نتایج جستجو برای: foraminifera
تعداد نتایج: 4350 فیلتر نتایج به سال:
The responses of Ammonia parkinsoniana (Foraminifera) exposed to different concentrations of lead (Pb) were evaluated at the cytological level. Foraminifera-bearing sediments were placed in mesocosms that were housed in aquaria each with seawater of a different lead concentration. On the basis of transmission electron microscopy and environmental scanning electron microscopy coupled with energy...
Foraminifera are single-celled organisms with internal calcerous shells, known as tests. The image above shows a shell with a planispiral chamber arrangement — during growth, chambers are added sequentially to form a coil in a flat spiral. Foraminiferan tests are quite diverse. The image shown here came from a study on the nature of the material in the calcerous test and how the foraminifera de...
In this research systematics and biostratigraphy of the Cretaceous deposits foraminifera in Kerch section, southwestern Qayen, in the eastern margin of the Lut Block, were studied in detail. This section with 260 meters thickness, mainly formed by gray to cream color marl and shale, marly limestone and limestone laid on a light-colored limestone bed at the base. Seventeen genera and twenty two ...
Dockyards and harbors are recognized as being important locations where sediment-associated pollutants can accumulate, which constitutes an environmental risk to aquatic life due to potential uptake and accumulation of heavy metals in the biota. The aim of this paper is to assess the concentrations and the effects of some heavy metals in the benthic foraminifera assemblage in Niterói Harbor. Lo...
the larger benthic foraminifera gyroconulina columellifera schroeder & darmoian, 1977 (type-locality: maastrichtian aqra formation of iraq) is described for the first time from two sections of the maastrichtian tarbur formation of the zagros fold-thrust-belt, sw iran. new details on its wall microstructure are provided. the microfacies is represented by bioclastic wacke-/pack-/grainstones with ...
Foraminifera are an important faunal element of the benthos in oxygen-depleted settings such as Oxygen Minimum Zones (OMZs) where they can play a relevant role in the processing of phytodetritus. We investigated the uptake of phytodetritus (labeled with (13)C and (15)N) by calcareous foraminifera in the 0-1 cm sediment horizon under different oxygen concentrations within the OMZ in the eastern ...
Deposits spanning the Radotruncana calcarata Taxon Range Zone at the Postalm section, Northern Calcareous Alps (Austria) are examined quantitatively for foraminiferal assemblages, especially the planktonic group. This study focuses on establishing a high resolution record spanning an 800 ka long stratigraphic interval from the active continental margin of the Penninic Ocean. The Postalm section...
We present stable isotope and geochemical data from four sediment cores from west of Prins Karls Forland (ca. 340 m water depth), offshore western Svalbard, recovered from close to sites of active methane seepage, as well as from shallower water depths where methane seepage is not presently observed. Our analyses provide insight into the record of methane seepage in an area where ongoing ocean ...
Cifelli, Richard. Textural Observations on Some Living Species of Planktonic Foraminifera. Smithsonian Contributions to Paleobiology, n u m b e r 45, 45 pages, 15 plates, 1982.—Wall textures of 11 species of spinose and quasi-spinose planktonic foraminifera collected in plankton tows from the Nor th and Equator ia l Atlantic have been studied with the scanning electron microscope. Il lustration...
Species-range expansions are a predicted and realized consequence of global climate change. Climate warming and the poleward widening of the tropical belt have induced range shifts in a variety of marine and terrestrial species. Range expansions may have broad implications on native biota and ecosystem functioning as shifting species may perturb recipient communities. Larger symbiont-bearing fo...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید