2:30 PM - 2:45 PM
[BPT23-15] In-situ iron isotope analysis of pyrite and organic carbon/nitrogen isotope ratios from the Middle Proterozoic sediments
Here we show iron isotope analysis of individual pyrite grains and whole rock carbon/nitrogen isotope analyses of middle Proterozoic sediments, mainly mudstones and black shales, from four drillcore samples (Mount Young 2, McArthur River 2, Urapunga 4 and 5) in McArthur Basin, Northern Australia.
Pyrites from the Wollogorang Formation of the Tawallah Group show the wide variation of δ56Fe values from -2 to +2 ‰. It suggests that the occurrence of partial oxidation, so their depositional environment of the Wollogorang Formation was ferruginous condition. δ15NTN values of the black shale in the Wollogorang and Barney Creek formations are from +4 to +7 ‰, relatively high values. The high δ15NTN values suggest the occurrence of partial denitrification in the water-column. δ15NTN values of black shale in the Wollogorang and Barney Creek Formations suggested that middle proterozoic sulfidic condition did not persist for long periods as previous studies insisted.