نتایج جستجو برای: sedimentary environment
تعداد نتایج: 527372 فیلتر نتایج به سال:
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 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...
High salt environment was widespread in modern and geological record, and sedimentation induced by microbes in these systems was an important part of sedimentary minerals and rocks. The mechanism of microbiologically induced carbonate precipitation has not been solved thoroughly although numerous scholars and experts have made specifically research of the problems with respect to minerals induc...
Genetic investigations on eukaryotic plankton confirmed the existence of modern biogeographic patterns, but analyses of palaeoecological data exploring the temporal variability of these patterns have rarely been presented. Ancient sedimentary DNA proved suitable for investigations of past assemblage turnover in the course of environmental change, but genetic relatedness of the identified lineag...
Sedimentary rocks are one component of the modern threefold classification of rocks. They derive from the lithification of sediments, which are produced in basically two ways: by the mechanical deposition of grains derived from the alteration of other rocks (detrital or clastic rocks), or as chemical precipitates or grains formed organically or inorganically from an aqueous solution. The whole ...
The primary objective of a gravity survey over a sedimentary basin is to delineate the shape of the basin. To fulfill this objective, information is needed about the densities within the sedimentary section. Densities of sedimentary rocks increase with depth (mainly due to compaction), approaching that of the basement in deep basins. Sedimentary basins are generally associated with low gravity ...
Identified as one of the most vulnerable environment to impacts sea-level rise, morphological and hydrological diversity coastal areas complicates their study. To understand evolution, it is essential characterize current morpho-sedimentary distributions processes. Morphologic interpretation, from LiDAR data, coupled with grain-size geochemical analyses 200 samples, subsequently interpreted sta...
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