|Quadrangle map, 1:250,000-scale||NM|
|Quadrangle map, 1:63,360-scale||D-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The occurrence is on the ridge crest between upper West Fork Grand Central River and the head of Windy Creek. It is at an elevation of about 2,250 feet. This is locality 12 of Hummel (1962 [MF 248]) and locality 101 of Hummel (1975).|
Graphite is disseminated in schist and with biotite in segregations as much as 18 inches thick. It also occurs as sparse disseminations in pegmatite. Moffit (1913, p. 135-136) described a graphite-rich layer 8 inches thick between pegmatite and schist walls.The host rocks to this graphite segregation are upper amphibolite facies metasedimentary rocks that are probably derived from Precambrian protolith (Sainsbury, 1972; Bunker and others, 1979; Till and Dumoulin, 1994). They are thought to have undergone regional high-pressure metamorphism along with many other rocks of Seward Peninsula in the Late Jurassic or Early Cretaceous (Sainsbury, Coleman, and Kachadoorian , 1970; Forbes and others, 1984; Thurston, 1985; Patrick, 1988; Patrick and Evans, 1989; Armstrong and others, 1986; Hannula and McWilliams, 1995). Higher temperature metamorphism overprinted these rocks in conjunction with regional extension, crustal melting, and magmatism in the mid-Cretaceous (Throckmorton and Hummel, 1979; Till, 1983; Evans and Patrick, 1987; Leiberman, 1988; Patrick and Leiberman, 1988; Miller and Hudson, 1991; Miller and others, 1992; Dumitru and others, 1995; Hannula and others, 1995; Hudson and Arth, 1983; Hudson, 1994; Amato and others, 1994; Amato and Wright, 1997, 1998). Uplift of the higher temperature metamorphic rocks took place in the mid- to Late Cretaceous and in the Eocene (Calvert, 1992; Dumitru and others, 1995).
|Geologic map unit||(-165.349133314852, 64.9648421121117)|
|Mineral deposit model||Lenses and disseminations of graphite in amphibolite facies metasedimentary rocks.|
|Age of mineralization||Mid-Cretaceous; the age of high temperature metamorphism in the Kigluaik Mountains|
|Indication of production||None|
Amato, J.M., and Wright, J.E., 1997, Potassic mafic magmatism in the Kigluaik gneiss dome, northern Alaska--A geochemical study of arc magmatism in an extensional tectonic setting: Journal of Geophysical Research, v. B102, no. 4, p. 8065-8084.
Amato, J.M., and Wright, J.E., 1998, Geochronologic investigations of magmatism and metamorphism within the Kigluaik Mountains gneiss dome, Seward Peninsula, Alaska, in Clough, J.G., and Larson, Frank, eds., Short Notes on Alaskan Geology 1997: Alaska Division of Geological and Geophysical Surveys Professional Report 118a, p. 1-21.
Armstrong, R.L., Harakal, J.E., Forbes, R.B., Evans, B.W., and Thurston, S.P., 1986, Rb-Sr and K-Ar study of metamorphic rocks of the Seward Peninsula and southern Brooks Range, Alaska, in Evans, B.W., and Brown, E.H., eds., Blueschists and eclogites: Geological Society of America Memoir 164, p. 184-203.
Bunker, C.M., Hedge, C.E., and Sainsbury, C.L., 1979, Radioelement concentrations and preliminary radiometric ages of rock in the Kigluaik Mountains, Seward Peninsula, Alaska: U.S. Geological Survey Professional Paper 1129-C, p. C-1 - C-12.
Calvert, A.T., 1992, Structural evolution and thermochronology of the Kigluaik Mountains, Seward Peninsula, Alaska: Stanford, Calif., Stanford University, M.Sc. thesis, 50 p.
Dumitru, T.A., Miller, E.L., O'Sullivan, P.B., Amato, J.M., Hannula, K.A., Calvert, A.T., and Gans, P.B., 1995, Cretaceous to Recent extension in the Bering Strait region, Alaska: Tectonics, v. 14, p. 549-563.
Evans, B.W. and Patrick, B.E., 1987, Phengite 3-T in high pressure metamorphosed granitic orthogneisses, Seward Peninsula, Alaska: Canadian Mineralogist, v. 25, part 1, p. 141-158.
