Integrated geophysical modelling of a giant, complex impact structure: anatomy of the Vredefort Structure, South Africa

Only three very large, confirmed impact structures are known on Earth: the Chicxulub Crater (Mexico), 65 Ma, ca. 180 km wide; the Sudbury Structure (Canada), 1.85 Ga, 200 km in diameter, and the Vredefort Structure in South Africa, 2.02 Ga. While extensive data on large impact structures have been o...

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Bibliographic Details
Published in:Tectonophysics 1998-03, Vol.287 (1), p.1-20
Main Authors: Henkel, Herbert, Uwe Reimold, Wolf
Format: Article
Language:English
Subjects:
geophysical modelling
gravity
impact structure
magnetics
seismics
Vredefort Structure
Witwatersrand Basin
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Summary:Only three very large, confirmed impact structures are known on Earth: the Chicxulub Crater (Mexico), 65 Ma, ca. 180 km wide; the Sudbury Structure (Canada), 1.85 Ga, 200 km in diameter, and the Vredefort Structure in South Africa, 2.02 Ga. While extensive data on large impact structures have been obtained by remote sensing studies of such features on other planetary bodies, only this small number of large terrestrial impact structures can provide data crucial to understanding these catastrophic impact processes on Earth. Integrated modelling of gravity and magnetic data, constrained by geological as well as refraction and reflection seismic data, accomplished the reconstruction of the Vredefort impact structure in South Africa, approximately 250 km wide. The original Vredefort impact structure covered the whole extent of the Archaean Witwatersrand Basin, distinguished by enormous gold resources, as it is structurally preserved today. In fact, it is clear that the preservation of vast volumes of economically important Witwatersrand strata is the direct result of the formation of the ring basin around the central uplift (the Vredefort Dome) of the impact structure. This study is the first attempt to create an integrated and geophysically well-constrained model of this very large, complex impact structure.
ISSN:0040-1951
1879-3266
DOI:10.1016/S0040-1951(98)80058-9