Do fracture zones define continental margin segmentation
... long-lived first- and second-order offsets in the Mid-Atlantic Ridge (MAR) which can be traced to each margin as fracture zones or fracture-zone-like features. The relatively narrow width of these zones suggests that the transition from rift- to transform-style structures is similarly abrupt. However ...
... long-lived first- and second-order offsets in the Mid-Atlantic Ridge (MAR) which can be traced to each margin as fracture zones or fracture-zone-like features. The relatively narrow width of these zones suggests that the transition from rift- to transform-style structures is similarly abrupt. However ...
A cool model for the Iceland hot spot
... A holistic appraisal of the evidence available from the Iceland melt anomaly suggests that, if the assumption of a plume is dropped, an upper-mantle, moderate-temperature model is natural, reasonable and not without support. The primary observations that require explanation are the local production ...
... A holistic appraisal of the evidence available from the Iceland melt anomaly suggests that, if the assumption of a plume is dropped, an upper-mantle, moderate-temperature model is natural, reasonable and not without support. The primary observations that require explanation are the local production ...
Exhumation processes - Perso-sdt
... surface. This distinction is not universally accepted, but we think it is useful and encourage its adoption. Walcott (1998) emphasized this usage in his synthesis of the Southern Alps orogen of New Zealand. The Southern Alps are characterized by a large gradient in surface erosion rates across the o ...
... surface. This distinction is not universally accepted, but we think it is useful and encourage its adoption. Walcott (1998) emphasized this usage in his synthesis of the Southern Alps orogen of New Zealand. The Southern Alps are characterized by a large gradient in surface erosion rates across the o ...
This PDF file is subject to the following conditions and... Copyright © 2006, The Geological Society of America, Inc. (GSA)....
... and it is possible for both greenstone belts and TTG suites to form during Hadean convective overturn, prior to the onset of Phanerozoic-style asymmetric subduction. As seen in Figure 1, even during thermal convection driven by heating from below, the sinking of previously created protocrust along s ...
... and it is possible for both greenstone belts and TTG suites to form during Hadean convective overturn, prior to the onset of Phanerozoic-style asymmetric subduction. As seen in Figure 1, even during thermal convection driven by heating from below, the sinking of previously created protocrust along s ...
Anderson and Natland, 2005
... history of explanations for “melting anomalies” we focus on the underlying assumptions, physics, and philosophy and on key turning points in that history. We concentrate on the anomalies, neglected physics, petrology, and deep mantle aspects rather than on the better-known tectonic, geochronological ...
... history of explanations for “melting anomalies” we focus on the underlying assumptions, physics, and philosophy and on key turning points in that history. We concentrate on the anomalies, neglected physics, petrology, and deep mantle aspects rather than on the better-known tectonic, geochronological ...
Tectonic stress field of the continental United States
... (1983). We have now restricted our consideration to faults in the eastern United States that show offsets of Miocene or younger strata. The age criteria for geological data from the western United States remains the same, < 5 Ma, although most data are younger than 3 Ma. A new category of in situ st ...
... (1983). We have now restricted our consideration to faults in the eastern United States that show offsets of Miocene or younger strata. The age criteria for geological data from the western United States remains the same, < 5 Ma, although most data are younger than 3 Ma. A new category of in situ st ...
Some remarks on subduction zones - Dipartimento di Scienze della
... Are the assumptions reliable? Most of the literature indicates that the slab pull is about 3.3x1013 N m-1 (e.g., Turcotte and Schubert, 2002). This is a force per unit length parallel to the trench. However this value is very small when compared to other energetic sources for Earth, such the energy ...
... Are the assumptions reliable? Most of the literature indicates that the slab pull is about 3.3x1013 N m-1 (e.g., Turcotte and Schubert, 2002). This is a force per unit length parallel to the trench. However this value is very small when compared to other energetic sources for Earth, such the energy ...
Crustal thickness anomalies in the North Atlantic Ocean Tingting Wang
... [2] Crustal accretion at the northern Mid‐Atlantic Ridge (MAR) (Figure 1a) is generally considered to be magma‐limited because of the slow spreading rate of the ridge (Figure 1b). This results in a relatively cold thermal structure with a strong lithosphere, leading to a deep axial rift valley and r ...
... [2] Crustal accretion at the northern Mid‐Atlantic Ridge (MAR) (Figure 1a) is generally considered to be magma‐limited because of the slow spreading rate of the ridge (Figure 1b). This results in a relatively cold thermal structure with a strong lithosphere, leading to a deep axial rift valley and r ...
2.01 Cosmochemical Estimates of Mantle Composition
... Apart from the structure of the asteroid belt, there is little evidence for compositional gradients within the inner solar system as represented by the terrestrial planets and the asteroids. There are no systematic variations with distance from the Sun, either in the chemistry of the inner planets, ...
