![evidence from Th, Sr and Pb isotope data for Tonga](http://s1.studyres.com/store/data/003444332_1-2029028deb00e66268ac238946c314d1-300x300.png)
evidence from Th, Sr and Pb isotope data for Tonga
... estimates of between 20 ka and 6 Ma for the residence time of U, Th and Be in the mantle wedge. These various estimates may reflect real differences in transport times between arcs, or variable transport rates for different elements. Recent studies have shown that although crustallevel contamination ...
... estimates of between 20 ka and 6 Ma for the residence time of U, Th and Be in the mantle wedge. These various estimates may reflect real differences in transport times between arcs, or variable transport rates for different elements. Recent studies have shown that although crustallevel contamination ...
Primitive off-rift basalts from Iceland and Jan Mayen: Os
... accepted as the expression of the interaction between a long-lived mantle plume and the Mid-Atlantic Ridge (MAR). Seismic investigations of the Iceland plume stem have been equivocal. For example, Foulger et al. (2001) and Montelli et al. (2004) have indicated that the plume is confined to the upper ...
... accepted as the expression of the interaction between a long-lived mantle plume and the Mid-Atlantic Ridge (MAR). Seismic investigations of the Iceland plume stem have been equivocal. For example, Foulger et al. (2001) and Montelli et al. (2004) have indicated that the plume is confined to the upper ...
Kinematics of the South Atlantic rift
... the African and South American plates during the final break-up of western Gondwana. While the relative motions between South America and Africa for post-break-up times are well resolved, many issues pertaining to the fit reconstruction and particularly the relation between kinematics and lithospher ...
... the African and South American plates during the final break-up of western Gondwana. While the relative motions between South America and Africa for post-break-up times are well resolved, many issues pertaining to the fit reconstruction and particularly the relation between kinematics and lithospher ...
Magma Ascent and Emplacement Topics Magma Generation
... • A layer of less dense material overlain by a denser material is unstable • The upper layer develops undulations and ...
... • A layer of less dense material overlain by a denser material is unstable • The upper layer develops undulations and ...
A New Mineral Province for PGEs, Au, Sc, Cu, Ni, Technology Metals
... Results of GSQ sponsored spinifex geochemistry study in the Simpson Desert. Discovery of phoscorite-carbonatite intrusions. Geodynamic interpretation: a Devonian age plume track in the Australian plate. Greenfield exploration opportunities in this new metallogenic province. Applications in ...
... Results of GSQ sponsored spinifex geochemistry study in the Simpson Desert. Discovery of phoscorite-carbonatite intrusions. Geodynamic interpretation: a Devonian age plume track in the Australian plate. Greenfield exploration opportunities in this new metallogenic province. Applications in ...
Chromium isotope fractionation during subduction
... carbonate rocks. The metamorphic age of these rocks range from Neoproterozoic to Phanerozoic. Although the pattern and depth of subduction may differ on the early and recent Earth, the underlying basic physicochemical processes (e.g., deformation, temperature- or concentration-driven diffusion) are ...
... carbonate rocks. The metamorphic age of these rocks range from Neoproterozoic to Phanerozoic. Although the pattern and depth of subduction may differ on the early and recent Earth, the underlying basic physicochemical processes (e.g., deformation, temperature- or concentration-driven diffusion) are ...
The three-dimensional thermo-mechanical signature of
... mantle should advect heat faster than it looses heat via conduction into the surrounding lithosphere, at least at the locus of upwelling. We chose to use a wet-quartzite flow law to constrain the flow strength of the lithosphere in our model. Due to the uncertainties of constraining the flow strength o ...
... mantle should advect heat faster than it looses heat via conduction into the surrounding lithosphere, at least at the locus of upwelling. We chose to use a wet-quartzite flow law to constrain the flow strength of the lithosphere in our model. Due to the uncertainties of constraining the flow strength o ...
What controls relay ramps and transfer faults within rift zones
... Schlische, 1994; Ferrill et al., 1999), the oceanic ridge of Iceland (Acocella et al., 2000) and the Gulf of Thailand (Kornsawan and Morley, 2002). In most of these cases, the relay ramps appear to control the shape or continuity of the rift and therefore they are considered significant at the rift ...
