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.
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.
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.
|Name||Location||Country||Diametre (km)||Age (Million Years)||b|
|Morokweng||Kalahari Desert||South Africa||70||145||26°28′S 23°32′E|
- Andreoli, M.A.G., Hart, R.J., Webb, S.J., Cooper, G.R.J. and Haddon, I., The 144 Ma Morokweng Impact Structure, South Africa: Evidence for a ~240 km Crater, Lunar and Planetary Science XXXIX, abstract #1236. 2008.
- Andreoli, M. A. G., Ashwal, L.D., Hart, R.J. and Tredoux,M., The charnockitic rocks of the sand-covered Morokweng impact structure, Southern Kalahari, South Africa: Evidence for a possible impact melt origin (abstract). Lunar and Planetary Science XXVII, pp. 29-30. 1996.
- Andreoli, M. A. G., Ellis, S., Webb, S.J., Pettit, W., Haddon, J., Ashwal, L.D., Gabrielli, F., Raubenheimer,E.and L.Ainslie., The 145 Ma Morokweng impact, South Africa: an unusual ~ 90 km crater with associated multi-ring structures and Early Cretaceous mafic dykes. Meteoritics and Planetary Science, v 34, n 4, p 9. 1999.
- Andreoli, M. A. G., Hart, R.J., Ashwal, L.D. and Tredoux,M., Nickel-and platinum-group-element-enriched quartz norite in the latest Jurassic Morokweng impact structure, South Africa (abstract). Large Meteorite Impacts and Planetary Evolution,. 1997.
- Andreoli, M.A.G., Hart, R.J., Cooper, G.R.J., Stengel, I., Webb, S., Haddon, I., Skala, R. and Viola, G., Morokweng; >100 km & still growing, Geobulletin, v.51, no.1, pp.12-15. 2008.
- Blenkinsop, T. G., Microstructures in Suevite from the Bosumtwi Impact, Ghana, Meteoritics; vol. 34, No. 4, Supp. p. A13. 1999.
- Bootsman, C. S., Reimold, W.U. and Brandt,D., Evolution of the Molopo drainage and its possible disruption by the Morokweng impact event at the Jurrasic-Cretaceous boundary, Journal of African Earth Sciences, v. 29(4), pp. 669-678. 1999.
- Cloete, M., Hart, R.J., Cloete, C.C., McDonald, I. andreoli,M.A.G., Inclusions from the Morokweng impact melt sheet, South Africa: Possible fragments of a Palaeometeorite, Meteoritics & Planetary Science, v. 36, No. 9, Supplement, p. A41. 2001.
- Cockell, C. S., Lee, P., The Biology of Impact Craters – a review. Biol. Rev., 77, P. 279 – 310. 2002.
Corner, B., Reimold, W.U., Brandt, D. and Koeberl,C., Evidence for a major impact structure in the northwest province of South Africa – the Morokweng impact structure (abstract). Lunar and Planetary Science XXVII, pp. 257-258. 1996.
- Corner, B., Reimold, W.U., Brandt, D. and Koeberl,C., Morokweng impact structure, Northwest Province, South Africa: geophysical imaging and shock petrographic studies. Earth and Planetary Science, v. 146, pp. 351-364. 1997.
- Dutta, R. K., Sideras-Haddad, E. , Andreoli, M. A. G. , Hart, R. J. and Cloete, T., Proton microprobe characterization of a unique siderophile element mineral assemblage in the melt sheet of the giant 145 Ma Morokweng impact structure, Southern Kalahari, South Africa. Nuclear Instruments and Methods in Physics Research B 181, P. 551 – 556. 2001.
- Hart, R. J., Andreoli, M.A.G., Tredoux, M., Moser, D., Ashwal, L.D., Eide, E.A., Webb, S.J. and Brandt,D., Late Jurassic age for the Morokweng impact structure, southern Africa. Earth and Planetary Science Letters, v. 147, pp. 25-35. 1997.
- Hart, R. J., Cloete, M. , McDonald, I. , Carlson, R. W. and Andreoli, M. A. G., Siderophile-rich inclusions from the Morokweng impact melt sheet, South Africa: possible fragments of a chondritic meteorite. Earth and Planetary Science Letters 198, P. 49 – 62. 2002.
- Henkel, H., Reimold, U. W., Koeberl,C., Magnetic and gravity model of the Morokweng impact structure, Journal of Applied Geophysics, v. 49, p. 129-147. 2002.
- Jourdan, F., Andreoli, M.A.G., McDonald, I. and Maier, W.D., 40Ar/39Ar thermochronology of the fossil LL6-chondrite from the Morokweng crater, South Africa, Geochimica et Cosmochimica Acta, v.74, pp. 1734-1747. 2010.
- Koeberl, C., Armstrong, R.A. and Reimold,W.U., Morokweng, South Africa: A large impact structure of Jurassic-Cretaceous boundary age. Geology, v. 25, pp. 731-734. 1997.
Koeberl, C., Martinez-Ruiz, F., The Stratigraphic Record of Impact Events: A Short Overview, Impact Markers in the Stratigraphic Record p. 1 – 40. 2003.
