Thermal Structure and Metamorphic Evolution of Subducting Slabs
... lavas (e.g., large-ion lithophile elements, B, Be) appear to be derived from the subducting slab [e.g., Gill, 1981; Hawkesworth et al., 1993; Davidson, 1996]. Most of these elements are readily transported in aqueous fluids, but recent experimental data suggest that the efficient transport of Be and ...
... lavas (e.g., large-ion lithophile elements, B, Be) appear to be derived from the subducting slab [e.g., Gill, 1981; Hawkesworth et al., 1993; Davidson, 1996]. Most of these elements are readily transported in aqueous fluids, but recent experimental data suggest that the efficient transport of Be and ...
2.03 Sampling Mantle Heterogeneity through Oceanic Basalts
... excess of 2 Ga in some cases. The melts that were extracted from these ophiolitic peridotites contained almost certainly much more radiogenic osmium and could, in any case, not have been in osmium-isotopic equilibrium with all of these isotopically diverse residual phases. Another strong indication ...
... excess of 2 Ga in some cases. The melts that were extracted from these ophiolitic peridotites contained almost certainly much more radiogenic osmium and could, in any case, not have been in osmium-isotopic equilibrium with all of these isotopically diverse residual phases. Another strong indication ...
The Architecture, Chemistry, and Evolution of - Cin
... subduction magmatism where the upper plate is continental and/or accreted transitional lithosphere. The active-type example is the Andean arc of South America. Well-studied deeply exhumed analogs to the Andean volcanic arc occur as composite batholiths along western North America. The South and Nort ...
... subduction magmatism where the upper plate is continental and/or accreted transitional lithosphere. The active-type example is the Andean arc of South America. Well-studied deeply exhumed analogs to the Andean volcanic arc occur as composite batholiths along western North America. The South and Nort ...
Crustal structure and evolution of the Mariana intra
... the crust as a part of the “crust.” The differentiated basalt layer is then remelted by basaltic underplating to produce tonalitic magmas (Tatsumi, 2000) that form the middle crust with a characteristic velocity of 6 km/s, and restites. Since the major product of surface volcanism at least in oceani ...
... the crust as a part of the “crust.” The differentiated basalt layer is then remelted by basaltic underplating to produce tonalitic magmas (Tatsumi, 2000) that form the middle crust with a characteristic velocity of 6 km/s, and restites. Since the major product of surface volcanism at least in oceani ...
Seismic structure of the crust and uppermost mantle of the Capricorn
... Australia, complements previous surface geological and other geophysical studies. Western Australia is an exceptionally large, well preserved region of ancient crust and hence this work also adds to the body of knowledge regarding Proterozoic orogenic processes in general. The new passive seismic wo ...
... Australia, complements previous surface geological and other geophysical studies. Western Australia is an exceptionally large, well preserved region of ancient crust and hence this work also adds to the body of knowledge regarding Proterozoic orogenic processes in general. The new passive seismic wo ...
High resolution image of the subducted Paci¢c (?) plate beneath
... overlying mantle wedge [13], similar to other subduction zones [14]. Alaska is one of the few places undergoing active accretion of exotic terranes, a process that has continued since the Mesozoic [10]. At the Earth’s surface, the Yakutat terrane presently impinges on the North American continent (F ...
... overlying mantle wedge [13], similar to other subduction zones [14]. Alaska is one of the few places undergoing active accretion of exotic terranes, a process that has continued since the Mesozoic [10]. At the Earth’s surface, the Yakutat terrane presently impinges on the North American continent (F ...
Revised Tectonic Evolution of the Eastern Indian Ocean
... A further difficulty in reconstructing the plate tectonic evolution of Australia and Antarctica is the absence of a clear paleo-plate boundary through the Central Kerguelen Plateau/Broken Ridge section of the margin prior to ~43 Ma. The conjugate, undulating rifted margins of the Central Kerguelen P ...
... A further difficulty in reconstructing the plate tectonic evolution of Australia and Antarctica is the absence of a clear paleo-plate boundary through the Central Kerguelen Plateau/Broken Ridge section of the margin prior to ~43 Ma. The conjugate, undulating rifted margins of the Central Kerguelen P ...
2D finite element modeling
... to as the elastic lithosphere on the basis of the theory of plate tectonics. One of the fundamental postulates of plate tectonics is that the surface plates constituting the lithosphere do not deform significantly on geological time scales. Bott (+33*) suggested that the uppermost ,* km of the contin ...
... to as the elastic lithosphere on the basis of the theory of plate tectonics. One of the fundamental postulates of plate tectonics is that the surface plates constituting the lithosphere do not deform significantly on geological time scales. Bott (+33*) suggested that the uppermost ,* km of the contin ...
Thermal structure of the shallow upper mantle beneath Italy and
... technique that includes the sensitivity of the temperature derived from Vs (shear-waves velocity) to the hydrous melt presence. This enhanced procedure provides supplementary information concerning the melt fraction (MF) in the upper mantle, corresponding to the temperature value inferred by the con ...
