نتایج جستجو برای: early permian
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Stratigraphic correlations presented here for the ductilely deformed and metamorphosed rocks exposed in the Shadow Mountains indicate that they formed on the North American continental margin and are not exotic or significantly displaced from their site of origin. These strata represent a depositional history that spans Late Proterozoic and Paleozoic passive margin development, late Paleozoic t...
The medial Permian (~270-260 Ma: Guadalupian) was a time of important tetrapod faunal changes, in particular reflecting a turnover from pelycosaurian- to therapsid-grade synapsids. Until now, most knowledge on tetrapod distribution during the medial Permian has come from fossils found in the South African Karoo and the Russian Platform, whereas other areas of Pangaea are still poorly known. We ...
[1] A series of sharp bends (oroclines) are recognized in the Paleozoic to early Mesozoic New England Orogen of eastern Australia. The exact geometry and origin of these bends is obscured by voluminous magmatism and is still debated. Here we present zircon U-Pb ages that confirm the lateral continuation of early Permian (296–288 Ma) granitoids and shed new light on the oroclinal structure. Orog...
Four supergiant and numerous giant gasfields have been discovered in the Southwest Iran which produce from Permian-Triassic carbonates belong to the upper member of Dalan Formation and Kangan Formation. In this research a detailed biostratigraphic, microfacies and sequence stratigraphic study of the late Middle Permian to Triassic successions was undertaken from 850 thin sections prepared from ...
Exceptionally well-preserved organic remains of thecamoebians (testate amoebae) were preserved in marine sediments that straddle the greatest extinction event in the Phanerozoic: the Permian-Triassic Boundary. Outcrops from the Late Permian Zewan Formation and the Early Triassic Khunamuh Formation are represented by a complete sedimentary sequence at the Guryul Ravine Section in Kashmir, India,...
Birds, dinosaurs, crocodilians, pterosaurs and their close relatives form the highly diverse clade Archosauriformes. Archosauriforms have a deep evolutionary history, originating in the late Permian, prior to the end-Permian mass extinction, and radiating in the Triassic to dominate Mesozoic ecosystems. However, the origins of this clade and its extraordinarily successful body plan remain obscu...
Burial and exhumation historyof Pennsylvanian strata, central Appalachian basin: an integrated study
An inferred burial and exhumation history of Pennsylvanian strata in the central Appalachian foreland basin is constrained by integrating palaeothermometers, geochronometers and estimated palaeogeothermal gradients.Vitrinite re£ectance data and £uid inclusion homogenization temperatures indicate that burial ofLower andUpperPennsylvanian strata of theAppalachianPlateau inWest Virginia exceeded 4...
The discovery of hydrocarbons (mainly gas) in commercial quantities from Gondwanan sediments in the Mandapeta ®eld of Krishna-Godavari Basin, India, provided impetus for intensi®ed exploration in Mandapeta and the adjoining Kommugudem, Draksharama and Endamuru ®elds. Both oil and gas have been found in the reservoirs of Mandapeta (Triassic) and Golapalli (Early Cretaceous) formations. Mature, l...
The transition during the Permian–Triassic interval from brachiopod-rich benthic marine assemblages to communities with diverse molluscs has been well constrained by measures of global taxonomic richness but its ecological context has not been studied using quantitative relative abundance data. New relative abundance data from Early, Middle, and Late Permian silicified fossil assemblages from o...
During the end-Permian mass extinction, marine ecosystems suffered a major drop in diversity, which was maintained throughout the Early Triassic until delayed recovery during the Middle Triassic. This depressed diversity in the Early Triassic correlates with multiple major perturbations to the global carbon cycle, interpreted as either intrinsic ecosystem or external palaeoenvironmental effects...
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