Karikkoselka--A New Impact Structure in Finland

Observations on a circular and deep small lake have revealed a new impact structure in Finland, hereafter called the Karikkoselka structure (Lat. 62 degrees 13'N; Long. 25 degrees 15'E). This simple impact structure, with an estimated present diameter of 1.5 km, is located in Central Finland, about 230 km north of Helsinki and 25 km west of the town of Jyvaskyla. Geologically the structure lies within the Central Finnish Granite Complex of Paleoproterozoic age (~1.88 Ga). The target rock is a porphyritic granite exposed in shoreline outcrops, where shatter cones have been found in situ. Preliminary morphological, geophysical and petrographic data of the Karikkoselka impact structure are summarized.