Petrogenesis of the low sulfidation gold mineralization in the Williams Brook area, Tobique-Chaleur Zone, New Brunswick
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Date
2014
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University of New Brunswick
Abstract
Gold mineralization in the Williams Brook area occurs within the Siluro-Devonian
bimodal volcano-sedimentary rocks of the Tobique-Chaleur Zone in northern New
Brunswick (Wapske Formation). Geotectonic discrimination diagrams show A-type
signatures. Such compositions indicate a transpressive tectonic setting and suggest that
oblique convergence of Gondwana and Laurentia as the driving force for basin
formation and coeval magma generation. Gold occurs in two types of mineralization,
which show slightly different Ar-Ar (muscovite) ages: 412 Ma from altered rhyolites
and 408 Ma from quartz veins. This younger age is supported by similar U-Pb zircon
ages determined from the rhyolite host rocks. A -414 Ma age of muscovite from a
foliation fabric suggests that there is a structural control to the gold mineralization.
Sphalerite, pyrite, and galena are the main hypogene sulfides associated with the gold
mineralization; however, supergene oxyhydroxides such as goethite and hematite are
also common. Stable isotopic (0, H, S) and radiogenic Pb evidence suggest fluids and
metals are from a magmatic source. Fluid inclusions and stable isotope geothermometers
suggest gold deposition was at an approximate temperature of 200°C, which is
interpreted to be via mixing with meteoric waters. Evidence from different scales
determined in this study support the theory that the study area is part of a low sulfidation
epithermal style mineralizing system, thus making the Tobique-Chaleur Zone
prospective for this style of mineralization.