|Quadrangle map, 1:250,000-scale||HE|
|Quadrangle map, 1:63,360-scale||D-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This site represents an area of about a square mile between upper Red Mountain Creek and Dry Creek. The map site is at an elevation of about 4,300 feet, on the west wall of the valley of upper Red Mountain Creek, in the SW1/4 of sec. 33, T. 11 S., R. 2 E., of the Fairbanks Meridian. This is locality 7 of Cox and others (1989).|
The country rocks in the area of this prospect are mapped as the Lower Mississippian to Middle Devonian Totatlanika Schist, composed predominantly of metavolcanic and metavolcaniclastic rocks, and subordinate amounts of intercalated metasedimentary rocks (Wilson and others, 1998). The dominant structural fabric on the property is a strong mylonitic foliation, and there is a consistent east-northeasterly lineation that plunges at about 20-30 degrees. The deposit is in greenschist-grade metasedimentary rocks and altered rhyolite schist, and consists of stratiform bodies of massive sulfides that occur on the northern and southern limbs of an east-trending synclinal fold. The southern limb of the syncline contains three ore horizons that dip to the north at about 70 to 80 degrees (Schuster, 1998). These are referred to as the DC zones, which have been subdivided into the DC-North, DC-South, and DC-17 zones.
The DC-North zone is defined by a 2-kilometer-long EM conductor. This zone has been further subdivided into three areas: Discovery, which roughly bisects the EM anomaly; Lago Creek, which is 200-400 meters west of the Discovery area; and Fosters Creek, about 800 meters west of the Discovery area. In the Fosters Creek area, drilling has intercepted a 29-meter interval (true width) grading 6.22 percent zinc, 2.56 percent lead and 0.22 percent copper, as well as 182.8 grams silver and 1.03 grams gold per tonne. A 3.7-meter intercept in the hole produced assay results as high as 23.58 percent zinc, 8.46 percent lead, 1.02 percent copper, and 531.5 grams silver and 2.24 grams gold (Schuster, 1998). The DC-South zone is virtually unexplored except for a few reconnaissance drill holes. The DC-17 zone is a 15-meter-thick bed of pyrite (with minor amounts of lead and zinc) that is believed to be genetically related to other zones.The northern limb of the syncline dips gently to the south and hosts the WTF zone, a layer of massive sulfides 0.3 to 5 meters thick that has been tested by 26 widely-spaced drill holes (Schuster, 1998).
|Geologic map unit||(-147.382317409369, 63.9195729527938)|
|Mineral deposit model||Kuroko massive sulfide (Cox and Singer, 1986; model 28a)|
|Mineral deposit model number||28a|
|Age of mineralization||Mineralization was syngenetic with the Lower Mississippian to Middle Devonian host rocks.|
|Alteration of deposit||The footwall schist contains chlorite and sericite.|
|Workings or exploration||
Exploration of the area includes an EM geophysical survey and extensive drilling. Press releases indicate that over 60 drill holes totaling approximately 7600 m have been drilled to date (Robertson, 1998; The Northern Miner, 1998 and 1999: v. 84, nos. 26 and 52).In February 2016, White Rock Minerals Ltd. announced the proposed acquisition of the Red Mountain polymetallic volcanogenic massive sulfide (VMS) project in the north-central Alaska Range, with two known deposits: Dry Creek (101 historical drill holes for 13,831 m) and West Tundra Flats (26 historical drill holes for 5,349 m). As of May 2016, White Rock acquired 100 percent ownership of the property. In March 2016, White Rock Minerals Ltd. staked 85 new mining claims in the Bonnifield district. In June through August 2016, White Rock focused on identifying high-priority magnetic, conductivity, and geochemical targets for future follow-up work utilizing geochemical vector analysis, detailed geologic maps published by DGGS, and contracted detailed interpretation of a DGGS airborne magnetic and electromagnetic survey of the area (Burns and others, 2016). The resulting integrated assessment led to an additional 114 claims being staked and prioritization of the ReRun, Smog (HE126) and Glacier target areas as highly prospective for additional VMS deposits, which are included within 30 geochemical-geophysical targets classified as of high interest (Athey and Werdon, 2017).
|Indication of production||None|
|Reserve estimates||Reserves for part of this deposit have been estimated at 1.10 million tonnes grading 0.15 percent copper, 2.5 percent lead, 7.9 percent zinc, and 270 grams silver, and 1.9 grams of gold per tonne (Nokleberg and others, 1987). An estimate based on 38 of 60 holes drilled to test the southern limb of the syncline gave an inferred resource of 2.9 million tonnes grading 4.4 percent zinc, 1.9 percent lead, 0.2 percent copper, and 0.55 gram gold and 93.6 grams silver per tonne. Included in this estimate is a higher-grade core of 1.5 million tonnes grading 6.4 percent zinc, 2.9 percent lead, 0.3 percent copper, and 0.79 gram gold and 123.8 grams silver per tonne. The bulk of the resource is in the Fosters Creek and Discovery zones, respectively in pyritic sedimentary rocks and intensely altered rhyolite. On the north limb of the syncline, the WTF resource currently (1999) stands at 2.8 million tonnes grading 6 percent zinc, 2.5 percent lead, 0.1percent copper, and 0.9 gram gold and 178.2 grams silver per tonne (The Northern Miner, 1998 and 1999: v. 84, nos. 26 and 52).|
Cox, D.P., Light, T.D., Csejtey, Bela, Jr., and Campbell, D.L., 1989, Mineral resource assessment map of the Healy quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map, MF-2058-A, 1 sheet, scale 1:250,000.
Nokleberg, W.J., and (seven) others, 1994, Metallogeny and major mineral deposits of Alaska and Metallogenic map of significant metalliferous lode deposits and placer districts of Alaska, in Plafker, G. and Berg, H.C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, Vol.. G1, p. 855-904, Plate 11, scale 1:2,500,000.
Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck, D.J., Robinson, M.S., Smith, T.E., and Yeend, W., 1987, Significant metalliferous lode deposits and placer districts of Alaska: U.S. Geological Survey Bulletin 1786, 104 p., 2 plates, scale 1:5,000,000.
Robertson, R., 1998, Grayd hits massive sulphide: The Northern Miner, v. 84, no. 17, p. 3.
Schuster, T., 1998, Grayd advances Alaskan properties: The Northern Miner, v. 84, no. 18, p. 2.
The Northern Miner, 1998, v. 84, nos. 26.
The Northern Miner, 1999, v. 84, nos. 52
|Reporters||N. Van Wyck (Stevens Exploration Management Corporation); M.B. Werdon (DGGS)|
|Last report date||8/26/2017|