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... of subsidence, sedimentation, and deformation required to create desirable juxtapositions paths, and reservoirs of sources, migration upon which the requisite thermal flux is superimposed. If so, we can therr seek these conditions in the geologic record of sedimentary basins. PLATE INIEMCTIO}'IS are ...
... of subsidence, sedimentation, and deformation required to create desirable juxtapositions paths, and reservoirs of sources, migration upon which the requisite thermal flux is superimposed. If so, we can therr seek these conditions in the geologic record of sedimentary basins. PLATE INIEMCTIO}'IS are ...
Channel flow and the Himalayan-Tibetan orogen: a critical review
... lowering the shear stress along the base of the wedge, which resulted in extrusion of the wedge by extension along the South Tibetan Detachment System. One problem with wedge tectonics, as applied to the Himalaya, is that the continuous post-collisional shortening across the orogen implies that extr ...
... lowering the shear stress along the base of the wedge, which resulted in extrusion of the wedge by extension along the South Tibetan Detachment System. One problem with wedge tectonics, as applied to the Himalaya, is that the continuous post-collisional shortening across the orogen implies that extr ...
The structure of the upper mantle beneath the Delamerian and
... Fig. 2. Fig. 4 shows the distribution of all events used to constrain the teleseismic tomography model described in the next section. An obvious concern with this distribution is that it has a very strong azimuthal variation, with many events located in the north and east and relatively few located ...
... Fig. 2. Fig. 4 shows the distribution of all events used to constrain the teleseismic tomography model described in the next section. An obvious concern with this distribution is that it has a very strong azimuthal variation, with many events located in the north and east and relatively few located ...
Harris, 2007
... lowering the shear stress along the base of the wedge, which resulted in extrusion of the wedge by extension along the South Tibetan Detachment System. One problem with wedge tectonics, as applied to the Himalaya, is that the continuous post-collisional shortening across the orogen implies that extr ...
... lowering the shear stress along the base of the wedge, which resulted in extrusion of the wedge by extension along the South Tibetan Detachment System. One problem with wedge tectonics, as applied to the Himalaya, is that the continuous post-collisional shortening across the orogen implies that extr ...
LitMod3D: An interactive 3-D software to model the
... density (bulk and single phase), seismic wave velocities, geoid and gravity anomalies, elevation, and lithospheric strength for any given model. These outputs can be used to obtain thermal and compositional models of the lithosphere and sublithospheric upper mantle that simultaneously fit all availa ...
... density (bulk and single phase), seismic wave velocities, geoid and gravity anomalies, elevation, and lithospheric strength for any given model. These outputs can be used to obtain thermal and compositional models of the lithosphere and sublithospheric upper mantle that simultaneously fit all availa ...
Geochemical evidence for interaction between oceanic crust and
... eastern China volcanic belt. A close spatial relationship between Paleogene basalts and sedimentary basins in eastern China suggests that Cenozoic basaltic magmatism was probably associated with extension and thinning of the lithosphere along the eastern edge of the Eurasian continent (Ma and Wu, 19 ...
... eastern China volcanic belt. A close spatial relationship between Paleogene basalts and sedimentary basins in eastern China suggests that Cenozoic basaltic magmatism was probably associated with extension and thinning of the lithosphere along the eastern edge of the Eurasian continent (Ma and Wu, 19 ...
Depth versus age: new perspectives from the chemical compositions
... Not every drill site on ancient crust that penetrates basement recovers material that was formed in place at an ocean ridge. Many sites are located on bathymetric highs that were created off-axis. Others penetrate basalts inferred to be off-axis sills on the basis of chilled margins and baked sedime ...
... Not every drill site on ancient crust that penetrates basement recovers material that was formed in place at an ocean ridge. Many sites are located on bathymetric highs that were created off-axis. Others penetrate basalts inferred to be off-axis sills on the basis of chilled margins and baked sedime ...
Chapter 9 - LSU Geology & Geophysics
... • But the extensive geographic distribution – of other conglomerates – and their associated glacial features – is distinctive, – such as striated and polished bedrock ...
... • But the extensive geographic distribution – of other conglomerates – and their associated glacial features – is distinctive, – such as striated and polished bedrock ...
Convergence and Collision
... When oceanic lithosphere first forms at a mid-ocean ridge, it is warm and relatively buoyant. But as lithosphere moves away from the ridge axis, it cools and the lithospheric mantle thickens, so that when lithosphere has aged more than 10 or 15 million years, it becomes negatively buoyant. In other ...
... When oceanic lithosphere first forms at a mid-ocean ridge, it is warm and relatively buoyant. But as lithosphere moves away from the ridge axis, it cools and the lithospheric mantle thickens, so that when lithosphere has aged more than 10 or 15 million years, it becomes negatively buoyant. In other ...
Tectonics of the lower mantle
... In the migration study we use shear-wave data recorded by broadband three-component seismic stations in networks across Europe (figure 1). Most are permanent stations, but some were deployed in a temporary network designed to image the deep Earth (Kendall and Helffrich 2001). Large deep-focus earthq ...
