Unnamed (near Ganes Creek)

Prospect, Active

Commodities and mineralogy

Main commodities As; Au; Cu; Pb
Ore minerals arsenopyrite; chalcocite; chalcopyrite; galena; pyrite
Gangue minerals carbonates; quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale ID
Quadrangle map, 1:63,360-scale D-1
Latitude 62.9662
Longitude -156.4988
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is along the ridge--locally known as Potosi Ridge--between Six Gulch, a west-flowing tributary to Ganes Creek and the first tributary to the north which is locally called Potosi Creek. The prospect is about 0.7 mile east of the junction of Six Gulch and Ganes Creek, about 0.2 mile north-northwest of the center of section 9. T. 33 N., R. 38 W. The location is accurate.

Geologic setting

Geologic description

This deposit was first described by Grady (2009) as a result of recent work in the Ganes Creek area that included the nearby and better-known Independence Mine (ID031). The prospect is in an area that has been explored by at least six companies since 1988, notably Great Basin Gold Ltd. in 2007 and 2008. The total work of these companies included more than 32,000 meters of trenching and continuous chip sampling of the trenches, as well as 83.6 line miles of ground IP, TMF, and HLEM geophysical surveys. In early 2010, the property was owned and operated by Clark-Winze Mining (Grady, 2009).
This prospect and the Independence mine are within the cores of major northeast-striking antiforms in Cretaceous Kuskokwim Group flysch. The hinges of the antiforms are thickened and marked by chevron folding and high angle faulting. In some cases, the cores of the some of the antiforms are deformed into brittle melange. The prospects are associated with northeast-striking swarms of mafic to granitic dikes and older biotite granodiorite to aplite sills. The dike swarms are offset by numerous north-northwest high-angle faults and joints and often have marginal dip-slip faults.
The mineralization in the area is marked by quartz-carbonate veins along fractures. The veins typically have early quartz-carbonate margins with cores of clear to white quartz and carbonates. Occasionally, the veins contains late-stage quartz, iron carbonates, and sericite. Sparse pyrite and arsenopyrite occur in the veins and wall rock. Rare chalcopyrite, galena, and chalcocite are present in the high-grade veins. Two samples contained 14 part per million gold; the sample were taken from quartz-carbonate veins that cut mafic sills and and shear zones.
3D modeling of gridded IP surveys show that geophysical anomalies are associated with high copper, nickel, lead, and zinc values in soils. Resistivity data outlines the the dike swarms; magnetic highs correspond to felsic intrusives and magnetic lows outline silicification and brecciation.
Geologic map unit (-156.501164322924, 62.9655675120358)
Mineral deposit model Low-sulfide gold-quartz veins.
Age of mineralization Cretaceous or younger based on the age of the host rock.
Alteration of deposit Silicification.

Production and reserves

Workings or exploration This deposit was first described by Grady (2009) in conjunction with recent work in the Ganes Creek area that also included the nearby and better-known Independence Mine (ID031). This prospect is within an area that has been explored by at least six companies since 1988, notably Great Basin Gold Ltd. in 2007 and 2008. Their work included more than 32,000 meters of trenching and continuous chip sampling of the trenches, as well as 83.6 line miles of IP, TMF, and HLEM ground geophysical surveys. In early 2010, the property was owned and operated by Clark-Winze Mining (Grady, 2009).
Indication of production None
Reserve estimates None.
Production notes None.

References

References

Grady, Jesse C., 2009, High-grade structurally controlled gold veins at Ganes Creek, Ophir mining district, southwestern Alaska: Abstracts, Alaska Miners Association, 2009 Annual Convention, p. 15-16. (As of Feb 2, 2010, on the Internet as: http://www.alaskaminers.org/abstracts2009.pdf).
Reporters D.J. Grybeck (Contractor, U.S. Geological Survey)
Last report date 4/2/2010