Epigenetic gold deposits and their tectonic setting in the New Brunswick Appalachians

CIM Bulletin, Vol. 83, No. 934, 1990

A.A. Ruitenberg, S.C. Johnson and L.R. Fyffe, Geological Surveys Branch, New Brunswick Department of Natural Resources and Energy

Several types of stratiform and epigenetic gold deposits have been found in New Brunswick. It is the purpose of this paper to describe and classify the epigenetic deposits and demonstrate their relationship to tectonic evolution. The stratiform deposits are mostly volcanogenic massive sulphide deposits that are described elsewhere (Davies et al., 1985). The auriferous epigenetic deposits include quartz-carbonate veins and stockworks, polymetallic veins, contact metasomatic, porphyry copper and volcanic breccia (epithermal) deposits. These epigenetic deposits are concentrated in major fault zones that define or are close to the boundaries of tectonostratigraphic terranes or terranes and cover sequences. The host rocks of the deposits were subjected to extensive crustal thickening resulting from thrusting and/or high angle reverse faulting. The gold deposits north of the Avalon Terrane occur in dila-tent structures related to mainly dextral wrench faulting that postdated the episode of crustal thickening. The deposits along the southern margin of the Avalon Terrane occur in structures related to late phase thrusting.

Keywords: Exploration, Gold deposits, New Brunswick Appalachians, Epigenetic deposits.