Portage Creek

Mine, Active

Commodities and mineralogy

Main commodities Au
Other commodities Ba
Ore minerals gold

Geographic location

Quadrangle map, 1:250,000-scale LC
Quadrangle map, 1:63,360-scale B-3
Latitude 60.363
Longitude -154.039
Nearby scientific data Find additional scientific data near this location
Location and accuracy Portage Creek, which flows southward, empties into Lake Clark. Mining extends from the mouth of Portage Creek to about 2.75 km upstream. This is locality 24 of Nelson and others (1985), locality 8 of MacKevett and Holloway (1977), and locality 9 of Cobb (1972). Sec. 7, 17, and 18 T. 3 N., R. 27 W., of the Seward Meridian.

Geologic setting

Geologic description

Bundtzen and Kline (1979) described the Portage Creek placer deposits. The stream gravels in the canyon (upper claims) are undergoing rapid transport by periodic floods which move large amounts of gravel and boulders. The stream gradient in the canyon drops about 500 ft/mile (100 m/km). Downstream from the canyon (lower claims) is a large alluvial fan delta. Former bedrock channels may be 120 ft (40 meters) or more in depth. The stream gradient in fan-delta complex drops about 200 ft/mile (40 m/km). Portage Creek is crossed by the NE-trending Lake Clark fault zone. Bundtzen and Kline (1979) indicate that the placer deposits formed in response to relatively short-term hydraulic events, contrasting with older, more developed heavy mineral placers of interior Alaska. Most or all gravel in the Portage Creek area are thawed.
Bedrock in the vicinity includes Tertiary volcanics (rhyolitic breccia, ash-flow tuff, flows and intrusive rocks - and subordinate mafic to intermediate flows) and late Paleozoic-early Mesozoic metamorphic rocks (Nelson and others, 1983; units Tv and MzPzm).
Geologic map unit (-154.041221352137, 60.3623380574231)
Mineral deposit model Placer Au (Cox and Singer, 1986; model 39a)
Mineral deposit model number 39a
Age of mineralization Quaternary.
Alteration of deposit Not applicable

Production and reserves

Workings or exploration Early mining work was by primitive pick and shovel methods. Hydraulic methods were used between 1939 and 1958 utilizing an earthen dam, flume, hydraulic pipe, and hydraulically operated winch.
Indication of production Yes; small
Reserve estimates No reserves
Production notes A total production figure for Portage Creek is not available. Probably no more than 1,000 oz of gold was produced since discovery in about 1900 (Bundtzen and Kline, 1979).

Additional comments

Lode source of gold has not been found, but believed to be close. Site is in Lake Clark National Park and Preserve.

References

MRDS Number A013000

References

Reporters M.L. Miller (USGS); D.P. Bickerstaff (USGS)
Last report date 6/15/1998