نتایج جستجو برای: lithospheric mantle

تعداد نتایج: 17971  

2013
Chelsea M. Allison Ryan C. Porter Matthew J. Fouch Steven Semken

[1] The Mojave Neovolcanic Province (MNVP), located in the Mojave block of southern California, comprises late Miocene to Quaternary small-volume basaltic centers. Geochemistry indicates an asthenospheric source for the MNVP beginning in the late Miocene, but no physical evidence of missing mantle lithosphere has been presented. We utilize receiver functions and ambient noise tomography to imag...

2008
Yi Wang Lianxing Wen Donald Weidner

We constrain SH and P wave velocity structures in the upper mantle beneath southern Africa, using triplicated phases recorded in the epicentral distance range of 11°–28° for one shallow event. We then explore thermal and compositional models appropriate for explaining the inferred seismic structures in the region. Both SH and P wave data suggest presence of a low velocity zone with velocity red...

2006
Boris J. P. Kaus Thorsten W. Becker

S U M M A R Y Although parts of the lithosphere may be expected to behave elastically over certain timescales, this effect is commonly ignored in models of large-scale mantle dynamics. Recently it has been demonstrated that elasticity, and in particular viscoelasticity, may have a significant effect on the buckling instability and on the creation of lithospheric-scale shearzones. It is, however...

The Eocene volcanic rocks exposed in the NW Sechangi area of Lut block, include pyroclastic deposits and lavas. These volcanic rocks are basalt, basaltic andesite, andesite, andesite-trachyandesite, trachydacite, dacite and rhyolite-ignimbrite in composition. Based on our field observations, the volcanic rocks erupted in four stages in the aquous to subaerial environments. The volcanic rocks ar...

2010
Clinton P. Conrad Mark D. Behn

[1] Although an average westward rotation of the Earth’s lithosphere is indicated by global analyses of surface features tied to the deep mantle (e.g., hot spot tracks), the rate of lithospheric drift is uncertain despite its importance to global geodynamics. We use a global viscous flow model to predict asthenospheric anisotropy computed from linear combinations of mantle flow fields driven by...

2015
Xiaobo Tian

Global mantle convection significantly impacts the processes at Earth’s surface and has been used to gain insights on plate driving forces, lithospheric deformation, and the thermal and compositional structure of the mantle. Upper-mantle seismic anisotropy has been widely employed to study both present and past deformation processes at lithospheric and asthenospheric depths. The eastern China r...

Journal: :Journal of Geophysical Research: Solid Earth 2018

2010
E. Sizova T. Gerya

a r t i c l e i n f o Plate tectonics is a self-organizing global system driven by the negative buoyancy of the thermal boundary layer resulting in subduction. Although the signature of plate tectonics is recognized with some confidence in the Phanerozoic geological record of the continents, evidence for plate tectonics becomes less certain further back in time. To improve our understanding of ...

2008
A. Ghosh W. E. Holt L. Wen A. J. Haines L. M. Flesch

[1] We provide new insights into the lithosphere-mantle coupling problem through a joint modeling of lithosphere dynamics and mantle convection and through comparison of model results with the high resolution velocity gradient tensor model along the Earth’s plate boundary zones. Using a laterally variable effective viscosity lithosphere model, we compute depth integrated deviatoric stresses ass...

2002
Matthew Gorring Brad Singer Jason Gowers Suzanne M. Kay

Plio–Pleistocene (3.4–0.125 Ma) post-plateau magmatism in the Meseta del Lago Buenos Aires (MLBA; 46.7jS) in southern Patagonia is linked with the formation of asthenospheric slab windows due to ridge collision along the Andean margin f 6 Ma ago. MLBA post-plateau lavas are highly alkaline (43–49% SiO2; 5–8% Na2O+K2O), relatively primitive (6–10% MgO) mafic volcanics that have strong OIB-like g...

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