Geologic descriptionCountry rock is dominantly Paleozoic and (or) Precambrian Yukon-Tanana terrane quartz-mica schist containing numerous discontinuous quartz veins, intruded by lower Tertiary granite of the Circle pluton. Nelson, West, and Matzko (1954) reported 10% monazite, 5% topaz and a small amount of scheelite in the heavy-mineral fraction of the granite bedrock. Other minerals present are pyrrhotite, garnet, ilmenite, zircon, biotite, topaz and malachite. Two other samples from the area are slightly anomalous in tungsten (2-3 ppm), fluorine (2300-2400 ppm), lead (11-25 ppm), and arsenic (12-24 ppm) (Nelson and others, 1954). Concentrates from gravel on upper Bedrock Creek contain tin and tungsten (Barker, 1979). Fluorometric tests indicated the presence of uranium in several minerals but not in amounts to be of economic interest. A slightly radioactive zone of iron-stained schist 0.5 to 2 feet wide by 8 feet long was staked for uranium. This iron-stained schist gave a radiometric reading of about 0.05 mR/hr while the unstained schist gave a reading of 0.04 mR/hr (Freeman, 1963, p. 32). Work on claims between 1976 and 1978 consisted of surface trenching on the slightly radioactive zone of the iron-stained schist. Bedrock Creek is noted for its absence of gold, even though it is surrounded by gold-producing creeks such as Independence, Mammoth, Crooked and Boulder Creeks (Yeend, 1991, p. 31). |