- Koeberl, C., Milkereit, B., Continental Drilling and the Study of Impact Craters and Processes – an ICDP Perspective, In: Continental Scientific Drilling (eds. Harms, U., Koeberl, C., and Zoback, M.D.), Springer, Heidelberg, p. 95-161. 2007.
- Koeberl, C., Peucker-Erenbrink, B., Reimold, W.U., Shukolyukov, A., Lugmair,G.W., Comparison of the osmium and chromium isotopic methods for the detection of meteoritic components in impactites: Examples from the Morokweng and Vredefort impact structures, South Africa, Geological Society of America, Special Paper 356 p. 607 – 617. 2002.
- Koeberl, C., Reimold, W. U., Geochemistry and petrography of impact breccias and target rocks from the 145 Ma Morokweng impact structure, South Africa, Geochimica Acta, Vol 67. No. 10; p. 1837 -1862. 2003.
- Koeberl, C., Reimold, W. U., Morokweng: Petrological and Geochemical Studies Comfirm Impact Origin of Large Proterozoic Structure in South Africa, GSA Abstracts with Programs, 1996, Session 40. P. 108. 1996.
- Koeberl, C., Reimold, W. U., The large Jurrasic-Cretaceous boundary age Morokweng (South Africa) Impact Structure – The search for ejecta, GSA Salt Lake City ’97, Annual-Meeting Abstracts. Abs. No. 50159. 1997.
- Koeberl, C., Reimold, W.U. and Armstrong,R.A., The Jurassic-Cretaceous boundary impact event: The Morokweng impact structure, South Africa (abstract). Large Meteorite Impacts and Planetary Evolution,. 1997.
- Koeberl, C., Reimold, W.U., Armstrong, R.A., Brandstätter, F. and Kruger,F.J., Morokweng, South Africa: The Jurassic-Cretaceous Boundary impact structure? (abstract). Lunar and Planetary Science XXVIII, pp. 741-742. 1997.
- Maier, W.D., Andreoli, M.A.G., McDonald, I., Franchi, I. and Greenwood, R., Confirmed LL chondritic meteorite within the melt sheet of the giant Morokweng impact crater, South Africa, Abstracts-Geological Society of Australia, v.89, pp.168. 2008.
- Mair, W.D., et al., Discovery of a 25-cm asteroid clast in the giant Morokweng impact crater, South Africa, Nature, v. 441, pp. 203-206, 2006
- McDonald, I., Andreoli, M.A.G, Hart, R.J. and Tredoux,M., Platinum-group elements in the Morokweng impact structure South Africa: Evidence for the impact of a large ordinary chondrite projectile at the Jurassic-Cretaceous boundary, Geochimica et Cosmochimica Acta, vol. 65 (2), pp. 299-309. 2001.
- Moynier, F., Koeberl, C, Quitte, G. and Telouk, P., A tungsten isotope approach to search for meteorite componenets in terrestrial impact rocks, Earth and Planetary Science Letters, v.286, pp.35-40. 2009.
- Pettit, W., Ellis, S. and M. A. G. Andreoli., A structural interpretation of the 145 Ma Morokweng impact structure based on processed potential field data. Meteoritics and Planetary Science, v 34, n 4, p 92. 1999.
Reimold, W. U., Armstrong, R. A., Koeberl., A deep drillcore from the Morokweng impact structure, South Africa: petrography, geochemistry, and constraints on the crater size. Earth and Planetary Science Letters 201 p. 221-232. 2002.
- Reimold, W. U., Corner, B., Koeberl, C. and Brandt,D., The Morokweng structure in the northwest porvince of South Africa: Remnant of a large impact structure? (abstract). Meteoritics & Planetary Science, v. 31, p. A114. 1996.
- Reimold, W. U., Corner, B., Koeberl, C. and Brandt,D., The Morokweng Structure in the Northwest Province of South Africa: Remnant of a large impact structure? 59th Annual Meteoritical Society Meeting Impact Craters and Ejecta II, METSOC (Meteoritical Society) ’96. Pp. A114. 1996.
- Reimold, W. U., Koeberl, C., Brandstatter, F., Kruger, F.J., Armstrong, R.A., Bootsman,K., The Morokweng impact structure, South Africa: Geological, petrographical, and isotopic results, and implications for the size of the structure. Geol. Soc. Am. Spec. Paper 339, pp. 61-90. 1999.
- Reimold, W. U., Koeberl, C., Petrography and Geochemical of a Deep Drill Core from the Edge of the Morokweng Impact Structure, South Africa, Impact Markers in the Stratigraphic Record p. 271 – 293. 2003.
- Reimold, W. U., Koeberl, C., The Deep Borehole into the Morokweng Impact Structure, Meteoritics; vol. 34, No. 4, Supp. p. A97. 1999.
- Shukolyukov, A., Lugmair, G.W., Koeberl, C. and Reimold,W.U., Chromium in the Morokweng impact melt: Isotopic evidence for extraterrestrial components and type of impactor, Meteoritics & Planetary Science, vol. 34, No. 4, Supplement, p. A107-108. 1999.