نتایج جستجو برای: depositional sequence
تعداد نتایج: 409161 فیلتر نتایج به سال:
Sedimentary rocks are the archives of environmental conditions and ancient planetary surface processes that led to their formation. Reconstructions of Earth's past surface behaviour from the physical sedimentary record remain controversial, however, in part because we lack a quantitative framework to deconvolve internal dynamics of sediment-transport systems from environmental signal preservati...
Polycyclic aromatic hydrocarbons (PAH) in lake sediments and nearby soils of two European high mountain regions, Pyrenees and Tatra, have been studied. Similar mixtures of parent PAH were observed in all cases, indicating predominance of airborne transported combustion products. Nevertheless, the composition of these atmospherically long-range transported PAH was better preserved in the superfi...
Age-coded multi-layered geological datasets are becoming increasingly prevalent with the surge in open-access geodata, yet there are few methodologies for extracting geological information and knowledge from these data. We present a novel methodology, based on the open-source GPlates software in which age-coded digital palaeogeographic maps are used to ‘‘data-mine’’ spatio-temporal patterns rel...
the alborz coal basin is located in northern part of iran. the coal deposits of shahrood in eastern alborz, zirab in central alborz and abyek in western alborz were studied as typical coalfields of the basin. shemshak formation which is the main coal-bearing sequence was formed during the triassic-jurassic in the basin. it consists of sandstone, siltstone, shale and claystone, which variedly al...
statistical studies on palynology contents of late cretaceous to paleocene age gurpi formation in a surface section in zagros basin,sw iran indicate changes in abundance, species diversity, ratio of spiniferites to cyclonephelium (s/c), palynological marine index(pmi) values and organic facies. these palynological variations clearly reflect fluctuations in relative sea-level and depositionalenv...
objective: the asmari formation is characterised by alternation thick carbonate and marl sequence of the oligocene- miocene in the zagros basin, southwest of iran that were deposited on the shelf of eastern paratethys. methods: this formation is exposed at tang-e-khoshk in the fars subcoastal zone with a thickness of 286 m comprising alternation of medium and thick to massive bedded carbonates,...
The formation of ordered particle arrays plays an essential role in nanotechnology, biological systems, and inorganic photonic structures in the geosphere. Here, we show how ordered arrays of amorphous silica spheres form in deeply weathered lithologies of the Great Artesian Basin (central Australia). Our multi-method approach, using optical and scanning electron microscopy, X-ray microdiffract...
[1] Pyroclastic density currents (PDCs) are gas-particle flows generated during explosive eruptions, which are often erupted over the flanks of stratovolcanoes. These volcanoes may have different shapes, which can affect the flow aerodynamics and hence the depositional processes. Here, multiphase numerical simulations are carried out in order to define semiquantitative relationships among the P...
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