THE REITZ RING: A SEPARATE CIRCULAR STRUCTURE OR AN OUTER RING OF THE VREDEFORT IMPACT?

The study of Vredefort Impact center as a model for MAPCIS (Massive Australian Precambrian/Cambrian Impact Structure) has been useful for understanding both impact sites. The similarities between the sizes of central structures suggest the missing outer ring of Vredefort should be much larger than predicted by the models. The Bouguer gravity image of Vredefort and the magnetic intensity image of MAPCIS show elongated paths suggesting both are the result of oblique impacts. The study of oblique impacts on Venus along with Chicxulub showed that offset central structures are more common than previously thought. The Consolidated Earth Impact Database shows the Vredefort Impact structure ~ 300 km diameter completely within the Reitz Ring ~500km diameter. The geographic center of the Reitz Ring is located approximated 120km from the center of Vredefort and falls within the elongated path presumably up range. Similarly, the geographic center of the ~600km diameter outer ring of MAPCIS also falls along its elongated path approximately 120km away from impact center and presumably up range. 

This combined set of clues allows one to paint a new picture of Vredefort ~2Ga and the Reitz Ring ~3Ga. The presumed older age of the Reitz Ring appears not to be relevant as the Vredefort Impact while producing this outer ring would not reset the age as it did at the impact center. The odds that two separate impacts of this size shared the same impact point are small to the extreme. As the missing outer ring of Vredefort was conservatively estimated from modelling and presumed concentricity, it is reasonable to conclude that the Reitz Ring ~500km diameter is the missing outer ring of the Vredefort Impact Structure.