T. Bjerkgard et A. Bjorlykke, THE STRATABOUND SULFIDE DEPOSITS IN THE FOLLDAL AREA, SOUTHERN TRONDHEIM REGION, NORWAY, Norsk geologisk tidsskrift, 74(4), 1994, pp. 213-237
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.