Displacements and the Siljan Ring Structure

ABSTRACT

The formation process of an impact structure is usually divided into two stages. During the first one a transient crater is formed, this stage is characterized by centrifugal displacements. The second stage, the modification stage, is characterized by centripetal displacements. Accordingly, in large eroded impact structures, where in general only displaced blocks and megablocks can be observed, geological studies should be made on separate sectors, not on the whole structure as a unit (the “sector principle”).

Geological observations in the Siljan ring structure are discussed from this point of view.