The Schaft Creek porphyry copper-gold-molybdenum-silver deposit, northwestern British Columbia.

摘要

Schaft Creek is a calc-alkaline porphyry Cu-Mo-Au deposit located in northwestern British Columbia. Hosted by Late Triassic basaltic to andesitic volcanic rocks of the Stuhini Group, the deposit formed as a result of crystallization of the underlying Hickman/Yehiniko batholith complex which released granodioritic porphyritic dykes and fluids into the overlying volcanic sequence. The age of the Hickman/Yehiniko batholith complex is approximately constrained by a composite U-Pb zircon date of 222.1 +/- 9.6 Ma, which is in broad agreement with a well-constrained age for mineralization of 222.0 +/- 0.8 Ma (Re-Os molybdenite). The deposit shares characteristics of both the classic and diorite porphyry models, with silica-poor sericite-chlorite alteration in mafic country rocks instead of more normal phyllic alteration. Mineralization occurs in hydrothermal veins and breccias and consists of bornite, chalcopyrite, molybdenite, and pyrite with potassic and sericite-chlorite alteration. Significant structural modification of the deposit occurred during and after its formation.