Geological records of meteoritic impacts in Brazil: evolution and current knowledge

Abstract

Meteoritic impacts are a rare geological process that, due to the extreme pressure and temperature conditions, can promote permanent transformations in crustal rocks. The results of such processes are the structures called “impact craters”. Over time, craters are generally modified by erosive, tectonic and sedimentary processes characteristic of the Earth’s dynamics until they are completely removed from its surface. Therefore, the geological record of impacts on Earth is quite incomplete, with a tendency to preserve only larger and relatively younger craters. Most of the known craters on Earth are just partially preserved, being referred to as “astroblemes”. There are about 200 such structures currently known on Earth. Eleven confirmed impact structures exist in South America, of which nine are in Brazil. They are part of two Phanerozoic intracratonic sedimentary basins, Paraná and Parnaíba. Their estimated ages range from the Permian-Triassic transition to the Late Cretaceous. This article presents the current state of geological knowledge about these structures and their main geological and geophysical characteristics. Some remarks about specific geoconservation and geoheritage actions are also made.