نتایج جستجو برای: supra subduction
تعداد نتایج: 12516 فیلتر نتایج به سال:
Thin oceanic crust is formed by decompression melting of the upper mantle at mid-ocean ridges, but the origin of the thick and buoyant continental crust is enigmatic. Juvenile continental crust may form from magmas erupted above intraoceanic subduction zones, where oceanic lithosphere subducts beneath other oceanic lithosphere. However, it is unclear why the subduction of dominantly basaltic oc...
The Kahnuj ophiolitic complex, a part of the Jazmurian ophiolitic belt, is located on the western boundary of the Jazmurian depression and is bounded by two major fault systems. There is a well-preserved, ophiolite pseudostratigraphy of early Cretaceous to early Palaeocene age and has a bearing on the Mesozoic development of southeastern part of Iran and adjacent region. The Kahnuj ophiolitic c...
Niabad-Qalaje ophiolitic complex is part of Sarvabad ophiolites in Kurdistan that exposed in northwest of Iran and the north of Kermanshah Ophiolites. The complex located in north of Zagros orogeny, consists of lens form, tectonically dismembered ophiolitic sequences located along the main Zagros trust. The ultramafic part includes serpentinized dunite and wherlite, serpentinite and chromitite ...
The Kermanshah ophiolite complex is located in outer Zagros ophiolitic belt and consists of both mantle and crustal suites as remnants of southern branch of the Neo-Tethys Ocean in Iran. Chemical composition determinative diagram of minerals indicates that olivine in dunite, harzburgite and lherzolites has forsteritic composition and in wherlitic rocks is chrysolite in composition likewise orth...
The chromite deposits of Aland (Barajok and Kochak villages) and Gheshlagh area in the Khoy ophiolite occur as layered, lenticular or irregular masses, surrounded by dunitie and harzburgites. These chromites are compositionally similar to alpine-type chromites, characterized by nodular, massive, disseminated and banded textures. EMPA data show that they vary widely in term of Cr-number [100Cr/C...
The study of ultramafic rocks in Western Yunnan is great significance for an understanding the tectonic evolution Neo-Tethys Ocean. zircon U–Pb data indicated that Santaishan serpentinized pyroxene peridotite (SSPP) was formed 186–190 Ma, and Yingjiang hornblende pyroxenite (YHP) 182–183 Ma. content MgO SSPP relatively high, but SiO2, Al2O3, CaO TiO2 ΣREE are low, while YHP has opposite charact...
Abstract The Gomati and Nea Roda ophiolites are located into the Serbo-Macedonian massif of Chalkidiki peninsula (Northern Greece). present work focuses on variability platinum-group elements (PGEs), geochemistry, spinel mineral chemistry, minerals (PGMs) — base metal (BMMs) assemblage in chromitites three localities (St. George, Tripes, Limonadika) Roda. studied show variable textures heavily ...
Abstract To constrain the closure mechanism and time of Paleo-Asian Ocean, we report new geochronological geochemical data for Triassic granites along a NW–SE corridor from Eastern Tianshan to Beishan, NW China. Seven have U-Pb ages that young southwards 245 Ma 234 in Kanguer accretionary complex, 237 eastern Central block, 229 223 Liuyuan complex. Granites complex formed by fractional crystall...
Density-driven sinking velocity Density-driven sinking velocity Slab-dip angle Plate-advance velocity Subduction-retreat velocity Subduction-retreat velocity Overriding slab Subducting slab transformations at 400–700 km down. The authors identify four central points. First, subducted material sinks at a velocity that is controlled solely by its negative buoyancy and the viscosity of the surroun...
In order to understand the potential controls on Asian tectonics during the subduction of the Tethys and Indian lithospheres, we reconstruct the coupled subduction-continent deformation history using tomographic imaging, kinematics constraints and numerical modeling. The global P-waves tomographic images of the mantle below the India-Asia collision zone provide constraints on the deep structure...
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