Geologic description
Minor amounts of pyrite and chalcopyrite occur widely over an area of about 36 square miles in this part of the Asik Mountain mafic-ultramafic complex which is as much as 60 miles long and 25 miles wide (Degenhart and others, 1978). Serpentine and dark green to black basalt with amygdules filled with calcite and epidote are the most common rock types. The serpentine commonly contains small amounts of fine-grained pyrite as disseminations and fracture fillings. The weathering of pyrite produces large orange- to red-stained areas on outcrops and along streams. A minor amount of malachite was noted on occasional calcite fillings in the basalt, and very minor chalcopyrite is associated with the serpentinite. Sixty-six stream sediment, soil, and rock samples were collected over an area of about 36 square miles and were analyzed for copper and nickel, and in some cases for lead, zinc, silver, and chromium (Degenhart and others, 1978). Seven stream sediment, silt, and soil samples had copper values above 250 parts per million (ppm) copper; six of these were attributed to minor amounts of chalcopyrite associated with serpentinite and basalt and were not considered significant (Degenhart and others, 1978). One sample from Uvgoon Creek contained 1,400 ppm copper, and 2,075 ppm zinc. Zn. No bedrock is exposed at this site; stream float consists mainly of pyritic serpentinite and diorite(?). The anomalous values of copper and zinc in this sample could not be explained. and were considered worthy of follow-up studies. |
