|Quadrangle map, 1:250,000-scale||MH|
|Quadrangle map, 1:63,360-scale||B-6|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||
This placer occurrence is in the headwaters of the West Fork Maclaren River at elevations between about 3,700 and 4,600 feet. The occurrence is shown as the approximate midpoint of the placer at the common south corner of section 1, T. 18 S., R. 5 E., and section 6, T. 18 S., R. 6 E., Fairbanks Meridian. The occurrence corresponds to locality A4 of Kurtak and others (1992).The topographic map of the area (Mount Hayes B-6, edition of 1951) shows the location as glacier and medial moraine. Since 1951, the glacier has receded at least one mile, and the site now is alluvial in character.
This placer occurrence is underlain by schist, amphibolite, slate, and schistose quartz probably of Cretaceous metamorphic age (Nokleberg and others, 1982). The metamorphic rocks are cut by quartz veinlets, some of which contain pyrite and trace amounts of molybdenite (to 22 parts per million molybdenum). Anomalous concentrations of tungsten in placer concentrate samples suggest the probable existence of scheelite at or near the site.Placer gold occurs both in glacial moraine and in active stream gravel. The maximum concentration in a panned concentrate was 10,000 parts per billion (ppb) gold in active stream alluvium; the moraine material contained as much as 1,800 ppb gold (Kurtak and others, 1992, locality A4). The concentrates also contained tungsten; four of five pan-concentrate samples contained from 120 to 310 parts per million (ppm) tungsten. In addition, sample 3005 contained 0.15 percent arsenic, and sample 2662 (concentrates from glacial moraine) contained 740 ppm arsenic. The bedrock sources of the gold, arsenic, and tungsten are unknown.
|Geologic map unit||(-146.681373059825, 63.3729680639759)|
|Mineral deposit model||Placer Au (Cox and Singer, 1986; model 39a).|
|Mineral deposit model number||39a|
|Age of mineralization||Holocene.|
|Workings or exploration||The area was sampled at a reconnaissance level by the U.S. Bureau of Mines (Kurtak and others, 1992).|
|Indication of production||None|
Additional commentsThe U.S. Bureau of Mines recommended additional prospecting along the margins of the glaciers for the bedrock sources of gold and tungsten (Kurtak and others, 1992).
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.
Nokleberg, W.J., Albert, N.R.D., Bond, G.C., Herzon, P.L., Miyaoka, R.T., Nelson, W.H., Richter, D.H., Smith T.E., Stout, J.H., Yeend, Warren, and Zehner, R.E., 1982, Geologic map of the southern Mount Hayes quadrangle, Alaska: U.S. Geological Survey Open-File Report 82-52, 27 p., 1 sheet,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||7/30/2001|