THE STRATABOUND SULFIDE DEPOSITS IN THE FOLLDAL AREA, SOUTHERN TRONDHEIM REGION, NORWAY

Five strata-bound massive sulphide deposits are situated at three diff erent stratigraphic levels in the volcanogenic Fundsjo group in the Fo lldal area. The deposits are hosted in metabasalts, metarhyodacites an d volcaniclastic rocks and belong to the Cu-Zn class of volcanic-assoc iated massive sulphide deposits. The metal content of the deposits ind icates that the sources of metals are underlying strata, possibly with a contribution from intrusives. Wall rock alteration varies according to differences in host rocks, and is probably a result of chemical va riations of the host rocks, temperature differences and proximity to t he hydrothermal vent. The clustering of deposits in the Folldal area i s considered to be due to the occurrence of a large subvolcanic trondh jemitic intrusion which acted as the major heat engine For convection. The small size of the deposits might be related to the shallow level of the intrusion.