A geophysical study of the Valentine Gold Project, West-Central Newfoundland

Abbott, Stephanie M. (2021) A geophysical study of the Valentine Gold Project, West-Central Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

The Valentine Lake Property is located in the west-central region of the island of Newfoundland and comprises five significant structurally controlled, orogenic gold deposits. These deposits, which have proven challenging targets for geophysics, occur proximal to a major thrust faulted contact between the Precambrian Valentine Lake Intrusive Complex (VLIC), which houses the majority of gold mineralization, and the Silurian Rogerson Lake Conglomerate (RLC). Hosted within the silicic quartz-eye porphyry and trondhjemite phases of the VLIC, the gold concentrations are associated with extensional and shear parallel quartz-tourmaline-pyrite (QTP) veining. While geophysical techniques, such as induced polarization (IP), magnetics and seismic, are commonly used to detect mineral prospects, their ability to delineate the ore zone at the Valentine Gold Project (VGP) has been largely unsuccessful, primarily because the gold is scattered throughout veins within the resistive, silicic host rocks. Consequently, to date the most successful methods for locating the ore have been prospecting, soil sampling and drilling. This study employs two fresh geophysical techniques, gravity and ground-penetrating radar (GPR), supplemented by sonar surveys, in an effort to map the subsurface extent of the gold-bearing alteration zone and assess the depth of overburden and water reserves for future mine development. Throughout 2019 and 2020, a 22 line-kilometre broad-scale gravity survey, comprising 252 stations was completed, targeting the slightly less dense altered host rock. GPR data acquired over 8 priority bogs and small ponds helped define the irregular overburden to aid in gravity corrections. Combined GPR and sonar bathymetry surveys of Valentine and Victoria Lakes covering 10 and 32 square kilometres, respectively, were completed to further assist with the gravity corrections and to ascertain water resources for mining. The resulting residual Bouguer gravity map revealed a -1.7 mGal thin linear anomaly corresponding partially to the alteration zone and the bog hypsometry maps yielded overburden thicknesses up to 4.8 metres.

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