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Four cycles of oxygenation in the phanerozoic


Large, RR and Halpin, JA and Danyushevsky, LV and Maslennikov, VV and Bull, S and Gregory, D and Lyons, TW and Lounejeva, E, Four cycles of oxygenation in the phanerozoic, Mineralogical Magazine: Goldschmidt 2013 Abstracts, 25-30 August 2013, Florence, Italy, pp. 1546. ISSN 0026-461X (2013) [Conference Extract]

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DOI: doi:10.1180/minmag.2013.077.5.12


   Sedimentary 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.

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)
UTAS Author:Bull, S (Dr Stuart Bull)
UTAS Author:Gregory, D (Dr Daniel Gregory)
UTAS Author:Lounejeva, E (Ms Elena Lounejeva Baturina)
ID Code:100947
Year Published:2013
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2015-06-03
Last Modified:2015-06-04

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