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Atmosphere oxygen cycling through the Proterozoic and Phanerozoic

Citation

Large, RR and Mukherjee, I and Gregory, D and Steadman, J and Corkrey, R and Danyushevsky, LV, Atmosphere oxygen cycling through the Proterozoic and Phanerozoic, Mineralium Deposita, 54 pp. 485-506. ISSN 0026-4598 (2019) [Refereed Article]

Copyright Statement

Copyright 2019 Springer-Verlag GmbH Germany, part of Springer Nature

DOI: doi:10.1007/s00126-019-00873-9

Abstract

Variations in atmosphere oxygen and ocean sulfate concentrations through time are regarded as important controls on the cycles of sediment-hosted and volcanic-hosted ore deposits. However, estimates of atmosphere oxygen in the Proterozoic have been frustrated by the lack of a direct measurement method and conflicting evidence from various proposed geochemical proxies. Studies in the 1970s to 1990s suggested a relatively oxygenated atmosphere (> 3 wt% O2) in the Proterozoic. However, since the late 1990s, new proxies and modelling have suggested very much lower levels of oxygen (< 0.02 wt% O2). Focusing on redox-sensitive trace elements, here we combine a dataset of over 3000 LA-ICP-MS trace-element analyses on sedimentary pyrite, standardised against Berner’s Phanerozoic O2 modelling and direct measurement of oxygen concentrations in fluid inclusions in sedimentary halite, to develop the first detailed estimate for atmosphere O2 concentration and secular variation from 2200 Ma to the present. The estimates suggest dynamic cycles of atmosphere oxygen that increased in frequency through time. There were possibly three first-order cycles in the Proterozoic varying from 400 to 600 million years in length and a further five first-order cycles in the Phanerozoic from 60 to 120 million years in length. Our estimates of oxygen concentration are at odds with most previous estimates. We suggest, rather than very low atmosphere oxygen in the Proterozoic, the mean concentration was about 7 wt%, rising to a mean of about 10 wt% in the Phanerozoic, but with significant cyclic variation of up to a maximum concentration of possibly over 30 wt%. We observe that the proposed oxygen cycles correlate with biodiversity cycles and to the timing of major stratiform base-metal deposits in sedimentary basins. For example, minima in atmosphere oxygenation correlate with mass extinction events and stratiform Zn–Pb–Ag deposits, whereas maxima in oxygenation correlate with major evolutionary events, global periods of evaporite formation and the timing of stratiform copper deposits.

Item Details

Item Type:Refereed Article
Keywords:Proterozoic atmosphere, Phanerozoic atmosphere, oxygen cycling, stratiform copper deposits, sediment-hosted zinc–lead deposits, pyrite
Research Division:Earth Sciences
Research Group:Geology
Research Field:Ore Deposit Petrology
Objective Division:Mineral Resources (excl. Energy Resources)
Objective Group:Mineral Exploration
Objective Field:Zinc Ore Exploration
UTAS Author:Large, RR (Professor Ross Large)
UTAS Author:Mukherjee, I (Ms Indrani Mukherjee)
UTAS Author:Steadman, J (Dr Jeffrey Steadman)
UTAS Author:Corkrey, R (Dr Ross Corkrey)
UTAS Author:Danyushevsky, LV (Professor Leonid Danyushevsky)
ID Code:131276
Year Published:2019
Deposited By:CODES ARC
Deposited On:2019-03-12
Last Modified:2019-04-10
Downloads:0

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