Metallogenic analysis of the Stewart area, British Columbia; a statistical approach

Abstract

A statistical analysis of mineral deposit data from the Stewart, British Columbia, area contained in MINFILE (a computerized mineral inventory), based on X 2 probabilities derived from contingency tables, shows that it is possible to define significant associations between the metal content of deposits, the lithostratigraphy of their host rocks, and the presence or absence of granitoid intrusions at each deposit. In volcanic and volcaniclastic units of the Hazelton assemblage, mineralization is predominantly Cu-Pb-Zn (+ or -Ag, Au) and shows no significant association with intrusions. These deposits are interpreted as syngenetic-volcanogenic in origin. Later intrusions may cause remobilization but do not alter the metal content of these deposits. In clastic sedimentary units of the Hazelton and Bowser assemblages, mineralization is predominantly Pb-Zn-Ag and significantly associated with granitoid intrusions. These deposits are interpreted as epigenetic veins. The statistically derived associations are in good agreement with field-based classifications of the deposits and demonstrate the possibilities of classifying mineral deposits based on the information contained in computerized data files. The noted lithostratigraphic associations also suggest that, in the Stewart area, the source of the metals in the deposits may be their adjacent wall rocks rather than the granitoid intrusions. The role of the intrusions may be only to provide a heat source to promote hydrothermal circulation and leaching of metals from favorable wall rocks to form mineral deposits.