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Morokweng crater beneath the Kalahari Desert, South Africa

The Morokweng crater (or Morokweng impact structure) is an impact crater buried beneath the Kalahari Desert near the town of Morokweng in the North-West Province of South Africa. The Morokweng Crater is close to the border with Botswana. This crater was formed by an asteroid 5-10 km in diameter, and is at least about 160 km (100 miles)in diameter and the age is estimated to be 145.0 ± 0.8 million years, placing it on the Jurassic-Cretaceous boundary.

Interpreted geology of the Morokweng impact structure. I, outer limit of suevite, melt breccia; II, outer limit of brecciated and faulted basement
Interpreted geology of the Morokweng impact structure. I, outer limit of suevite, melt breccia; II, outer limit of brecciated and faulted basement

Morokerng Crater was discovered in 1994 and it is not exposed at the surface but has been mapped by magnetic and gravimetric surveys. Core samples have shown it to have been formed by the impact of an L chondrite asteroid. In May, 2006, a group of scientists drilling into the site announced the discovery of a 25-centimetre (9.8 in) diameter fragment of the original asteroid at a depth of 770 metres (2,500 ft) below the surface, along with several much smaller pieces a few millimetres across at other depths. These fragments may not have been attached to the asteroid but may have trailed behind it as it entered Earth’s atmosphere. They are among the oldest meteorite specimens ever found on this planet.

Simplified stratigraphy of boreholes drilled in the melt sheet
Simplified stratigraphy of boreholes drilled in the melt sheet

This discovery was unexpected since previous drillings on large impact craters had not produced such fragments, and it was thought that the asteroid had been almost entirely vaporised. Some of the fragments can be seen in the Antenna Wing of London’s Science Museum.

MODIS – M: Morokweng Crater; V: Vredefort Image provided by the Morokweng Consortium
MODIS – M: Morokweng; V: Vredefort
Image provided by the Morokweng Consortium
Name Location Country Diametre (km) Age (Million Years) b
Morokweng Kalahari Desert South Africa 70 145 26°28′S 23°32′E
Morokweng Crater - Image Provided by Dr. Carlos Roberto de Souza Filho
Morokweng Crater – Image Provided by Dr. Carlos Roberto de Souza Filho
MOROKWENG_RGB EXAG63_3D - Image Provided by Dr. Carlos Roberto de Souza Filho
MOROKWENG_RGB EXAG63_3D – Image Provided by Dr. Carlos Roberto de Souza Filho

 

DEM image Provided by Dr. Carlos Roberto de Souza Filho
DEM image Provided by Dr. Carlos Roberto de Souza Filho
Landsat 7 ETM+ (2000 data; spectral bands 7-4-2 (RGB), each band sharpened with a panchromatic band of 15x15 m resolution. Image provided by the MorokwengConsortium
Landsat 7 ETM+ (2000 data; spectral bands 7-4-2 (RGB), each band sharpened with a panchromatic band of 15×15 m resolution. Image provided by the MorokwengConsortium

 

References:

  • http://www.passc.net/EarthImpactDatabase/morokweng.html
  • http://www.daviddarling.info/encyclopedia/M/Morokweng_crater.html
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