... technique that includes the sensitivity of the temperature derived from Vs (shear-waves velocity) to the hydrous melt presence. This enhanced procedure provides supplementary information concerning the melt fraction (MF) in the upper mantle, corresponding to the temperature value inferred by the con ...
Origin of Archean subcontinental lithospheric mantle: Some
... results in progressive change in the composition of the residue, from fertile lherzolite at the first, high-pressure stage of melting, to highly refractory dunite at the final low-pressure stage. As a result of a process that is not well understood, the residues of melting then accumulate near the sur ...
... results in progressive change in the composition of the residue, from fertile lherzolite at the first, high-pressure stage of melting, to highly refractory dunite at the final low-pressure stage. As a result of a process that is not well understood, the residues of melting then accumulate near the sur ...
Ultrahigh-pressure metamorphism: tracing continental crust into the
... rocks were buried to conditions of low T/P ratio, consistent with a subduction-zone context. Decompression occurred in most instances under continuous cooling, implying continuous heat loss to the footwall and hangingwall of the rising body. This rise along the subduction channel ^ an obvious mechan ...
... rocks were buried to conditions of low T/P ratio, consistent with a subduction-zone context. Decompression occurred in most instances under continuous cooling, implying continuous heat loss to the footwall and hangingwall of the rising body. This rise along the subduction channel ^ an obvious mechan ...
Lithium Isotope Variations in Ocean Island
... thought to be generated by mantle plumes that sample mantle domains with different geochemical and isotopic compositions (Fig. 1b and c). The sampled regions were selected to encompass a large part of the Sr^Nd^Pb isotopic compositional range of OIB and to be as close as possible to the various isot ...
... thought to be generated by mantle plumes that sample mantle domains with different geochemical and isotopic compositions (Fig. 1b and c). The sampled regions were selected to encompass a large part of the Sr^Nd^Pb isotopic compositional range of OIB and to be as close as possible to the various isot ...
The Lithosphere-Asthenosphere Boundary
... lithosphere to a hydrated, fertile asthenosphere (Figure 1d ). The variation in shear velocity resulting from depletion effects is debated; it ranges from less than a percent (Schutt & Lesher 2006) to 2.5% (Lee 2003). The velocity variation associated with the degree of hydration strongly depends on ...
... lithosphere to a hydrated, fertile asthenosphere (Figure 1d ). The variation in shear velocity resulting from depletion effects is debated; it ranges from less than a percent (Schutt & Lesher 2006) to 2.5% (Lee 2003). The velocity variation associated with the degree of hydration strongly depends on ...
Iceland is cool: An origin for the Iceland volcanic province in the
... Observations from the Iceland region that appear paradoxical in the plume model are as follows. Since the opening of the north Atlantic at ~ 54 Ma, the locus of melt extraction has been at the mid-Atlantic ridge (MAR) where it crosses the Caledonian suture. In the context of a plume, this is a coinc ...
... Observations from the Iceland region that appear paradoxical in the plume model are as follows. Since the opening of the north Atlantic at ~ 54 Ma, the locus of melt extraction has been at the mid-Atlantic ridge (MAR) where it crosses the Caledonian suture. In the context of a plume, this is a coinc ...
Origin of ocean island basalts: A new perspective from petrology
... [8] The significant coupling between radiogenic isotopes and incompatible element abundances and ratios in many OIB suites, seamount lavas, and MORB [e.g., Saunders et al., 1988; Sun and McDonough, 1989; Niu and Batiza, 1997; Niu et al., 1999, 2002a] suggests that the source materials of these basal ...
... [8] The significant coupling between radiogenic isotopes and incompatible element abundances and ratios in many OIB suites, seamount lavas, and MORB [e.g., Saunders et al., 1988; Sun and McDonough, 1989; Niu and Batiza, 1997; Niu et al., 1999, 2002a] suggests that the source materials of these basal ...
Primary magmas and mantle temperatures
... mantle temperatures — and in doing so, undergo melting in lithologies with lower solidus temperatures than normal mantle. In a later section we return to discussion of melting in an inhomogeneous mantle source comprised of asthenospheric mantle, refractory lithosphere and subducted oceanic crust. Th ...
... mantle temperatures — and in doing so, undergo melting in lithologies with lower solidus temperatures than normal mantle. In a later section we return to discussion of melting in an inhomogeneous mantle source comprised of asthenospheric mantle, refractory lithosphere and subducted oceanic crust. Th ...
Physics and Chemistry of Deep Continental Crust
... spreading centers) and destruction at downwellings (subduction zones), the resistance of continents to subduction makes them thermal insulators. Thus, the thermal history of Earth depends on the evolution of continental crust volume through time (Lenardic et al., 2005). The growth of continents may ...
