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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  28-Dec-1988 by Dorthe E. Jakobsen (DEJ)

Summary Help Help

NMI
Name VIRGINIA Mining Division Alaska, USA
BCGS Map 104B010
Status Showing NTS Map 104B01E
Latitude 056º 02' 23'' UTM 09 (NAD 83)
Longitude 130º 02' 38'' Northing 6210992
Easting 434963
Commodities Gold, Lead, Zinc, Copper Deposit Types I05 : Polymetallic veins Ag-Pb-Zn+/-Au
I02 : Intrusion-related Au pyrrhotite veins
Tectonic Belt Intermontane Terrane Stikine
Capsule Geology

The Virginia showing is located near the junction of the Salmon River and Boundary Creek on the banks of Cascade Creek in southeastern Alaska.

Located in the Intermontane Belt, the area, bounded on the west by the Coast Crystalline Complex and on the east by the Bowser Basin, is part of the Stikinia Terrane.

The showing is hosted by the Upper Triassic to Lower Jurassic Hazelton Group Unuk River Formation metavolcanics. The Hazelton Group is a northwest trending, steeply east dipping belt of folded andesitic lapilli tuffs, flows and breccia containing a thick sequence of argillite and siltstone infolded along a synclinal axis. The sequence is intruded by the Early Jurassic Texas Creek plutonic suite of dacitic porphyry dykes and sills, Eocene granitic Hyder intrusives and lamprophyre dykes.

An adit has been driven in intensely altered porphyry and a drift exposed a mineralized shoot in a 61.0 centimetre wide shear zone. The shoot strikes 130 degrees, dips southward and consists of almost solid sulphide in quartz gangue. These sulphides are pyrrhotite, sphalerite pyrite and a little galena and tetrahedrite. Mineralized bands are also exposed in the roof of the drift and quartz veins and calcite veinlets are common. Near the portal of the adit a lamprophyre dyke was intersected. Values as high as 154.30 grams per tonne gold are reported from selected samples of ore (United States Geological Survey Bulletin 807). Another adit, 46.0 metres upstream, exposed sparse similiar mineralization with the addition of minor chalco- pyrite and a notable quantity of epidote in bands and veins. Mineralization on the property occurs in veins, stringers, threads, blebs, and as fracture fillings and disseminated in host rocks.

Contact metamorphism has produced epidote and rare garnet near several dykes on the property.

Bibliography
EMPR AR 1923-A87
EMPR BULL 58; 63
EMPR FIELDWORK 1983, pp. 149-165; 1984, pp. 316-342; 1985, pp. 217-219
EMPR OF 1987-22
EMPR REGIONAL PF (Mineral Terranes of Alaska, 1982 Plate F; Sutherland-Brown, A., (1951): Cordilleran Structure in Canada and Alaska)
GSC MEM 175
GSC P 89-1E, pp. 145-154
CIM Spec. Vol. 8, pp. 149-170,215-229
CJES VOL 10, Part 1, 1973, pp. 408-420
USGS BULL 722; 800; *807-88,89; 1024; 1425
Brown, D.A., (1987): Geological Setting of the Volcanic-Hosted Silbak Premier Mine, Northwestern British Columbia, M.Sc. Thesis, University of British Columbia (in Property File: 104B 054)
EMPR PFD 18927, 18928

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