نتایج جستجو برای: foraminifera
تعداد نتایج: 4350 فیلتر نتایج به سال:
We compare foraminifera and macrofauna as bio-indicators of oil-based drill mud disposal site off Congo. The most polluted sites are characterized by poor faunas, dominated by some very tolerant taxa. Slightly further from the disposal site, there is an area with strongly increased densities, heavily dominated by opportunistic taxa. Still further, macrofauna appears to be similar to that at the...
the qom formation, a series of shales, sandstones and carbonate deposits, is the last transgression of the sea in central iran sedimentary basin. foraminifera are one of the most important and numerous fossil groups present in the qom formation. in this study, the micropaleontology of the qom formation in three measured stratigraphic sections in south and west of tafresh (rakin, band-e-ali nagh...
a sequence of permian rocks crops out in northwest of khur in central alborz, north of iran. this sequence consists of the dorud (asselian-sakmarian), ruteh (artinskian-murgabian) and nesen (early djulfian) formations. the ruteh and nesen formations in alborz range were deposited in a shallow marine environment of the continental margin in the paleo-tethys. the ruteh formation with a thickness ...
Salt-marsh foraminifera have been used to reconstruct Holocene sea-level changes from coastlines around the world. In this work, we compile the results of surface foraminiferal surveys from fifteen study sites located on the east, south and west coasts of Great Britain, and the west coast of Ireland. These data, which comprise 236 samples and 84 species, are used to summarize the contemporary d...
A latest Maastrichtian global warming event, which began approximately 450 k.y. and ended about 22 k.y. prior to the K/T boundary, is associated with the poleward migration of the warm-water planktonic foraminifer Pseudotextularia elegans. The warming event was apparently inititated by greenhouse warming due to the main outpouring of the Deccan Traps in India and is now well documented in the N...
Understanding the interaction between climate and biotic evolution is crucial for deciphering the sensitivity of life. An enigmatic mass extinction occurred in the deep oceans during the Mid Pleistocene, with a loss of over 100 species (20%) of sea floor calcareous foraminifera. An evolutionarily conservative group, benthic foraminifera often comprise >50% of eukaryote biomass on the deep-ocean...
The relationship between seawater temperature and the average Mg/Ca ratios in planktic foraminifera is well established, providing an essential tool for reconstructing past ocean temperatures. However, many species display alternating high and low Mg-bands within their shell walls that cannot be explained by temperature alone. Recent experiments demonstrate that intrashell Mg variability in Orb...
—Foraminiferal tests are a common component of many marine sediments. The oxygen isotope ratio (δ18O) of test calcite is frequently used to reconstruct aspects of their life environment. The δ18O depends mainly on the isotope ratio of the water it is precipitated from, the temperature of calcification, and, to a lesser extent, the carbonate ion concentration. Foraminifera and other organisms ca...
planktonic foraminifera are useful in determining the relative age of the upper cretaceous strata. based on distribution of planktonic foraminifera in kuh-e siah section (212 m thickness), eight biozones have been recognized including dicarinella concavata interval zone (earliest santonian), dicarinella asymetrica total range zone (santonian to earliest campanian), globotruncanita elevata parti...
Raja Ampat is an archipelago of about 1,500 small islands located northwest off the Bird's Head Peninsula of Indonesia's West Papua province. It is part of the Coral Triangle, a region recognized as the "epicenter" of tropical marine biodiversity. In the course of a large-scale survey on shallow benthic foraminifera we have discovered one new genus and five new species of recent miliolid benthi...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید