نتایج جستجو برای: crustal matter
تعداد نتایج: 222571 فیلتر نتایج به سال:
S U M M A R Y We compare 3-D upper mantle anisotropic structures beneath the North American continent obtained using standard and improved crustal corrections in the framework of Non-linear Asymptotic Coupling Theory (NACT) applied to long period three component fundamental and higher mode surface waveform data. Our improved approach to correct for crustal structure in high-resolution regional ...
[1] Subduction zones alter the upper plate in a variety of ways, including metasomatism via slab-derived fluids and accretion of exotic terranes. These processes should produce distinctive seismic signatures, as seismic velocities are sensitive to compositional variations. A new method is developed to estimates depths to interfaces and Poisson’s ratio (Vp/Vs ratio) for dipping layered structure...
Coupling between erosion and tectonics are thought to play a determinant role in mountains evolution. Here, we investigate the interplay in this coupling between the assumed erosion law and the crustal rhe-ology at the margin of a collisional plateau, like the Himalaya of central Nepal. Lithospheric deformation is calculated over a time scale of 100 kyr by a two-dimensional finite elements mode...
A sensitivity study of stochastic crustal and Moho models on Moho refracted first arrivals is presented. The crustal model is a self-affine velocity structure superposed on a linear velocity gradient. The Moho is represented by a first-order discontinuity with a topography which is also self-affine. The sensitivity of both travel-time and wave-field is considered. We found that the full wave-fi...
The lava section in the Troodos ophiolite, Cyprus, is chemically stratified and divided into a shallow lava sequence with low TiO2 content and a deeper lava sequence with high TiO2 content. We calculate the viscosity at magmatic temperature based on major element chemistry of lavas in Cyprus Crustal Drilling Project (CCSP) Holes CY-1 and 1A. We find that typical shallow low-Ti lavas have a magm...
Rare ultrahigh-temperature–(near)ultrahigh-pressure (UHT–near-UHP) crustal xenoliths erupted at 11 Ma in the Pamir Mountains, southeastern Tajikistan, preserve a compositional and thermal record at mantle depths of crustal material subducted beneath the largest collisional orogen on Earth. A combination of oxygen-isotope thermometry, major-element thermobarometry and pseudosection analysis reve...
Formation of new continental crust in Western British Columbia during transpression and transtension
Crustal growth in the Coast Mountains, along the leading edge of the Canadian Cordillera, was the result of processes associated with horizontal flow of material during transpression and subsequent transtension, and the vertical accretion of mantle derived melts. From 85 to 58 Ma, as exotic terranes were translated northward during transpression, the crust was thickened to about 55 km, and melt...
in this study we use the p receiver function technique to determine the moho depth and vp/vs ratio for 8 short period stations of qochan and mashhad seismic networks and map the variations of moho depth under kope dagh region. it is shown that a receiver function can provide a relatively good point measurement of moho depth under a short period station. the crustal thickness estimated from the ...
The mechanics and petrological signature of a collisional mountain belt can be significantly influenced by topographic and erosional effects at the scale of large river gorges. The geomorphic influence on crustal scale processes arises from the effects of both stress localization due to existing topography, and also erosional removal of advected crustal mass. The shear stress concentration and ...
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