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LZ East

Prospect, Inactive

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Commodities and mineralogy

Main commodities Cu; Pb; Zn
Other commodities Ag; Au
Ore minerals arsenopyrite; chalcopyrite; galena; marcasite; pyrite; pyrrhotite; sphalerite; tennantite
Gangue minerals calcite; chlorite; dolomite; graphite; quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale A-1
Latitude 63.1791
Longitude -144.1465
Nearby scientific data Find additional scientific data near this location
Location and accuracy The LZ East prospect is along strike 2,000 feet southeast of the LZ prospect (MH327). It is between Rumble Creek and the Tok River at an elevation of about 6,900 feet. It is about one-half mile east-southeast of the center of section 7, T. 16 N, R. 7 E., Copper River Meridian. The location is accurate.

Geologic setting

Geologic description

The LZ East prospect is one in a series of massive sulfide occurrences (MH327-MH328, MH350-MH353) that are intermittently exposed for 7 miles along strike in a thrust-repeated section of the lower Lagoon unit (Dashevsky and others, 2003). The LZ East deposit occurs as multiple thin massive sulfide sheets associated with felsic metavolcanic rocks in a sequence of graphitic siltstone, graphitic dolomite, and minor quartz-sericite-schist and marble. The average grade is 0.25 percent copper, 2.78 percent lead, 2.82 percent zinc, 80.2 grams of silver per ton, and 0.16 grams of gold per ton (Lange and others, 1993). American Copper and Nickel Company drilled two core holes in 1997 and intersected at least three massive sulfide bands 1.0 to 5.6 feet thick with grades of 0.4 to 1.0 percent copper, 3.4 to 8.9 percent lead, 5 to 11 percent zinc, 3.5 to 6.0 ounces of silver per ton, and 0.02 to 0.08 ounce of gold per ton (E. Hunter, unpublished data, 1998).
Geologic map unit (-144.148743524783, 63.1787205832567)
Mineral deposit model Kuroko massive sulfide (Cox and Singer, 1986; model 28a).
Mineral deposit model number 28a
Age of mineralization The lower Lagoon metamorphic sequence that hosts the this prospect has been dated as Devonian on the basis of one SHRIMP U-Pb zircon age of 372 +/- 6 Ma (Dashevsky and others, 2003).

Production and reserves

Workings or exploration Extensive field work has been done to define the PP-LZ mineralized zone, including geologic mapping, soil sampling, stream-sediment sampling, and geophysical analysis (Rodney A. Blakestad and others, unpublished Resource Associates of Alaska Inc. report, 1976).
Indication of production None

Additional comments

The unpublished data that is cited can be seen by contacting Grayd Resources Inc. in Vancouver, B.C., Canada (www.grayd.com), or Northern Associates Inc. in Fairbanks, Alaska.

References

References

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 W.J. Nokleberg (USGS)
Last report date 3/20/2003