Geology and Mineral Deposits of the Bethlehem Properties, B.C., Canada

Abstract

Igneous activities which followed to the Laramide Revolution gave rise to the intrusion of an intermediate or acidic composite stock into the Guichon Batholith. This composite stock consists mainly of the Bethlehem quartz diorite, but intrusion of dacite-porphyry took place successively, forming a marginal facies or later phase of the stock. On this occasion tiny cupolas around the composite stock formed several intrusive breccia pipes due to brecciation by explosions. Owing to the deformation resulting from the intrusion of the stock and breccia pipes, fractures appeared in the earlier quartz diorite. On the other hand, magmatic differentiation of the stock, cooling and cementing began, and, alteration was performed by hydrothermal solution at high temperatures.
In the later stage of differentiation of the stock, mineralization, composed of chalcopyrite, bornite and a small quantity of molybdenite, occurred selectively in the breccia pipes and fractures. It also formed network and vein-disseminate deposits.The mineralization is represented by several combined masses near the contact between the earlier quartz diorite and the later composite stock.Up to date, three economical ore deposits have been confirmed in the zones of East Jersey, Jersey and Huestis. Except that pyrite is very rare and supergene enrichment is unobserved, the mineralizations, in their mode of occurrence, have many points of similarity to the so-called porphyry copper deposits in South America and South western U.S.A.