نتایج جستجو برای: lower paleozoic
تعداد نتایج: 693427 فیلتر نتایج به سال:
Remains of parasites in vertebrates are rare from the Mesozoic and Paleozoic. Once most parasites that live in - or pass through - the gastrointestinal tract of vertebrates, fossil feces (coprolites) or even intestinal contents (enterolites) can eventually preserve their remains. Here we announce the discovery of a spiral shark coprolite from the Paleozoic bearing a cluster of 93 small oval-ell...
به منظور مطالعه بیواستراتیگرافی و پالئواکولوژی رسوبات دونین پسین، برشی در استان کرمان انتخاب گردید، که از لحاظ موقعیت زمین شناسی در ناحیه ایران مرکزی قرار دارد. برش باغین در شمال شرق باغین و 20 کیلومتری غرب کرمان واقع شده است. قدیمی ترین واحد دونین در این منطقه، سازند پادهاست که شامل ماسه سنگ های سفید و قرمز می باشد، این سازند به وسیله واحد هایی از دونین که معادل سازند بهرام می باشد، پوشیده می...
Integration of ichnologic, sedimentologic, and stratigraphic studies of cores from Lower Pennsylva-nian oil and gas reservoirs (lower Morrow Sandstone, southwest Kansas) allows researchers to distinguish between estuarine-and open-marine deposits. This study represents one of the first published ichnologic analyses of a Paleozoic reservoir and, therefore, provides a unique opportunity to test t...
Many black shales, phosphorites, and cherts that formed at low paleolatitudes on the North American continent during the late Paleozoic were a direct consequence of equatorial upwelling and an equatorial undercurrent in an ocean that spanned much of the globe. In equatorial parts of modern oceans, wind stress divergence leads to high surface productivity. Sinking organic matter is remineralized...
Gigantism-very large body size-is an ecologically important trait associated with competitive superiority. Although it has been studied in particular cases, the general conditions for the evolution and maintenance of gigantism remain obscure. I compiled sizes and dates for the largest species in 3 terrestrial and 7 marine trophic and habitat categories of animals from throughout the Phanerozoic...
The Japanese mudskipper (Periophthalmus modestus), an amphibious fish that possesses many respiratory and locomotive specializations for sojourns onto land, was used as a model to study how changing atmospheric oxygen concentrations during the middle and late Paleozoic Era (400-250 million years ago) may have influenced the emergence and subsequent radiation of the first tetrapods. The effects ...
[1] Orogens with multiple (ultra)high-pressure ((U)HP) and (ultra)high-temperature ((U) HT) metamorphic events provide a complex but telling record of oceanic and continental interaction. The Early Paleozoic history of the “Heart of China,” the Qinling orogenic collage, offers snapshots of at least three (U)HP and two (U)HT metamorphic events. The preservation of remnants of both oceanic and co...
Abstract To investigate the characteristics of graphitized shale and influence organic matter graphitization on gas accumulation, Raman spectroscopy analysis, hydrocarbon generation simulation technique, reservoir physical property test, rock mechanics experiment, field emission scanning electron microscopy (FE-SEM) were carried out nongraphitized shales Longmaxi Formation in Changning area, so...
The internal layering and provenance of feldspar in 3 tills and in one outwash deposit at Gahanna, Ohio, were studied by determining pebble lithologies and Rb-Sr dates of feldspar. Variations in lithology of pebbles and in the Rb-Sr ratios of feldspar in the 125—250 micrometer fractions reveal discontinuities which divide the upper 2 tills into 2 subunits each. Each of the lower subunits appear...
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