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Phanerozoic O2 cycles

conference contribution
posted on 2023-05-24, 13:47 authored by Ross LargeRoss Large, Jacqueline HalpinJacqueline Halpin, Leonid Danyushevsky
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.


Publication title

Goldschmidt 2014 Book of Abstracts




School of Natural Sciences

Event title

Goldschmidt 2014

Event Venue

Sacramento, USA

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