Forbes, R.B., Evans, B.W., and Thurston, S.P., 1984, Regional progressive high-pressure metamorphism, Seward Peninsula, Alaska: Journal of Metamorphic Geology, v. 2, p. 43-54.
Hannula, K.A., and McWilliams, M.O., 1995, Reconsideration of the age of blueschist facies metamorphism on the Seward Peninusla, Alaska, based on phengite 40Ar/39Ar results: Journal of Metamorphic Geology, v. 13, p. 125-139.
Hannula, K.A., Miller, E.L., Dumitru, T.A., Lee, Jeffrey, and Rubin, C.M., 1995, Structural and metamorphic relations in the southwest Seward Peninsula, Alaska; Crustal extension and the unroofing of blueschists: Geological Society of America Bulletin, v. 107, p. 536-553.
Hawley, C.C., and Associates, 1978, Uranium evaluation of the Seward-Selawik area, Alaska: Department of Energy, Grand Junction, Colo., Open-File Report GJBX-105(78), 91 p.
Hudson, T.L., 1994, Crustal melting events in Alaska, in Plafker, G., and Berg, H. C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, Vol. G-1, p. 657-670.
Hudson, T.L., and Arth, J. G., 1983, Tin granites of Seward Peninsula, Alaska: Geological Society of America Bulletin, v. 94, p. 768-790.
Hummel, C.L., 1962, Preliminary geologic map of the Nome D-1 quadrangle, Seward Peninsula, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-248, 1 sheet, scale 1:63,360.
Hummel, C.L., 1975, Mineral deposits and occurrences, and associated altered rocks in southwest Seward Peninsula, western Alaska: U.S. Geological Survey Open-File Report 75-2, 1 sheet, scale 1:125,000.
Leiberman, J.E., 1988, Metamorphic and structural studies of the Kigluaik Mountains, western Alaska: Seattle, University of Washington, Ph.D. dissertation, 191 p.
Miller, E.L., and Hudson, T.L., 1991, Mid-Cretaceous extensional fragmentation of a Jurassic-Early Cretaceous compressional orogen, Alaska: Tectonics, v. 10, p. 781-796.
Miller, E.L., Calvert, A.T., and Little, T.A., 1992, Strain-collapsed metamorphic isograds in a sillimanite gneiss dome, Seward Peninsula, Alaska: Geology, v. 20, p. 487-490.
Moffit, F.H., 1913, Geology of the Nome and Grand Central quadrangles, Alaska: U.S. Geological Survey Bulletin 533, 140 p.
Patrick, B.E., 1988, Synmetamorphic structural evolution of the Seward Peninsula blueschist terrane, Alaska: Journal of Structural Geology, v. 10, p. 555-565.
Patrick, B.E., and Evans B.W., 1989, Metamorphic evolution of the Seward Peninsula blueschist terrane: Journal of Petrology, v. 30, p. 531-555.
Patrick, B.E., and Leiberman, J.E., 1988, Thermal overprint on blueschists of the Seward Peninsula, the Lepontine in Alaska: Geology, v. 16, p. 1100-1103.
Sainsbury, C.L., 1972, Geologic map of the Teller quadrangle, Seward Peninsula, Alaska: U.S. Geological Survey Map I-685, 4 p., 1 sheet, scale 1:250,000.
Sainsbury, C.L., Coleman, R.G., and Kachadoorian, Reuben, 1970, Blueschist and related greenschist faces rocks of the Seward Peninsula, Alaska, in Geological Survey research 1970: U.S. Geological Survey Professional Paper 700-B, p. B33-B42.
Thurston, S.P., 1985, Structure, petrology, and metamorphic history of the Nome Group blueschist terrane, Salmon Lake area, Seward Peninsula, Alaska: Geological Society of America Bulletin, v. 96, p. 600-617.
Till, A.B., 1980, Crystalline rocks of the Kigluaik Mountains, Seward Peninsula, Alaska: Seattle, University of Washington, M.Sc. thesis, 97 p.
Till, A.B., 1983, Granulite, peridotite, and blueschist--Precambrian to Mesozoic history of Seward Peninsula: Alaska Geological Society Journal, Proceedings of the 1982 Symposium on Western Alaska Resources and Geology, p. 59-65.
|Reporters||C.C. Hawley and Travis L. Hudson|
|Last report date||10/22/1999|