Ophiolite concept and its evolution
... within geosynclines. The genetic association of mantle peridotites with volcanic and plutonic rocks in ophiolites was not considered in these studies, and the emplacement of serpentinized ultramafic rocks in orogenic belts remained a topic of debate regarding ophiolites among the North American geos ...
... within geosynclines. The genetic association of mantle peridotites with volcanic and plutonic rocks in ophiolites was not considered in these studies, and the emplacement of serpentinized ultramafic rocks in orogenic belts remained a topic of debate regarding ophiolites among the North American geos ...
Mechanism and timing of Pb transport from subducted oceanic crust
... New high-precision (double-spike) Pb isotope analyses of lavas from Tafahi and Niuatoputapu, the northernmost islands of the Tonga–Kermadec Island Arc, are used to examine the source of Pb in these samples, and the relative timing of Pb addition from the subducting oceanic crust and subducting sedim ...
... New high-precision (double-spike) Pb isotope analyses of lavas from Tafahi and Niuatoputapu, the northernmost islands of the Tonga–Kermadec Island Arc, are used to examine the source of Pb in these samples, and the relative timing of Pb addition from the subducting oceanic crust and subducting sedim ...
A detrital record of the Nile River and its catchment
... Arabian–Nubian Shield, consisting of granitoid gneisses, staurolitebearing schists and marbles (Tadesse et al. 2003), and Phanerozoic sedimentary rocks found in the pre-rift sedimentary succession of the Blue Nile Canyon. Despite both rivers draining similar lithologies in the Ethiopian Highlands, t ...
... Arabian–Nubian Shield, consisting of granitoid gneisses, staurolitebearing schists and marbles (Tadesse et al. 2003), and Phanerozoic sedimentary rocks found in the pre-rift sedimentary succession of the Blue Nile Canyon. Despite both rivers draining similar lithologies in the Ethiopian Highlands, t ...
Behaviour of high field strength elements in subduction zones
... rare earth elements (REE) and large ion lithophile elements (LILE) (e.g., [1]) despite their similar compatibility during mantle melting. This depletion is the consequence of mass flux processes from the subducting plate to the subarc mantle. Most arc magmas originate from the subarc mantle wedge (e ...
... rare earth elements (REE) and large ion lithophile elements (LILE) (e.g., [1]) despite their similar compatibility during mantle melting. This depletion is the consequence of mass flux processes from the subducting plate to the subarc mantle. Most arc magmas originate from the subarc mantle wedge (e ...
Multiple sulfur isotope composition of oxidized Samoan melts and
... which defines the enriched-mantle-2 (EM2) endmember. Bulk S abundances vary between 835 and 2279 ppm. About 17 ± 11% of sulfur is oxidized (S6+ ) but displays no consistent trend with bulk S abundance or any other geochemical tracer. The S isotope composition of both dissolved sulfide and sulfate yiel ...
... which defines the enriched-mantle-2 (EM2) endmember. Bulk S abundances vary between 835 and 2279 ppm. About 17 ± 11% of sulfur is oxidized (S6+ ) but displays no consistent trend with bulk S abundance or any other geochemical tracer. The S isotope composition of both dissolved sulfide and sulfate yiel ...
PDF (Chapter 9. The Source Region)
... of the source region. The existence of meteorites rich in olivine has provided support for the argument that peridotite is the parental basalt material in the Earth. On the other hand, cosmochemical models of the Earth have more pyroxene and less olivine than most peridotite models for the mantle, a ...
... of the source region. The existence of meteorites rich in olivine has provided support for the argument that peridotite is the parental basalt material in the Earth. On the other hand, cosmochemical models of the Earth have more pyroxene and less olivine than most peridotite models for the mantle, a ...
Baltica in the Cryogenian, 850–630 Ma
... Baltica’s northeastern and eastern regions document episodic intracratonic rifting throughout the Mesoproterozoic, followed by pericontinental passive margin deposition throughout the Cryogenian. In the northeast platformal and deeper-water basin deposits are preserved, whereas the eastern region wa ...
... Baltica’s northeastern and eastern regions document episodic intracratonic rifting throughout the Mesoproterozoic, followed by pericontinental passive margin deposition throughout the Cryogenian. In the northeast platformal and deeper-water basin deposits are preserved, whereas the eastern region wa ...
Alfred Wegener`s Hypothesis on Continental Drift and Its Discussion
... of South America fit precisely into the west coast of Africa so as if they had been connected in the past. This seems even more true, when one looks at a bathygraphical map of the Atlantic Ocean and compares not the rims of continental dry lands but the edges of the continental shelves to the deep s ...
... of South America fit precisely into the west coast of Africa so as if they had been connected in the past. This seems even more true, when one looks at a bathygraphical map of the Atlantic Ocean and compares not the rims of continental dry lands but the edges of the continental shelves to the deep s ...
2011 - University of Colorado Boulder
... the supercontinent Pangea — likely the most significant global tectonic event in the last 500 Ma. In this study, we reconstruct temporal evolution of the surface and CMB heat fluxes since the Paleozoic by formulating three-dimensional spherical models of mantle convection with plate motion history for ...
