New aspects to the geology of the Outokumpu region

Abstract

This study provides a general picture of the geology of the Outokumpu region with no attempt at being a detailed description. Special attention is paid to the areas occupied by Karelian and Prekarelian rocks and the location of the Outokumpu region in relation to the Prekarelian rocks. Age determinations carried out from the area assign an average age of 2680 Ma to the Prekarelian rocks and 1900 Ma to the Karelian rocks (Maarianvaara granite). The differences between the rocks of the serpentinite-quartz rock series and the epicontinental series are elucidated on the basis of analytical data and with triangular diagrams. In the opinion of the present author, the Outokumpu region shows features characteristic of an Alpinotype orogenesis and hence an Alpinotype model is applied to the region. A contrary view has been presented by H. J. Zwart (1967), who considers that the Svecofennian-Karelian area exhibits features typical of Hercynotype orogeny. Finally the genesis of the Outokumpu ore is discussed, the conclusion being reached that it is of submarine origin.