... In the migration study we use shear-wave data recorded by broadband three-component seismic stations in networks across Europe (figure 1). Most are permanent stations, but some were deployed in a temporary network designed to image the deep Earth (Kendall and Helffrich 2001). Large deep-focus earthq ...
PDF
... arbitrary but conservative limit, useful for the purposes of this study.] In terms of the entire zircon population from ANS rocks dated by single-zircon methods, about 5 percent of the zircons give ages greater than 880 Ma (table 1). There is nothing spatially systematic about the occurrences of ign ...
... arbitrary but conservative limit, useful for the purposes of this study.] In terms of the entire zircon population from ANS rocks dated by single-zircon methods, about 5 percent of the zircons give ages greater than 880 Ma (table 1). There is nothing spatially systematic about the occurrences of ign ...
101 - Durham University Community
... mantle source for OIB is heterogeneous on all scales. By accepting the assumption that the entire mantle is largely in the solid state and that solid-state elemental fractionation is practically unlikely[14], it is logical to suspect that processes known to occur in the upper mantle and crust (e.g., ...
... mantle source for OIB is heterogeneous on all scales. By accepting the assumption that the entire mantle is largely in the solid state and that solid-state elemental fractionation is practically unlikely[14], it is logical to suspect that processes known to occur in the upper mantle and crust (e.g., ...
Zinc isotope evidence for a large-scale carbonated mantle beneath
... investigate the application of Zn isotopes as a new tracer of deep carbonate cycling. All of the basalts with ages of <110 Ma have systematically heavy δ 66 Zn (relative to JMC 3-0749L) ranging from 0.30h to 0.63h (n = 44) compared to the mantle (0.28 ± 0.05h; 2sd) and >120 Ma basalts from eastern C ...
... investigate the application of Zn isotopes as a new tracer of deep carbonate cycling. All of the basalts with ages of <110 Ma have systematically heavy δ 66 Zn (relative to JMC 3-0749L) ranging from 0.30h to 0.63h (n = 44) compared to the mantle (0.28 ± 0.05h; 2sd) and >120 Ma basalts from eastern C ...
Chapter 8 Let`s take it from the top: the crust and upper mantle
... The Moho is a sharp seismological boundary and in some regions appears to be laminated. There are three major crustal types- continental, transitional and oceanic. Oceanic crust generally ranges from 5-15 km in thickness and comprises 60% of the total crust by area and more than 20% by volume. In so ...
... The Moho is a sharp seismological boundary and in some regions appears to be laminated. There are three major crustal types- continental, transitional and oceanic. Oceanic crust generally ranges from 5-15 km in thickness and comprises 60% of the total crust by area and more than 20% by volume. In so ...
eastern european alpine system and the carpathian
... double looped trend of mountains. Structures within these two belts generally follow the two mountainous belts, and superficially the structures appear more or less continuous, but nothing could be further from the truth. Structures within the two belts have formed diachronously over a period of nea ...
... double looped trend of mountains. Structures within these two belts generally follow the two mountainous belts, and superficially the structures appear more or less continuous, but nothing could be further from the truth. Structures within the two belts have formed diachronously over a period of nea ...
Meddelelser fra Dansk Geologisk Forening, vol. 17/4, pp. 504-516
... of uplift. These have apparently been rather small. In some areas postCarboniferous uplift has amounted to not more than a few kilometres. In other areas it has been greater, but probably rarely exceeds 15 to 20 km. Another feature of the Hercynian belt is the abundancy of intrusive granitic rocks. ...
... of uplift. These have apparently been rather small. In some areas postCarboniferous uplift has amounted to not more than a few kilometres. In other areas it has been greater, but probably rarely exceeds 15 to 20 km. Another feature of the Hercynian belt is the abundancy of intrusive granitic rocks. ...
A review of the isotopic and trace element evidence for
... reflects 4.5 billion years of geological evolution. While present plate tectonic processes (summed up as the “Wilson cycle”), driven by subduction and its consequent return flow, adequately explain much of the surface topography and composition of the crust and lithosphere, it is not known how plate ...
... reflects 4.5 billion years of geological evolution. While present plate tectonic processes (summed up as the “Wilson cycle”), driven by subduction and its consequent return flow, adequately explain much of the surface topography and composition of the crust and lithosphere, it is not known how plate ...
mantle plumes and hot spots - The Centre for Earth Evolution and
... and ridges, concerning the depth extent of these lowvelocity regions : low seismic velocities beneath hotspots extend to a depth of 200 km, whereas low seismic velocities beneath ridges are confined to the upper 100 km. This suggests that hotspots are caused by active upwellings (mantle plumes) with ...
... and ridges, concerning the depth extent of these lowvelocity regions : low seismic velocities beneath hotspots extend to a depth of 200 km, whereas low seismic velocities beneath ridges are confined to the upper 100 km. This suggests that hotspots are caused by active upwellings (mantle plumes) with ...