... the supercontinent Pangea — likely the most significant global tectonic event in the last 500 Ma. In this study, we reconstruct temporal evolution of the surface and CMB heat fluxes since the Paleozoic by formulating three-dimensional spherical models of mantle convection with plate motion history for ...
Slab behaviour and its surface expression: new insights
... the subsurface. In both cases, Bouguer and free-air anomalies are the same for the uncompensated stage (Fig. 1b,d). The broad free-air anomalies indicate that isostatic equilibrium is not realized and the Bouguer anomalies reveal the uncompensated mass deficit and mass excess for the two models. Not ...
... the subsurface. In both cases, Bouguer and free-air anomalies are the same for the uncompensated stage (Fig. 1b,d). The broad free-air anomalies indicate that isostatic equilibrium is not realized and the Bouguer anomalies reveal the uncompensated mass deficit and mass excess for the two models. Not ...
A detrital record of the Nile River and its catchment
... Arabian–Nubian Shield, consisting of granitoid gneisses, staurolitebearing schists and marbles (Tadesse et al. 2003), and Phanerozoic sedimentary rocks found in the pre-rift sedimentary succession of the Blue Nile Canyon. Despite both rivers draining similar lithologies in the Ethiopian Highlands, t ...
... Arabian–Nubian Shield, consisting of granitoid gneisses, staurolitebearing schists and marbles (Tadesse et al. 2003), and Phanerozoic sedimentary rocks found in the pre-rift sedimentary succession of the Blue Nile Canyon. Despite both rivers draining similar lithologies in the Ethiopian Highlands, t ...
A detrital record of the Nile River and its catchment
... Arabian–Nubian Shield, consisting of granitoid gneisses, staurolitebearing schists and marbles (Tadesse et al. 2003), and Phanerozoic sedimentary rocks found in the pre-rift sedimentary succession of the Blue Nile Canyon. Despite both rivers draining similar lithologies in the Ethiopian Highlands, t ...
... Arabian–Nubian Shield, consisting of granitoid gneisses, staurolitebearing schists and marbles (Tadesse et al. 2003), and Phanerozoic sedimentary rocks found in the pre-rift sedimentary succession of the Blue Nile Canyon. Despite both rivers draining similar lithologies in the Ethiopian Highlands, t ...
Early opening history of the North Atlantic — I. Structure
... marginal areas prior to and during the early stages of rifting is now presumed to be dominated by the gross modification of large areas of continental crust and/or the adjacent oceanic crust. We propose to challenge these views by showing that the Faeroe-Shetland Escarpment has no direct relevance t ...
... marginal areas prior to and during the early stages of rifting is now presumed to be dominated by the gross modification of large areas of continental crust and/or the adjacent oceanic crust. We propose to challenge these views by showing that the Faeroe-Shetland Escarpment has no direct relevance t ...
Thermal and metamorphic environment of subduction zone episodic
... truncated at the tip of the mantle wedge to satisfy surface heat flow measurements. Note that the choice of mantle rheology does not significantly affect the temperatures calculated for the shallow fore arc, unless flow in the mantle wedge corner were to extend updip to depths <50 km, which would be ...
... truncated at the tip of the mantle wedge to satisfy surface heat flow measurements. Note that the choice of mantle rheology does not significantly affect the temperatures calculated for the shallow fore arc, unless flow in the mantle wedge corner were to extend updip to depths <50 km, which would be ...
Flow and melting of a heterogeneous mantle: 2. Implications for a
... We have recently examined the importance of upper mantle flow and melting of a heterogeneous mantle on the incompatible trace element and isotope composition of ocean island basalts (OIBs) and mid-ocean ridge basalts (MORBs) [G. Ito, J. Mahoney, Flow and melting of a heterogeneous mantle 1: method a ...
... We have recently examined the importance of upper mantle flow and melting of a heterogeneous mantle on the incompatible trace element and isotope composition of ocean island basalts (OIBs) and mid-ocean ridge basalts (MORBs) [G. Ito, J. Mahoney, Flow and melting of a heterogeneous mantle 1: method a ...
Zuni–Bandera volcanism, Rio Grande, USA — Melt formation in
... The Zuni–Bandera Volcanic Field (ZBVF) is a late-Neogene volcanic field on the boundary of the stable Colorado Plateau and the active Rio Grande Rift. Alkalic and tholeiitic magmas have erupted through Proterozoic continental crust with the tholeiitic magmas having undergone shallow-level fractional ...
... The Zuni–Bandera Volcanic Field (ZBVF) is a late-Neogene volcanic field on the boundary of the stable Colorado Plateau and the active Rio Grande Rift. Alkalic and tholeiitic magmas have erupted through Proterozoic continental crust with the tholeiitic magmas having undergone shallow-level fractional ...
Geodynamic models of Cordilleran orogens
... roots has been inferred from geological field evidence, xenolith data, and seismic tomography studies (e.g., Ducea, 2002; Saleeby et al., 2003; Zandt et al., 2004; Behn and Kelemen, 2006). However, there have only been limited geodynamic studies of the removal process. Jull and Kelemen (2001) modele ...
