DOI: 10.1016/j.gloplacha.2017.01.002
论文题名: Redox conditions and marine microbial community changes during the end-Ordovician mass extinction event
作者: Smolarek J. ; Marynowski L. ; Trela W. ; Kujawski P. ; Simoneit B.R.T.
刊名: Global and Planetary Change
ISSN: 0921-8181
出版年: 2017
卷: 149 起始页码: 105
结束页码: 122
语种: 英语
英文关键词: Biomarkers
; Black shales
; Microbial communities
; Paleoenvironment
; Redox conditions
; Zbrza Basin
Scopus关键词: Biomarkers
; Carbon
; Climate change
; Microorganisms
; Oil shale
; Organic carbon
; Sea level
; Shale
; Black shales
; Microbial communities
; Paleo-environment
; Redox condition
; Zbrza Basin
; Glacial geology
; Cyanobacteria
英文摘要: The end-Ordovician (Hirnantian) crisis is the first globally distinct extinction during the Phanerozoic, but its causes are still not fully known. Here, we present an integrated geochemical and petrographic analysis to understand the sedimentary conditions taking place before, during and after the Late Ordovician ice age. New data from the Zbrza (Holy Cross Mountains) and Gołdap (Baltic Depression) boreholes shows that, like in other worldwide sections, the total organic carbon (TOC) content is elevated in the upper Katian and uppermost Hirnantian to Rhudannian black shales, but depleted (below 1%) during most of the Hirnantian. Euxinic conditions occurred in the photic zone in both TOC-rich intervals. This is based on the maleimide distribution, occurrence of aryl isoprenoids and isorenieratane, as well as a dominance of tiny pyrite framboids. Euxinic conditions were interrupted by the Hirnantian regression caused by glaciation. Sedimentation on the deep shelf changed to aerobic probably due to intense thermohaline circulation. Euxinia in the water column occurred directly during the time associated with the second pulse of the mass extinction with a termination of the end-Ordovician glaciation and sea level rise just at the Ordovician/Silurian (O/S) boundary. In contrast, we suggest based on inorganic proxies that bottom water conditions were generally oxic to dysoxic due to upwelling in the Rheic Ocean. The only episode of seafloor anoxia in the Zbrza basin was found at the O/S boundary, where all inorganic indicators showed elevated values typical for anoxia (U/Th > 1.25; V/Cr > 4.25; V/(V + Ni): 0.54–0.82 and Mo > 10–25 ppm). Significant differences in hopanes to steranes ratio and in C27–C29 sterane distribution between the Katian, Rhudannian and Hirnantian deposits indicate changes in marine microbial communities triggered by sharp climate change and Gondwana glaciation. The increase from biomarkers of cyanobacteria (2α-methylhopanes) after the O/S boundary implied enhanced microbial activity following the mass extinction event. © 2017 Elsevier B.V. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010053608&doi=10.1016%2fj.gloplacha.2017.01.002&partnerID=40&md5=d6392489e111424b6dce7a745f360329
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/11767
Appears in Collections: 全球变化的国际研究计划 气候变化与战略
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作者单位: Faculty of Earth Sciences, University of Silesia, Będzińska 60, Sosnowiec, Poland
Recommended Citation:
Smolarek J.,Marynowski L.,Trela W.,et al. Redox conditions and marine microbial community changes during the end-Ordovician mass extinction event[J]. Global and Planetary Change,2017-01-01,149.