|Quadrangle map, 1:250,000-scale||MG|
|Quadrangle map, 1:63,360-scale||B-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Ozzna Creek prospect is on the north facing slopes of Ozzna Creek, a west-flowing tributary of the Windy Fork of the Kuskokwim River; it is at an elevation of about 4,750 feet in the SE1/4 sec. 32, T. 26 N., R. 25 W., of the Seward Meridian. The location is accurate.|
The Ozzna Creek prospect consists of base metal sulfide veins and replacement deposits in an extensive quartz-sericite-pyrite halo rimming a 450-meter-wide, quartz-monzonite breccia pipe,. The pipe forms the core of a distinctive, precipitous, 7,205-foot -high peak. A biotite separate from the quartz monzonite pipe gave a K-Ar age of 58 Ma. (Solie and others, 1991). A pronounced magnetic high rims the edge of the breccia pipe (Rob Kell, written communication, 1983). (The magnetic anomaly that rims the quartz monzonite breccia pipe is similar to geophysical features found in porphyry copper systems throughout the North American Cordillera.)
The vein and replacement deposits consist of small pods and lenses of pyrrhotite, sphalerite, argentiferous galena, and pyrite in a gangue of carbonate, epidote, and quartz along shear zones in felsic dikes and igneous breccia. Most of the sulfide pods are from 0.2 to 1.5 meters wide and 0.5 to 6.0 meters long. Selected samples contained 1,623 to 2,189 grams of silver per tonne (Reed and Elliott, 1968).
The quartz-sericite-pyrite halo that surrounds the quartz-monzonite breccia pipe is from 15 to 60 meters wide and can be traced along strike for about 450 meters. Disseminated chalcopyrite and traces of molybdenite occur in pyrite-rich igneous breccia. Selected samples from the quartz-sericite-pyrite halo contain up to 0.08 percent copper, 150 parts per million molybdenum, 1.50 percent lead, 1.00 percent zinc, 14.6 grams of silver per tonne, and 2.48 grams of gold per tonne. (Bundtzen, Kline, and Clough, 1982; Bundtzen, Harris, and Gilbert, 1997).In 2008, this prospect was one of several in a block of claims that covered more than 70 square miles, known collectively as the BMP project (International Tower Hill Mines, Ltd., (2008).
|Geologic map unit||(-153.950719833317, 62.2941823542538)|
|Mineral deposit model||Porphyry copper molybdenum deposit? (Cox and Singer, 1986; model 21a?).|
|Mineral deposit model number||21a?|
|Age of mineralization||Early Tertiary (58 Ma), based on K-Ar biotite age of intrusion.|
|Alteration of deposit||Pyritic and sericitic alteration in breccia pipe.|
|Workings or exploration||Surface sampling by several government agencies. As of 2008, the prospect was within a large block of claims called the BMP project by International Tower Hill MIne, Ltd. (2008).|
|Indication of production||None|
Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic Map of the eastern McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 97-14, 34 p., 1 sheet, scale 1:125,000.
Bundtzen, T.K., Kline, J.T., and Clough, J.G., 1982, Preliminary geology of the McGrath B-2 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Open-File report 149, 22 p., 1 sheet, scale 1:40,000.
Cobb, E.H., 1972, Metallic mineral resources map of the McGrath quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-379, 1 sheet, 1:250,000 scale.
Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-485, 101 p.
International Tower Hills Mines, Ltd., 2008, BMP: http://www.ithmines.com/s/BMP.asp (as of April 30, 2008).
Reed, B.L. and Elliott, R.L., 1968, Geochemical anomalies and metalliferous deposits between Windy Fork and Post River, southern Alaska: U.S. Geological Survey Circular 569, 22 pages.
Smith, T.E., and Albanese, M.D., 1985, Preliminary prospect examinations in the McGrath A-2, A-3, and B-2 quadrangles, Alaska: Alaska Division of Geological and Geophysical Surveys Public Data File 85-54, 19 p.
|Reporters||T.K. Bundtzen (Pacific Rim Geological Consulting); D.J. Grybeck (Port Ludlow, WA)|
|Last report date||6/5/2008|