Pinion Gold Deposit, Elko County, Nevada

摘要

Pinion is a Carlin-type gold deposit at the south end of the Railroad District, on the southeast part of the Carlin Trend of Eocene gold deposits. Gold Standard Ventures Corp (GSV) assembled the Pinion land package for the first time in March 2014. In September 2014, APEX Geoscience Ltd, using a 0.14 g/t Au cut-off grade, estimated a NI 43-101-compliant Indicated Mineral Resource of 20.84 million tonnes grading 0.63 g/t Au, totaling 423,000 ounces of gold; and, an additional Inferred Resource of 55.93 million tonnes grading 0.57 g/t Au, totaling 1,022,000 ounces of gold. An Inferred Mineral Resource of 76.77 million tonnes grading 3.82 g/t Ag, totaling 9,430,000 ounces of silver, was also reported. Gold mineralization is nearly all oxidized. In October-November 2014, after the resource calculation, GSV completed an additional 44 reverse-circulation drill holes at Pinion, further defining the gold zones and expanding the deposit in several directions. At Pinion, gold mineralization is concentrated within a multi-lithic, dissolution collapse breccia developed along the unconformable contact between underlying Devonian Devils Gate Limestone calcarenite (275 meters thick) and overlying Mississippian Tripon Pass Formation silty micrite (50 meters). The silty micrite provided a second calcareous host to react with mineralizing fluids. The Tripon Pass grades up into the Mississippian Webb Formation non-calcareous silty mudstone (40 meters). These two finer-grained units together were a less-permeable cap to hydrothermal fluids which were channeled beneath it. The Mississippian Chainman Formation chert-clast sandstone to conglomerate (> 300 meters) overlies the Webb. At southeast Pinion, feldspar-quartz porphyry sills (2-30 meters) are common, and felty-textured feldspar-amphibole-pyroxene porphyry dikes (2-20 meters) are sparse. NNE-trending anticlines occur at central and southeast Pinion. A gently west-dipping thrust, separating an overlying normal Devils Gate to Chainman section from an underlying Chainman section, is drill defined beneath the southeast Pinion anticline and the east limb of the central Pinion anticline. Gold is concentrated along the anticline axis and east fold limb at central Pinion, and to a lesser extent along the anticline at southeast Pinion. Thicker and higher-grade dissolution collapse breccia occurs along the footwall of the steeply NNE-dipping Main Zone Fault, which apparently down-drops the section 40 to 120 meters. This structure could be a left-lateral tear fault related to ESE-WNW compression that also produced the anticlines and thrust. Alternately, the structure could be a fault developed along the steeper limb of a NNE-verging asymmetric fold. At the North Gold Zone, the host section could be the left-laterally displaced east limb of the central Pinion anticline. Gold mineralization is controlled by the Bullion Fault on the east, and/or a west-northwest structure parallel to the Main Zone. The Pinion deposit is contained within a northwest-trending horst. Faults on the northeast horst margin are linking structures to the more northerly striking, range-bounding structures of the Bullion fault system. The greater Pinion 2.3-kilometer trend of gold concentrations occurs along the footwall of the Bullion fault system where it is offset at the linking structures.