En petrografisk karakteristik av en sent postorogen mafisk intrusion i östra Värmland
1984
Annertz, Kristian
A basic intrusion (approximate1y 18 km2) occurs in southeastern Värmland about 20 km southeast of Kristinehamn. A few thin dikes of the basite penetrates the surrounding Filipstad granite. Adjacent to the basite the granite is magnetite- and garnetbearing and also secondary hypersthene and spinel are found in the granite. These observations indicate that the basite is postgranitic. The basite varies from a dark grey, mediumgrained diorite in the south, to a grey, mediumgrained quartzmonzodioritic and quartzmonzonitic rock in the north. Two small ultramafic outcrops are also found in the south. The rock consists mainly of plagioclase (which often show oscillatory, normal zoning, with an anorthite content between 38 % and 58 %), orthoclase, quartz, biotite, hornblende and clinopyroxene. As accessories orthopyroxene, epidote, apatite, sphene and opaques occur. The results from the chemical analyses display trends, which can be interpreted as due to magmatic differentiation. The consistent trends make it possible to interprete all of this basic intrusion as one intrusion, but the outcrop pattern and the regional distribution of rock types cast some doubts on such an interpretation.
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