... Apart from the structure of the asteroid belt, there is little evidence for compositional gradients within the inner solar system as represented by the terrestrial planets and the asteroids. There are no systematic variations with distance from the Sun, either in the chemistry of the inner planets, ...
Author`s Personal Copy
... and provided more detailed information on shear as well as compressional wave propagation in ultramafic rocks [Christensen, 1971; Kumazawa et al., 1971; Christensen and Ramananantoandro, 1971; Babuska, 1972]. If the oceanic mantle is strongly anisotropic due to the preferred orientation of olivine, ...
... and provided more detailed information on shear as well as compressional wave propagation in ultramafic rocks [Christensen, 1971; Kumazawa et al., 1971; Christensen and Ramananantoandro, 1971; Babuska, 1972]. If the oceanic mantle is strongly anisotropic due to the preferred orientation of olivine, ...
Craton stability and longevity
... These rheological parameters also result in a reasonable viscosity at asthenosphere between 1018 Pa∙s and 1019Pa∙s that is constant with the value suggested by Solomatov and Moresi, 2000. A two- layer cratonic keel model (modified from Afonso et al. (2008)‘s three-layer model) was used: a highly dep ...
... These rheological parameters also result in a reasonable viscosity at asthenosphere between 1018 Pa∙s and 1019Pa∙s that is constant with the value suggested by Solomatov and Moresi, 2000. A two- layer cratonic keel model (modified from Afonso et al. (2008)‘s three-layer model) was used: a highly dep ...
Pacific plate slab pull and intraplate deformation in the
... critical value (known as the von Mises yield criterion) yielding of the plate will occur (possibly expressed through volcanism in the geological record). This “likelihood” for a plate to fracture increases if an area of high σe values has preexisting weakness or is under stress from some other mecha ...
... critical value (known as the von Mises yield criterion) yielding of the plate will occur (possibly expressed through volcanism in the geological record). This “likelihood” for a plate to fracture increases if an area of high σe values has preexisting weakness or is under stress from some other mecha ...
Front, left to right: Mark Handy, Tuncay Taymaz, Jean
... Monitoring of active faults with continuous and semi-continuous GPS instruments shows a variety of transient deformational events. The recognition of creep events on large areas of several major subduction zone interfaces shows that, for at least some parts of some subduction zone systems, much inte ...
... Monitoring of active faults with continuous and semi-continuous GPS instruments shows a variety of transient deformational events. The recognition of creep events on large areas of several major subduction zone interfaces shows that, for at least some parts of some subduction zone systems, much inte ...
Today`s Quiz -
... Take Home Message 1) The less dense the crust, the more buoyant it is with respect to the mantle and the greater elevation it will “float”. Conversely, the more dense the curst, the lower it “floats” and thus will have lower elevation. 2) The thicker the crust, the greater its “floating” elevation a ...
... Take Home Message 1) The less dense the crust, the more buoyant it is with respect to the mantle and the greater elevation it will “float”. Conversely, the more dense the curst, the lower it “floats” and thus will have lower elevation. 2) The thicker the crust, the greater its “floating” elevation a ...
How Mantle Slabs Drive Plate Tectonics
... zones), while overriding plates in the slab pull model move at the right speed but in the wrong direction (away from subduction zones). This suggests that a combination of the two models should cause both subducting and overriding plates to move in the correct direction at the correct speed. For sim ...
... zones), while overriding plates in the slab pull model move at the right speed but in the wrong direction (away from subduction zones). This suggests that a combination of the two models should cause both subducting and overriding plates to move in the correct direction at the correct speed. For sim ...
Kistufell: Primitive Melt from the Iceland Mantle
... Kistufell (64°48′N, 17°13′W) is a previously uninvestigated monogenetic table mountain located in the neovolcanic northern rift zone (NRZ) at the NW margin of the Vatnajökull ice cap (Fig. 1). The central axis of the plume is thought to be located below this region, which is at present the locus of ...
... Kistufell (64°48′N, 17°13′W) is a previously uninvestigated monogenetic table mountain located in the neovolcanic northern rift zone (NRZ) at the NW margin of the Vatnajökull ice cap (Fig. 1). The central axis of the plume is thought to be located below this region, which is at present the locus of ...
Absolute plate motions and regional subduction evolution
... unavoidably lead to uncertainty in their estimation [e.g., Doubrovine et al., 2012]. At best an estimate of the local plate motion can be obtained that results from the global interaction of plates and underlying mantle, i.e., representing far-field forcing. In Chert14, the influence of far field forci ...
... unavoidably lead to uncertainty in their estimation [e.g., Doubrovine et al., 2012]. At best an estimate of the local plate motion can be obtained that results from the global interaction of plates and underlying mantle, i.e., representing far-field forcing. In Chert14, the influence of far field forci ...
