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Four cycles of oxygenation in the phanerozoic
conference contribution
posted on 2023-05-24, 13:47 authored by Ross LargeRoss Large, Jacqueline HalpinJacqueline Halpin, Leonid Danyushevsky, Maslennikov, VV, Stuart BullStuart Bull, Gregory, D, Lyons, TW, Elena LounejevaElena LounejevaSedimentary pyrite captures trace elements (TE) from the oceans and tracks variations in their seawater concentrations through time [1]. LA-ICPMS analysis of sedimentary pyrites, based on newly developed standards, has enabled the development of temporal ocean concentration curves for 22 TE [2].
Our results show that TE variations over the last 700 million years of ocean history have been strongly cyclical. We interpret these cycles to indicate that the Late Neoproterozoic to Phanerozoic oceans went through dramatic changes in mean oxygen content. Four major cycles are recognised: Late Cryogenian to Late Ordovician, Early Silurian to late Devonian, Early Carboniferous to Late Permian and Triassic to Quaternary. Oxygen maxima, indicated by Se, U and Mo proxies, occur at 540, 390, 310 and 0 Ma, supporting previous models [3, 4]. Oxygen minima, indicated by trace element drawdown, occur at 700, 455, 365 and 200 Ma. Extended periods of low oxygen in the oceans have led to extreme deficiency of some elements that are critical for life. The periods of extreme Se depletion coincide with the mass extinction events at end Ordovician, Late Devonian and the Triassic-Jurassic boundary, suggesting that Se-deficiency in the oceans may be a contributing cause of marine mass extinctions.
Our results show that TE variations over the last 700 million years of ocean history have been strongly cyclical. We interpret these cycles to indicate that the Late Neoproterozoic to Phanerozoic oceans went through dramatic changes in mean oxygen content. Four major cycles are recognised: Late Cryogenian to Late Ordovician, Early Silurian to late Devonian, Early Carboniferous to Late Permian and Triassic to Quaternary. Oxygen maxima, indicated by Se, U and Mo proxies, occur at 540, 390, 310 and 0 Ma, supporting previous models [3, 4]. Oxygen minima, indicated by trace element drawdown, occur at 700, 455, 365 and 200 Ma. Extended periods of low oxygen in the oceans have led to extreme deficiency of some elements that are critical for life. The periods of extreme Se depletion coincide with the mass extinction events at end Ordovician, Late Devonian and the Triassic-Jurassic boundary, suggesting that Se-deficiency in the oceans may be a contributing cause of marine mass extinctions.
History
Publication title
Mineralogical Magazine: Goldschmidt 2013 AbstractsVolume
77Pagination
1546ISSN
0026-461XDepartment/School
School of Natural SciencesEvent title
Goldschmidt 2013Event Venue
Florence, ItalyDate of Event (Start Date)
2013-08-25Date of Event (End Date)
2013-08-30Repository Status
- Restricted