Topic
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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TL;DR: In this article, a finite element method with constrained elements and Lagrange multipliers is used to study tectonic faults in a viscous medium, representing the interface between overriding and subducting plates, in which both thermal buoyancy and the buoyancy associated with the phase change from olivine to spinel are included.
Abstract: A finite element method with constrained elements and Lagrange multipliers is used to study tectonic faults in a viscous medium. A fault, representing the interface between overriding and subducting plates, has been incorporated into a viscous flow model of a subduction zone in which both thermal buoyancy and the buoyancy associated with the phase change from olivine to spinel are included. The fault causes stress to concentrate in its vicinity, giving rise to a weak plate margin and a mobile plate if a power law rheology is used. Surface dynamic topography with either a Newtonian or a power law rheology and with typical subduction zone parameters is characterized by a narrow and deep trench and a broadly depressed back arc basin. This suggests that oceanic trenches and back arc basins over subduction zones are dynamically compensated by viscous flow. Our models show that trench depth increases with fault dip angle, slab dip angle, slab length, and age of oceanic lithosphere just prior to subduction. The influence of fault dip angle and age of lithosphere on trench depth is greater than the influence of slab dip angle and slab length. These relationships of trench depth versus subduction zone parameters explain well the statistics of observed trench depths. For those subduction zones with oceanic lithosphere on both sides of the trench, observed trench depths have been corrected for fault and slab dip angles, based on the relationships from the dynamic models. After correction to a common set of parameters, trench depth correlates linearly with age of lithosphere prior to subduction with a slope which is close to what models having high viscosities within the transition zone and lower mantle predict. Comparison between the trench depths, corrected for fault and slab dip angles, and model trench depths suggests that the resisting tangential stress on faults in subduction zones may range from 15 MPa to 30 MPa, depending on model details.
156 citations
TL;DR: In this article, the authors show that the upwelling of a warmer asthenospheric material and the partial melts of the slab are likely consequences that are consistent with the anhydrous tholeiitic late Oligocene volcanism and the anomalous adakite-type magmatism of the early Miocene, respectively.
156 citations
TL;DR: In this article, the authors performed global mantle circulation computations to test the role of slab pull and mantle upwellings as driving forces for the kinematics of the Arabia-Anatolia-Aegean (AAA) system.
156 citations
TL;DR: The second critical endpoint in the basalt-H2O system was directly determined by a high-pressure and high-temperature X-ray radiography technique and it is indicated that the melting temperature of the subducting oceanic crust can no longer be defined beyond this critical condition and that the fluid released from subducted Oceanic crust at depths greater than 100 km under volcanic arcs is supercritical fluid rather than aqueous fluid and/or hydrous melts.
Abstract: The second critical endpoint in the basalt-H2O system was directly determined by a high-pressure and high-temperature X-ray radiography technique. We found that the second critical endpoint occurs at around 3.4 GPa and 770 °C (corresponding to a depth of approximately 100 km in a subducting slab), which is much shallower than the previously estimated conditions. Our results indicate that the melting temperature of the subducting oceanic crust can no longer be defined beyond this critical condition and that the fluid released from subducting oceanic crust at depths greater than 100 km under volcanic arcs is supercritical fluid rather than aqueous fluid and/or hydrous melts. The position of the second critical endpoint explains why there is a limitation to the slab depth at which adakitic magmas are produced, as well as the origin of across-arc geochemical variations of trace elements in volcanic rocks in subduction zones.
155 citations
TL;DR: In this article, the influence of the velocity of the subducting plate on the hinge-migration velocity and the geometry of the slab was investigated and three subduction modes with accompanying slab geometry can be recognized.
155 citations