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Slab

About: Slab is a research topic. Over the lifetime, 31617 publications have been published within this topic receiving 318693 citations.


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Journal ArticleDOI
TL;DR: In this paper, a new IERS-based solution is presented for the geodynamic reconstruction of the eastern Mediterranean by assuming that the velocity field decreases moving away from the source area of energy, i.e., the supposed squeezing of Anatolia due to the Arabia indenter, or the collapse of the Anatolian orogen.
Abstract: Geodynamic reconstructions of the eastern Mediterranean suggesting either westward anatolian extrusion, or gravitational collapse of thickened lithosphere, can be ruled out because plates velocity vectors increase from eastern Anatolia to the Aegean and Greece. This contradicts the basic rule that the velocity field decreases moving away from the source area of the energy, i.e. the supposed squeezing of Anatolia due to the Arabia indenter, or the collapse of the Anatolian orogen. Moreover the topographic gradient between Anatolia and the Ionian deep basin is too small (<1 °) for providing sufficient energy relief able to explain present deformation. The simplistic view of the westward Anatolian escape would rather close the Aegean Sea. We interpret the extension in western Turkey, Aegean sea, Greece and Bulgaria as a result of the differential convergence rates between the northeastward directed subduction of Africa relative to the hangingwall disrupted Eurasian lithosphere. Considering fixed Africa, the faster southeastward motion of Greece relative to Cyprus- Anatolia determines the Aegean extension. A new IERS-based solution is presented. The differences in velocity are ascribed to differential decoupling with the asthenosphere. Unlike west-Pacific backarc basins where the asthenosphere replaces a subducted and retreated slab, the study area represents a different type of extension associated to a subduction zone, where the hangingwall plate overrode the slab at different velocities, implying internal deformation. The slab may be folded by the isostatic rebound of the mantle beneath the ' backarc'rift, and stretched for the increasing length of the slab between Greece and Anatolia. A sort of window then formed both in the slab and between the two upper plates, allowing uprise of mantle derived Na-rich magmas.

137 citations

Journal ArticleDOI
TL;DR: In this article, the effects of plate length, rheology and Clapeyron slope on phase change dynamics have been investigated with convection models and two complementary methods to simulate plates and slabs are used: material property and imposed surface velocity methods with temperature-dependent viscosity.
Abstract: The effects of plates and slabs on phase change dynamics have been investigated with convection models. Two complementary methods to simulate plates are used: material property and imposed surface velocity methods with temperature-dependent viscosity. For a wide range of model parameters, plates and slabs exert a significant control on phase change dynamics. As plate length (and hence plate age and convection cell aspect ratio) increases, both the propensity for slab penetration and the mass flux across an endothermic phase change increase. When cold downwellings are stiffened with a temperature-dependent rheology, slab penetration is enhanced, but total mass flux changes little. Plates organize large-scale flow and thermal structure and thereby affect phase change dynamics. As plates become larger, the resulting largerscale structures are influenced less by endothermic phase changes, thus reducing the degree of layering. A model showing completely layered convection for a plate of unit length becomes unlayered when the plate is 3 or 5 times longer. For a given Clapeyron slope, the proportion of time for slab penetration increases from zero for cases with small plates to more than 0.5 for cases with large plates. The degree of layering, plate velocity, and mass flux are controlled by large-scale structures, while slab penetration may be more related to small-scale features. Therefore, whether or not subducted slabs penetrate the phase change may not necessarily indicate that convection is entirely layered or entirely unlayered. The episodicity of convection induced by an endothermic phase change strongly depends on plate length, rheology, and Clapeyron slope. A large plate and a stiff slab both weaken the episodicity of convection. Only for a certain range of Clapeyron slopes can the phase change induce a strong episodic thermal convection.

137 citations

Journal ArticleDOI
20 Mar 1997-Nature
TL;DR: In this paper, a tomographic image of the subducted trailing fragments of the Farallon plate in the upper mantle beneath the western margin of North America is presented, where the relatively cold, subducting fragments appear as an intricate region of high seismic S-wave velocity.
Abstract: The Farallon plate was an enormous oceanic plate located west of the Americas during the Cenozoic and Mesozoic eras. This plate has now been almost completely subducted beneath the American plates. In the Northern Hemisphere, the Farallon plate broke up to form a number of independent smaller plates1–3 when its western edge approached the North American plate. Here we present a tomographic image of the subducted trailing fragments of the Farallon plate in the upper mantle beneath the western margin of North America. The relatively cold, subducted fragments appear as an intricate region of high seismic S-wave velocity. Comparison of the structure of this high-velocity region with tectonic plate reconstructions and volcanic records enables us to identify individual fragments of the subducted Farallon plate and thus reconstruct qualitatively the kinematic evolution of the Farallon slab in the upper mantle beneath North America.

136 citations

Journal ArticleDOI
TL;DR: In this paper, a structural wood-concrete composite system is presented, which is formed by joining a wood component, such as a floor beam or laminated plate, to a concrete slab utilizing a continuous steel mesh of which one half is glued into a slot in the wood while the other half is embedded into the concrete.
Abstract: This paper introduces a new, structural wood-concrete composite system. The system is formed by joining a wood component, such as a floor beam or laminated plate, to a concrete slab utilizing a continuous steel mesh of which one half is glued into a slot in the wood while the other half is embedded into the concrete. Two series of tests were performed and are presented: static push-out tests to establish shear properties of the connector and a full scale bending test with a span of approximately 10 m. Test results reveal that the steel mesh performs favorably—as a stiff yet ductile shear connector between the wood and the concrete. Design equations, per European standards in absence of North American standards are described and used to predict the failure load of the bending test. Calculations indicate that the tested beam performs with near full composite action—specifically, 97% effective stiffness and 99% strength of that of a beam with full composite action. This is a marked improvement in the efficiency of wood-concrete systems developed to date. The system shows itself to be superior to alternative systems in its high structural efficiency as well as being relatively easy to install and economic.

136 citations

Journal ArticleDOI
TL;DR: In this article, it was shown that a low-velocity zone having seismic velocities of crust materials exists in the mantle wedge just above the Pacific slab and makes direct contact with the upper surface of the PLS.

136 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20242
20231,170
20222,180
2021774
20201,133
20191,317