Oceanic Lithosphere
... Oceanic lithosphere cools by conduction as it moves away from the oceanic ridge, leading to a thickening of oceanic lithosphere. Oceanic lithosphere is reabsorbed into the mantle by sinking at subduction zones. The subducting lithosphere however does not generally melt unless it is quite young (< 2 ...
... Oceanic lithosphere cools by conduction as it moves away from the oceanic ridge, leading to a thickening of oceanic lithosphere. Oceanic lithosphere is reabsorbed into the mantle by sinking at subduction zones. The subducting lithosphere however does not generally melt unless it is quite young (< 2 ...
The Tectonostratigraphy and Structural Evolution of the Sitas Area
... the Rombak Complex from its crystalline basement, imbr icated the cover and eventually delamina ted the upper most metres to hundreds of metre s of the basement form ing the Storriten Complex. Below this level, the crysta lline basement was not penetratively deformed by Caledonian events . Peter D. ...
... the Rombak Complex from its crystalline basement, imbr icated the cover and eventually delamina ted the upper most metres to hundreds of metre s of the basement form ing the Storriten Complex. Below this level, the crysta lline basement was not penetratively deformed by Caledonian events . Peter D. ...
A Dynamic Model of Rifting Between Galicia Bank and Flemish Cap
... whole-extension rate of 20 mm/yr during rifting. This is consistent with area balancing of the cross section in Fig. 2. Restoration of the cross section to a uniform crust thickness of 32 km requires an extension rate of 20 mm/yr to produce the observed amount of stretching in 25 m.y. Pre-rift litho ...
... whole-extension rate of 20 mm/yr during rifting. This is consistent with area balancing of the cross section in Fig. 2. Restoration of the cross section to a uniform crust thickness of 32 km requires an extension rate of 20 mm/yr to produce the observed amount of stretching in 25 m.y. Pre-rift litho ...
A new look at the Altaids: A superorogenic complex in northern and
... plate tectonic model that guided our estimation of what the evolutionary course of the individual units would be. We followed Şengör et al. (1993) and Şengör and Natal'in (1996) in choosing initially a subduction-accretion model along two arc fronts for the entire Altaid System with no collisions of ...
... plate tectonic model that guided our estimation of what the evolutionary course of the individual units would be. We followed Şengör et al. (1993) and Şengör and Natal'in (1996) in choosing initially a subduction-accretion model along two arc fronts for the entire Altaid System with no collisions of ...
Near-Ultrahigh Pressure Processing of Continental Crust: Miocene
... Textural analysis was accomplished through optical microscopy and back-scattered electron microscopy. Mineral modes were determined by point counting with an optical microscope (Table 1). Mineral compositions were determined using a University of California, Santa ...
... Textural analysis was accomplished through optical microscopy and back-scattered electron microscopy. Mineral modes were determined by point counting with an optical microscope (Table 1). Mineral compositions were determined using a University of California, Santa ...
1. Introduction - GEIN-NOA
... the seismic events (1993-1999): 1 – Rocks: a) metamorphic, b) Paleogene sediments and vulcanites, c) NeogeneQuaternary sediments; 2 – faults; 3 – photo lineament; 4 – earthquake epicentres: a) with M>3, b) M=2.0-3.0; c) M<2; 5 – locality of the research area. The regional Pg-Q Upper Thracian Depress ...
... the seismic events (1993-1999): 1 – Rocks: a) metamorphic, b) Paleogene sediments and vulcanites, c) NeogeneQuaternary sediments; 2 – faults; 3 – photo lineament; 4 – earthquake epicentres: a) with M>3, b) M=2.0-3.0; c) M<2; 5 – locality of the research area. The regional Pg-Q Upper Thracian Depress ...
Petrology, mineralogy, and origin of the Feragen ultramafic body
... Feragen body (Du Rietz 1955, Hultin 1965), although it is often difficult to distinguish be tween them in thin sections because of the high degree of alteration. This makes it difficult to give accurate estimates of the proportions of each. However, even in some severely altered samples the clinopy ...
... Feragen body (Du Rietz 1955, Hultin 1965), although it is often difficult to distinguish be tween them in thin sections because of the high degree of alteration. This makes it difficult to give accurate estimates of the proportions of each. However, even in some severely altered samples the clinopy ...
Relationship between Moldanubicum, the Kutn· Hora Crystalline
... Institute of Geology and Palaentology, Charles University, Albertov 6, 128 43 Praha 2, Czech Republic The Moldanubian Zone, forming a highly metamorphosed root of the Variscan orogenic belt in Central Europe, is surrounded by several different lithotectonic units within the Bohemian Massif. These un ...
... Institute of Geology and Palaentology, Charles University, Albertov 6, 128 43 Praha 2, Czech Republic The Moldanubian Zone, forming a highly metamorphosed root of the Variscan orogenic belt in Central Europe, is surrounded by several different lithotectonic units within the Bohemian Massif. These un ...
Chapter 8 Let`s take it from the top: the crust and upper mantle
... in Figure 8.1. Earth is conventionally divided into crust, mantle and core, but each of these has subdivisions that are almost as fundamental (Tables 8.1 and 8.2). Bullen subdivided the Earth's interior into shells, from A (the crust) through G (the inner core). The lower mantle, starting at 1000 km ...
