Fluctuations of redox conditions across the Permian–Triassic boundary : new evidence from the GSSP section in Meishan of South China

Li, Guoshan, Wang, Yongbiao, Shi, G. R., Liao, Wei and Yu, Lixue 2016, Fluctuations of redox conditions across the Permian–Triassic boundary : new evidence from the GSSP section in Meishan of South China, Palaeogeography, palaeoclimatology, palaeoecology, vol. 448, pp. 48-58, doi: 10.1016/j.palaeo.2015.09.050.

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Title Fluctuations of redox conditions across the Permian–Triassic boundary : new evidence from the GSSP section in Meishan of South China
Author(s) Li, Guoshan
Wang, Yongbiao
Shi, G. R.ORCID iD for Shi, G. R. orcid.org/0000-0002-5126-4036
Liao, Wei
Yu, Lixue
Journal name Palaeogeography, palaeoclimatology, palaeoecology
Volume number 448
Start page 48
End page 58
Total pages 11
Publisher Elsevier
Place of publication Amsterdam, The Netherlands
Publication date 2016-04-15
ISSN 0031-0182
Keyword(s) Permian – Triassic boundary
End-Permian mass extinction
Pyrite framboids
Redox geochemistry
Meishan section
Summary Oceanic anoxia has long been considered as one of the main causes for the end-Permian mass extinction. However, the results obtained by different researchers are rather divergent from different sections, or even on the same section using the same redox proxy. This study aims to examine the causes for some of these divergent results using high-resolution pyrite framboid sampling at the Meishan GSSP section in South China. Detailed microfacies analysis shows that the uppermost Late Permian strata comprises two significantly different sedimentary facies: one characterized by silicious muddy limestone and recognized as representing autochthonous background sediments; the other distinguished by bioclastic grainstone, interpreted to be allochthonous in origin and have been transported from the nearby platform margin. These two different sedimentary facies represent two distinctly different redox conditions. Together with the facies analysis, a statistical analysis of pyrite framboids was carried out to evaluate the redox evolution across the Permian-Triassic boundary. Abundant framboids with average diameters of about 6μm are found in background sediments beneath the extinction boundary, indicating generally anoxic bottom water conditions. But this condition was punctuated by transient intervals of rapid oxygenation interpreted to have been caused by intrusion of intermittent turbidity flows. Our study also showed that anoxic conditions persisted into the immediate aftermath of the mass extinction, thereafter it was quickly followed by a relatively long period of oxic conditions (with rare framboids). However, the redox conditions returned to anoxia (with abundant pyrite framboids averaging about 5μm in diameter), accompanied by a rapid global transgression. The oxygenation manifested near the Permian-Triassic boundary coincides with the negative excursion of carbon isotope. This would imply that, contrary to previous interpretations, this great δ13C negative excursion was probably not caused by the upwelling of anoxic deep ocean waters.
Language eng
DOI 10.1016/j.palaeo.2015.09.050
Field of Research 040308 Palaeontology (incl Palynology)
060399 Evolutionary Biology not elsewhere classified
0403 Geology
020602 Field Theory and String Theory
0603 Evolutionary Biology
Socio Economic Objective 970104 Expanding Knowledge in the Earth Sciences
HERDC Research category C1 Refereed article in a scholarly journal
Copyright notice ©2015, Elsevier
Persistent URL http://hdl.handle.net/10536/DRO/DU:30080101

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