Woodleigh crater
The Woodleigh crater is a large crater formed by the impact of a meteorite in Australia Western Australia in the center of Woodleigh Station of east Shark Bay originated in Western Australia. The crater lies in the geological Carnarvon Basin , a sedimentary basin .
There are more than two dozen impact craters in Australia, the largest being Woodleigh, Acraman and Tookoonooka craters .
discovery
A team of scientists from the Geological Survey of Western Australia and the Australian National University , led by Arthur J. Mory, announced the impact crater on April 15, 2000 in the Earth and Planetary Science Letters .
The crater cannot be seen on the surface as it is covered by a 100 meter thick layer of sediments from the Jurassic and Cretaceous , so its size cannot be precisely determined. The exploration team believe the crater's diameter is around 120 kilometers, while others believe the diameter is much smaller. One study assumes a diameter of less than 60 kilometers. The larger estimate - if correct - would mean that the crater on the list of craters would be the fourth largest crater on earth, caused by an impact by an asteroid or comet with a diameter of 5 to 6 kilometers.
After the first drilling in the 1970s, the central elevation in Woodleigh Crater was interpreted as an elevation with a diameter of 20 kilometers; the impact structure was not recognized until 1997 through gravitational studies. In 1999 an investigation of the crater rim was undertaken. The thin veins of molten glass, breccias, and altered quartz crystals that were found were created under pressures 100,000 times greater than sea level air pressure or 10 to 100 times greater than volcanic or earthquake activity. Only a large impact could cause such geological changes.
Creation time of the crater
The Woodleigh impact likely occurred in the late Upper Devonian 364 ± 8 million years ago. This point in time roughly corresponds to two major species extinctions ( Kellwasser and Hangenberg events ), to which it is estimated that more than 50 percent of all marine organisms fell victim. There are indications of further meteorite impacts from this epoch, so that there may be a connection between the biological crises mentioned and several impact events.
Web links
Individual evidence
- ↑ a b passc.net ( memento of the original from August 25, 2012 on WebCite ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. : Woodleigh (Earth Impact Database), accessed May 23, 2012.
- ^ A b A. J. Mory, RP Iasky, AY Glikson, F. Pirajno: Woodleigh, Carnarvon Basin, Western Australia: a new 120 km diameter impact structure . In: Earth and Planetary Science Letters . tape 117 , 2000, pp. 119–128 , doi : 10.1016 / S0012-821X (00) 00031-5 , bibcode : 2000E & PSL.177..119M .
- ↑ kimberleysociety.org (PDF; 18 kB): Geology Survey in the Kimberleys. P. 2 f., Accessed on May 23, 2012.
- ^ WU Reimold, C. Koeberl, RM Hough, I. Mcdonald, A. Bevan, K. Amare, BM French: Woodleigh impact structure, Australia: Shock petrography and geochemical studies . In: Meteoritics & Planetary Science . tape 38 , no. 7 , 2003, p. 1109–1130 , doi : 10.1111 / j.1945-5100.2003.tb00301.x , bibcode : 2003M & PS ... 38.1109R .
- ↑ a b A. Mory, R. Iasky: Woodleigh - Australia's largest impact structure? In: Fieldnotes, Geological Survey of Western Australia . tape 16 , 2000, ISBN 0-7307-5642-4 , pp. 1–2 ( http://www.doir.wa.gov.au/documents/gswa/gsd_fld_woodleigh.pdf ( Memento from 23 August 2006 in the Internet Archive ) ). Woodleigh - Australia's largest impact structure? ( Memento of the original from August 23, 2006 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
Coordinates: 26 ° 3 ′ 0 ″ S , 114 ° 39 ′ 36 ″ E