Big Boulder Creek

Occurrence, Inactive

Commodities and mineralogy

Main commodities Au
Other commodities Ag
Ore minerals gold
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SK
Quadrangle map, 1:63,360-scale B-4
Latitude 59.44
Longitude -136.2
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is on Boulder Creek about 0.2 miles upstream from the Haines Highway. It is in the NE1/4, section 22, T. 28 S., R. 54 E. of the Copper River Meridian. It is shown as number 41 by Still and others (1984).

Geologic setting

Geologic description

Wright (1904 [B 225 and B 236]) cites the presence of placer gold in Boulder Creek stream gravels but doubts that there are sufficient quantities to warrant mining. Still and others (1984) noted that gold was found in stream gravels and boulders that included argillite float and that porphyritic andesite float was present at the mouth of the canyon just above the the alluvial fan near the Haines Highway.
Winkler and MacKevett (1970) collected several bedrock samples, MK 13A, MK 13D-1, and MK 13E, along Boulder Creek below the 1,000 foot elevation. Their description of MK 13A mentions an altered fault zone with quartz pods. The descriptions of MK 13D-1 and MK 13E mention quartz stringers. Sample MK 13A contained 1,500 ppm barium, 300 ppm lanthanum, 500 ppm niobium, 20 ppm tin, 200 ppm yttrium, and greater than 9,999 ppm zirconium. The description by MacKevett and others (1974) of an altered fault zone on Big Boulder Creek mentions fragmented pegmatitic material and apparently refers to the site sampled by MK 13A.
Bedded rocks within the Big Boulder Creek drainage area are variably metamorphosed, metasediments and metavolcanics of the Cheetdeekahyu Group of Redman and others (1985). North of the Klehini River, the metamorphic grade and average grain size of these rocks increases to the north and northeast towards Four Winds Mountain. These rocks have been included in the Four Winds metamorphic complex (Forbes and others, 1987; Gilbert and others, 1987). They are of probable Devonian or Late Triassic age (Gilbert and others, 1987).
Geologic map unit (-136.201853831999, 59.4396755749442)
Mineral deposit model Quaternary Au placer (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Quaternary placer.

Production and reserves

Workings or exploration Worked by hand methods in early 1900s, but no production is documented.
Indication of production None
Production notes Probably minor, at best.

References

MRDS Number A013100

References

Forbes, R.B., Gilbert, W.G., and Redman, E.C., 1987, The Four Winds Complex; a newly recognized Paleozoic metamorphic terrane in southeastern Alaska [abs.]: Geological Society of America, Abstracts with Program, v. 19, no. 6, p. 378.
Reporters T.C. Crafford (T. Crafford & Associates, Anchorage)
Last report date 2/4/2001