The Ordovician Tetagouche Group, Bathurst Camp, Northern New Brunswick, Canada: History, Tectonic Setting, and Distribution of Massive-Sulfide Deposits

Exploration & Mining Geology, Vol. 1, No. 2, 1992

CEES R. VANSTAAL, Continental Geostience Division, Geological Survey of Canada, LESLIE R. FYFFE, JOHN P. LANGTON and STEVE R. McCUTCHEON, Department of Natural Resources and Energy, Mineral Resources , New Brunswick, Canada

The volcanic-dominated Tetagouche Group in northern New Brunswick contains numer ous massive-sulfide deposits and intimately associated metalliferous sediments. The massive sulfides i: are generally hosted by Llanvirnian-Llandeilian volcaniclastic sedimentary rocks of the Nepisiguit ; Falls, Patrick Brook, and Boucher Brook formations. These formations are intercalated or closely associated with rhyolitic-dacitic flows and/or domes, and minor continental tholeiites of the Flat Landing Brook Formation. Pyroclastic rocks are relatively scarce in the silicic volcanic complex. Tuffites and epiclastic sandstones, of the Nepisiguit Falls and Patrick Brook formations, respectively, generally occur along the fringes of the silicic volcanic complex. The flows and tuffites are intruded by quartz- and feldspar-phyric rhyolite (porphyry) dykes, sills, and domes. Although the volume 5 " of the silicic volcanic complex is large, evidence for a previously proposed collapsed-caldera model is lacking. On the basis of host-rock type and stratigraphic position, the sediment-hosted massive sulfides have been divided into three groups: the Brunswick-, Caribou- and Halfmile Lake-type deposits. Syngenetic feeder pipes and asociated alteration zones are generally not present beneath the Caribou- and the Halfmile Lake-type deposits and, if present at all, are poorly developed underneath the Brunswick-type.