Yarrabubba crater
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Yarrabubba crater refers to an impact structure (or astrobleme), the eroded remnant of a former impact crater, situated in the northern Yilgarn Craton between the towns of Sandstone and Meekatharra, central Western Australia.[1],[2]
The original crater has been completely eroded and is not readily visible on aerial or satellite images; the evidence for impact comes rather from the presence of shocked quartz and shatter cones in outcrops of granite interpreted the be near the centre of the original crater, and from geophysical data. The diameter of the original crater is uncertain, but has been estimated to be in the range 30–70 km.[1] The age of the impact event is also uncertain, but it must be younger than the granite that has been shocked, which has been dated at about 2650 Ma (late Archaean).[1] Veins of pseudotachylite (rocks melted by friction) in the granite have given a date of 1134±26 Ma using the Ar-Ar method, and although the significance of this age is not fully clear it is currently considered by some to provide the best tentative estimate for the age.[3] The Earth Impact Database prefers an intermediate estimate of about 2000 Ma.[4]
[edit] References
- ^ a b c Macdonald F.A., Bunting J.A. & Cina S.E. 2003. Yarrabubba—a large, deeply eroded impact structure in the Yilgarn Craton, Western Australia. Earth and Planetary Science Letters 213, 235–247. Abstract
- ^ Bunting J.A. & Macdonald F.A. 2004. The Yarrabubba structure, Western Australia—clues to identifying impact events in deeply eroded ancient cratons. Geological Society of Australia Abstracts 73, 227.
- ^ Pirajno F. 2005. Hydrothermal processes associated with meteorite impact structures: the evidence from three Australian examples and implications for economic resources. Australian Journal of Earth Sciences 52, 587–605. Abstract
- ^ Yarrabubba. Earth Impact Database. Retrieved on 2007-02-18
