SEDIMENT DISTRIBUTION IN THE OCEANS: THE ATLANTIC
... zone (HEEZEN and THARP, 1965, fig.5). The sea floor in the depression is about 40 m less deep than at 13-E and, on this cross-section, seems to form one plane with the westward sloping floor of the abyssal plain. The basement depression between 13-C and 13-D and especially the one at 13-E might also ...
... zone (HEEZEN and THARP, 1965, fig.5). The sea floor in the depression is about 40 m less deep than at 13-E and, on this cross-section, seems to form one plane with the westward sloping floor of the abyssal plain. The basement depression between 13-C and 13-D and especially the one at 13-E might also ...
Upper-mantle S-velocity structure of central and western South
... South American stations. These seismograms are from a mix of relatively uniformly distributed, permanent stations and from concentrated groups of stations from temporary experiments using portable seismometers [Van der Lee et al., 2000], as described in the next section. This combination results in ...
... South American stations. These seismograms are from a mix of relatively uniformly distributed, permanent stations and from concentrated groups of stations from temporary experiments using portable seismometers [Van der Lee et al., 2000], as described in the next section. This combination results in ...
Changes in seismic anisotropy shed light on the nature of the
... layer (layer 2) by a better alignment with the APM. Layer 1 is also characterized by high seismic velocities away from ocean ridges [4-5% with respect to our reference model (16)], and its thickness increases with crustal age, similar to past surface wave studies (13, 17-19). Furthermore, layer 1 is ...
... layer (layer 2) by a better alignment with the APM. Layer 1 is also characterized by high seismic velocities away from ocean ridges [4-5% with respect to our reference model (16)], and its thickness increases with crustal age, similar to past surface wave studies (13, 17-19). Furthermore, layer 1 is ...
Edmond and Huh 2003 - Department of the Geophysical Sciences
... relative to the rate of fixation by weathering, mechanisms that maintain this apparently precarious balance dominate current thinking. At present, the Atlantic and Indian oceans are major depocenters of CaCO3 , but subduction of ocean floor and the deposits on it is minimal in these basins. The locu ...
... relative to the rate of fixation by weathering, mechanisms that maintain this apparently precarious balance dominate current thinking. At present, the Atlantic and Indian oceans are major depocenters of CaCO3 , but subduction of ocean floor and the deposits on it is minimal in these basins. The locu ...
The plate tectonics of Cenozoic SE Asia and the
... were complex. Island arcs at the margins may have been underlain by continental and oceanic crust, and there were probably many small ocean basins behind the arcs and above the subduction zones. The widespread ophiolites are fragments of oceanic lithosphere now found on land, and much of this lithos ...
... were complex. Island arcs at the margins may have been underlain by continental and oceanic crust, and there were probably many small ocean basins behind the arcs and above the subduction zones. The widespread ophiolites are fragments of oceanic lithosphere now found on land, and much of this lithos ...
Lithospheric thickness under the Dinarides
... the "slab gap" beneath the Dinarides (taken from Handy et al. 2014). ...
... the "slab gap" beneath the Dinarides (taken from Handy et al. 2014). ...
Subduction erosion modes: Comparing finite
... During subduction erosion, the upper plate is tectonically eroded by the subducting plate and carried into the mantle. The geological record suggests that subduction erosion is a fundamental process at subduction margins; however the underlying causes are not well constrained. Finite-element numeric ...
... During subduction erosion, the upper plate is tectonically eroded by the subducting plate and carried into the mantle. The geological record suggests that subduction erosion is a fundamental process at subduction margins; however the underlying causes are not well constrained. Finite-element numeric ...
as a PDF
... were complex. Island arcs at the margins may have been underlain by continental and oceanic crust, and there were probably many small ocean basins behind the arcs and above the subduction zones. The widespread ophiolites are fragments of oceanic lithosphere now found on land, and much of this lithos ...
... were complex. Island arcs at the margins may have been underlain by continental and oceanic crust, and there were probably many small ocean basins behind the arcs and above the subduction zones. The widespread ophiolites are fragments of oceanic lithosphere now found on land, and much of this lithos ...
Plate Tectonics: A Unifying Theory
... nents to their present-day locations. Wegener amassed a similarities of fossils on these continents were due to the tremendous amount of geologic, paleontologic, and climaappearance and disappearance of the connecting land tologic evidence in support of continental drift, but the inibridges. tial re ...
... nents to their present-day locations. Wegener amassed a similarities of fossils on these continents were due to the tremendous amount of geologic, paleontologic, and climaappearance and disappearance of the connecting land tologic evidence in support of continental drift, but the inibridges. tial re ...
Behaviour of high field strength elements in subduction zones
... Hf/177Hf analyses on arc rocks from Kamchatka and the western Aleutians. The volcanic rocks of the Kamchatka region comprise compositional end members for both fluid and slab melt controlled mantle regimes, thus enabling systematic studies on the HFSE mobility at different conditions in the subarc m ...
