Variations in magmatic processes along the East Greenland
... (McKenzie & Bickle 1988). Anderson (2000) proposed normal potential temperatures for the upper mantle of 1400 ± 200 ◦ C, and rapid convection giving rise to 3-D-heterogenities in the lithosphere that are responsible for the excess magmatism. Foulger & Anderson (2005) considered mantle heterogeneitie ...
... (McKenzie & Bickle 1988). Anderson (2000) proposed normal potential temperatures for the upper mantle of 1400 ± 200 ◦ C, and rapid convection giving rise to 3-D-heterogenities in the lithosphere that are responsible for the excess magmatism. Foulger & Anderson (2005) considered mantle heterogeneitie ...
Indentation of a continent with a built
... transferred from the subducting plate onto the non-subducting plate, continental suturing is thought to be followed by the transfer of weak warm upper crust onto cold stiff continent. The transfer of sediments scraped off the subducting ocean floor into an accretionary prism on the non-subducting pl ...
... transferred from the subducting plate onto the non-subducting plate, continental suturing is thought to be followed by the transfer of weak warm upper crust onto cold stiff continent. The transfer of sediments scraped off the subducting ocean floor into an accretionary prism on the non-subducting pl ...
13 Oxygen Isotopes in Zircon - University of Wisconsin
... independently determined by Eiler et al. (1997). These to 5‰ in δ O (Bindeman and Valley (2000a, data show that Hf substitution measurably affects data 2001, 2003). correction (from Peck et al. 2001). A relatively new and very promising approach to zircon separation is the Electric Pulse Disintegrat ...
... independently determined by Eiler et al. (1997). These to 5‰ in δ O (Bindeman and Valley (2000a, data show that Hf substitution measurably affects data 2001, 2003). correction (from Peck et al. 2001). A relatively new and very promising approach to zircon separation is the Electric Pulse Disintegrat ...
Yin and yang of continental crust creation and destruction by plate
... by Armstrong 1991), but when the question ‘has continental crust volume increased or decreased with time?’ is addressed thoughtfully, it must be admitted that there is much that is not known. It is clear from truncations of ancient orogenic belts (Dickinson 2009) and the presence of >4.0 Ga zircons ...
... by Armstrong 1991), but when the question ‘has continental crust volume increased or decreased with time?’ is addressed thoughtfully, it must be admitted that there is much that is not known. It is clear from truncations of ancient orogenic belts (Dickinson 2009) and the presence of >4.0 Ga zircons ...
Geology, 39
... Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen, Denmark ...
... Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen, Denmark ...
Thermal structure of the Costa Rica – Nicaragua subduction zone
... where the slab dips steeply and is at a minimum in the Costa Rica arc (Carr et al., 1990; Morris et al., 1990; Leeman et al., 1994). The rapid along-strike change in arc geochemistry occurs close to the border between Nicaragua and Costa Rica where the position of the volcanic front shifts, some 150 ...
... where the slab dips steeply and is at a minimum in the Costa Rica arc (Carr et al., 1990; Morris et al., 1990; Leeman et al., 1994). The rapid along-strike change in arc geochemistry occurs close to the border between Nicaragua and Costa Rica where the position of the volcanic front shifts, some 150 ...
Possible density segregation of subducted oceanic
... follow the 600 to 700 °C isotherm predicted by thermal models [29,30]. When taken together, all these independent observations suggest the existence of a weak serpentinite layer just beneath the oceanic crust even though alternative explanations may exist for any individual observation (Fig. 1A). Th ...
... follow the 600 to 700 °C isotherm predicted by thermal models [29,30]. When taken together, all these independent observations suggest the existence of a weak serpentinite layer just beneath the oceanic crust even though alternative explanations may exist for any individual observation (Fig. 1A). Th ...
Not Getting the Drift - Personal webpages at NTNU
... Afterward, he split the subject into two major books, his Principles of Geology, which deals mostly with geological processes and how they operate, and his Elements of Geology, which records the events that have taken place in historical geology. He kept these two textbooks up to date for decades, t ...
... Afterward, he split the subject into two major books, his Principles of Geology, which deals mostly with geological processes and how they operate, and his Elements of Geology, which records the events that have taken place in historical geology. He kept these two textbooks up to date for decades, t ...
Melting Relations of MORB^Sediment Me
... are produced within the continental crust. Currently accepted intra-crustal models include: (1) assimilation of continental crustal rocks by basalt magmas (e.g. De Paolo, 1981; Patin‹o-Douce, 1995); (2) coupled magma mixing and crustal assimilation, involving hydrous basalts and continental crustal ...
