نتایج جستجو برای: permian

تعداد نتایج: 3143  

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1981
R M Garrels A Lerman

A reservoir model of a Recent steady-state sedimentary system in which the reduced sulfur and oxidized sulfur reservoirs were coupled with the oxidized carbon and reduced carbon reservoirs was constructed. The time curve of the sulfur isotope ratios of the sedimentary sulfate reservoir was used to drive the model back to the beginning of Cambrian time (600 million years ago), producing the rese...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2012
Jun Wang Hermann W Pfefferkorn Yi Zhang Zhuo Feng

Plant communities of the geologic past can be reconstructed with high fidelity only if they were preserved in place in an instant in time. Here we report such a flora from an early Permian (ca. 298 Ma) ash-fall tuff in Inner Mongolia, a time interval and area where such information is filling a large gap of knowledge. About 1,000 m(2) of forest growing on peat could be reconstructed based on th...

2017
Björn Baresel Hugo Bucher Borhan Bagherpour Morgane Brosse Kuang Guodun Urs Schaltegger

New high-resolution U-Pb dates indicate a duration of 89 ± 38 kyr for the Permian hiatus and of 14 ± 57 kyr for the overlying Triassic microbial limestone in shallow water settings of the Nanpanjiang Basin, South China. The age and duration of the hiatus coincides with the Permian-Triassic boundary (PTB) and the extinction interval in the Meishan Global Stratotype Section and Point, and strongl...

2000
M. S. Raza Khan A. K. Sharma S. K. Sahota M. Mathur

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...

2016
Peter A. Hochuli Anna Sanson-Barrera Elke Schneebeli-Hermann Hugo Bucher

Generally Early Triassic floras are believed to be depauperate, suffering from protracted recovery following the Permian-Triassic extinction event. Here we present palynological data of an expanded East Greenland section documenting recovered floras in the basal Triassic (Griesbachian) and a subsequent fundamental floral turnover, postdating the Permian-Triassic boundary extinction by about 500...

2013
Rui Castanhinha Ricardo Araújo Luís C. Júnior Kenneth D. Angielczyk Gabriel G. Martins Rui M. S. Martins Claudine Chaouiya Felix Beckmann Fabian Wilde

Dicynodontia represent the most diverse tetrapod group during the Late Permian. They survived the Permo-Triassic extinction and are central to understanding Permo-Triassic terrestrial ecosystems. Although extensively studied, several aspects of dicynodont paleobiology such as, neuroanatomy, inner ear morphology and internal cranial anatomy remain obscure. Here we describe a new dicynodont (Ther...

2013
Lauren P. Birgenheier Tracy D. Frank Christopher R. Fielding Michael C. Rygel

Proxy geochemical records from high-latitude, ice-proximal deposits have the potential to provide key insights into past icehouse climates, but such records are rare. The Permian System of eastern Australia contains a rich record of environmental and climatic changes that occurred in areas proximal to glaciation during the acme and waning stages of the late Paleozoic ice age. Within this succes...

2002
M. H. Holtz Katherine G. Jackson

The complex interplay between depositional facies and diagenesis in dolostones presents numerous challenges for calculating petrophysical properties from wireline logs. Complex pore geometries and mineralogies control rock petrophysical properties, and equations for calculating porosities and saturations must therefore be tailored to specific pore geometry-mineralogy combinations. The complex m...

2017
Christopher R. Fielding Tracy D. Frank Lauren P. Birgenheier Michael C. Rygel Andrew T. Jones John Roberts

Stratigraphic and sedimentological data from New South Wales and Queensland, eastern Australia, indicate that the Late Paleozoic Ice Age comprised at least eight discrete glacial intervals (each 1–8 Ma in duration, here termed “glaciations”), separated by nonglacial intervals of comparable duration. These events spanned an interval from mid-Carboniferous (c. 327 Ma) to the early Late Permian (c...

Journal: :Proceedings. Biological sciences 2011
Robert R Reisz Sean P Modesto Diane M Scott

The initial stages of evolution of Diapsida (the large clade that includes not only snakes, lizards, crocodiles and birds, but also dinosaurs and numerous other extinct taxa) is clouded by an exceedingly poor Palaeozoic fossil record. Previous studies had indicated a 38 Myr gap between the first appearance of the oldest diapsid clade (Araeoscelidia), ca 304 million years ago (Ma), and that of i...

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