|Plate-splitting impact in the Congo Basin;
bedrock geology, plate motions and diamonds.
As noted by Wegener in 1912, African and South
American geological provinces and mineral belts reconstruct into systematic
alignment (below). The geologic strata are disposed and fractured
about a suspected impact structure forming the Congo basin (Cuvette
Centrale). Outboard rings of uplift and subsidence have the same dimensions
as for the Chicxulub impact on the North
American Plate. Kimberlite pipes and lamprohyre dikes with associated
diamond occurrences display systematic geometry with respect to a multi-ringed
impact structure, suggesting impact-fracturing to mantle depths, and perhaps
the cause of kimberlite igneous activity. The crustal fracture pattern through
the basin region radiates outward toward the NNW, indicating the path of
crustal compression from an oblique impact. The stratigraphic relationships
are compatible with a Changhsingian impact at the end of the
Paleozoic. The realigned position of South America is
ghost-image with the Somali Plate. The impact
may haven spurred continental breakup and spreading and eventual formation
of the Atlantic Ocean.
Current plate motions are shown below. Red vectors are proportionately scaled
to emphasize relative horizontal velocity.
Impacttectonics.org Rev 11/07