Summit High Bench

Mine, Probably inactive

Commodities and mineralogy

Main commodities Au
Ore minerals gold

Geographic location

Quadrangle map, 1:250,000-scale NM
Quadrangle map, 1:63,360-scale C-1
Latitude 64.5785
Longitude -165.3596
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Summit high-level placer gold deposit is at an elevation of about 530 feet on the low divide between upper Specimen Gulch (NM312) and Grass Gulch. It is 5,500 feet north-northeast of the summit of Anvil Mountain in the west-central part of section 31, T. 10 S., R. 33 W., Kateel River Meridian. Summit was a former station on the abandoned Seward Peninsula railway. The locality is included in numer 18 of Cobb (1972 [MF 463], 1978 [OFR 78-93]).

Geologic setting

Geologic description

The Summit high-level bench placer mine worked a gravel deposit 600 to 800 feet wide at the surface. The pay streak was in a 50 to 80-foot-wide bedrock channel incised in schist. The mine was developed by shafts and drifts. On the Summit claim (at about 525 feet surface elevation), the gravel was 106 feet thick, and the elevation of the underlying surface of the schist was about 420 feet (Collier and others, 1908, p. 206). At the bottom of the Summit shaft, the local pay streak trended N 82 W. The pay gravel was about 6 to 7 feet thick and was composed of waterworn boulders and cobbles of schist, limestone (marble), and granite. In contrast to the deposit on Dexter divide (NM246), gold nuggets were well rounded and appeared to have been transported for some distance. The pay streak averaged about 7 to 8 dollars per yard (gold at 20.67 dollars per ounce), but some ground was appreciably richer yielding pans worth as much as 150 dollars. One nugget weighed about 7 ounces. Collier and his associates thought that gneiss and granite boulders 'must have come from a great distance and seem to indicate that the stream which deposited them was a long one' (Collier and others, 1908, p. 206).
The high-level gravels were originally interpreted to be alluvial deposits in stream channels of former drainage systems, but David Hopkins has proposed that they are ice-marginal systems (Hopkins and others, 1960; cited in Cobb, 1973 [B 1374, p. 83]; Nelson and Hopkins, 1972). Unlike the Dexter area, where exotic boulders appear to be mostly been in the shallow gravels, at Summit, granite, gneiss, schist, and marble occur throughout the pay gravel. The age and origin of the high-level gravels thus still seem in question. The richness of some of the placers suggests extensive reworking, proximity to lode sources, or both.
Bedrock is mostly graphitic schist, probably of early Paleozoic protolith age (Hummel, 1962 [MF 247]; Sainsbury, Hummel, and Hudson, 1972 [OFR 72-326]; Till and Dumoulin, 1994). Bundtzen and others (1994) map the bedrock at Summit as a porphyroclastic, micaceous graphitic schist.
Geologic map unit (-165.362206683761, 64.5777358038059)
Mineral deposit model Alluvial placer Au; buried high-level alluvial channel (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Quaternary; possibly as old as late Tertiary.

Production and reserves

Workings or exploration The workings at the Summit mine were underground. They included several shafts as deep as 106 feet and more than 600 to 700 feet of drifts; 300 feet of the pay streak was worked out by 1903 (Collier and others, 1908).
Indication of production Yes; small
Production notes Production from the high-level gravels of the general area totaled about 100,000 ounces by 1903 (Collier and others, 1908). About 5000 ounces of gold were probably produced from the high level deposits on the Summit and nearby claims.

References

MRDS Number A012909

References

Hopkins, D.M., MacNeil, F.S. and Leopold, E.B., 1960, The coastal plain at Nome, Alaska, A late Cenozoic type section for the Bering Sea region, in Chronology and climatology of the Quaternary: International Geological Congress, 21st, Copenhagen, Proceedings, Part 4, p. 46-57.
Till, A.B., and Dumoulin, J.A, 1994, Geology of Seward Peninsula and St. Lawrence Island, in Plafker, G., and Berg, H.C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, v. G-1, p. 141-152.
Reporters C.C. Hawley and Travis L. Hudson
Last report date 7/10/2000