Diverse occurrences of galena-cemented sandstones in the Paleozoic, northern Appalachians, Quebec
CIM Bulletin, Vol. 80, No. 908, 1987
K. SCHRIJVER and G. BEAUDOIN INRS-Georessources Sainte-Foy, Quebec
Four occurrences of galena-cemented sandstones, exposed in the Lower St. Lawrence - Gasp&sie area, are described. They constitute a new, insufficiently explored type of deposit in Quebec.
One mineralized body, a minor occurrence, is hosted in Lower Devonian rocks deposited in an estuarine, intertidal river channel during a marine regression; major cements are dolomite and sulphides. Another occurrence, a drilled prospect, is hosted in Upper Silurian rocks deposited unconformably on Cambro-Ordovician basement during a marine transgression. With galena and quartz as main cementing minerals, it is similar to some wellknown, economic sandstone-lead deposits. A third and fourth, a drilled prospect and a minor occurrence, are hosted in Upper Cambrian rocks deposited on continental slopes. In both, sulphides mainly occupy a secondary porosity. The differences between the third and fourth occurrences are: (1) cementing translucent minerals (carbonates and barite in one; chlorite in the other); (2) chronology of final subsurface dissolution (prior and subsequent to sulphide precipitation, respectively); and (3) important fracture porosity only in the barite-bearing deposit.
The diversity of the four occurrences, and the unequal geological knowledge of their respective features, prohibit the formulation of uniform guidelines for further exploration.
Exploration, Geology, Sandstone, Mineral exploration, Mineral deposits, Galena, Barite, Sphalerite.