GEOCHEMICAL EVIDENCE OF SULFIDE MINERALIZATION AT WEBSTER PASS, SUMMIT AND PARK COUNTIES, COLORADO

Webster Pass is the Continental Divide between the Snake River and Handcart Gulch drainages in Summit and Park counties, Colorado. Located about 75 miles west of Denver, the region is within the Colorado mineral belt, and was host to Tertiary igneous activity and associated hydrothermal mineralization. Ferricrete deposits up to three miles (5 km) long line the bottoms of both the Snake River valley and Handcart Gulch. Samples from springs that continue to feed the ferricrete deposits, and of the deposits themselves, with rock-chip samples from along the Divide support a conclusion that rocks of the region contain sulfide mineralization.

Two springs from Handcart Gulch and one from the head of the Snake River ferricrete contain silver (0-9 ppb), lead (0-118 ppb), zinc (87-444 ppb), copper (6-432 ppb), and molybdenum (11-16 ppb) - samples not analyzed for gold. Twenty-four samples of Handcart Gulch ferricrete and nine of Snake River ferricrete contain Au (0-17 ppb), Ag (0-1.1 ppm), Pb (0-380 ppm), Zn (20-2240 ppm), Cu (13-632 ppm), and Mo (0-25 ppm). The Snake River ferricrete also was analyzed for Sn (3-15 ppm) and W (0-5 ppm). Twenty-two samples of fractured and micro-veined sillimanite gneiss were collected along the Continental Divide, across the region of suspected sulfide mineralization between the Snake River valley and Handcart Gulch. The samples average for Au (5.8 ppb, maximum 15 ppm), Ag (5.5 ppm, max 8 ppm), Pb (57, max 300 ppm), Zn (60, max 279 ppm), Cu (35, max 70 ppm), Mo (7, max 31 ppm), Sn (3, max 6 ppm), and W (4, max 15 ppm). A sample of iron-stained vein material from the center of the profile contained 38 ppb gold, 250 ppm copper, 64 ppm molybdenum, and 35 ppm tungsten. These numbers, together with the presence of the ferricrete deposits on both sides of the Divide suggest that significant sulfide mineralization may be present beneath Webster Pass.