Pleistocene glass in the Australian desert: The case for an impact origin
- 1School of Earth Sciences, University of Tasmania, GPO Box 252-97, Hobart, Tasmania 7001, Australia
- 2Department of Geology and Geophysics, University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia
- 3Department of Earth Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA, UK
Abstract
Irregular masses and flat slabs of vesicular, slaglike, and glassy melt (referred to herein as Edeowie glass) are locally abundant on a desert plain in central South Australia, where the material appears to be associated with an old land surface being exhumed by deflation and water erosion. The slabs of melt are associated with outcrops of baked sediment having very similar geochemistry, suggesting an origin by in situ surface fusion. Embedded clasts displaying shock metamorphism in quartz suggest that the thermal source may have been in some way associated with an impact event, although an obvious crater is lacking. If Edeowie glass is related to impact, a different thermal mechanism from that generally ascribed to the production of impact melt is required because of evidence for in situ generation of melt distal from any crater. 40Ar/39Ar laser probe dating of two samples has produced overlapping dates of 0.67 ± 0.07 and 0.78 ± 0.33 Ma.
Footnotes
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↵GSA Data Repository item 2001103, Appendix Tables A–D, is available on request from Documents Secretary, GSA, P.O. Box 9140, Boulder, CO 80301, editing@geosociety.org, or at www.geosociety.org/ pubs/ft2001.htm.
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↵*Peter.Hainesutas.edu.au.
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- Accepted May 24, 2001.
- Received February 21, 2001.
- Revision received May 10, 2001.
- Geological Society of America
