphism in the central Kootenay Arc, British
... and thrust belt and associated foreland basin (Fig. 1). This part of the orogen developed in response to convergence between cratonic North America and westward terranes in the Early Jurassic, and continued convergence led to further shortening, thickening, and eastward propogation (relative to Nort ...
... and thrust belt and associated foreland basin (Fig. 1). This part of the orogen developed in response to convergence between cratonic North America and westward terranes in the Early Jurassic, and continued convergence led to further shortening, thickening, and eastward propogation (relative to Nort ...
Convergence and Collision
... F I G U R E 1 7 . 1 (a) Photo of the southern Andes Mountains of Chile. Rocks exposed on these peaks include relicts of old accretionary prisms, as well as granitic intrusions of a continental volcanic arc. (b) Photo of the central Himalaya Mountains, Nepal. The highest peak, which appears to be nuc ...
... F I G U R E 1 7 . 1 (a) Photo of the southern Andes Mountains of Chile. Rocks exposed on these peaks include relicts of old accretionary prisms, as well as granitic intrusions of a continental volcanic arc. (b) Photo of the central Himalaya Mountains, Nepal. The highest peak, which appears to be nuc ...
Text
... Understanding how the Earth’s first continental land masses were generated is important because the processes responsible directly affected the evolution of the planet’s primordial silicate interior, and also its atmosphere and hydrosphere. Archaean continental crust is dominated by rocks of the tro ...
... Understanding how the Earth’s first continental land masses were generated is important because the processes responsible directly affected the evolution of the planet’s primordial silicate interior, and also its atmosphere and hydrosphere. Archaean continental crust is dominated by rocks of the tro ...
PDF version - Western Washington University
... Fractional crystallization was also used to explain the formation of middle-upper crustal intermediate and felsic plutonic rocks (Rioux et al. 2007, 2010; Johnsen 2007). Isotopic signatures from these intermediatefelsic plutonic rocks are mostly intra-oceanic with little or no involvement of contine ...
... Fractional crystallization was also used to explain the formation of middle-upper crustal intermediate and felsic plutonic rocks (Rioux et al. 2007, 2010; Johnsen 2007). Isotopic signatures from these intermediatefelsic plutonic rocks are mostly intra-oceanic with little or no involvement of contine ...
Noble Gas Constraints on Mantle Structure and Convection
... Different ocean islands have distinct 21Ne/22Ne ratios; either reflects varying amounts of MORB mantle addition to the OIB source(s) or different parts of the mantle have been degassed and processed to different degrees ...
... Different ocean islands have distinct 21Ne/22Ne ratios; either reflects varying amounts of MORB mantle addition to the OIB source(s) or different parts of the mantle have been degassed and processed to different degrees ...
PPT - Margins
... • Reduction of differences in buoyancy forces (Bialas and Buck, 2007; submitted): earlier transition to narrow rift mode • Diffuse deformation, after transition to narrow rift mode (Persaud et al., 2003) • Build new transitional crust at rifted margins (Fuis et al., 1984; Nicolas, 1985) … ...
... • Reduction of differences in buoyancy forces (Bialas and Buck, 2007; submitted): earlier transition to narrow rift mode • Diffuse deformation, after transition to narrow rift mode (Persaud et al., 2003) • Build new transitional crust at rifted margins (Fuis et al., 1984; Nicolas, 1985) … ...
Physics and Chemistry of Deep Continental Crust
... Plateau in southwestern United States and the Hangay Dome in Mongolia, both far from plate boundaries) as well as the magmatism and enhanced surface heat flow often associated with these anomalous uplifts. Bird (1979) may have been the first to highlight that these nonplate tectonic geologic phenome ...
... Plateau in southwestern United States and the Hangay Dome in Mongolia, both far from plate boundaries) as well as the magmatism and enhanced surface heat flow often associated with these anomalous uplifts. Bird (1979) may have been the first to highlight that these nonplate tectonic geologic phenome ...
A Field, Petrographic, and Geochemical Study of Gabbros and
... A Field, Petrographic, and Geochemical Study of Gabbros and Related Rocks from the Sandy Islands Gabbro Complex, Wollaston Domain 1 C. Madore 2 and I.R. Annesley 2 Madore, C. and Annesley, I.A. (1994): A field, petrographic, and geochemical study of gabbros and related rocks from the Sandy Islands G ...
