Geology and lithogeochemistry of the Powderhorn Lake VMS deposit, Newfoundland

Jacobson, Regan (2023) Geology and lithogeochemistry of the Powderhorn Lake VMS deposit, Newfoundland. Masters thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (58MB)

Abstract

The Powderhorn Lake volcanogenic massive sulfide (VMS) deposit is hosted within the Ordovician Buchans-Roberts Arm (volcanic) belt (BRAB) in central Newfoundland. The deposit is hosted by coherent and clastic rhyolitic rocks that are interpreted to have formed within a rifted continental arc setting. The stratigraphy, alteration, and mineralization of the deposit is preserved within multiple, imbricated thrust panels that comprise a regional domal antiform. Mineralization occurs as multiple stacked lenses consisting of stringer to semimassive and massive pyrrhotite, sphalerite, chalcopyrite, pyrite, and minor galena. Sulfide lenses typically contain relicts of host rocks and are interpreted to have formed by replacement-style processes at or below the seafloor. Hydrothermal alteration assemblages at Powderhorn Lake consist of weak to intense quartz-sericite and quartz-sericite-chlorite+/- pyrite. Lithogeochemical data, mass change calculations, and short-wave infrared spectroscopy identified key element associations and alteration assemblages that provide vectors towards mineralization. The lithogeochemical data have been used to create a 3D alteration model of the Powderhorn Lake deposit that highlights spatial relationships between key alteration characteristics and stratigraphy.

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