MINFILE Mineral Inventory

MINFILE Record Summary

MINFILE No 104B 066

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

SUMMARY

Summary Help


		NMI
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.

Bibliography

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; *807-84; 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)