... Hf/177Hf analyses on arc rocks from Kamchatka and the western Aleutians. The volcanic rocks of the Kamchatka region comprise compositional end members for both fluid and slab melt controlled mantle regimes, thus enabling systematic studies on the HFSE mobility at different conditions in the subarc m ...
Structure and rheology of lithosphere in Italy and surrounding.
... to the brittle continental crust, placing the Moho depth at about 30 km, and to interpret the remaining 23 km as very soft mantle. The interpretation of Vs models in the cells with recent volcanism (b1, b2, a2, a3, A-2, A-1, A3, A4, A5, B-2, B-1, B1, B2, B4, C3, C4, C5, D2, D5) is given by Panza et ...
... to the brittle continental crust, placing the Moho depth at about 30 km, and to interpret the remaining 23 km as very soft mantle. The interpretation of Vs models in the cells with recent volcanism (b1, b2, a2, a3, A-2, A-1, A3, A4, A5, B-2, B-1, B1, B2, B4, C3, C4, C5, D2, D5) is given by Panza et ...
Geophysical assessment of migration and storage conditions of
... low-velocity zone can be distinctly observed in the mantle wedge where partial melt is expected (Rondenay et al. 2008), whereas electrical data clearly identified conductive zones interpreted as fluid accumulation areas, noted as A, B, C (Figure 2C; Evans et al. 2013). Region A is consistent with th ...
... low-velocity zone can be distinctly observed in the mantle wedge where partial melt is expected (Rondenay et al. 2008), whereas electrical data clearly identified conductive zones interpreted as fluid accumulation areas, noted as A, B, C (Figure 2C; Evans et al. 2013). Region A is consistent with th ...
Plate Tectonics Packet with Notes and Questions
... • The plate in plate tectonics is a large chunk of lithosphere that can carry continental crust, oceanic crust, or some of each. • Plates can be identified by the locations of earthquake epicenters. At the boundaries of plates are mid-ocean ridges, trenches, and large faults. • Plates move by seaflo ...
... • The plate in plate tectonics is a large chunk of lithosphere that can carry continental crust, oceanic crust, or some of each. • Plates can be identified by the locations of earthquake epicenters. At the boundaries of plates are mid-ocean ridges, trenches, and large faults. • Plates move by seaflo ...
Chapter 13 - The Theory of Plate Tectonics
... soil and particles of organic material. This process is called erosion. Wind, glaciers, and gravity cause erosion. Chemical processes break down and change rock through reactions. When the water flow slows or stops, the particles may be deposited as sediment. ...
... soil and particles of organic material. This process is called erosion. Wind, glaciers, and gravity cause erosion. Chemical processes break down and change rock through reactions. When the water flow slows or stops, the particles may be deposited as sediment. ...
An Entirely New 3D-View of the Crustal and Mantle Structure of a
... The upper brittle continental crust tends to be a seismically poorly reflective layer, practically a blind zone (Figure 2). The top of the crystalline basement is rarely a significant reflection. Most of the times, it was tentatively interpreted at the basal termination of the reflective and stratif ...
... The upper brittle continental crust tends to be a seismically poorly reflective layer, practically a blind zone (Figure 2). The top of the crystalline basement is rarely a significant reflection. Most of the times, it was tentatively interpreted at the basal termination of the reflective and stratif ...
In situ measurements of thermal diffusivity in sediments of the
... TD measurements were acquired during the R/V ATLANTIS cruise AT26-04, where the primary research goal was to study heat flow and fluid flux on the Washington continental margin ( Johnson et al., 2013). During this cruise, an instrumented fiberglass probe was inserted into the seafloor for approximat ...
... TD measurements were acquired during the R/V ATLANTIS cruise AT26-04, where the primary research goal was to study heat flow and fluid flux on the Washington continental margin ( Johnson et al., 2013). During this cruise, an instrumented fiberglass probe was inserted into the seafloor for approximat ...
as a PDF
... horizontal, or if the fluid pressure is low, then dikes and volcanoes will not be able to penetrate the plate, even if, as seems likely [Anderson and Sammis, 1970; Anderson and Bass, 1984] the upper mantle is near or above the melting point almost everywhere. We use the term “tensional tectonics” to ...
... horizontal, or if the fluid pressure is low, then dikes and volcanoes will not be able to penetrate the plate, even if, as seems likely [Anderson and Sammis, 1970; Anderson and Bass, 1984] the upper mantle is near or above the melting point almost everywhere. We use the term “tensional tectonics” to ...
Configuration of subducting Philippine Sea plate and crustal
... record section of one shot. It was very difficult to locate accurately the subducting Philippine Sea plate because of the trade-off between the dip-angle of the boundary and velocity structure. To estimate the location of the subducting Philippine Sea plate precisely, the reflected waves have to be ...
... record section of one shot. It was very difficult to locate accurately the subducting Philippine Sea plate because of the trade-off between the dip-angle of the boundary and velocity structure. To estimate the location of the subducting Philippine Sea plate precisely, the reflected waves have to be ...
