Mystery of Siljan Crater

Abstract

Abstract A substantial number of ring structures have been identified on the Earth's surface. The overwhelming majority of these structures are considered meteorite craters. Signs of impact metamorphism argue for the impact origin of such structures although this cannot be considered an indisputable confirmation of their origin. Impact appearance can be explained by both exogenous and endogenous causes. Among the latter are high-temperature mantle gas explosions. We have found at least four stages of tectonic dislocations in the basement rocks of the Siljan ring structure, which favor the explosive eruptions origin hypothesis. It can thus be assumed that many ring structures referred to as impact structures are of terrestrial origin.