Shoemaker impact structure
Template:Short description Template:Use Australian English {{#invoke:other uses|otheruses}} Template:Infobox terrestrial impact site
Shoemaker (formerly known as Teague Ring) is an impact structure, the deeply eroded remnant of a former impact crater, situated in arid central Western Australia, about Template:Convert north-northeast of Wiluna.<ref name=EIDBShoemaker>Template:Cite Earth Impact DB</ref> It is named in honour of planetary geologist Eugene Shoemaker.<ref name="Pirajno1998">Pirajno F. & Glikson A.Y. 1998. Shoemaker impact structure Western Australia (formerly Teague ring structure). Celestial Mechanics and Dynamical Astronomy 69, 25–30.</ref>
Description
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.<ref name="Butler1974">Butler H. 1974. The Lake Teague ring structure, Western Australia: an astrobleme? Search 5, 536–537.</ref> Subsequent research revealed definitive evidence for this hypothesis, including the presence of shatter cones and shocked quartz.<ref name="Bunting1980">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 Template:Webarchive</ref><ref name="Pirajno2003">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</ref><ref name="Shoemaker_1996">Shoemaker E.M. & Shoemaker C.S. 1996. The Proterozoic impact record of Australia. AGSO Journal of Australian Geology and Geophysics 16, 379-398.</ref> The feature has a central circular region of uplifted Archaean Granite (Teague Granite) about Template:Convert in diameter, surrounded by a downwarped ring (ring syncline) of sedimentary rocks with an outer limit of disturbance at about Template:Convert diameter, which is a minimum estimate of the size of the original crater.<ref name="Pirajno2003" />
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).<ref name="Pirajno2003" /> The most commonly cited age of about 1630 Ma<ref name="Bunting1980" /> represents a re-heating event affecting the granite; while this may be the impact event, it could simply be a regional tectonic event.<ref name="Pirajno2003" /> More recent dating by K–Ar methods yield ages as young as 568 ± 20 Ma;<ref name="Pirajno2002">Pirajno F. 2002. Geology of the Shoemaker impact structure. Geological Survey of Western Australia Report 82. GSWA download search Template:Webarchive</ref> this age could also date the impact event or represent tectonic activity.<ref name="Pirajno2003" />