|Quadrangle map, 1:250,000-scale||GU|
|Quadrangle map, 1:63,360-scale||C-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The occurrence is on the north flank of a hill which is locally called Grizzly Hill, a broad ridge trending east-northeast of VABM Cobb. The site is approximately centered along the south half of the section line dividing sections 17 and 18, T. 11 N., R. 7 E., Copper River Meridian.|
The higher part of the area consists of Border Phase rocks of the Pennsylvanian to Permian, Ahtell pluton. These rocks are apparently underlain by the Grubstake Phase of the pluton and are cut by east-northeast-trending dikes and masses of younger Jurassic diorite (Richter, 1966; Richter and Matson, 1968).The approximate center of the occurrence is on the east end of a locally sulfidized, silica-carbonate zone, included within the area 3a of WGM Inc. (1980, fig. 3) which is anomalous in gold. The area also has anomalous lead and zinc (Richter, 1966). A stream-sediment sample in the drainage on the north side of the occurrence contained 7,100 ppb gold (Richter and Matson, 1978). The occurrences may extend over the ridge to the south where Kirk Stanley reported (written communication, 2000) low-grade, gold-tourmaline mineral occurrences, also argentiferous galena-quartz veins. Stanley speculated that there was a large tourmaline breccia pipe in the area.
|Geologic map unit||(-144.152184733676, 62.7296054716771)|
|Mineral deposit model||Polymetallic veins, Au porphyry? (Cox and Singer, 1986; model 22c).|
|Mineral deposit model number||22c?|
|Age of mineralization||Uncertain; possibly composite mineralization related to both the Pennsylvanian to Permian, Ahtell pluton and the crosscutting Jurassic diorite, but could be related to either.|
|Alteration of deposit||Silicification; formation of silica-carbonate and tourmaline-bearing rocks.|
|Workings or exploration||Most of the area has only been mapped in reconnaissance and sampled with stream sediments. Kirk Stanley (written communication, 2000) trenched a nearby area on the south flank of the Grizzly Hills in about 1970.|
|Indication of production||None|
Additional commentsAdditional information can be obtained from Ahtna Minerals in Anchorage, Alaska.
Richter, D.H., 1966, Geology of the Slana district, southcentral Alaska: Alaska Division of Geological and Geophysical Surveys Geological Report 2l, 54 p., 3 sheets, scale 1:63,360.
Richter, D.H., and Matson, N.A., Jr., 1968, Distribution of gold and some base metals in the Slana area, eastern Alaska Range, Alaska: U.S. Geological Survey Circular 593, 20 p.
WGM Inc., 1980, 1979 Summary report of gold potential, Slana District, Ahtna project: WGM Inc., 10 p., map, scale 1:63,360. (Report held by Ahtna Mineral Co., Anchorage, Alaska).
|Reporters||W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (U.S. Geological Survey)|
|Last report date||12/7/2000|