Large Meteorite Impacts and Planetary Evolution VI
CONTAINS OPEN ACCESS
This volume represents the proceedings of the homonymous international conference on all aspects of impact cratering and planetary science, which was held in October 2019 in Brasília, Brazil. The volume contains a sizable suite of contributions dealing with regional impact records (Australia, Sweden), impact craters and impactites, early Archean impacts and geophysical characteristics of impact structures, shock metamorphic investigations, post-impact hydrothermalism, and structural geology and morphometry of impact structures—on Earth and Mars. Many contributions report results from state-of-the-art investigations, for example, several that are based on electron backscatter diffraction studies, and deal with new potential chronometers and shock barometers (e.g., apatite). Established impact cratering workers and newcomers to the field will appreciate this multifaceted, multidisciplinary collection of impact cratering studies.
Sedimentation across the Paraburdoo spherule layer: Implications for the Neoarchean Earth system
*E-mail addresses: Souders: corresponding author, [email protected]; Davatzes: [email protected]; Ziegler: [email protected]
*E-mail addresses: Souders: corresponding author, [email protected]; Davatzes: [email protected]; Ziegler: [email protected]
*E-mail addresses: Souders: corresponding author, [email protected]; Davatzes: [email protected]; Ziegler: [email protected]
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Published:August 02, 2021
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CiteCitation
Katrina S. Souders*, Alexandra K. Davatzes*, Brady A. Ziegler*, Steven Goderis, Thomas Déhais, Philippe Claeys, 2021. "Sedimentation across the Paraburdoo spherule layer: Implications for the Neoarchean Earth system", Large Meteorite Impacts and Planetary Evolution VI, Wolf Uwe Reimold, Christian Koeberl
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ABSTRACT
Large bolide impacts in the Phanerozoic produced global change identifiable in the postimpact sediments. Aside from a few isolated examples, however, evidence of postimpact change associated with Precambrian impacts is sparse. This study used the Neoarchean Paraburdoo spherule layer as a case study to search for impact-induced change in the sediments above the spherule layer. We found possible minor sedimentary changes that may have been due to either a disturbance by bottom currents or changing diagenetic conditions. Contrary to the trends found with several post–Great Oxidation Event large bolide impacts, we found no evidence of shifts in tectonic regime, sediment weathering and deposition, or paleoenvironment induced by the Paraburdoo spherule layer impact, for which the impactor is estimated to have been approximately three times larger than the Cretaceous–Paleogene bolide. This lack of a clear signal of climatic shift may be due to one or more mechanisms. Either the Paraburdoo spherule layer’s deposition in several-hundred-meter-deep water within the Hamersley Basin of Western Australia was too deep to accumulate and record observable changes, or the Neoarchean’s high-CO2 atmospheric composition acted as a threshold below which the introduction of more impact-produced gases would not have produced the expected climatic and weathering changes. We also report minor traces of elevated iron and arsenic concentrations in the sediments immediately above the Paraburdoo spherule layer, consistent with trends observed above other distal impact deposits, as well as distinctive layers of hematite nodules bracketing the spherule layer. These geochemical changes may record ocean overturn of the Neoarchean stratified water column, which brought slightly oxygenated waters to depth, consistent with the observation of tsunami deposits in shallower impact deposits and/or heating of the global oceans by tens to hundreds of degrees Celsius in the wake of the Paraburdoo spherule layer impact. Either or both of these mechanisms in addition to impact-induced shallow-water ocean evaporation may also have caused a massive die-off of microbes, which also would have produced a postimpact increase in iron and arsenic concentrations.
- Archean
- arsenic
- Australasia
- Australia
- climate change
- depositional environment
- Hamersley Basin
- impact craters
- impact features
- impacts
- iron
- lithofacies
- mass extinctions
- metals
- Neoarchean
- oceanic anoxic events
- paleoclimatology
- paleoenvironment
- Precambrian
- sedimentation
- spherules
- Western Australia
- Paraburdoo spherule layer