The Siljan ring impact structure: Possible connections with minor ores in its neighborhood

Abstract

Mårtanberg and Slättberg are two old, small mines situated outside, but near the Siljan Ring structure and possibly both are influenced by the impact. The bedrock formed in the main c. 1700 Ma ago. Mårtanberg is known as a small abandoned copper mine with chalcopyrite and pyrite. Its ore seems to have been formed during two widely separated periods. Slättberg is an old nickel mine which has been worked intermittently, most recently during the two world wars. The host rock is an amphibolite dike which possibly has changed its mineralogical composition during a later event. Both these ores may be explained as a result of the Siljan impact about 360 Ma ago. Wickman, F.E., 1994: The Siljan Ring impact structure: possible connections with minor ores in its neighborhood. GFF, Vol. 116 (Pt. 3, September), pp. 145–146. Stockholm. ISSN 1103–5897.