نتایج جستجو برای: paleozoic
تعداد نتایج: 1972 فیلتر نتایج به سال:
Wrangellia Superterrane. The Paleozoic to Mesozoic Wrangellia superterrane (Insular terrane) consists of intraoceanic volcanic assemblages and basement rocks of the Peninsular, Wrangellia, and Alexander terranes (Plafker et al, 1994). The magmatic-arc assemblages of the Peninsular terrane appear to have been built upon the Wrangellia composite terrane prior to the midCretaceous and include: 1) ...
Among the diverse clade of Paleozoic dissorophoid amphibians, the small, terrestrial amphibamids and the neotenic branchiosaurids have frequently been suggested as possible antecedents of either all or some of the modern amphibian clades. Classically, amphibamids and branchiosaurids have been considered to represent distinct, but closely related clades within dissorophoids, but despite their im...
Arpylorus antiquus, erected by Calandra (1964), was isolated from Upper Silurian sedimentary rocks from the Mechiguig-1 borehole in southern Tunisia, with other palynomorphs. The folded vesicle and the quadrangular form of the aperture breaks down into plate-like fragments, resembling the tabulation of dinoflagellates. The presence of these elements, have been used to interpret A. antiquus as a...
Thuy et al. (2017) meant to present evidence that some Paleozoic stem-group echinoderms survived the end-Permian extinction. If valid, this would be an important discovery because it radically challenges severe evolutionary bottleneck experienced by echinoderms during that time. However, given the far-reaching implications of such a matter, the onus and burden of proof must be high and applied....
This paper spotlights on determining the concentrations and distribution of radionuclides in paleozoic lateritic paleosol samples from El-Gor area, southwestern Sinai, Egypt, using high-resolution gamma spectrometry. The concentrations of eU (ppm), eTh (ppm), and K (in percentage) were determined. The obtained data of eU, eTh and their ratios were used for calculations of uranium migration tend...
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