A continuous plate-tectonic model using geophysical data to
... plates are abstractions based on the simple assumptions where is the position vector of a point on the surface of and are of the standard plate model, and are therefore unrealis- the Earth, at longitude and latitude , and tic as well as unrealizable. However, the actual continu- the angular velocity ...
... plates are abstractions based on the simple assumptions where is the position vector of a point on the surface of and are of the standard plate model, and are therefore unrealis- the Earth, at longitude and latitude , and tic as well as unrealizable. However, the actual continu- the angular velocity ...
PDF (Chapter 8. Chemical Composition of the Mantle)
... of differentiation, or separation, processes. In some geochemical models it is assumed that large parts of the Earth escaped partial melting, or melt removal, and are therefore still "primitive." Some petrological models assume that melts being delivered to the Earth's surface are samples from previ ...
... of differentiation, or separation, processes. In some geochemical models it is assumed that large parts of the Earth escaped partial melting, or melt removal, and are therefore still "primitive." Some petrological models assume that melts being delivered to the Earth's surface are samples from previ ...
Very low frequency earthquakes excited by the 2004 off the... earthquakes: A dynamic deformation process in the large accretionary prism
... are considered as regular micro-aftershocks, which are too small to be detected by JMA. On the other hand, we can see some wave trains only in the low-frequency component panel without corresponding high-frequency signals during the time period T2 and T3 in Fig. 2. These are the VLF ...
... are considered as regular micro-aftershocks, which are too small to be detected by JMA. On the other hand, we can see some wave trains only in the low-frequency component panel without corresponding high-frequency signals during the time period T2 and T3 in Fig. 2. These are the VLF ...
Lithosphere, Asthenosphere, and Perisphere
... olivine-rich rock. Picrites probably result from high temperature and extensive melting. Picrites are often depleted and are often attributed to plume stem melts. They may evolve to more common basalt types by crystal fractionation. Depleted picrites often occur at the base of CFB sequences. Plate: ...
... olivine-rich rock. Picrites probably result from high temperature and extensive melting. Picrites are often depleted and are often attributed to plume stem melts. They may evolve to more common basalt types by crystal fractionation. Depleted picrites often occur at the base of CFB sequences. Plate: ...
Ischuk, A., R. Bendick, A. Rybin, P. Molnar, S. F. Khan, S. Kuzikov, S. Mohadjer, U. Saydullaev, Z.
... [7] We supplemented our regional solution with 21 additional velocities reported by Zubovich et al. [2010], primarily to add additional information about the velocity of the Tarim Basin relative both to stable Eurasia and to the study sites. In order to include these sites, we calculated a sixparame ...
... [7] We supplemented our regional solution with 21 additional velocities reported by Zubovich et al. [2010], primarily to add additional information about the velocity of the Tarim Basin relative both to stable Eurasia and to the study sites. In order to include these sites, we calculated a sixparame ...
Thermal Structure and Metamorphic Evolution of Subducting Slabs
... convection and the negative buoyancy of slabs (slab pull) drives plate tectonics [Forsyth and Uyeda, 1975]. Subduction zones are regions of intense earthquake activity, explosive volcanism, and complex mass transfer between the crust, mantle, hydrosphere, and atmosphere. In this contribution, I focu ...
... convection and the negative buoyancy of slabs (slab pull) drives plate tectonics [Forsyth and Uyeda, 1975]. Subduction zones are regions of intense earthquake activity, explosive volcanism, and complex mass transfer between the crust, mantle, hydrosphere, and atmosphere. In this contribution, I focu ...
Collision of continental corner from 3
... the continental collision side (slab break-off and topography uplift). Slab break-off occurs at a depth (100 km to ∼300 km) that depends on the convergence velocity. The numerical models produce lateral extrusion of the overriding crust from the collisional side to the subduction side, which is als ...
... the continental collision side (slab break-off and topography uplift). Slab break-off occurs at a depth (100 km to ∼300 km) that depends on the convergence velocity. The numerical models produce lateral extrusion of the overriding crust from the collisional side to the subduction side, which is als ...
Post-glacial rebound
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Post-glacial rebound (sometimes called continental rebound) is the rise of land masses that were depressed by the huge weight of ice sheets during the last glacial period, through a process known as isostatic depression. Post-glacial rebound and isostatic depression are different parts of a process known as either glacial isostasy, glacial isostatic adjustment, or glacioisostasy. Glacioisostasy is the solid Earth deformation associated with changes in ice mass distribution. The most obvious and direct affects of post-glacial rebound are readily apparent in northern Europe (especially Scotland, Estonia, Latvia, Fennoscandia, and northern Denmark), Siberia, Canada, the Great Lakes of Canada and the United States, the coastal region of the US state of Maine, parts of Patagonia, and Antarctica. However, through processes known as ocean siphoning and continental levering, the effects of post-glacial rebound on sea-level are felt globally far from the locations of current and former ice sheets.