|Quadrangle map, 1:250,000-scale||CH|
|Quadrangle map, 1:63,360-scale||D-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This occurrence is at an elevation of about 4,500 feet on a ridge approximately 1 1/2 miles southwest of the headwater lake on Thru Creek (NE1/4 sec. 9, T. 35 N., R. 5 W., of the Fairbanks Meridian). The location is accurate within a 1/2-mile radius.|
Geologic descriptionThe Bob prospect is one of several Pb-Zn-Ag plus or minus Cu prospects near this site (DeYoung, 1978). Information specific to the property is sparse and only describes the prospect as galena and sphalerite with silver values in skarn associated with limestone (Grybeck, 1977). Newberry and others (1997) include the Bob prospect in a group of calcic Zn-Pb skarns and replacement bodies. These Zn-Pb skarns are described by Newberry and others (1986) as distal to Devonian(?) porphyry Cu-Mo systems associated with the Horace Mountain plutons in the Chandalar copper belt. The bedrock near of the prospect is mapped as Devonian Hunt Fork Shale near its contact with Skajit Limestone (Brosgé and Reiser, 1964). Intercalated diorite sills and andesitic flows(?) are also present in the section.
|Geologic map unit||(-148.682769039402, 67.8796143793321)|
|Mineral deposit model||Zn-Pb skarn deposits? (Cox and Singer, 1986; model 18c?).|
|Mineral deposit model number||18c?|
|Age of mineralization||Devonian(?) based on reported Early Devonian Pb/Pb zircon ages from the associated Baby Creek batholith and Horace Mountain plutons (Dillon and others, 1996).|
|Alteration of deposit||Calc-silicate.|
|Workings or exploration||Claims were located in 1972 and 1976 by Placid Oil. No other information is available.|
|Indication of production||None|
Additional commentsSee also: Bibban prospect (CH090). Alaska Kardex No. 031-61A (Kardex is a card file mining claim information system located at the State of Alaska DNR Public Information Center in Fairbanks).
Cobb, E.H., and Cruz, E.L., 1983, Summaries of data and lists of references to metallic and selected nonmetallic mineral deposits in the Chandalar quadrangle, Alaska: U.S. Geological Survey Open-File Report 83-278, 91 p.
DeYoung, J.H., Jr., 1978, Mineral resources map of the Chandalar quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-878-B, 2 sheets, scale 1:250,000.
Grybeck, Donald, 1977, Known mineral deposits of the Brooks Range, Alaska: U.S. Geological Survey Open-File Report 77-166C, 45 p., 1 sheet, scale 1:1,000,000.
Newberry, R.J., Allegro, G.L., Cutler, S.E., Hagen-Levelle, D.D., Adams, D.D., Nicholson, L.C., Weglarz, T.B., Bakke, A.A., Clautice, K.H., Coulter, G.A., Ford, M.J., Myers, G.L., and Szumigala, D.J., 1997, Skarn deposits of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 355-395.
Newberry, R.J., Dillon, J.T., and Adams, D.D., 1986, Regionally metamorphosed calc-silicate-hosted deposits of the Brooks Range, northern Alaska: Economic Geology, v. 81, p. 1728-1752.
|Reporters||J.M. Britton (Anchorage)|
|Last report date||11/17/1999|