Mathematics – Logic
Scientific paper
Dec 2002
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002m%26ps...37.1765b&link_type=abstract
Meteoritics & Planetary Science, vol. 37, no. 12, pp. 1765-1779 (2002)
Mathematics
Logic
2
Scientific paper
The 3.4 km wide, so-called Kgagodi Basin structure, which is centered at longitude 27o34.4' E and latitude 22o 28.6' S in eastern Botswana, has been confirmed as a meteorite impact structure. This crater structure was first recognized through geophysical analysis; now, we confirm its impact origin by the recognition of shock metamorphosed material in samples from a drill core obtained close to the crater rim. The structure formed in Archean granitoid basement overlain and intruded by Karoo dolerite. The crater yielded a gravity model consistent with a simple bowl-shape crater form. The drill core extends to a depth of 274 m and comprises crater fill sediments to a depth of 158 m. Impact breccia was recovered only between 158 and 165 m depth, below which locally brecciated basement granitoids grade into fractured and eventually undeformed crystalline basement, from ~250 m depth. Shock metamorphic effects were only found in granitoid clasts in the narrow breccia zone. This breccia is classified as suevitic impact breccia due to the presence of melt and glass fragments, at a very small abundance. The shocked grains are exclusively derived from granitoid target material. Shock effects include multiple sets of planar deformation features in quartz and feldspar; diaplectic quartz, and partially and completely isotropized felsic minerals, and rare melt fragments were encountered. Abundances of some siderophile elements and especially, Ir, in suevitic breccia samples are significantly elevated compared to the contents in the target rocks, which provides evidence for the presence of a small meteoritic component. Kgagodi is the first impact structure recognized in the region of the Kalahari Desert in southern Africa. Based on lithological and first palynological evidence, the age of the Kgagodi structure is tentatively assigned to the upper Cretaceous to early Tertiary interval. Thus, the crater fill has the potential to provide a long record of paleoclimatic conditions.
Brandt Daniel
Hancox Philip John
Holmes H.
Koeberl Christian
Paya B. K.
No associations
LandOfFree
Kgagodi Basin: The first impact structure recognized in Botswana does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Kgagodi Basin: The first impact structure recognized in Botswana, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Kgagodi Basin: The first impact structure recognized in Botswana will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-967992