Morphological and geophysical evolution of terrestrial impact craters

Hyper-velocity meteorite impacts on planetary surfaces give rise to craters whose morphology evolves under the influence of external factors such as atmospheric processes, as well as internal factors including tectonics and metamorphism. On Earth erosion processes related to climate, such as water, wind, and glaciers, gradually erase these topographic anomalies, or even bury them, while tectonics and other internal processes can play a role too. Nevertheless, the geophysical signature of impact structures often remains preserved, even after hundreds of millions of years.

In this study, we model the morphological evolution of terrestrial impact craters to derive their associated gravimetric signatures. We explore different models for impact craters evolution in terms of regional erosion rate, size and geological composition using landlab landscape evolution model. Our models account for erosion and displacement of sediment by fluvial and hillslope processes, as well as lithospheric flexure. In addition to the landlab simulations, we computed the gravimetric anomaly disturbance throughout the evolution. Theoretical morphologies of complex impact craters with diameters ranging from approximately 10 to 50 km are used and placed under different lithological and climatic conditions.

Unlike previous studies, our approach explicitly takes into account the physical processes driving erosion and sediment deposition. We observe that, for some cases, there is an increase in the amplitude of the negative gravimetric disturbance, and that the extent of the central gravity anomaly may be smaller than the potential rim of the final impact structure.

Our goal is to identify reliable markers which could be used for the systematic detection of impact structures, the assessment of their initial size, and the characterization of their evolution. Indeed this approach will also help to better differentiate impact structures from other geological structures as well to improve our understanding of post-impact processes and their long-term influence on planetary landscapes.