... Schlische, 1994; Ferrill et al., 1999), the oceanic ridge of Iceland (Acocella et al., 2000) and the Gulf of Thailand (Kornsawan and Morley, 2002). In most of these cases, the relay ramps appear to control the shape or continuity of the rift and therefore they are considered significant at the rift ...
Basement structures from satellite-derived gravity field: South China
... oceanic areas the short-wavelength component of the observed signal is generally well correlated with the bathymetry, a fact which was used by Sandwell and Smith [2001] and Smith and Sandwell [1997] to formulate the global bathymetric model derived from the integration of the global gravity anomaly ...
... oceanic areas the short-wavelength component of the observed signal is generally well correlated with the bathymetry, a fact which was used by Sandwell and Smith [2001] and Smith and Sandwell [1997] to formulate the global bathymetric model derived from the integration of the global gravity anomaly ...
extra revision sheet grade 7 Q 4 Multiple Choice Identify the choice
... a. stress breaking an object b. stress releasing an object ...
... a. stress breaking an object b. stress releasing an object ...
Meso- and Cenozoic Tectonics of the Central Asian Mountain Belt
... over wide territories, from the Tarim to Baikal and Altay areas. However, intensification of the deformation and uplift later were propagated northward, with development of the Qinghai Tibetan Plateau (20 to 12 Ma), Tien Shan mountains (18 to 11 Ma), Junggar mountains and depression (8 to 5 Ma), an ...
... over wide territories, from the Tarim to Baikal and Altay areas. However, intensification of the deformation and uplift later were propagated northward, with development of the Qinghai Tibetan Plateau (20 to 12 Ma), Tien Shan mountains (18 to 11 Ma), Junggar mountains and depression (8 to 5 Ma), an ...
Author`s personal copy - School of Arts and Sciences
... magnitudes (∼ 530–150 km) involving cover-to-basement rocks, an isostatically-compensated thick crust (∼ 80–65 km), high heat flow, and zones of variable velocity and attenuation in the crust and mantle. These observations have invoked interpretations such as a hot/weak lithosphere, partial melt, cru ...
... magnitudes (∼ 530–150 km) involving cover-to-basement rocks, an isostatically-compensated thick crust (∼ 80–65 km), high heat flow, and zones of variable velocity and attenuation in the crust and mantle. These observations have invoked interpretations such as a hot/weak lithosphere, partial melt, cru ...
Perspectives on the origin of plagiogranite in ophiolites from oxygen
... absence of felsic plutons of comparable scale along modern mid-ocean ridges possibly reflects limited drilling within plutonic crust, or differences in the geodynamic setting in which most ophiolites form. Dilek and Furnes (2011) classify two general categories for ophiolites. Subduction-related ophi ...
... absence of felsic plutons of comparable scale along modern mid-ocean ridges possibly reflects limited drilling within plutonic crust, or differences in the geodynamic setting in which most ophiolites form. Dilek and Furnes (2011) classify two general categories for ophiolites. Subduction-related ophi ...
Kinematics of the South Atlantic rift
... a large Jurassic-Cretaceous intraplate rift zone between the African and South American plates during the final breakup of western Gondwana. While the relative motions between South America and Africa for post-breakup times are well resolved, many issues pertaining to the fit reconstruction and part ...
... a large Jurassic-Cretaceous intraplate rift zone between the African and South American plates during the final breakup of western Gondwana. While the relative motions between South America and Africa for post-breakup times are well resolved, many issues pertaining to the fit reconstruction and part ...
The Ocean Bottom
... produced by the break down of rocks on land Biogenic sediment produced by organisms Authigenic sediment produced in place by chemical reactions in seawater or within the upper sediment Volcanogenic sediment produced from the ejections of volcanic eruptions Cosmogenic sediments produced from ...
... produced by the break down of rocks on land Biogenic sediment produced by organisms Authigenic sediment produced in place by chemical reactions in seawater or within the upper sediment Volcanogenic sediment produced from the ejections of volcanic eruptions Cosmogenic sediments produced from ...
Adiabatic decompression and melting of mantle rocks
... the upwelling system. In this case, the process has been considered to be incrementally isentropic. Asimov [2002] has presented a comprehensive discussion of the various source terms for entropy production during adiabatic decompression melting, and evaluated the effects of entropy production due to ...
