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

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Name PORTLAND, USA Mining Division Alaska, USA
BCGS Map 104B010
Status Showing NTS Map 104B01E
Latitude 056º 01' 19'' UTM 09 (NAD 83)
Longitude 130º 03' 13'' Northing 6209023
Easting 434327
Commodities Lead, Zinc, Copper Deposit Types I05 : Polymetallic veins Ag-Pb-Zn+/-Au
Tectonic Belt Intermontane Terrane Stikine
Capsule Geology

The Portland showing is located east of the Salmon River 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.

A 61.0 centimetre quartz vein has been exposed in a 4.6 metre adit driven in argillite. The vein strikes 120 degrees, dips 52 degrees south and has been traced for approximately 452 metres by pits and surface exposures. Mineralization consists of sparse disseminated pyrite, galena and blebs of sphalerite and minor chalcopyrite. The argillite contains other quartz veins and stringers.

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 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; *807-84; 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)