|Quadrangle map, 1:250,000-scale||NM|
|Quadrangle map, 1:63,360-scale||D-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||Fluorite Creek was a local name assigned by Sainsbury, Kachadoorian, and Smith (1970) to an upper tributary to Tisuk River in the NW1/4 section 4, T. 7 S., R. 36 W., Kateel River Meridian. The occurrence is at an elevation of about 1,800 feet and located within about 1,000 feet of the coordinates.|
Fluorite was found in two breccia pipes at this locality (Sainsbury, Kachadoorian, and Smith, 1970). The easternmost pipe is 40 to 60 percent fluorite and 20 feet wide; it consists of a central core of crystalline fluorite surrounded by a margin of banded silica and fluorite with pyrite. Locally this breccia is silicified, pyritized, and cemented by fluorite. The central fluorite-rich core is cut by iron-stained veinlets 0.25 to 0.5 inch thick. The second pipe, located 350 feet west of the first, is smaller and more pyritized and contains a higher percentage of silicified breccia. A large fault, spatially associated with the pipes, is marked by a 30- to 40-foot-wide jasperoid containing a few percent fluorite. A sample of the pyrite-bearing jasperoid breccia contained 3 ppm silver and 70 ppm molybdenum; no gold was detected. The wall rock along normal faults in the general area are mineralized with pyrrhotite, pyrite, and traces of other sulfides.Mid-Cretaceous granite stocks and felsic dikes are common in the western Kigluaik Mountains where they intrude amphibolite facies metasedimentary schist and gneiss (Sainsbury, Smith, and Kachadoorian, 1972). The metasedimentary rocks are derived from a late Proterozoic or early Paleozoic protolith (Till and Dumoulin, 1994; Hannula and others, 1995), perhaps correlative with parts of the Nome Group. Like the Nome Group, these rocks probably underwent regional blueschist facies metamorphism in the Late Jurassic or Early Cretaceous (Sainsbury, Coleman, and Kachadoorian, 1970; Forbes and others, 1984; Thurston, 1985; Armstrong and others, 1986; Hannula and McWilliams, 1995). The blueschist facies rocks were recrystallized to greenschist facies or higher metamorphic grades in conjunction with regional extension, crustal melting, and magmatism in the mid-Cretaceous (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||(-165.97774168717, 64.9123317933554)|
|Mineral deposit model||Fluorite breccia pipe in amphibolite facies metasedimentary rocks.|
|Age of mineralization||Cretaceous; breccias crosscut mid-Cretaceous amphibolite facies metamorphic rocks and may be related to Cretaceous granitic rocks in the area.|
|Alteration of deposit||Fluorite and silica replacement.|
|Workings or exploration||Only natural surface exposures are present.|
|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.
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.
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.
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.
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.
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.
Sainsbury, C.L., Kachadoorian, Reuben, and Smith, T.E., 1970, Fluorite prospects in the northwestern Kigluaik Mountains, Nome D-2 quadrangle, Alaska: U.S. Geological Survey Open-File Report 70-284, 8 p.
Sainsbury, C.L., Smith, T.E., and Kachadoorian, Reuben, 1972, Reconnaissance geologic map of the Nome D-3 quadrangle, Alaska: U.S. Geological Survey Open-File Report 72-327, 14 p., 1 sheet, scale 1:63,360.
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., and Dumoulin, J.A, 1994, Geology of Seward Peninsula and St. Lawrence Island, in Plafker, G., and Berg, H.C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, v. G-1, p. 141-152.
|Reporters||C.C. Hawley and Travis L. Hudson|
|Last report date||10/22/1999|