Weasel Mountain Occurrence, Alaska Peninsula District, Lake and Peninsula Borough, Alaska, USA
This page is currently not sponsored. Click here to sponsor this page.
Location: This occurrence is located approximately 2 miles northwest of Weasel Mountain and 2 miles west of Hook Bay in T. 42 and 43 S., R. 56 and 57 W., of the Seward Meridian (Cox and others, 1981, locality 4; MacKevett and Holloway, locality 25?). Location is accurate to within 1 mile.
Geology: The area of this site is underlain by strata of the Cretaceous Chignik Formation and by the interbedded sediments, volcaniclastics, and andesite of the Oligocene-Pliocene Meshik Formation. Fields (1977) describes two major intrusive systems, a diorite porphyry dike or sill and a younger quartz porphyry mass. The diorite is approximately 1/2 mile in width and extends in a northeast direction for more than a mile. The quartz porphyry intrudes the the diorite, extends in a northeast direction, and measures approximately 700 by 3000 feet in outcrop. Butherus (1981) reports these intrusive phases as occupying approximately two square miles. Large areas of hornfels have resulted from thermal metamorphism of the nearby sedimentary rock. The site is marked by a color anomaly which contains 1 to 6 percent sulfides over an area 2 miles in long by 1 mile wide. Fields (1977) describes the sulfides as mostly fracture controlled, primarily along certain marginal zones of the diorite and quartz porphyry and in the metasediments to the west. Chalcopyrite and sparse molybdenite occur in the marginal areas of the diorite, mostly along northeast-trending fracture zones. The resulting copper anomaly is approximately 700 by 1500 feet and contains 500 to 2100 ppm copper. The molybdenum anomaly coincides in part with the copper but has a more easterly trend. This anomaly is approximately 1000 by 2000 feet and contains 22 to 160 ppm molybdenum. Low gold values (0.04 to 0.18 ppm) coincide with the molybdenum. Diffuse peripheral lead-zinc values are present. Alteration is diffuse with no strong focus on a core. A broad sericitic zone exists within the area of higher sulfide content. Sericite occurs pervasively and along fractures. Propylitic alteration in the sediments is patchy and consists of chlorite and epidote clots. Butherus (1981) reports intrusive breccia near the head of a valley in the NW1/4 sec. 2, T. 43 S., R. 57 W., of the Seward Meridian. The breccia, approximately 800 feet in diameter, contains traces of chalcopyrite and sphalerite in a quartz-tourmaline matrix. Other minerals present include pyrite, calcite, and barite. One sample contained >10,000 ppm copper, 0.06 ppm gold, 13 ppm lead, 28 ppm silver, and 1800 ppm zinc. Three other samples contained up to 750 ppm copper, 0.02 to 0.04 ppm gold, and 1.2 to 11.4 ppm silver.
Workings: Bear Creek Mining Company mapped and sampled this occurrence in 1975-1976, and Resource Associates of Alaska explored it in 1979 and 1981. Copper values of 500 to 2100 ppm occur in an area of 700 by 1500 feet. Molybdenum values of 22 to 160 ppm occur in an area of 1000 by 2000 feet. Gold values are up to 0.18 ppm.
Age: Tertiary.
Alteration: Alteration consists of a broad sericitic zone within the area of higher sulfide content and a peripheral, patchy propylitic zone.
Commodities (Major) - Cu, Mo; (Minor) - Ag, Au, Pb, Zn
Development Status: None
Deposit Model: Porphyry copper; porphyry copper-molybdenum (Cox and Singer, 1986; models 17, 2
Mineral List
8 entries listed. 7 valid minerals.
The above list contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to
visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders
for access and that you are aware of all safety precautions necessary.
References
Anderson, G.D., Fitch, G.M., Lappie, D.W., Lindberg, P.A., and Fankhauser, R.E., 1979, Exploration and evaluation of Bristol Bay Native Corporation Lands, Vol. II, Book 1: Prepared for Houston Oil and Minerals Company by Resource Associates of Alaska, 78 p. (Report held by Alaska Earth Sciences, Inc., Anchorage, Alaska.) Butherus, D.L., White, D.C., Smith, W.H., Radford, G., Sandberg, R.J., and Pray, J.C., 1981, Exploration and evaluation of precious metal potential of Bristol Bay Native Corporation Lands, southwest Alaska, 1981, Vol. 1: Prepared for NERCO by Resource Associates of Alaska, 90 p. (Report held by Alaska Earth Sciences, Inc. Anchorage, Alaska.) Cox, D.P., Detra, D.E., and Detterman, R.L., 1981, Mineral resource maps of the Chignik and Sutwik Island quadrangles, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1053-K, 2 sheets, scale 1:250,000. Detterman, R.L., Miller, T.P., Yount, M.E., and Wilson, F.H.,1981, Geologic map the Chignik and Sutwik Island quadrangles Alaska: U.S. Geologic Survey Miscellaneous Investigations Series Map I-1229, 1 sheet, scale 1:250,000. Fields, E.D., 1977, 1976 Annual report: Alaska search, Chignik area-Bristol Bay region: Bear Creek Mining Company, 44 p., 22 map sheets. (Report held by the Aleut Corporation, Anchorage, Alaska.) MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous mineral deposits in the western part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-F, 38 p., 1 sheet, scale 1:1,000,000. Young, L.E., St. George, P., and Bouley, B., 1997, Porphyry copper deposits in relation to the magmatic history and palinspastic restoration of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral deposits of Alaska: Economic Geology Monograph 9, p. 306-333.
