نتایج جستجو برای: late neoproterozoic
تعداد نتایج: 196368 فیلتر نتایج به سال:
late neoproterozoic-early cambrian schists have been occurred in southwest of zanjan city from the soltanieh belt. the soltanieh belt in northwest of iran is uplifted basement of precambrian-paleozoic in main central iran zone and includes outcrops of precambrian, paleozoic and mesozoic formations. late neoproterozoic-early cambrian schists, the oldest stratigraphy unit in the region, consist o...
Aeolian sandstones are found intimately associated with Late Neoproterozoic ‘snowball Earth’ glacial deposits. Studying the nature of these aeolian deposits offers the great potential to elicit new and important information regarding the wind conditions during these extreme glacial intervals. Wind direction is the dominant paleoclimatic indicator that can be derived from aeolian deposits and on...
Geologic investigations of the Arabian-Nubian Shield (ANS) are supported by a valuable, expanding dataset of geochronologic ages and isotopic analyses. U-Pb zircon SIMS, TIMS, and evaporation data provide robust temporal control on depositional, volcanic, and intrusive events. Nd, Sr, O and, increasingly, Hf isotopic studies provide insights into magma sources and constraints on crustal recycli...
Late Neoproterozoic-Early Cambrian schists have been occurred in southwest of Zanjan city from the Soltanieh belt. The Soltanieh belt in northwest of Iran is uplifted basement of Precambrian-Paleozoic in main central Iran zone and includes outcrops of Precambrian, Paleozoic and Mesozoic Formations. Late Neoproterozoic-Early Cambrian schists, the oldest stratigraphy unit in the region, consist o...
The recent proliferation of stratigraphic studies of delta 13C variation in carbonates and organic C in later Neoproterozoic and basal Cambrian successions (approximately 850-530 Ma) indicates a strong oscillating trend in the C-isotopic composition of surface seawater. Alone, this trend does not adequately characterize discrete intervals in Neoproterozoic time. However, integrated with the vec...
The Majerad metamorphic complex is located in the northern margin of the Central Iran structural zone and southeast of Shahrood, includes a wide variety of metacarbonate, metabasite (greenschist, amphibolite and garnet amphibolite), metapelite, metapsammite and metarhyolite. The protolith of metabasites has been submarine basaltic lava flows which erupted in the Late Neoproterozoic intracontine...
Overview The paleogeographic reconstruction of the late Neoproterozoic assumes a marked significance due to the fact that the interactions between the biosphere, atmosphere, hydrosphere, and geosphere during this time strongly influenced the evolution of life and initiated a remarkable phase of organic evolution, well documented in the rocks of this age. Time-related changes in these carbon res...
The northern margin of the Yangtze Block (NYB) experienced distinct tectono-magmatic evolution during mid- and late-Neoproterozoic, as compared with northwestern margins (NWYB), although geodynamic mechanism remains controversial. South Qinling Belt (SQB), which forms northernmost NYB, is a significant target for studying Neoproterozoic tectonic NYB. Here we present U-Pb geochronology Lu-Hf iso...
Metapelites of the Do Chah complex (SE Shahrood) are composed of micaschist, garnet micaschist, chloritoid schist and garnet-bearing gneiss. In the highest degree of metamorphism, metapelites have been affected by partial melting, resulting as granitization. A significant part of these rocks, imposed by compressional tectonic regime and show typical evidence of plastic deformation and intensive...
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