... the upwelling system. In this case, the process has been considered to be incrementally isentropic. Asimov [2002] has presented a comprehensive discussion of the various source terms for entropy production during adiabatic decompression melting, and evaluated the effects of entropy production due to ...
PDF (Chapter 11. Evolution of the Mantle)
... in the North and South Atlantic, where the cross section cuts across the Mid-Atlantic Ridge. Dashed lines are plate boundaries. Circles in upper panel are hotspots. (Model from Nataf and others, 1986.) ...
... in the North and South Atlantic, where the cross section cuts across the Mid-Atlantic Ridge. Dashed lines are plate boundaries. Circles in upper panel are hotspots. (Model from Nataf and others, 1986.) ...
Wilson cycle
... Rift is generally asymmetric, possibly due to disequilibrium between surface processes and deeper ...
... Rift is generally asymmetric, possibly due to disequilibrium between surface processes and deeper ...
Crustal and Upper-mantle Structure Beneath Ice
... the Cretaceous Newfoundland–Iberia rifted margins and the Mesozoic-Tertiary North Sea rift as tectonic analogues. The low-to-moderate heat flow reported for the Newfoundland–Iberia margins (40–65 mW m−2 ) and North Sea rift (60–85 mW m−2 ) suggest that heat flow across the WARS also may not be eleva ...
... the Cretaceous Newfoundland–Iberia rifted margins and the Mesozoic-Tertiary North Sea rift as tectonic analogues. The low-to-moderate heat flow reported for the Newfoundland–Iberia margins (40–65 mW m−2 ) and North Sea rift (60–85 mW m−2 ) suggest that heat flow across the WARS also may not be eleva ...
Seismic low-velocity layer at the top of subducting slabs
... Layered structure persists at the tops of subducting plates to depths in excess of 150 km. A low-velocity channel several km thick produces guided seismic guided waves, which indicate that the top of the downgoing plate remains coherent and probably has not eclogitized to >150 km depth. The surround ...
... Layered structure persists at the tops of subducting plates to depths in excess of 150 km. A low-velocity channel several km thick produces guided seismic guided waves, which indicate that the top of the downgoing plate remains coherent and probably has not eclogitized to >150 km depth. The surround ...
geologic trips to the Sea Ranch
... so that periodically the sediments became unstable, probably during storms or earthquakes. When the sediments became unstable, they mixed with sea water and formed a dense turbidity flow that moved down the flank of the basin like an underwater avalanche.The sediments were then deposited on the ocea ...
... so that periodically the sediments became unstable, probably during storms or earthquakes. When the sediments became unstable, they mixed with sea water and formed a dense turbidity flow that moved down the flank of the basin like an underwater avalanche.The sediments were then deposited on the ocea ...
Plate tectonics
Plate tectonics (from the Late Latin tectonicus, from the Greek: τεκτονικός ""pertaining to building"") is a scientific theory that describes the large-scale motion of Earth's lithosphere. This theoretical model builds on the concept of continental drift which was developed during the first few decades of the 20th century. The geoscientific community accepted the theory after the concepts of seafloor spreading were later developed in the late 1950s and early 1960s.The lithosphere, which is the rigid outermost shell of a planet (on Earth, the crust and upper mantle), is broken up into tectonic plates. On Earth, there are seven or eight major plates (depending on how they are defined) and many minor plates. Where plates meet, their relative motion determines the type of boundary; convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative movement of the plates typically varies from zero to 100 mm annually.Tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, subduction carries plates into the mantle; the material lost is roughly balanced by the formation of new (oceanic) crust along divergent margins by seafloor spreading. In this way, the total surface of the globe remains the same. This prediction of plate tectonics is also referred to as the conveyor belt principle. Earlier theories (that still have some supporters) propose gradual shrinking (contraction) or gradual expansion of the globe.Tectonic plates are able to move because the Earth's lithosphere has greater strength than the underlying asthenosphere. Lateral density variations in the mantle result in convection. Plate movement is thought to be driven by a combination of the motion of the seafloor away from the spreading ridge (due to variations in topography and density of the crust, which result in differences in gravitational forces) and drag, with downward suction, at the subduction zones. Another explanation lies in the different forces generated by the rotation of the globe and the tidal forces of the Sun and Moon. The relative importance of each of these factors and their relationship to each other is unclear, and still the subject of much debate.