نتایج جستجو برای: sedimentary structures
تعداد نتایج: 464979 فیلتر نتایج به سال:
Vibracoring is a subsurface sediment acquisition (sediment coring) technique (Pierce and Howard, 1969; Howard and Frey, 1975; dreher et al., 2008) that returns sediment preserved within its stratigraphic and sedimentologic context. This process (see appendix 1) generates a continuous, contiguous sediment sample at a point by vibrating an aluminum core barrel vertically into the sediment (fig. 1...
in this research work the classification of the southern coasts of the caspian sea is performed using sedimentary and morphodynamic indices. this includes field study of morphodynamic characteristics of the shore structures. field measurements include in situ samplings of sediments and actual observations of structures on site. these field activities were done along six transects in the dry coa...
Raman spectra of carbonaceous materials in one of the world’s oldest sedimentary rock formations – the Strelley Pool Chert (Pilbara Craton, Western Australia) – are analysed to determine whether primary structural characteristics of organic molecules may have survived to the present day. We use Raman spectral parameters to identify variations in molecular structure of the carbon and determine w...
The association of coal and oil shale had been a hot topic for a long time. Various types of association of coal and oil shale can be found in one basin, for instance, the coal can act as the roof or floor or interlayer of the oil shale, etc. The most crucial factor for the formation of oil shale is stratification and seasonal blooming of lower plankton, while the final formation of the coal st...
Terrestrial planetary surfaces, other than Earth, are overwhelmingly basaltic in character. Because of this, among the most intriguing and significant results from recent studies of Mars are the occurrences of high-silica rocks at the Pathfinder site and orbital thermal emission spectroscopy evidence for a global petrological dichotomy with andesites dominating the entire northern hemispheric p...
The Copper Harbor Conglomerate is a Mesoproterozoic (1.09 Ga) freshwater sedimentary sequence that outcrops in the Upper Peninsula of Michigan. The formation was deposited during infilling of the failed Midcontinent Rift and contains fluvial, lacustrine, and alluvial fan facies. This study describes and analyzes the formation of small domal structures preserved in fluvial sandstone facies withi...
The global geographic distribution of subseafloor sedimentary microbes and the cause(s) of that distribution are largely unexplored. Here, we show that total microbial cell abundance in subseafloor sediment varies between sites by ca. five orders of magnitude. This variation is strongly correlated with mean sedimentation rate and distance from land. Based on these correlations, we estimate glob...
Processes that operate at planetary surfaces have the potential to record a history of planetary evolution in the form of sedimentary rocks. This is important because our experience on Earth shows that sediments and sedimentary rocks are the dominant archive of high-resolution proxies of present and past tectonic, climatic, and biological processes. Our understanding of the evolution of Earth’s...
Time resolved data on the carbon isotopic composition of carbonate minerals and the sulfur isotopic composition or sulfate minerals show a strong negative correlation during the Cretaceous. Carbonate minerals are isotopically heavy during this period while sulfate minerals are isotopically light. The implication is that carbon is being transferred from the oxidized, carbonate reservoir to the r...
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