Carbonate-rich Footwall Alteration at the Mobrun Mine, a Possible Mattabi-type VMS Deposit hi the Noranda Camp

Exploration & Mining Geology, Vol. 2, No. 2, 1993

ADRIENNE C.L. LAROCQUE and C. JAY HODGSON Department of Geological Sciences, Queen's University, Kingston, Ontario, Canada

The Mobrun VMS deposit in northwestern Quebec does not fit the classic Noranda-type model, but exhibits characteristics more consistent with a Mattabi-type deposit. The orebodies are underlain by fragmental volcanic rocks indicative of explosive volcanism in shallow water. Felsic volcanic rocks are more abundant than mafic rocks. Alteration assemblages comprise chlorite, carbonate, sericite, and quartz. Broad semi-conformable alteration occurs high in the footwall to the 1100 lens. Mobrun occurs higher in the stratigraphic sequence than most of the other deposits in the Noranda camp. In this part of the stratigraphy, zones of pervasive carbonatization may be more useful guides for exploration than zones of silicification.