COMPARISON OF THE SOUTHERN TRANS-HUDSON OROGEN, USA AND THE DAMARA OROGEN, NAMIBIA: IMPLICATIONS FOR INTERPRETING THE CRUSTAL FRAMEWORK OF THE NORTHERN GREAT PLAINS

The southern Trans-Hudson orogen of western North and South Dakota is the result of the Paleoproterozoic collision between the Wyoming and Superior cratons. The well-exposed Damara orogen of north-central Namibia marks the collision between the Congo and Kalahari cratons of southern Africa during the Neoproterozoic. Although these two orogenies differ in timing by a billion years, there are distinct similarities in their crustal framework, scale, and lithotectonic environments.

The Black Hills of South Dakota provides the only exposure of Trans-Hudson rocks in the United States where otherwise it is overlain by a thick sequence of Phanerozoic sedimentary rocks. Due to the cryptic nature of this orogenic belt, previous interpretations have been made solely from drill holes and geophysical data as well as correlation with the surface exposures of central Canada. The Damara orogen, however, is well exposed and documented with detailed geologic maps, remotely sensed imagery, and high-resolution geophysical data.

The southern end of the Trans-Hudson orogen is truncated by the Central Plains orogen in a nearly perpendicular configuration. The southwestern terminus of Damara orogen was formed by the suturing of South America to Africa in a like manner. In addition, to shared collision geometries, both of these orogenic belts show similar geophysical features, metamorphic grades, and have associated post-tectonic, S-type granite magmatism. Major geophysical anomalies common to both orogens could be the result of lithologies associated with specific tectonic settings. It is because of these striking similarities that a comparison of this type can yield useful insights for interpreting major crustal structures in the subsurface of South Dakota utilizing innovative geophysical techniques.