Early oxidation events in the Neoarchean as determined by whole rock geochemistry, LA-ICPMS and S isotopes

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Early oxidation events in the Neoarchean as determined by whole rock geochemistry, LA-ICPMS and S isotopes

DD Gregory,RR Large,JA Halpin,Arthur Hickman,T. R. Ireland,Holden Peter-2014-01-01-eCite Digital Repository (University of Tasmania)

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TL;DRAbstract

Early examples of both atmospheric oxygenation and euxinia are found within the Hamersley and Fortescue Basins. Chemical changes in the Neoarchean are examined using a combination of whole rock geochemistry, LA-ICPMS analyses and S isotope measurements (SHRIMP-SI) of sedimentary pyrite and pyrrhotite from shales from drill core (ABDP9 and WRL1). Three different periods of oxygen enrichment have been identified in these basins. The earliest event occurred during the deposition of the Jeerinah Formation and is indicated by an increase of O<sub>2</sub> sensitive trace elements in whole rock and pyrite near the middle of the formation. This event does not exhibit a corresponding S isotope signature indicative of sulfide oxidation and thus, is considered to be minor and did not significantly alter the Neoarchean S cycle. The second enrichment phase occurs from the Paraburdoo Member through to the midpoint of the Bee Gorge member of the Hamersley Basin. This is indicated by an in

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Early examples of both atmospheric oxygenation and euxinia are found within the Hamersley and Fortescue Basins. Chemical changes in the Neoarchean are examined using a combination of whole rock geochemistry, LA-ICPMS analyses and S isotope measurements (SHRIMP-SI) of sedimentary pyrite and pyrrhotite from shales from drill core (ABDP9 and WRL1). Three different periods of oxygen enrichment have been identified in these basins. The earliest event occurred during the deposition of the Jeerinah Formation and is indicated by an increase of O<sub>2</sub> sensitive trace elements in whole rock and pyrite near the middle of the formation. This event does not exhibit a corresponding S isotope signature indicative of sulfide oxidation and thus, is considered to be minor and did not significantly alter the Neoarchean S cycle. The second enrichment phase occurs from the Paraburdoo Member through to the midpoint of the Bee Gorge member of the Hamersley Basin. This is indicated by an in

Keywords

PyriteGeochemistryGeologyIsotopes of oxygenSulfideSedimentary rockTrace elementIsotope geochemistry

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