... spreading centers) and destruction at downwellings (subduction zones), the resistance of continents to subduction makes them thermal insulators. Thus, the thermal history of Earth depends on the evolution of continental crust volume through time (Lenardic et al., 2005). The growth of continents may ...
ž / Evidence from mantle xenoliths for relatively thin -100
... Garnet peridotite xenoliths in the Quaternary Pali-Aike alkali olivine basalts of southernmost South America are samples of the deeper portion of continental lithosphere formed by accretion along the western margin of Gondwanaland during the Phanerozoic. Core compositions of minerals in garnet perid ...
... Garnet peridotite xenoliths in the Quaternary Pali-Aike alkali olivine basalts of southernmost South America are samples of the deeper portion of continental lithosphere formed by accretion along the western margin of Gondwanaland during the Phanerozoic. Core compositions of minerals in garnet perid ...
KENT C. CONDIE
... The parental theory of plate tectonics, seafloor spreading, states that new lithosphere is formed at ocean ridges and moves away from ridge axes with a motion like that of a conveyor belt as new lithosphere fills in the resulting crack or rift. The mosaic of plates, which range from 50 to over 200 k ...
... The parental theory of plate tectonics, seafloor spreading, states that new lithosphere is formed at ocean ridges and moves away from ridge axes with a motion like that of a conveyor belt as new lithosphere fills in the resulting crack or rift. The mosaic of plates, which range from 50 to over 200 k ...
Thermal modelling of the Laramide orogeny: testing the £at
... dynamics that this point is inconclusive. If frictional heating along the subduction interface, and/or a non-linear mantle wedge rheology are used in these models (e.g. [24]), the mantle wedge and subducting slab will be hotter, such that slab dehydration will occur at shallower depths, and inboard ...
... dynamics that this point is inconclusive. If frictional heating along the subduction interface, and/or a non-linear mantle wedge rheology are used in these models (e.g. [24]), the mantle wedge and subducting slab will be hotter, such that slab dehydration will occur at shallower depths, and inboard ...
The structure and dynamics of the mantle wedge
... Subduction zones are the dominant tectonic features of the Earth. They form the location of the major underthrusting earthquakes, explosive arc volcanism and are the only sites of deep earthquakes in the Earth’s mantle. The role of subduction zones in the plate tectonic framework is reasonably well ...
... Subduction zones are the dominant tectonic features of the Earth. They form the location of the major underthrusting earthquakes, explosive arc volcanism and are the only sites of deep earthquakes in the Earth’s mantle. The role of subduction zones in the plate tectonic framework is reasonably well ...
Lateral Density Inhomogeneities of the Continental and Oceanic
... notable anomalies related to the isostatic disequilib rium of these structures been noted. Therefore, all the data beyond these structures will be further considered as isostatically compensated for. Correspondingly, all the FMS depth anomalies in the considered structures denote density inhomogene ...
... notable anomalies related to the isostatic disequilib rium of these structures been noted. Therefore, all the data beyond these structures will be further considered as isostatically compensated for. Correspondingly, all the FMS depth anomalies in the considered structures denote density inhomogene ...
Reference crust-mantle density contrast beneath Antarctica based
... and Anandakrishnan (2004). Ritzwoller et al., (2001) used the simultaneous inversion of broadband group velocity measurements to compile a seismic model of the crust and upper mantle beneath Antarctica and surrounding oceans. Some studies have been based on airborne gravity surveys, for instance by ...
... and Anandakrishnan (2004). Ritzwoller et al., (2001) used the simultaneous inversion of broadband group velocity measurements to compile a seismic model of the crust and upper mantle beneath Antarctica and surrounding oceans. Some studies have been based on airborne gravity surveys, for instance by ...
Differentiation of the continental crust by relamination
... recorded in some arc sections (DeBari and Sleep, 1991; Kelemen et al., 2003a), loss of these rocks still yielded a mafic arc crust very different from continental crust (DeBari and Sleep, 1991; Greene et al., 2006). This is so because garnet-free mafic rocks that are either density-stable or too visco ...
... recorded in some arc sections (DeBari and Sleep, 1991; Kelemen et al., 2003a), loss of these rocks still yielded a mafic arc crust very different from continental crust (DeBari and Sleep, 1991; Greene et al., 2006). This is so because garnet-free mafic rocks that are either density-stable or too visco ...
Isostasy, flexure, and dynamic topography
... structure in various tectonic environments can be deduced in a way that missing parameters can be approximated; or does each area behave differently, making generalizations problematic. We contribute to this issue analyzing the Asia–Africa–Arabia–Europe domain following a top-down strategy. We compi ...
... structure in various tectonic environments can be deduced in a way that missing parameters can be approximated; or does each area behave differently, making generalizations problematic. We contribute to this issue analyzing the Asia–Africa–Arabia–Europe domain following a top-down strategy. We compi ...
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.