نتایج جستجو برای: tectonic element
تعداد نتایج: 213582 فیلتر نتایج به سال:
Geological models of subduction zones impact thinking about many of the central problems in the structure, dynamics, chemistry, and history of the solid earth. Should those models change, the effects will reach across the earth sciences. We are currently in the midst of such a change, brought on by several causes. First, the earth science community recently began an organized, multi-disciplinar...
The Himalaya-Tibetan orogen has become the paradigm for continental collision and is central to deciphering continental tectonics. Neogene extension in the orogen is not predicted by plate tectonic theory, and its significance is widely debated. In the Himalaya, north-south extension is restricted to the Southern Tibetan Detachment System (STDS), which juxtaposes the High Himalayan Crystalline ...
The petrography, as well as major and trace element (including rare earth element) compositions of 10 sandstone samples from the Late Proterozoic Buem Structural Unit, southeast Ghana, have been investigated to determine their provenance and tectonic setting. The petrographic analysis has revealed that the sandstones are quartz-rich and were primarily derived from granitic and metamorphic basem...
Erosion, sediment production, and routing on a tectonically active continental margin reflect both tectonic and climatic processes; partitioning the relative importance of these processes remains controversial. Gulf of Alaska contains a preserved sedimentary record of the Yakutat Terrane collision with North America. Because tectonic convergence in the coastal St. Elias orogen has been roughly ...
Abstract The best exposed Early Miocene (820 m. thick. ) shales and interbedded silty sandstones beds of the Pyawbwe Formation at Sakangyi- Thayat area,Magway Region are investigated geochemically by using Siemens SRS- X Ray 303 AS XRF Spectrometer. Major and some trace element concentrations have been determined to achieve their provenance, tectonic setting ,paleoweathering , paleoclimate and ...
Bagham pluton is located in 23 km of the southeastern of Ardestan and it is near the main road of Esfahan-Ardestan. The study area is a part of central Iranian zone and Urumieh-Dokhtar magmatic belt. Minerlogically, the rocks include plagioclase, pyroxene, amphibole and opaque. The rocks have SiO2 = 44.75-47.08 and occur in gabbroic field. The chondrite normalized REE pattern show low enrichmen...
Aims and Backgrounds: Almost no area in the world can be found that has not been affected by tectonic processes. The morpho-tectonic indices of the basin are used to investigate the active tectonics. Morphometry can be defined as the quantitative measurement of the shape of the Earth's landscape that using these quantitative measurements can identify areas with active tectonics. The purpose o...
Quantitative assessment of relative tectonic activity in the Alamarvdasht river basin, south of Iran
Tectonic processes are major factors controlling landform development in tectonically active areas. In order to evaluate quantitative measurement of tectonic activities in the Alamarvdasht basin in the south of Iran, six different morphological indices including stream-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), valley floor width-valley height ratio (Vf), dra...
Earthquakes far from tectonic plate boundaries generally exploit ancient faults, but not all intraplate faults are equally active. The North American Great Plains exemplify such intraplate earthquake localization, with both natural and induced seismicity generally clustered in discrete zones. Here we use seismic velocity, gravity and topography to generate a 3D lithospheric density model of the...
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