Shepard (ARDF #MD034) Au, Cu, Zn

Shepard

Occurrence, Active?

Commodities and mineralogy

Main commodities	Au; Cu; Zn
Other commodities	Co
Ore minerals	arsenopyrite; chalcopyrite
Gangue minerals	quartz

Geographic location

Quadrangle map, 1:250,000-scale	MD
Quadrangle map, 1:63,360-scale	C-3
Latitude	63.592
Longitude	-154.225
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	The Shepard occurrence is situated on a north-facing spur of a sharp 3,160 foot high peak that overlooks Shepard Creek. The occurrence is at an elevation of 3,080 feet (939 m) in section 9, T. 22 S., R. 24 E., of the Kateel River Meridian. The site is accurate to within 500 feet (152 m).

Geologic setting

Geologic description The Shepard occurrence consists of quartz veins in and near a northwest trending quartz monzonite dike swarm (DiMarchi and others, 1992). The quartz veins contain disseminated arsenopyrite, chalcopyrite, and carry gold values; they are found in zones of silicic and phyllic alteration in the quartz monzonite dikes. Surface samples collected by DiMarchi and others (1992) contain up to 500 ppb gold. Nine samples averaged 100 ppb gold. Copper, cobalt, and arsenic values were not reported. Soil samples collected by Newmont Mining Corporation in 2011 demonstrated high-grade gold assays of up to 18 ppm gold. These samples are associated with 5 to 10 centimeter wide quartz veins hosted in intensely hornfelsed Kuskokwim metamorphic rocks (Newmont Mining Corp, 2011).
Geologic map unit	(-154.22734690197, 63.5914102234212)
Mineral deposit model	Polymetallic veins (Cox and Singer, 1986; model no. 22c)
Mineral deposit model number	22c
Age of mineralization	The Shepard prospect is inferred to be Late Cretaceous based on isotopic age of Mystery Mountains intrusive complex (Moll and others, 1981).
Alteration of deposit	Silicic and phyllic in intrusion.

Production and reserves

Workings or exploration	Surface samples taken by DiMarchi and others (1992) contain up to 500 ppb gold. Nine samples averaged 100 ppb gold. Copper, cobalt, and arsenic values are not reported. Newmont Mining Corporation collected 222 soil samplings and 21 rock chip samples in conjunction with detailed geologic mapping in 2011. Soil samples were collected along ridges and spurs on a nominal spacing of 100 meters. High-grade gold assays in soil samples of up to 18 ppm gold, are associated with 5 to 10 centimeter wide quartz veins hosted in intensely hornfelsed Kuskokwim metasediments (Newmont Mining Corp, 2011).
Indication of production	None
Reserve estimates	None.
Production notes	None.
Additional comments The Shepard occurrence is on lands selected or owned by Doyon Ltd. For further information, contact Doyon Ltd. at 210 1st Ave., Fairbanks, Alaska, 99701.

References

References Cox, D.P., and Singer, D.A., eds., 1986, Mineral deposit models: U.S. Geological Survey Bulletin 1693, 379 p. DiMarchi, J.J., Weglarz, T.B., Freeman, L.K., Nicholson, L.C., and Barker, J.C., 1992, Annual Report for 1992--Doyon Option Lands, Block 10: ASA Inc. Report, 121 p. (Report held by Doyon, Limited, Fairbanks, Alaska.) Newmont Mining Corp., 2011, Doyon Kuskokwim Block 10, 2011 Work Summary, Doyon limited report 2012-03 (Report held by Doyon Limited, Fairbanks, Alaska.)
Reporters	Bundtzen, T.K. (Pacific Rim Geological Consulting); V.C. Zinno (Alaska Earth Sciences, Inc.)
Last report date	9/2/2014