Geology of the Lake George antimony deposit southern New Brunswick

CIM Bulletin, Vol. 73, No. 822, 1980

C.J. MORRISSY Mine Geologist, Consolidated Durham Mines and Resources Ltd. Prince William, New Brunswick, A.A. RUITENBERG, Regional Geologist, Mineral Resources Branch, New Brunswick Department of Natural Resources, Sussex, New Brunswick

The Lake George antimony deposit comprises a system of stibnite-bearing quartz veins that cut Silurian greywacke and slate. The stibnite-bearing ore zone is in part enveloped by a uraniferous zone.The ore-bearing quartz vein system occupies an easterly striking, gently north-dipping fracture system that cuts across north-northeasterly trending gently southwest-plunging, tight Acadian (early Middle Devonian) folds. This vein system continues at depth into a siliceous skarn zone intruded by altered granite porphyry dykes, which constitute probably a late phase of the Hawkshaw granitoid intrusion to the north.Most of the ore occurs in a northeast-plunging, trough-shaped vein structure that formed where the vein system (gently north-dipping) intersects the axial surface zone (steeply northwest-dipping) of an Acadian synform. The trough-shaped structure resulted from deflection of the fracture zone (containing the vein system) by competent beds.Emplacement of the quartz-stibnite veins was preceded by, and is in part penecontemporaneous with, the formation of a micaceous-argillaceous alteration halo, which in turn intersects a patchy biotite alteration zone.The hypabyssal intrusions associated with the Lake George deposit probably represent a late phase (early Carboniferous?) of the nearby Hawkshaw intrusive granitoid complex.
Keywords: Geology, Mineral deposits, Antimony deposits, Lake George deposit, New Brunswick, Stibnite, Uranium minerals.