نتایج جستجو برای: permian system
تعداد نتایج: 2233955 فیلتر نتایج به سال:
Gypsum karst problems in the Permian and Triassic sequences of England have caused difficult conditions for bridge and road construction. In Northern England, the Ripon Bypass crosses Permian strata affected by active gypsum karst and severe subsidence problems. Here, the initial borehole site investigation for the road was supplemented by resistivity tomography studies. The roadway was reinfor...
■ Abstract Growth of the Japanese arc system, which has mainly taken place along the continental margin of Asia since the Permian, is the result of subduction of the ancient Pacific ocean floor. Backarc basin formation in the Tertiary shaped the presentday arc configuration. The neotectonic regime, which is characterized by strong eastwest compression, has been triggered by the eastward motion ...
Extreme warming at the end-Permian induced profound changes in marine biogeochemical cycling and animal habitability, leading to largest metazoan extinction Earth’s history. However, a causal mechanism for that is consistent with various proxy records of geochemical conditions through interval has yet be determined. Here we combine an Earth system model global local redox interpretations from P...
Among extant large reptiles, juveniles often occupy different habitats from those of adults or subadults and thus avoid competition with and predation from the older animals; small juveniles often choose cryptic habitats because they are vulnerable to a wide variety of predators. Evidence from fossil humeri and femora of Early Permian reptiles collected from sediments of several distinct habita...
The Markley Formation of north-central Texas is composed predominantly of terrestrial rocks that span the Pennsylvanian-Permian boundary. Plant-fossil-bearing outcrops of the Markley are complex and preserve distinct environments that probably differed in position on the landscape and habitat conditions. In superpositional order, basal paleosols evidence well drained but wet conditions and supp...
Claraia Bittner, 1901 is a prominent extinct bivalve genus of the Permian-Triassic transition (Newell and Boyd, 1995). Although it first appeared in Wuchiapingian (Late Permian; Fang Zong-Jie, 2010), its massive proliferation immediate wake end-Permian mass extinction makes archetype cosmopolitan eurytopic disaster species hallmark base Triassic (e.g., Schubert Bottjer, Diener (1923, p. 38) fix...
[1] Two recent studies [Hotinski et al., 2001; Zhang et al., 2001] have modeled and discussed Late Permian ocean circulation and oxygenation. These studies have reached significantly different conclusions. Zhang et al. [2001] find that a ‘‘thermal mode’’ ocean circulation driven by cooling in polar latitudes is unlikely to support deep-sea anoxia, but a ‘‘haline mode’’ ocean circulation, a shal...
Pedogenic goethites in each of two Early Permian paleosols appear to record mixing of two isotopically distinct CO2 components—atmospheric CO2 and CO2 from in situ oxidation of organic matter. The C values measured for the Fe(CO3)OH component in solid solution in these Permian goethites are 13.5‰ for the Lower Leonardian ( 283 Ma BP) paleosol (MCGoeth) and 13.9‰ for the Upper Leonardian ( 270 M...
We welcome the examination by Marshall (1) of our study (2), particularly his corrected statistical analysis of confidence intervals on stratigraphic ranges, which we accept. We believe, however, that in the process he has misinterpreted both our original data and his own reanalysis. We argued for both gradual and abrupt aspects to the Permian-Triassic (P-T) extinction, whereas Marshall suggest...
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