|Quadrangle map, 1:250,000-scale||MH|
|Quadrangle map, 1:63,360-scale||B-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The PG West occurrence is 0.2 mile southwest of peak 7630 and in the NW1/4 section 16, T. 18 N., R. 5 E., Copper River Meridian. The location is accurate.|
The PG West occurrence is a massive sulfide deposit with chalcopyrite, galena, pyrite, and sphalerite in a quartz-ankerite gangue. The deposit is in altered and brecciated quartz sericite schist and carbonaceous schist. Fine to very coarse grained quartz arenite and quartzite units underlie the occurrence, which is above a mafic intrusive body below the PG West occurrence. A gray siltstone composed of quartz, sericite, and graphite forms the hanging wall of the deposit; the overlying rocks consist of chloritic phyllites and intermediate to felsic schists thought to have originally been volcanic sediments and rhyolite tuffs (J. K. Muntzert and others, unpublished Resource Associates of Alaska Inc. report, 1977).
The occurrence was originally described as a volcanogenic massive sulfide deposit. Subsequent examination by American Copper and Nickel in 1994 indicated that the sulfides may be related to skarn developed beside a mafic intrusive (W. Shalosky, written communication, 1994).Resource Associates of Alaska Inc. drilled one core hole in 1977 after finding pyritic massive sulfides in talus. Some pyrite was was intersected in a 1-foot interval in the core; it contained 0.1 percent copper, 0.8 percent lead, 1.5 percent zinc, 27.8 parts per million (ppm) silver, and 0.1 ppm gold (E. Hunter, unpublished data, 1998).
|Geologic map unit||(-144.47444997055, 63.3420219688953)|
|Mineral deposit model||Kuroko massive sulfide (Cox and Singer, 1986; model 28a).|
|Mineral deposit model number||28a|
|Age of mineralization||The enclosing Drum unit has been dated at the Devonian-Mississippian boundary on the basis of one SHRIMP U-Pb zircon age of 359+/- 6 Ma determined at the DD South deposit (MH325) (Dashevsky and others, 2003).|
|Alteration of deposit||Strong enveloping pyrite; ankerite; regional carbonate alteration (Lange and others, 1993).|
|Workings or exploration||Surface sampling and mapping that found the massive sulfide float led to Resource Associates of Alaska Inc. drilling one core hole in 1977.|
|Indication of production||None|
Additional commentsUnpublished data cited is available for viewing by contacting Grayd Resources Inc. in Vancouver, B. C., Canada (www.grayd.com), or Northern Associates Inc. in Fairbanks, Alaska.
Dashevsky, S.S., Schaefer, C.F., and Hunter, E.N., 2003, Bedrock geologic map of the Delta mineral belt, Tok mining district, Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 122, 2 sheets, scale 1:63,360.
Lange, I. M., Nokleberg, W.J., Newkirk, S. R., Aleinikoff, J.N., Church, S.E., and Krouse, R.H., 1993, Devonian volcanogenic massive sulfide deposits and occurrences, southern Yukon-Tanana terrane, eastern Alaska Range, Alaska: Economic Geology, v. 88, p. 344-376.
|Reporters||W. T. Ellis (Alaska Earth Sciences), A.S. Wyatt and S.S. Dashevsky (Northern Associates, Inc. ), and Nokleberg, W.J., (USGS)|
|Last report date||3/20/2003|