... are produced within the continental crust. Currently accepted intra-crustal models include: (1) assimilation of continental crustal rocks by basalt magmas (e.g. De Paolo, 1981; Patin‹o-Douce, 1995); (2) coupled magma mixing and crustal assimilation, involving hydrous basalts and continental crustal ...
Plate Tectonics - The Open University
... http://www.open.edu/openlearn/science-maths-technology/science/geology/platetectonics/content-section-0. There you'll also be able to track your progress via your activity record, which you ...
... http://www.open.edu/openlearn/science-maths-technology/science/geology/platetectonics/content-section-0. There you'll also be able to track your progress via your activity record, which you ...
Continental Growth and Recycling in Convergent Orogens with
... basement are accreted to continents represent important sites of continental crustal growth and recycling. Crust accreted in these settings is dominated by an upper layer of recycled crustal and arc detritus (turbidites) underlain by a layer of tectonically imbricated upper oceanic crust and/or thin ...
... basement are accreted to continents represent important sites of continental crustal growth and recycling. Crust accreted in these settings is dominated by an upper layer of recycled crustal and arc detritus (turbidites) underlain by a layer of tectonically imbricated upper oceanic crust and/or thin ...
47. the ocean/continent transition beneath the iberia abyssal plain
... (1964). As a result of its elevated location, Galicia Bank has long been starved of sediment and this has helped in the study of the sediment seismostratigraphy and basement tectonics. The elevated location of Galicia Bank has been explained by 3000 m of Eocene uplift during the Pyrenean compression ...
... (1964). As a result of its elevated location, Galicia Bank has long been starved of sediment and this has helped in the study of the sediment seismostratigraphy and basement tectonics. The elevated location of Galicia Bank has been explained by 3000 m of Eocene uplift during the Pyrenean compression ...
BASIN TYPES ACCORDING TO TECTONIC by Prof. Dr. Abbas
... the Sirte embayment was infilled by nearly a kilometre of interbedded carbonates and evaporites. The final phase of basin infilling during the Oligocene and Miocene involved terrigenous and carbonate sedimentation in both marine and continental environments. The active history of the basin was concl ...
... the Sirte embayment was infilled by nearly a kilometre of interbedded carbonates and evaporites. The final phase of basin infilling during the Oligocene and Miocene involved terrigenous and carbonate sedimentation in both marine and continental environments. The active history of the basin was concl ...
Geology
... Showa-machi 3173-25, Kanazawa-ku, Yokohama, Japan Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, Natsushima 2-15, Yokosuka, Japan ...
... Showa-machi 3173-25, Kanazawa-ku, Yokohama, Japan Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, Natsushima 2-15, Yokosuka, Japan ...
Incipient shortening of a passive margin: the mechanical roles of
... Key words: analogue modelling, incipient shortening, obduction, passive margin, post-breakup, strength profiles, subduction. ...
... Key words: analogue modelling, incipient shortening, obduction, passive margin, post-breakup, strength profiles, subduction. ...
Petrological models of magma evolution and deep crustal structure
... Seismic experiments imaging the deep crustal structure beneath hotspot tracks and oceanic plateaus indicate unusually high seismic velocities (V, = 7.3-7.8 km/s) at the base of the crust. These high-velocity ‘layers’, up to 10 km thick, are generally interpreted as large igneous intrusions. In this ...
... Seismic experiments imaging the deep crustal structure beneath hotspot tracks and oceanic plateaus indicate unusually high seismic velocities (V, = 7.3-7.8 km/s) at the base of the crust. These high-velocity ‘layers’, up to 10 km thick, are generally interpreted as large igneous intrusions. In this ...
Mantle Exhumation in an Early Paleozoic Passive Margin, Northern
... aureole surrounding the peridotite body. A, Patches of granoblastic orthopyroxene (Opx) and plagioclase (Pl) in distinct pockets between quartz grains (Qz) in leucosome from sample KE004. Scale bar is 300 mm. B, Closer view of A showing orthopyroxene (Opx), plagioclase (Pl), and quartz (Qz) overgrow ...
... aureole surrounding the peridotite body. A, Patches of granoblastic orthopyroxene (Opx) and plagioclase (Pl) in distinct pockets between quartz grains (Qz) in leucosome from sample KE004. Scale bar is 300 mm. B, Closer view of A showing orthopyroxene (Opx), plagioclase (Pl), and quartz (Qz) overgrow ...
