Wignall, P.B. and Newton, R. (2003) Contrasting Deep-water Records from the Upper Permian and Lower Triassic of South Tibet and British Columbia: Evidence for a Diachronous Mass Extinction. Palaios, 18 (2). pp. 153-167. ISSN 0883-1351Full text available as:
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Remarkably different Late Permian–Early Triassic marine records are seen in sections fromthe western deep-water margin of Pangea (Ursula Creek, British Columbia) and the high paleolatitude, southern margin of the Neotethyan Ocean (Selong, South Tibet). The Ursula Creek section reveals the progressive decline of seafloor oxygen values in the Changxingian Stage (loss of bioturbation, authigenic U enrichment, appearance of pyrite framboid populations), followed by the persistent development of euxinic conditions in the latest Changxingian and throughout the Early Triassic; an event that coincides with the disappearance of a siliceous sponge fauna and the loss of diverse radiolarian populations. The Selong section, which was located on a distal passive margin, records regression and erosion in the mid-Changxingian, followed by a phase of deepening that began in the late Changxingian. The boundary interval is associated with a marked diversity increase due to the appearance of equatorial taxa (foraminifera, brachiopods, and sponges), suggesting warming without extinction in marine waters at high southern paleolatitudes. Only in the late Griesbachian Stage are the diverse Permian holdovers eliminated, again at a level showing evidence for dysoxia (thinly-bedded, authigenic U-enriched, pyrite-rich limestone). Thus, the end-Permian mass extinction is seen to be diachronous by half a million years ormore, with late Changxingian extinction in Panathalassa coinciding with diversity increase associated the migration of warm-water taxa into the high southerly paleolatitudes regions of Neotethys.
|Copyright, Publisher and Additional Information:||Copyright © 2003, SEPM (Society for Sedimentary Geology)|
|Academic Units:||The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds)|
|Depositing User:||Sherpa Assistant|
|Date Deposited:||20 May 2005|
|Last Modified:||08 Feb 2013 17:01|
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