Settings of Meteorite Impact Structures in the Svecofennian Crustal Domain

Abstract

The Svecofennian Domain, located on the western part of the East European Craton, is a uniform crustal segment with an age of the basement of similar to 1.9 Ga. Together with younger (1.5 - 1.8 Ga) transition zones it occupies an area of similar to 1.56 x 10(6) km(2). The domain unites shield and platform areas including the submerged Baltic Sea. It includes 22 confirmed, 6 possible, and tens of supposed impact structures that survived recurrent erosional epochs during the long geological history. Signatures of impact-induced tectonics depended much on the syn-impact structure of the target, i.e., presence and thickness of sedimentary deposits covering the basement. Due to differentiated tectonic movements, post-impact scenarios of structures of even the same age differ from place to another within the domain. The present paper analyses the up to 1.2 Ga long post-impact histories of impact structures in accord with the geological development of the domain, i.e. past vertical movements of the crust, which predicted formation and destruction of the sedimentary cover, and variable distribution of shield and platform areas. A great number of at least small- and medium-size craters, which have been located within the past sedimentary cover on top of the crystalline rocks of the Fennoscandian Shield and sediments of the Russian Platform, have been eroded completely or partially. However, between the time intervals with low cratering rates, the Early Palaeozoic is extremely rich in survived structures. It gives hints for unequal erosion history within the Domain and the existence of many hidden (buried) structures. Therefore, we can expect that there is still a large number of partially eroded craters, presently hidden under Quaternary, and also under or within Phanerozoic deposits, to be discovered in the future.