... in Figure 8.1. Earth is conventionally divided into crust, mantle and core, but each of these has subdivisions that are almost as fundamental (Tables 8.1 and 8.2). Bullen subdivided the Earth's interior into shells, from A (the crust) through G (the inner core). The lower mantle, starting at 1000 km ...
Late 20th Century Tests of the Continental Drift Hypothesis
... In 1960 Harry Hess proposed a new hypothesis about what happens in the ocean. It was based on three emerging observations about the oceanic crust. At the time it was not clear whether these were really observable facts or just some geologists reading too much into their data instead. So Hess’s hypo ...
... In 1960 Harry Hess proposed a new hypothesis about what happens in the ocean. It was based on three emerging observations about the oceanic crust. At the time it was not clear whether these were really observable facts or just some geologists reading too much into their data instead. So Hess’s hypo ...
Glossary a - Teacher Friendly Guides
... a soil order; these are highly productive soils often formed from volcanic materials. They possess very high water- and nutrient-holding capabilities, and are commonly found in cool areas with moderate to high levels of precipitation. See also: soil, soil order, volcanic ...
... a soil order; these are highly productive soils often formed from volcanic materials. They possess very high water- and nutrient-holding capabilities, and are commonly found in cool areas with moderate to high levels of precipitation. See also: soil, soil order, volcanic ...
Electromagnetic imaging of magma across the Narmada Son lineament, central India
... of complex tectonic processes. These processes have being active since the Precambrian times, along the 1600 km long Narmada Son lineament (NSL) and its contiguous areas (Fig. 1). Some of the tectonic manifestations across this zone of weakness can be observed through seismicity, numerous gravity an ...
... of complex tectonic processes. These processes have being active since the Precambrian times, along the 1600 km long Narmada Son lineament (NSL) and its contiguous areas (Fig. 1). Some of the tectonic manifestations across this zone of weakness can be observed through seismicity, numerous gravity an ...
turkish association of petroleum geologists the geological field guide
... limestones filling up the irregularities in the sea floor (Fig. 7). There are also large number of Neptunian dykes, sills and veins in the phyllites filled by Eocene carbonates. The Neptunian dykes are of variable thickness (1 cm to several meters) and show a range of orientation. The irregular sea ...
... limestones filling up the irregularities in the sea floor (Fig. 7). There are also large number of Neptunian dykes, sills and veins in the phyllites filled by Eocene carbonates. The Neptunian dykes are of variable thickness (1 cm to several meters) and show a range of orientation. The irregular sea ...
The link between the Moho depth of the NE Atlantic margin and
... For example the Moho boundary generally deepens from the centre of the Fennoscandian Shield towards the continent–ocean transition. Typical values at the coastline are 30–35 km and the depth decreases to values around 10–15 km at the continental edge. Over the stable shelf of the Barents Sea the cru ...
... For example the Moho boundary generally deepens from the centre of the Fennoscandian Shield towards the continent–ocean transition. Typical values at the coastline are 30–35 km and the depth decreases to values around 10–15 km at the continental edge. Over the stable shelf of the Barents Sea the cru ...
6. The main mineralization types of the Arabian Shield
... metamorphosed and constitutes one of the best preserved and exposed Neoproterozoic assemblages resulting from the accretion of several volcanic-arcs. It is overlain to the east, north and south by a thick Phanerozoic sedimentary formation. The more than 500 U-Pb, Rb-Sr, Sm-Nd, K-Ar and Ar-Ar age det ...
... metamorphosed and constitutes one of the best preserved and exposed Neoproterozoic assemblages resulting from the accretion of several volcanic-arcs. It is overlain to the east, north and south by a thick Phanerozoic sedimentary formation. The more than 500 U-Pb, Rb-Sr, Sm-Nd, K-Ar and Ar-Ar age det ...
59 4. DESCRIPTION OF STUDY AREA 4.1. Physiography and
... Instead, it is generally in a state of horizontal extension which may be a result of the unbroken lithosphere’s resistance to relative rotation between the Somalia Plate and the Africa Plate. More specific to the study area, Bird et al. (2006) highlighted that the ENE-WSW trending TshipiseBosbokpoor ...
... Instead, it is generally in a state of horizontal extension which may be a result of the unbroken lithosphere’s resistance to relative rotation between the Somalia Plate and the Africa Plate. More specific to the study area, Bird et al. (2006) highlighted that the ENE-WSW trending TshipiseBosbokpoor ...
(43.5-46°S): Implications for Magma Genesis
... high-K (K2O>1 wt% at 50 wt% SiO2), high incompatible element abundance (HA) types. Macá and Cay are low-K, low incompatible element abundance (LA) centers, while Mentolat has very low K, Rb and other incompatible element contents (VLA), similar to Huequi, Calbuco and Nevados de Longaví further north ...
