Geology and petrogenesis of the Serb Creek intrusive complex near Smithers, British Columbia

The Serb Creek molybdenite property is 26 miles west-northwest of Smithers, B. C. on the northeast flank of the Howson Range of the Coast Range physiographic province. The property lies within an upper mesozonal to lower epizonal batholithic offshoot of the Coast Range Intrusive Complex. Small irregular plutons and a series of northwesterly-striking dykes intrude the batholith. The rocks are quartz monzonitic and, in texture range from coarse-grained granitic to porphyritic. Plots of optic angle against composition show that feldspars are of intermediate structural type indicating an increasingly rapid rate of cooling from the oldest to the youngest intrusive body. This increase in the rate of cooling is ascribed to smaller size of intrusive body with decreasing age. Plots of normative Q:AbOr ratios suggest that, if one believes the magma to have formed by anatexis, high pressures of volatiles, HC1, or of both were present during crystallization. Two general attitudes—N20° W to N^5°w and N75° E--control the emplacement of intrusive bodies, hydrothermal alteration, and, to a large extent, molybdenite mineralization. Hydrothermal alteration and molybdenite mineralization appear to be related to igneous activity because they are closely associated in time and space.Science, Faculty ofEarth, Ocean and Atmospheric Sciences, Department ofGraduat