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Phanerozoic O2 cycles


Large, RR and Halpin, JA and Danyushevsky, LV, Phanerozoic O2 cycles, Goldschmidt 2014 Book of Abstracts, 8-13 June 2014, Sacramento, USA, pp. 1359. (2014) [Conference Extract]


   Previous workers have considered that O2 content in the Phanerozoic atmosphere was relatively stable compared to the Precambrian. However we present a very different scenario of significant, systematic cycles in atmosphere-ocean O2 contents, on wavelengths of 70 to 150 Ma, that have had an influence on ocean trace element nutrients, organic productivity, ocean anoxia, petroleum source-rock generation, glaciation events, marine metal deposition and mass extinction events. An integrated Earth-Ocean O2 cyclic pattern places major marine geochemical and geo-biological events through the Phanerozoic into a systematic framework.
   The selenium content of sedimentary pyrite has been demonstrated to be a robust proxy for ocean-atmosphere oxygenation et al[1], and is used here as the basis for the recognition of five cycles during the Phanerozoic. Cobalt in sedimentary pyrite is concentrated during periods of low O2 and exhibits the opposite pattern to Se. Cycle peaks that represent periods of maximum trace metals in the ocean, leading to maximum productivity and O2 occur around 515, 395, 310, 235, 150 Ma and the present. Cycle troughs that represent periods of trace metal deficiency (but Co enrichment), sulfidic oceans, minimum O2 and marine extinction maxima occur at 450, 370, 295, 200 and 70 Ma. At present the Earth is at the peak of the sixth cycle, enjoying a period of maximim ocean O2, nutrient trace elements and organic productivity.

Item Details

Item Type:Conference Extract
Keywords:pyrite, palaeo-oceanography, seawater proxy
Research Division:Earth Sciences
Research Group:Geology
Research Field:Structural geology and tectonics
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the earth sciences
UTAS Author:Large, RR (Professor Ross Large)
UTAS Author:Halpin, JA (Dr Jacqueline Halpin)
UTAS Author:Danyushevsky, LV (Professor Leonid Danyushevsky)
ID Code:100950
Year Published:2014
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2015-06-03
Last Modified:2015-06-04

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