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| Titel |
Geochemistry of pyrite from diamictites of the Hamersley Basin, Western Australia with implications for the GOE and Paleoproterozoic ice ages. |
| VerfasserIn |
Elizabeth Swanner, Nicole Cates, Ernesto Pecoits, Andrey Bekker, Kurt O. Konhauser, Stephen J. Mojzsis |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074812
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| Zusammenfassung |
| Sediments of the ca. 2400 Ma Turee Creek Group of Western Australia span the oxygenation
of Earth’s surface resulting from the ‘Great Oxidation Event’ (GOE). Diamictite
within the Boolgeeda Iron Formation from the Boundary Ridge section at Duck
Creek Syncline have been correlated to the glaciogenic Meteorite Bore Member of
the Turee Creek Group at Hardey Syncline (Martin, 1999). The Meteorite Bore
Member is thought to be correlative and time-equivalent with the Paleoproterozoic
glacial diamictites of North America. If diamictite units at Boundary Ridge represent
worldwide Paleoproterozoic glaciations, they should record the disappearance of
mass independently fractionated (MIF) sulfur. Triple S-isotope compositions for
pyrites from the Boundary Ridge sections measured by in situ multi-collector ion
microprobe yielded both mass-dependent and mass-independently fractionated (MIF) S
isotope values (Δ33S values from -0.65 to 6.27). Trace element heterogeneities
were found by measurements at multiple spatial scales within rounded pyrites in
the Boundary Ridge section, signifying multiple generations of pyrite from sulfur
processed in an anoxic atmosphere. S-isotope data from pyrite in the Boundary
Ridge diamictites analyzed in this study and previous work (Williford et al., 2011)
define multiple δ34S vs. δ33S arrays, linked to a source of detrital pyrite from the
overlying Hamersley and Fortescue groups. Authigenic pyrite in an overlying shale unit
from Boundary Ridge plot along the terrestrial fractionation line but retain positive
MIF-S and detrital pyrite, results that are incompatible with a correlation to North
American Paleoproterozoic glacially-influenced successions where the MIF-S signal
permanently disappears. The diamictites at the Duck Creek Syncline are older than the
Meteorite Bore Member because of their stratigraphic position within the Boolgeeda
Iron Formation underlying the Turee Creek Group, which is separated from the
Meteorite Bore Member by nearly 1000 m of Kungarra shale at Hardey Syncline. |
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