Geology, 40Ar/39Ar geochronology and Sn-W-Mo-bearing sheeted veins of the Mount Douglas Granite, southwestern New Brunswick

CIM Bulletin, Vol. 81, No. 918, 1988

M.J. McLEOD, New Brunswick Department of Natural Resources and Energy ,Minerals and Energy Division, Sussex, New Brunswick, P.P. TAYLOR, Department of Geology, Carleton University Ottawa, Ontario, and D.R. LUX, Department of Geological Sciences, University of Maine, Orono, Maine

The Mount Douglas Granite constitutes the eastern part of the Saint George Batholith and contains the youngest, most differentiated phases of the batholith. It also contains extensive endogranitic, low-grade, Sn-W-Mo-bearing sheeted vein systems. Early phases of the Mount Douglas Granite are coarse- to medium-grained, seriate granites that represent the slowly cooled carapace of the intrusion. Late phases are medium- to fine-grained, equigranular and porphyritic granites that were accompanied by repeated and widespread fracturing of the carapace and injection of mineralizing fluids. These granites represent a highly differentiated suite with "A " type affinities developed in a "within plate" transitional to "syn-collision" tectonic setting. 40Ar/39Ar dates for biotites from the various phases indicate emplacement circa 367 Ma.

Mots Clés: Economic geology, Geochronology, Sn-W-Mo bearing veins, Mount Douglas Granite, Geochemistry, Mineralization.