... high-K (K2O>1 wt% at 50 wt% SiO2), high incompatible element abundance (HA) types. Macá and Cay are low-K, low incompatible element abundance (LA) centers, while Mentolat has very low K, Rb and other incompatible element contents (VLA), similar to Huequi, Calbuco and Nevados de Longaví further north ...
Superposed Fault Systems of the Southernmost
... lithotectonic belts are important for unraveling the geologic history of this part of the Appalachian orogen and have widespread implications for the tectonic history of the southern Appalachians in general. Following Neoproterozoic rifting of the Rodinian supercontinent and deposition of a thick me ...
... lithotectonic belts are important for unraveling the geologic history of this part of the Appalachian orogen and have widespread implications for the tectonic history of the southern Appalachians in general. Following Neoproterozoic rifting of the Rodinian supercontinent and deposition of a thick me ...
Abstract Volume
... Petrology and SHRIMP U-Pb Zircon Chronology of Ultrahigh-Temperature Granulite from South Altay Orogenic Belt, Northwestern China Zilong LI, Yinqi LI, Hanlin CHEN, M Santosh, Wenjiao XIAO and Huihui WANG .............................................27 Geochemistry and SHRIMP Zircon Geochronology of ...
... Petrology and SHRIMP U-Pb Zircon Chronology of Ultrahigh-Temperature Granulite from South Altay Orogenic Belt, Northwestern China Zilong LI, Yinqi LI, Hanlin CHEN, M Santosh, Wenjiao XIAO and Huihui WANG .............................................27 Geochemistry and SHRIMP Zircon Geochronology of ...
The Yellowstone Hotspot: Plume or Not?
... example is the Yellowstone–Snake River Plain (YSRP) system, where some observations have led to the conclusion that the YSRP originated from the ascending tail of a deep mantle plume (e.g., Armstrong et al., 1975; Smith and Braile, 1994; Camp, 1995; Pierce and Morgan, 2009). The YSRP is an age-progr ...
... example is the Yellowstone–Snake River Plain (YSRP) system, where some observations have led to the conclusion that the YSRP originated from the ascending tail of a deep mantle plume (e.g., Armstrong et al., 1975; Smith and Braile, 1994; Camp, 1995; Pierce and Morgan, 2009). The YSRP is an age-progr ...
Did westward subduction cause Cretaceous
... or utilized plate models for the main development of the Cordilleran orogenic belt postulate Neoproterozoic to Cambrian rifting of Laurentia to form a westerly facing passive margin, active until the late Devonian; then 110 m.y., from the Late Devonian to the early Triassic, punctuated by the succes ...
... or utilized plate models for the main development of the Cordilleran orogenic belt postulate Neoproterozoic to Cambrian rifting of Laurentia to form a westerly facing passive margin, active until the late Devonian; then 110 m.y., from the Late Devonian to the early Triassic, punctuated by the succes ...
Types of Metamorphism
... - Where?: Impact of fall meteorites with different size on the Earth’s crust. - This impact yielded shock waves with extreme higher P-T conditions, up to 1000 kbar and 5000 °C - Duration time is very short, microsecond. - The impacted rocks were vaporized, but in less condition, they melted to produ ...
... - Where?: Impact of fall meteorites with different size on the Earth’s crust. - This impact yielded shock waves with extreme higher P-T conditions, up to 1000 kbar and 5000 °C - Duration time is very short, microsecond. - The impacted rocks were vaporized, but in less condition, they melted to produ ...
Erosion, Himalayan Geodynamics, and the Geomorphology of
... between surface and lithospheric processes during orogeny, three-dimensional geodynamic models have been developed to explain particular patterns of crustal deformation and metamorphic exposures (e.g., Koons, 1994; Royden et al., 1997; see below). The general conclusion is that erosion can be a sign ...
... between surface and lithospheric processes during orogeny, three-dimensional geodynamic models have been developed to explain particular patterns of crustal deformation and metamorphic exposures (e.g., Koons, 1994; Royden et al., 1997; see below). The general conclusion is that erosion can be a sign ...
Convection in a partially molten metasedimentary crust? Insights
... granitic dikes have been observed in the schlieren migmatites or metasedimentary unit supports the conclusion that most melt was trapped in the source. The high CaO content in the biotite + amphibole–bearing S-type granitoids above, south of the migmatite region (Fig. 1B) and its ferromagnesian-rich ...
... granitic dikes have been observed in the schlieren migmatites or metasedimentary unit supports the conclusion that most melt was trapped in the source. The high CaO content in the biotite + amphibole–bearing S-type granitoids above, south of the migmatite region (Fig. 1B) and its ferromagnesian-rich ...
Early Paleozoic Tectonic and Thermomechanical
... magmatic arc. Petrologic, geochronologic, and geochemical studies indicate that the protolith of the UHP metamorphic rocks was a mixture of continental and mafic/ultramafic materials, derived either from oceanic mélanges or pieces of a rifted continental margin tectonically incorporated into an ocea ...
... magmatic arc. Petrologic, geochronologic, and geochemical studies indicate that the protolith of the UHP metamorphic rocks was a mixture of continental and mafic/ultramafic materials, derived either from oceanic mélanges or pieces of a rifted continental margin tectonically incorporated into an ocea ...
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.