气候变化领域集成服务门户(CCPortal): Late Ordovician paleoceanographic change: Sedimentary and geochemical evidence from Northwest Tarim and Middle Yangtze region; China

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DOI	10.1016/j.palaeo.2020.110070
	Late Ordovician paleoceanographic change: Sedimentary and geochemical evidence from Northwest Tarim and Middle Yangtze region; China
	Chang X.; Hou M.; Woods A.; Chen Z.-Q.; Liu X.; Liao Z.; Liu Y.; Chao H.
发表日期	2020
ISSN	0031-0182
英文摘要	Redox variation during the Late Ordovician were an important driver of palaeoceanographic and ecologic changes that may have eventually facilitated biotic extinction in the end of the Ordovician. Previously, the Late Ordovician paleoredox studies have focused mostly on the last 1–2 million years prior to the end of the Ordovician; redox conditions during the Sandbian–Katian time (early–middle Late Ordovician) are poorly understood. In order to fully evaluate the effects of palaeoceanographic variations on biotic evolutionary trends through the entire Late Ordovician, it is important to fully understand redox variations following the Great Ordovician Biodiversification Event (GOBE) and prior to the end-Ordovician mass extinction. The present study reconstructs paleoredox conditions from the Sandbian–Katian successions of the Dawangou section, northwestern Tarim Basin, northwest China and the Puxihe section of the Middle Yangtze region, South China using pyrite framboidal and redox-sensitive element analyses. The distribution of volcanic microspherules, fossil fragment content and elemental analysis were also applied to reveal possible volcanisms and chemical weathering conditions, and to evoluate their effects on palaeoxygenation and biotic variations. The new results indicate three distinct periods of fluctuating paleoredox conditions during the Late Ordovician in the northwest Tarim and the Middle Yangtze regions, China. Overall, redox conditions varied from mainly oxic but punctuated by short-lived anoxic–dysoxic episodes to rapid fluctuations between reducing and oxidizing conditions, to persistent euxinic conditions. The varition of oxygen minimum zone (OMZ) that developed in the midwater column might be the main cause of anoxic events during the Sandbian–early Katian. Moreover, abundant volcanic microspheres, enhanced chemical weathering, decreasing fossil fragments of benthos, and positive europium anomaly from the study sections collectively indicate that intermittent volcanism during the early–middle Katian may have triggered anoxic-euxinic events during this interval. If integrating the newly obtained redox data with previously published data for the Katian to Hirnantian from the Middle Yangtze area, the long-term, stepwisely accelerated oxyen-poor conditions during the Late Ordovician may have facilitated biotic extinctions in the end of the Ordovician. © 2020
英文关键词	Elemental geochemistry; Framboidal pyrite; Paleoceanography; Redox history; Upper Ordovician
语种	英语
来源期刊	Palaeogeography, Palaeoclimatology, Palaeoecology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/150720
作者单位	Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, 610059, China; State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu, 610059, China; Geological Sciences Department, California State University, Fullerton, CA 92834–6850, United States; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Wuhan), Wuhan, 430074, China; School of Resources and Environmental Science, Chongqing University, Chongqing, 400044, China
推荐引用方式 GB/T 7714	Chang X.,Hou M.,Woods A.,et al. Late Ordovician paleoceanographic change: Sedimentary and geochemical evidence from Northwest Tarim and Middle Yangtze region; China[J],2020.
APA	Chang X..,Hou M..,Woods A..,Chen Z.-Q..,Liu X..,...&Chao H..(2020).Late Ordovician paleoceanographic change: Sedimentary and geochemical evidence from Northwest Tarim and Middle Yangtze region; China.Palaeogeography, Palaeoclimatology, Palaeoecology.
MLA	Chang X.,et al."Late Ordovician paleoceanographic change: Sedimentary and geochemical evidence from Northwest Tarim and Middle Yangtze region; China".Palaeogeography, Palaeoclimatology, Palaeoecology (2020).