... A Field, Petrographic, and Geochemical Study of Gabbros and Related Rocks from the Sandy Islands Gabbro Complex, Wollaston Domain 1 C. Madore 2 and I.R. Annesley 2 Madore, C. and Annesley, I.A. (1994): A field, petrographic, and geochemical study of gabbros and related rocks from the Sandy Islands G ...
Role of the subducted slab, mantle wedge and
... Kay l992; Kay et al. l993). Xenoliths of lower crustal origin, found in the Patagonian plateau basalts both along (CF, Fig. 1; Kilian l995) and east of (PA, Fig. 1; Selverstone and Stern l983) the eastern margin of the Austral Andes, are pyroxene 1 plagioclase granulites without garnet, consistent w ...
... Kay l992; Kay et al. l993). Xenoliths of lower crustal origin, found in the Patagonian plateau basalts both along (CF, Fig. 1; Kilian l995) and east of (PA, Fig. 1; Selverstone and Stern l983) the eastern margin of the Austral Andes, are pyroxene 1 plagioclase granulites without garnet, consistent w ...
The deep subsurface biosphere in igneous ocean crust: frontier
... Researchers are pursuing fundamental questions concerning ridge flank crustal microbiology, including: what is the activity of life within ridge flanks? How are evolutionary forces expressed in these settings? What are the physical and chemical limits for survival and reproduction in the subseafloor? W ...
... Researchers are pursuing fundamental questions concerning ridge flank crustal microbiology, including: what is the activity of life within ridge flanks? How are evolutionary forces expressed in these settings? What are the physical and chemical limits for survival and reproduction in the subseafloor? W ...
Lower crustal earthquakes near the Ethiopian rift induced by
... variations in composition and temperature alone and require the presence of a small fraction fluid phase, which is likely to be partial melt considering that the MER is unaffected by subduction processes that could hydrate the mantle [Bastow et al., 2005, 2008]. In contrast, the SE Plateau is underl ...
... variations in composition and temperature alone and require the presence of a small fraction fluid phase, which is likely to be partial melt considering that the MER is unaffected by subduction processes that could hydrate the mantle [Bastow et al., 2005, 2008]. In contrast, the SE Plateau is underl ...
Author`s personal copy
... Widespread intermediate to silicic composition volcanism affected much of western U.S. and northern Mexico during the mid-Tertiary (Elston, 1984a; Best and Christiansen, 1991; Lipman, 1992). As with other silicic large igneous provinces, such as the Early Cretaceous Whitsunday Volcanic Province of e ...
... Widespread intermediate to silicic composition volcanism affected much of western U.S. and northern Mexico during the mid-Tertiary (Elston, 1984a; Best and Christiansen, 1991; Lipman, 1992). As with other silicic large igneous provinces, such as the Early Cretaceous Whitsunday Volcanic Province of e ...
AbdolnaserFazlnia-Word offic file
... mantle diapirs at Upper Paleozoic (Ghaemi, 2004). As a result of this process, continental rifting was developed into the area and crustal thinning occurred as well as basaltic magmas were formed from the upper mantle. Based on field observations, the Mamakan gabbros are two groups: a) layered gabbr ...
... mantle diapirs at Upper Paleozoic (Ghaemi, 2004). As a result of this process, continental rifting was developed into the area and crustal thinning occurred as well as basaltic magmas were formed from the upper mantle. Based on field observations, the Mamakan gabbros are two groups: a) layered gabbr ...
Chromium isotope fractionation during subduction
... impetus to investigate the magnitude of Cr isotope fractionation associated with metamorphic processes. For this reason, we analyzed a set of subduction-related metamorphosed ultramafic rocks and fluid-altered carbonate rocks. The metamorphic age of these rocks range from Neoproterozoic to Phanerozoic ...
... impetus to investigate the magnitude of Cr isotope fractionation associated with metamorphic processes. For this reason, we analyzed a set of subduction-related metamorphosed ultramafic rocks and fluid-altered carbonate rocks. The metamorphic age of these rocks range from Neoproterozoic to Phanerozoic ...
composition of biotite from granitic rocks
... Biotite, the dominant ferromagnesian mineral in Paleozoic granitic rocks of the Canadian Appalachians, has been analyzed with an electron microprobe (wavelength dispersion) for major elements and by 57Fe Mössbauer spectroscopy. We sampled a wide variety of rock types, ranging from gabbro, diorite, s ...