Pacific plate slab pull and intraplate deformation in the
... Conrad et al., 2011) that shear mantle flow within the asthenosphere mostly explains this type of intraplate volcanism. However, lithospheric extension driven by plate boundary forces, plate motion, and small-scale convection may be causing intraplate volcanism as well (Ballmer et al., 2009; Koppers ...
... Conrad et al., 2011) that shear mantle flow within the asthenosphere mostly explains this type of intraplate volcanism. However, lithospheric extension driven by plate boundary forces, plate motion, and small-scale convection may be causing intraplate volcanism as well (Ballmer et al., 2009; Koppers ...
A mantle convection perspective on global tectonics
... 2010). Spreading rates and transform faults permit relative plate motion reconstructions in the past (e.g., Müller et al., 2016; Seton et al., 2012). With the increasing scarcity of preserved seafloor as a function of age, one may use paleomagnetic data to constrain the absolute motion of continents ...
... 2010). Spreading rates and transform faults permit relative plate motion reconstructions in the past (e.g., Müller et al., 2016; Seton et al., 2012). With the increasing scarcity of preserved seafloor as a function of age, one may use paleomagnetic data to constrain the absolute motion of continents ...
Evolution of magma-poor continental margins from rifting to sea¯oor
... 550 8C. Syn-rift melt products (contemporaneous with the rifting process) are absent. We estimate that durations of continental extension were, respectively, a few tens of Myr (at ,5 mm yr-1) for the Tethyan margins19 and ,10 Myr (®nal phase, at .3.5 mm yr-1) off Iberia20. The ZECM in the SIAP is 40 ...
... 550 8C. Syn-rift melt products (contemporaneous with the rifting process) are absent. We estimate that durations of continental extension were, respectively, a few tens of Myr (at ,5 mm yr-1) for the Tethyan margins19 and ,10 Myr (®nal phase, at .3.5 mm yr-1) off Iberia20. The ZECM in the SIAP is 40 ...
Weakening of the subduction interface and its effects on surface
... that upward migration of aqueous fluids from the dehydrating slab is possible only through permeability creation via hydrofracturing [Peacock and Hyndman, 1999]. Hydrofracturing requires pore fluid pressure to exceed the minimum principal stress, and the most likely place to reach this state is the ...
... that upward migration of aqueous fluids from the dehydrating slab is possible only through permeability creation via hydrofracturing [Peacock and Hyndman, 1999]. Hydrofracturing requires pore fluid pressure to exceed the minimum principal stress, and the most likely place to reach this state is the ...
Melting under the Colorado Plateau, USA
... step-like change in lithospheric thickness from relatively thicker (>90 km) to thin (<70 km) lithosphere that occurs over distances of <30 km. When cross sections through the crust and mantle beneath three of these volcanic fields are considered—as imaged in PS common conversion point stacks and by ...
... step-like change in lithospheric thickness from relatively thicker (>90 km) to thin (<70 km) lithosphere that occurs over distances of <30 km. When cross sections through the crust and mantle beneath three of these volcanic fields are considered—as imaged in PS common conversion point stacks and by ...
The Quest for Self-Consistent Generation of Plate Tectonics in
... long-lived ‘pre-existing’ zones of weakness, and plate boundaries, once formed, may persist for hundreds of millions of years, possibly changing from one form to another [Scotese, 1991; Scotese et al., 1988]. The present state of the lithosphere is thus related to history spanning billions of years. ...
... long-lived ‘pre-existing’ zones of weakness, and plate boundaries, once formed, may persist for hundreds of millions of years, possibly changing from one form to another [Scotese, 1991; Scotese et al., 1988]. The present state of the lithosphere is thus related to history spanning billions of years. ...
Deformation of Indian Ocean lithosphere
... A model of a thin sheet of power-law fluid, which has been used before to successfully represent lithospheric deformation in the continents, may be equally useful for estimating the vertically averaged properties of deforming oceanic lithosphere. For example, Zatman et al. [2001, 2005] used simple an ...
... A model of a thin sheet of power-law fluid, which has been used before to successfully represent lithospheric deformation in the continents, may be equally useful for estimating the vertically averaged properties of deforming oceanic lithosphere. For example, Zatman et al. [2001, 2005] used simple an ...
Oceanic trench
The oceanic trenches are hemispheric-scale long but narrow topographic depressions of the sea floor. They are also the deepest parts of the ocean floor. Oceanic trenches are a distinctive morphological feature of convergent plate boundaries, along which lithospheric plates move towards each other at rates that vary from a few mm to over ten cm per year. A trench marks the position at which the flexed, subducting slab begins to descend beneath another lithospheric slab. Trenches are generally parallel to a volcanic island arc, and about 200 km (120 mi) from a volcanic arc. Oceanic trenches typically extend 3 to 4 km (1.9 to 2.5 mi) below the level of the surrounding oceanic floor. The greatest ocean depth to be sounded is in the Challenger Deep of the Mariana Trench, at a depth of 11,034 m (36,201 ft) below sea level. Oceanic lithosphere moves into trenches at a global rate of about 3 km2/yr.