نتایج جستجو برای: sedimentary environment

تعداد نتایج: 527372  

2003
Scott M. McLennan

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...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2012
Jens Kallmeyer Robert Pockalny Rishi Ram Adhikari David C Smith Steven D'Hondt

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...

Journal: :Astrobiology 2011
John Grotzinger David Beaty Gilles Dromart Sanjeev Gupta Mitch Harris Joel Hurowitz Gary Kocurek Scott McLennan Ralph Milliken Gian Gabrielle Ori Dawn Sumner

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...

Journal: :Marine geology 1986
J C Walker

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...

2017
Zuozhen Han Dan Li HuaXiao Yan Peiyuan Li

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...

2015
Kathleen R. Stoof-Leichsenring Ulrike Herzschuh Luidmila A. Pestryakova Juliane Klemm Laura S. Epp Ralph Tiedemann

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...

2011
Alessandro Iannace

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 ...

2005
Leslie A. Melim Douglas I. Benn

2002
Coşkun Sari

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 ...

Journal: :Journal of Maps 2023

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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