|Quadrangle map, 1:250,000-scale||MH|
|Quadrangle map, 1:63,360-scale||B-5|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This placer prospect extends from elevations of about 3,000 to 3,350 feet on the East Fork Maclaren River, about 2 miles west of the outwash plain of the Eureka Glacier. The prospect is near the center of section 17, T. 19 S., R. 7 E., Fairbanks Meridian. The site corresponds to the approximate midpoint of placer locality A14 of Kurtak and others (1992). This is Kardex site number KX86-206 (Heiner and Porter, 1972).|
The upper East Fork Maclaren River below Eureka Glacier cuts tuffaceous rocks of Triassic age. Lowermost Eureka Glacier appears to cross a dunite-rich zone of the Fish Lake mafic-ultramafic complex about a mile wide (Stout, 1976, plate 1). Eureka Glacier trends nearly north-south; the uppermost East Fork Maclaren River trends about east-west; consequently it is uncertain if the glacier scoured the upper East Fork and removed any placer concentrations of pre-glacial age.The U.S. Bureau of Mines collected three pan-concentrate samples from this placer (Kurtak and others, 1992, table A14). All contained particulate gold. Sample 1036 contained 0.0019 ounce of recoverable gold per cubic yard. Platinum-group metals were not determined. Sample 1576 (bank gravel) had 1 fine and 30 very fine gold flakes; a pan-concentrate sample assayed 40 parts per billion (ppb) platinum, 6 ppb palladium, and 1 part per million silver.
|Geologic map unit||(-146.444863453328, 63.2676715936287)|
|Mineral deposit model||Placer Au-PGE (Cox and Singer, 1986; model 39a).|
|Mineral deposit model number||39a|
|Age of mineralization||Holocene.|
|Workings or exploration||
The Three Bears claims were staked along the East Fork in 1979-80. From 1981 to 1986, claims were tested by backhoe test holes and by suction dredging. During its investigation of the Valdez Creek district, the U.S. Bureau of Mines collected three placer samples (Kurtak and others, 1992), one of which contained 0.0019 ounce of recoverable gold per cubic yard. Another sample contained 40 parts per billion (ppb) platinum and 6 ppb palladium.The occurrence is now covered by claims owned by MAN Resources (W.T. Ellis, written communication, 2001).
|Indication of production||None|
Additional commentsThe presence of gold and platinum-group metals suggests that more testing is warranted.
Kurtak, J.M., Southworth, D.D., Balen, M.D., and Clautice, K.H., 1991, Mineral investigations in the Valdez Creek Mining District, south-central Alaska: U.S. Bureau of Mines Open-File Report 1-92, 658 p., 2 sheets, scale 1:250,000.
|Reporters||W.T. Ellis (Alaska Earth Science), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)|
|Last report date||8/6/2001|