Field-based structural analyses addressing the formation of large terrestrial impact structures are rare. We present a field-based kinematic analysis and a three-dimensional (3-D) block model of prominent structures from supracrustal strata of the Vredefort Dome, the central uplift of the Vredefort impact structure. This study aims to better understand the kinematics of complex crater formation. Specifically, the configuration of prominent concentric and radial faults supports the hypothesis that the Vredefort Dome formed by centripetal rock movement followed by radial spreading of uplifted rocks. Centripetal rock movement led to the formation of radially disposed transpression zones, whereby distorted supracrustal strata are characterized by a remarkable structural continuity during central uplift formation. This continuity points to a rather strong mechanical coherence of strata throughout the process. Distortion of layers at the exposed crustal level was accomplished mostly by folding on the hundred-meter scale and is at variance with the concept of concentric normal faults accomplishing kilometer-scale slip within and toward the center of complex impact structures. Displacement magnitudes calculated for strata exposed in the Vredefort Dome indicate that the diameter of the transient cavity of the Vredefort impact structure was ~70 km at surface. All prominent structural elements of the Vredefort Dome can be explained by central uplift formation.

The internal structures of central uplifts of impact craters are among the most complex geologic features within Earth's crust. Upheaval Dome, Utah, is used as a reference and case study to display the internal geometry of a central uplift and to deduce mechanisms of uplift formation in impact craters within a sedimentary, siliciclastic target. Geological and structural data gained from our high-resolution mapping of the central part of the structure were combined with topographic data in an ArcGIS database. A three-dimensional visualization of the geometry of faults and strata within the central uplift is presented and interpreted with respect to their deformation history. Central uplift formation is induced by an inward and upward directed convergent flow of the crater floor during gravity-driven collapse of the transient crater cavity. Radial folds and a concentric stacking of imbricated thrust slices are prominent deformation features and result from a constrictive strain pattern. The arrangement of structural elements in the inner part of the Upheaval Dome roughly displays some bilateral symmetry, trending northwest. The dominance of northwest-dipping reverse faults indicates a material transport of top to the southeast, which may be caused by an oblique impact. Fault planes commonly dip steeply and are bent due to a passive distortion after activation. The macroscopic coherence of large target units and blocks and the anisotropy of the layered target cause remarkable deviations from an ideal convergent flow field. Stratified siliciclastic rocks are commonly deformed by localized brittle faulting, and massive sandstones are deformed by a distributed cataclastic flow. During crater collapse, pervasively crushed sandstones will flow locally as a granular medium, resulting in the formation of dikes. Acting as lubricants, they accommodate the complex mesoscale folding and faulting of the neighboring strata. A standard numerical model of impact cratering was designed for comparison with the observed structures and to estimate impact parameters like initial crater size, amount of erosion, and the time of impact. The best fit between model and field data is found when the White Rim Sandstone is buried ∼2000 m beneath the target surface. This most likely corresponds to an Upper Cretaceous age of Upheaval Dome during deposition of the Mancos shales. The initial diameter of the Upheaval Dome impact crater would have been ∼7–8 km.