Influence of continental roots and asthenosphere on plate
... thick. Increased plate-mantle coupling beneath thick continental lithosphere may increase plate-driving forces, surface deformation, and mantle-derived lithospheric stresses in these regions. By contrast, a low-viscosity asthenosphere does not decouple the lithosphere from mantle flow, highlighting ...
... thick. Increased plate-mantle coupling beneath thick continental lithosphere may increase plate-driving forces, surface deformation, and mantle-derived lithospheric stresses in these regions. By contrast, a low-viscosity asthenosphere does not decouple the lithosphere from mantle flow, highlighting ...
accepted manuscript
... collision (Xiao et al., 2004, 2009a; Li, 2006; Jian et al., 2008, 2010; Johnson et al., 2008; Ao et al., 2012; Long et al., 2012a, b; Mao et al., 2012a). Furthermore, it is unclear whether some terranes can be mutually correlated, and whether certain displaced ...
... collision (Xiao et al., 2004, 2009a; Li, 2006; Jian et al., 2008, 2010; Johnson et al., 2008; Ao et al., 2012; Long et al., 2012a, b; Mao et al., 2012a). Furthermore, it is unclear whether some terranes can be mutually correlated, and whether certain displaced ...
Deep Sea Drilling Project Initial Reports Volume 80
... in northwestern Spain. This interpretation is reinforced by seismic refraction data. Velocities ranging between 5.1 and 5.8 km/s, observed in the interpreted basins, seem to be, as elsewhere in Brittany, characteristic of slightly metamorphosed upper Precambrian and Paleozoic rocks (Lefort, 1975). D ...
... in northwestern Spain. This interpretation is reinforced by seismic refraction data. Velocities ranging between 5.1 and 5.8 km/s, observed in the interpreted basins, seem to be, as elsewhere in Brittany, characteristic of slightly metamorphosed upper Precambrian and Paleozoic rocks (Lefort, 1975). D ...
101 Questions and Answers Concerning
... Q89 89. Is there convincing observational evidence for flow in the mantle today? Q90 90. Is it true that continuous sediment layers lie beneath today’s Appalachian Mountains? Q91 91. How do overthrusts occur and folded mountain ranges arise? Q92 92. How can so much catastrophic tectonic change unfol ...
... Q89 89. Is there convincing observational evidence for flow in the mantle today? Q90 90. Is it true that continuous sediment layers lie beneath today’s Appalachian Mountains? Q91 91. How do overthrusts occur and folded mountain ranges arise? Q92 92. How can so much catastrophic tectonic change unfol ...
PDF 51 - The Open University
... (i.e. core, mantle and crust). There are physical and chemical differences between those three layers, differences that distinguish the mantle and the crust, the heat that is generated within them makes its way to the surface to be lost into space. It is the movement of this internal heat that drive ...
... (i.e. core, mantle and crust). There are physical and chemical differences between those three layers, differences that distinguish the mantle and the crust, the heat that is generated within them makes its way to the surface to be lost into space. It is the movement of this internal heat that drive ...
2.1.1 Introduction
... phase becomes progressively longer as the length of the travel path increases. By making use of a standard model for the velocity stratification of the Earth, and employing many seismic phases corresponding to different travel paths along which the seismic waves are refracted or reflected at velocit ...
... phase becomes progressively longer as the length of the travel path increases. By making use of a standard model for the velocity stratification of the Earth, and employing many seismic phases corresponding to different travel paths along which the seismic waves are refracted or reflected at velocit ...
Crust recycling in the sources of two parallel volcanic chains in
... The origin of wide-spread Cenozoic continental volcanism in eastern China is problematic because there is no obvious cause of melting, since only some of this volcanism is directly associated with rifting. Recent seismic tomography has identified a low velocity region in the upper mantle beneath the ...
... The origin of wide-spread Cenozoic continental volcanism in eastern China is problematic because there is no obvious cause of melting, since only some of this volcanism is directly associated with rifting. Recent seismic tomography has identified a low velocity region in the upper mantle beneath the ...
Supercontinent
In geology, a supercontinent is the assembly of most or all of the Earth's continental blocks or cratons to form a single large landmass. However, the definition of a supercontinent can be ambiguous. Many tectonicists such as P.F. Hoffman (1999) use the term ""supercontinent"" to mean ""a clustering of nearly all continents"". This definition leaves room for interpretation when labeling a continental body and is easier to apply to Precambrian times. Using the first definition provided here, Gondwana (aka Gondwanaland) is not considered a supercontinent, because the landmasses of Baltica, Laurentia and Siberia also existed at the same time but physically separate from each other. The landmass of Pangaea is the collective name describing all of these continental masses when they were in a close proximity to one another. This would classify Pangaea as a supercontinent. According to the definition by Rogers and Santosh (2004), a supercontinent does not exist today. Supercontinents have assembled and dispersed multiple times in the geologic past (see table). The positions of continents have been accurately determined back to the early Jurassic. However, beyond 200 Ma, continental positions are much less certain.