Rhenium–osmium isotope and elemental behaviour during
... thought to reflect the processes of differentiation and recycling that have occurred throughout geological history, and this chemical heterogeneity of the mantle is sampled at the present-day by basaltic volcanism. Mid-ocean ridge basalts (MORB) sample mantle material that is depleted in incompatibl ...
... thought to reflect the processes of differentiation and recycling that have occurred throughout geological history, and this chemical heterogeneity of the mantle is sampled at the present-day by basaltic volcanism. Mid-ocean ridge basalts (MORB) sample mantle material that is depleted in incompatibl ...
Thematic Article Tethyan ophiolites and Pangea break-up
... South America. During the Middle–Late Triassic, an ocean basin cutting the eastern equatorial portion of the Pangea opened as a prograding branch of the Paleotethys or as a new ocean (the Eastern Tethys); westwards, continental rift basins developed. The Western Tethys and Central Atlantic began to ...
... South America. During the Middle–Late Triassic, an ocean basin cutting the eastern equatorial portion of the Pangea opened as a prograding branch of the Paleotethys or as a new ocean (the Eastern Tethys); westwards, continental rift basins developed. The Western Tethys and Central Atlantic began to ...
Physics of the Earth and Planetary Interiors Bulldozing the core
... American stations. Here we present scattering images of the D region beneath the Caribbean using precursors to the PKIKP phase recorded by a broadband seismic array in northern South America and the Caribbean from earthquakes in the Western Pacific. Scattering of P waves in the lower mantle can be ...
... American stations. Here we present scattering images of the D region beneath the Caribbean using precursors to the PKIKP phase recorded by a broadband seismic array in northern South America and the Caribbean from earthquakes in the Western Pacific. Scattering of P waves in the lower mantle can be ...
Thermal Structure due to Solid-State Flow in the Mantle
... with petrologic constraints. One caveat is that trajectories of melt migration beneath an arc might not be vertical. Porous flow might lead to melt migration vectors that ascend diagonally toward the wedge corner either due to pressure gradients in the mantle flow [Spiegelman and McKenzie, 1987; Phi ...
... with petrologic constraints. One caveat is that trajectories of melt migration beneath an arc might not be vertical. Porous flow might lead to melt migration vectors that ascend diagonally toward the wedge corner either due to pressure gradients in the mantle flow [Spiegelman and McKenzie, 1987; Phi ...
Terrestrial Heat Flow and the Mantle Convection Hypothesis
... argument on the phase transition zone have led to the suggestion by many authors that convection is restricted to the upper mantle. The computations presented in this paper mainly assume a horizontal cell dimension of the order of the thickness of the mantle, but most of them could also be applied i ...
... argument on the phase transition zone have led to the suggestion by many authors that convection is restricted to the upper mantle. The computations presented in this paper mainly assume a horizontal cell dimension of the order of the thickness of the mantle, but most of them could also be applied i ...
Evolution of the continental crust
... Differentiation of the continental crust is dominated by igneous processes19. The degree of differentiation constrains how the rates at which the upper crust is generated relate to those at which new crust is generated, and the amounts of residual crustal material recycled back into the mantle. The ...
... Differentiation of the continental crust is dominated by igneous processes19. The degree of differentiation constrains how the rates at which the upper crust is generated relate to those at which new crust is generated, and the amounts of residual crustal material recycled back into the mantle. The ...
Formation and Exhumation of Ultrahigh
... The earliest models for UHP tectonism assumed that it occurs during subduction of a continental margin because the metamorphic pressure–temperature (P–T) conditions of UHP rocks are typical of subduction zones and not of overthickened continental collision zones, such as the Tibetan Plateau. A secon ...
... The earliest models for UHP tectonism assumed that it occurs during subduction of a continental margin because the metamorphic pressure–temperature (P–T) conditions of UHP rocks are typical of subduction zones and not of overthickened continental collision zones, such as the Tibetan Plateau. A secon ...
39. crustal structure along the leg 152 drilling transect
... the 70- to 80-km-wide shelf along the Leg 152 drilling transect. The seismic data include a detailed grid of shallow high-resolution seismic data; a regional grid of conventional multichannel seismic data (including sonobuoy refraction data); and a deep crustal, vertical incidence multichannel seism ...
... the 70- to 80-km-wide shelf along the Leg 152 drilling transect. The seismic data include a detailed grid of shallow high-resolution seismic data; a regional grid of conventional multichannel seismic data (including sonobuoy refraction data); and a deep crustal, vertical incidence multichannel seism ...
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.