Modeling simple craters using gravity measurements

Abstract

A study was carried out for two early Paleozoic impact structures in Sweden. These two impact structures (Granby and Tvaren) are located in the southern part of Sweden. Common features can be identified of these two structures as similar diameter of ca 2 km and a substantial post impact fill with Paleozoic sedimentary rocks. The Granby structure represents an almost completely preserved impact crater within a Paleozoic sedimentary rock sequence — only the uppermost part of the raised crater rim might be eroded and was subsequently covered by Quaternary sediments. The Tvaren structure is eroded below the surrounding pre-impact Paleozoic cover rocks into the underlying crystalline basement and has a Quaternary sediment fill. Gravity measurements were carried out on land and sea ice. The inverse gravity modeling shows a gradual change of density and the equivalent porosity with radial distance from the explosion center within the damage zone around and below simple craters.