... Biotite, the dominant ferromagnesian mineral in Paleozoic granitic rocks of the Canadian Appalachians, has been analyzed with an electron microprobe (wavelength dispersion) for major elements and by 57Fe Mössbauer spectroscopy. We sampled a wide variety of rock types, ranging from gabbro, diorite, s ...
Sierra Nevada uplift - University of Missouri
... INTRODUCTION The formation of the Sierra Nevada mountain range in eastern California has been a subject of considerable controversy. The Sierra Nevada was uplifted mainly in the past 20 m.y. (Huber, 1981) and is now ~2800 m above the adjacent lowlands (Fig. 1A). Some seismic studies suggested that t ...
... INTRODUCTION The formation of the Sierra Nevada mountain range in eastern California has been a subject of considerable controversy. The Sierra Nevada was uplifted mainly in the past 20 m.y. (Huber, 1981) and is now ~2800 m above the adjacent lowlands (Fig. 1A). Some seismic studies suggested that t ...
Mantle transition zone thickness beneath Cameroon
... volcanic centres range in age from Eocene to Recent, and are generally alkaline massifs emplaced in a N30◦ trend, similar to more than 60 Paleocene to early Oligocene anorogenic plutonic complexes (Déruelle et al. 1991). The volcanism was initiated as early as 42 Ma, and became widespread along the ...
... volcanic centres range in age from Eocene to Recent, and are generally alkaline massifs emplaced in a N30◦ trend, similar to more than 60 Paleocene to early Oligocene anorogenic plutonic complexes (Déruelle et al. 1991). The volcanism was initiated as early as 42 Ma, and became widespread along the ...
The placement of the Trans-European Suture Zone on the Romanian... electromagnetic arguments
... Initially, two 2D models are presented in order to emphasize the possible placement of the Trans-European Suture in the rooted zone of the Eastern Carpathians’ Flysch Nappes System. Then, a conclusive review of the distribution of the main geoelectrical properties on this area is accomplished, point ...
... Initially, two 2D models are presented in order to emphasize the possible placement of the Trans-European Suture in the rooted zone of the Eastern Carpathians’ Flysch Nappes System. Then, a conclusive review of the distribution of the main geoelectrical properties on this area is accomplished, point ...
Christiansen, EH, and Keith, JD, 1996, Trace
... decompression, the amount of fluxing volatiles introduced, or the proportions of hydrous minerals for dehydration melting. Regarding this latter point, a crustal protolith with abundant hydrous minerals may produce a magma with low incompatible element concentrations because a larger proportion of t ...
... decompression, the amount of fluxing volatiles introduced, or the proportions of hydrous minerals for dehydration melting. Regarding this latter point, a crustal protolith with abundant hydrous minerals may produce a magma with low incompatible element concentrations because a larger proportion of t ...
Crustal structure and evolution of the Mariana intra
... generated in the mantle wedge. At the juvenile stage of arc evolution, the mantle-derived basalt magma forms the initial arc crust, which is most simply composed of differentiated basalt and cumulate layers. This model regards the basaltic materials underplated at the bottom of the crust as a part o ...
... generated in the mantle wedge. At the juvenile stage of arc evolution, the mantle-derived basalt magma forms the initial arc crust, which is most simply composed of differentiated basalt and cumulate layers. This model regards the basaltic materials underplated at the bottom of the crust as a part o ...
Baltic Shield
The Baltic Shield (sometimes referred to as the Fennoscandian Shield) is located in Fennoscandia (Norway, Sweden and Finland), northwest Russia and under the Baltic Sea. The Baltic Shield is defined as the exposed Precambrian northwest segment of the East European Craton. It is composed mostly of Archean and Proterozoic gneisses and greenstones which have undergone numerous deformations through tectonic activity (see Geology of Fennoscandia map [1]). The Baltic Shield contains the oldest rocks of the European continent. The lithospheric thickness is about 200-300 km. During the Pleistocene epoch, great continental ice sheets scoured and depressed the shield's surface, leaving a thin covering of glacial material and innumerable lakes and streams. The Baltic Shield is still rebounding today following the melting of the thick glaciers during the Quaternary Period.