|Quadrangle map, 1:250,000-scale||SL|
|Quadrangle map, 1:63,360-scale||C-6|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This site is on the north bank of the Moghoweyik River, 3/4 mile upstream from the mouth on the west coast of St. Lawrence Island. It is located within 1/4 mile and is locality 4 of Cobb (1972). Cobb (1980) summarized relevant references under the name 'Moghoweyik R., lower'.|
Geologic descriptionMolybdenite mineralization here is in the Sevuokuk pluton, a mid-Cretaceous (108 +/- 3.2 Ma) composite body that includes biotite hornblende quartz monzonite and biotite quartz monzonite phases (Csejtey, Patton, and Miller, 1971; Patton and Csejtey, 1980). At this site, molybdenite occurs in thin veinlets cutting highly oxidized pyritiferous biotite quartz monzonite. The quartz monzonite is also cut by quartz veins and aplite dikes (Patton and Csejtey, 1971, p. C10). Three grab samples contained 7, 500, and 1,500 ppm molybdenum and 700, 150, and 15 ppm copper respectively (Patton and Csejtey, 1971. p. C8). A pan concentrate from the riverbed gravels at this locality contained 70 ppm molybdenum and 5,000 ppm tungsten (Patton and Csejtey, 1971, p. C10).
|Geologic map unit||(-171.744787862025, 63.4680667381745)|
|Mineral deposit model||Porphyry Mo, low-F? (Cox and Singer, 1986; model 21b?).|
|Mineral deposit model number||21b?|
|Age of mineralization||Mid-Cretaceous, the age of the host Sevuokuk pluton (108 +/- 3.2 Ma; Patton and Csejtey, 1980).|
|Alteration of deposit||Pyrite is apparently abundant and disseminated in the biotite quartz monzonite as well as accompanying molybdenite in veins. Pyrite oxidation is well-developed and other alteration is probably present although not described.|
|Workings or exploration||Three grab samples contained 7, 500, and 1,500 ppm molybdenum and 700, 150, and 15 ppm copper respectively (Patton and Csejtey, 1971. p. C8). A pan concentrate from the riverbed gravels at this locality contained 70 ppm molybdenum and 5,000 ppm tungsten (Patton and Csejtey, 1971, p. C10).|
|Indication of production||None|
Cobb, E.H., 1972, Metallic mineral resources map of the Saint Lawrence quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-465, 1 sheet, scale 1:250,000.
Cobb, E.H., 1980, Summaries of data and lists of references to metallic and selected nonmetallic mineral deposits in fifteen quadrangles in southwestern and west-central Alaska: U.S. Geological Survey Open-File Report 80-909, 103 p.
Csejtey, Bela, Jr., Patton, W.W., Jr., and Miller, T.P., 1971, Cretaceous plutonic rocks of St. Lawrence Island, Alaska, a preliminary report: U.S. Geological Survey Professional Paper 750-D, p. D68-D76.
Patton, W.W., Jr., and Csejtey, Bela, Jr., 1971, Preliminary geologic investigations of western St. Lawrence Island, Alaska: U.S. Geological Survey Professional Paper 684-C, p. C1-C15.
|Reporters||Travis L. Hudson (Applied Geology)|
|Last report date||9/10/1998|