... roots has been inferred from geological field evidence, xenolith data, and seismic tomography studies (e.g., Ducea, 2002; Saleeby et al., 2003; Zandt et al., 2004; Behn and Kelemen, 2006). However, there have only been limited geodynamic studies of the removal process. Jull and Kelemen (2001) modele ...
Eduard Suess` conception of the Alpine orogeny related to
... to which Suess himself contributed a substantial amount of research, supported his geological work and tectonic reasoning to some extent. Since the publication of „Die Entstehung der Alpen“, Physics of the Earth has made tremendous progress and geophysical data and models have become of fundamental ...
... to which Suess himself contributed a substantial amount of research, supported his geological work and tectonic reasoning to some extent. Since the publication of „Die Entstehung der Alpen“, Physics of the Earth has made tremendous progress and geophysical data and models have become of fundamental ...
The Origin, Evolution and Present State of Subcontinental Lithosphere
... Scientific questions to be considered and discussed: (1) What may have caused the lithosphere thinning? (2) Is it plausible that the buoyant SCLM sinks into the dense asthenosphere by a process called “delamination”? (3) If so, why doesn’t such “delamination” seem to occur beneath ancient cratons su ...
... Scientific questions to be considered and discussed: (1) What may have caused the lithosphere thinning? (2) Is it plausible that the buoyant SCLM sinks into the dense asthenosphere by a process called “delamination”? (3) If so, why doesn’t such “delamination” seem to occur beneath ancient cratons su ...
A normalised seawater strontium isotope curve: possible
... Edmond, 1989; Peucker-Ehrenbrink and Miller, 2006), reflects a mixture of Sr from the weathering of carbonates (87 Sr/86 Sr = 0.7077) and silicates (87 Sr/86 Sr = 0.7178). Using these estimates, approximately 55% of the Sr in modern rivers derives from the weathering of sedimentary carbonate mineral ...
... Edmond, 1989; Peucker-Ehrenbrink and Miller, 2006), reflects a mixture of Sr from the weathering of carbonates (87 Sr/86 Sr = 0.7077) and silicates (87 Sr/86 Sr = 0.7178). Using these estimates, approximately 55% of the Sr in modern rivers derives from the weathering of sedimentary carbonate mineral ...
The American Cordillera: Part III, The North American Taphrogen
... at more southerly latitudes. It may not be coincidence that the MFZ grew significantly in length during the latter period of the Laramide orogeny. Could the growth of the MFZ be in response to the impingement of a large oceanic plateau with North America between latitudes 30 and 40N? ...
... at more southerly latitudes. It may not be coincidence that the MFZ grew significantly in length during the latter period of the Laramide orogeny. Could the growth of the MFZ be in response to the impingement of a large oceanic plateau with North America between latitudes 30 and 40N? ...
LOW RES
... + Ti). High rates of shear heating increase interface temperatures, but the low surface heat flux observed in forearcs requires that advective cooling, and not shear heating, controls the shallow thermal structure of subduction zones. In general, there is good agreement among the different thermal m ...
... + Ti). High rates of shear heating increase interface temperatures, but the low surface heat flux observed in forearcs requires that advective cooling, and not shear heating, controls the shallow thermal structure of subduction zones. In general, there is good agreement among the different thermal m ...
Shape and origin of the East-Alpine slab constrained by the
... European plate and extension during the post-collision phase of the Alpine orogeny. Between 350 km and 400 km depth, a “deep slab” extends from below the central Eastern Alps to under the Pannonian realm. It is interpreted as subducted lithosphere of the Alpine Tethys. At greater depth, there is a c ...
... European plate and extension during the post-collision phase of the Alpine orogeny. Between 350 km and 400 km depth, a “deep slab” extends from below the central Eastern Alps to under the Pannonian realm. It is interpreted as subducted lithosphere of the Alpine Tethys. At greater depth, there is a c ...
Mechanisms of crustal growth in large igneous
... Bergreen et al. (1995) time scale. The emplacement of Paleocene flood-basalts spanned about 6 Ma, from -62 to -57/-56 Ma (Hitchen and Richtie, 1993). Ar-Ar ages from the East-Greenland coastal dike swarm (Lenoir et al., 2003) indicate that the break-up is bracketed between 54 and 51 Ma, which is con ...
... Bergreen et al. (1995) time scale. The emplacement of Paleocene flood-basalts spanned about 6 Ma, from -62 to -57/-56 Ma (Hitchen and Richtie, 1993). Ar-Ar ages from the East-Greenland coastal dike swarm (Lenoir et al., 2003) indicate that the break-up is bracketed between 54 and 51 Ma, which is con ...
Serpentinization of the forearc mantle
... the incoming plate or incorporated into the oceanic crust have not been included, but they could be a signi¢cant additional source of £uids (e.g., [34,35]). At shallow depths in subducting plates, there are two competing processes in the underthrusting sediments and oceanic crust: £uid loss from the ...
... the incoming plate or incorporated into the oceanic crust have not been included, but they could be a signi¢cant additional source of £uids (e.g., [34,35]). At shallow depths in subducting plates, there are two competing processes in the underthrusting sediments and oceanic crust: £uid loss from 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.