Initialer Magmatismus und seine Erzbildung in der Beleuchtung des Koli-Kaltimogebiets

Abstract

In the Koli—Kaltimo area, North Karelia, Finland, the initial igneous activity of the Karelidic zone has produced diabase dikes and spilitic sills. Some of the sills have differentiated forming spilitic rock associations, which range from peridotite to albite diabase rich in albite. The discussion of the spilites and the ore forming processes in the crystallisation of spilites is based on field observations, microscopical investigation, the geochemical distribution of some metals in the rocks and minerals, and the isotope ratio of sulphur. Both the diabase dikes and the spilitic sills have originated from the same tholeitic parent magma, the diabases from the »dry» magma and the spilites from the magma that has been rich in water and carbon dioxide. Also the ore-forming processes are different in these two magmas.