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UBC Theses and Dissertations

The telescoped silver-lead-zinc deposits of the contact group mineral claims, Cassiar district, B.C. McDougall, James John


The regional geology of the McDame Area is described briefly and a detailed description of the "Contact Group" mineral claims within this area is presented. The "Contact" vein deposit described herein is apparently unique, as far as geological literature is concerned, in its primary mineral associations. This vein, in a contact-metamorphic environment, possesses the form and textural characteristics of a mesothermal deposit. Typical high, medium and low temperature minerals are present in relationships that suggest unbroken deposition in the vein and a genetic relation to both the associated intrusive and related pyrometasomatic deposits. The occurrence and origin of native sulfur, wad, and hydrocarbon in the vein are discussed. Alabandite (MnS), which is a common constituent, is classified, on grounds of ex-solution phenomena, as having crystallized at temperatures greater than those previously assigned to it. The role of manganese in this deposit is given special attention. The conclusion is reached that the Contact Vein was formed at shallow depth under conditions of high but rapidly falling temperature and locally high pressure. Accordingly, it illustrates telescoping within the mesothermal-pyrometasomatic range of physical conditions.

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