|Quadrangle map, 1:250,000-scale||NM|
|Quadrangle map, 1:63,360-scale||C-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This prospect is on the bench east of the mouth of Twin Mountain Creek (Twin Mtn Ck on the map) and north of Boulder Creek. Boulder Creek is a west tributary to Snake River; it flows east from headwaters in the eastern Nome C-2 quadrangle. Mineralization continues to the west, and the prospect is also probably related to quartz and sulfide vein mineralization reported as the Dakota group of some 13 claims (NM174) on Boulder Creek below Twin Mountain Creek (Mertie, 1918 [B 662-I, p. 429]). The prospect includes two adits reported to be driven in the east bank of Twin Mountain Creek (Cathcart, 1922, p. 248-249).|
Geologic descriptionThis prospect was discovered in 1992 by following up results of a soil geochemistry survey. Mineralization continues to the south and the prospect is also probably related to quartz and sulfide vein mineralization reported as the Dakota group of some 13 claims (NM174) on Boulder Creek below Twin Mountain Creek (Mertie, 1918 [B 662-I, p. 429]). A soil geochemistry survey was completed on the northeast bench of Boulder Creek downstream from its confluence with Twin Mountain Creek in 1991. Soil samples were collected on 50-foot intervals on northeast lines about 200 feet apart. Some samples contained more than 1 percent arsenic and more than 2,000 ppb gold. In general, a strong arsenic anomaly (values in hundreds of parts per million) extends northwesterly across the bench. A series of five trenches with a total length of 900 feet was excavated; four were parallel to the soil sample lines and one crossed them. All trenches found mineralized zones, although establishing continuity between individual zones was difficult. A trench excavated on the soil line with values greater than 1 percent arsenic and 2,000 ppb gold (Trench NEBLdr-T1, Kennecott Exploration Company, written communication, 1992) found a massive quartz-arsenopyrite vein below 10 feet of overburden. A 30-foot-long zone in bedrock centered on the vein averaged 6.4 ppm gold and greater than 1 percent arsenic. Trenches 80 feet west and 100 feet east found lower values; these consisted of as much as 10 feet of 1,020 ppb gold 100 feet to the east and 10 feet of 4,400 ppb gold 80 feet to the west. A trench excavated 400 feet to the west of Trench NEBLdr-T1 contained one 10-foot sample with greater than 10 ppm gold and a 30-foot sample with about 500 ppb gold. This mineralization probably extends northwesterly into Twin Mountain Creek and could include the occurrences described in two adits driven into the east side of Twin Mountain (Cathcart, 1922, p. 251). One of these adits reportedly contained scheelite in a quartz-feldspar vein. The northwesterly trending mineralization at this prospect may be cut off or displaced by the Rodine fault (Bundtzen and others, 1994).
|Geologic map unit||(-165.504607873542, 64.6495327937166)|
|Mineral deposit model||Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a).|
|Mineral deposit model number||36a|
|Age of mineralization||Mid-Cretaceous; postdates regional metmorphism and is probably similar in age to other low-sulfide Au-quartz veins of the Nome district (see, for example, the Divide prospect, NM058).|
|Alteration of deposit||Sulfidation of schist.|
|Workings or exploration||Kennecott Expiration Company completed about 900 feet of trenches in 1992 to follow up arsenic and gold soil anomalies on the bench northeast of the confluence of Twin Mountain and Boulder Creek. The trenches were back filled and reclaimed after mapping and sampling.|
|Indication of production||None|
Additional commentsThe northwesterly trending mineralization at this prospect may be cut off or displaced by the Rodine fault (Bundtzen and others, 1994).
|MRDS Number||A012820; A012824|
Bundtzen, T.K., Reger, R.D., Laird, G.M., Pinney, D.S., Clautice, K.H., Liss, S.A., and Cruse, G.R., 1994, Progress report on the geology and mineral resources of the Nome mining district: Alaska Division of Geological and Geophysical Surveys, Public Data-File 94-39, 21 p., 2 sheets, scale 1:63,360.
Cathcart, S.H., 1922, Metalliferous lodes in southern Seward Peninsula: U.S. Geological Survey Bulletin 722-F, p. 163-261.
|Reporters||C.C. Hawley and Travis L. Hudson|
|Last report date||3/12/2000|