Shoemaker crater

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Shoemaker Crater from space.
The Shoemaker impact site.

Shoemaker (formerly known as Teague Ring) is an impact structure (or astrobleme), the deeply eroded remnant of a former impact crater, situated in arid central Western Australia, about 100 km (62 mi) north-northeast of Wiluna.[1] It is named in honour of planetary geologist Eugene Shoemaker.[2] The prominent ring-like topographic feature, easily seen in satellite images, lies on the boundary between the Palaeoproterozoic Earaheedy Basin and the Archaean Yilgarn Craton. The area contains a number of seasonal salt lakes, the largest being Lake Teague.

The first suggestion that the ring-like topographic feature may be an impact structure was published in 1974.[3] Subsequent research revealed definitive evidence for this hypothesis, including the presence of shatter cones and shocked quartz.[4][5][6] The feature has a central circular region of uplifted Archaean Granite (Teague Granite) about 12 km (7.5 mi) in diameter, surrounded by a downwarped ring (ring syncline) of sedimentary rocks with an outer limit of disturbance at about 30 km (19 mi) diameter, which is a minimum estimate of the size of the original crater.[5]

The age of the impact event is uncertain. It must be younger than the Teague Granite in the centre, dated at 2648 ± 8 Ma (million years ago).[5] The most commonly cited age of about 1630 Ma[4] represents a re-heating event affecting the granite; while this may be the impact event it could simply be a regional tectonic event.[5] More recent dating by K–Ar methods yield ages as young as 568 ± 20 Ma,[7] this age could also date the impact event or represent tectonic activity.[5]

References[edit]

  1. ^ "Shoemaker". Earth Impact Database. University of New Brunswick. Retrieved 2007-03-27. 
  2. ^ Pirajno F. & Glikson A.Y. 1998. Shoemaker impact structure Western Australia (formerly Teague ring structure). Celestial Mechanics and Dynamical Astronomy 69, 25–30.
  3. ^ Butler H. 1974. The Lake Teague ring structure, Western Australia: an astrobleme? Search 5, 536–537.
  4. ^ a b Bunting J.A., De Laeter J.R. & Libby W.G. 1980. Evidence for the age and cryptoexplosive origin of the Teague Ring structure, Western Australia. Geological Survey of Western Australia, Annual Review 1980, 81–85. GSWA download search
  5. ^ a b c d e Pirajno F., Hawke P., Glikson A.Y., Haines P.W. & Uysal T. 2003. Shoemaker impact structure, Western Australia. Australian Journal of Earth Sciences 50, 775–796. Abstract
  6. ^ Shoemaker E.M. & Shoemaker C.S. 1996. The Proterozoic impact record of Australia. AGSO Journal of Australian Geology and Geophysics 16, 379-398.
  7. ^ Pirajno F. 2002. Geology of the Shoemaker impact structure. Geological Survey of Western Australia Report 82. GSWA download search

Coordinates: 25°52′S 120°53′E / 25.867°S 120.883°E / -25.867; 120.883