|Quadrangle map, 1:250,000-scale||MH|
|Quadrangle map, 1:63,360-scale||B-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Hail Creek prospect is at an elevation of about 4,200 feet, about 2.8 miles north-northwest of the junction of the North Fork and West Fork of Rainy Creek. It is about 0.2 mile east of the center of section 25, T. 18 S., R. 9 E.|
The North Rainy prospect is in the Late Triassic, Rainy ultramafic-mafic complex that intrudes the Slana Spur Formation of Pennsylvanian and Permian age. The Rainy complex is up to 5,000 feet thick, dips shallowly north, and can be traced for more than 15 miles; it is mainly serpentinized dunite with subordinate peridotite, pyroxenite, and gabbro (Nokleberg and others, 1992 [Open-File]; Nokleberg and others, 1992 [MF]; Bittenbender and others, 2007). The base of the complex is a layered gabbro as much as 1,500 feet thick.
The area was staked by American Copper and Nickel Company ACNC in 1995 but the Hail Creek prospect was not discovered until 1998 when their exploration followed up a reconnaissance large-loop geophysical survey and an anomalous float sample found in 1995 (W.T. Ellis, oral communication, 2001). They drilled a 250-foot hole in 1998 but it failed to intersect mineralization.
The Hail Creek prospect is on an elongate east-northeast-trending magnetic high that coincides with nine airborne electromagnetic anomalies (W.T. Ellis, oral communication, 2001). The eastern string of four anomalies marks an iron oxide-stained, serpentinized and silicified zone in a dunite that contains local copper- and iron-stained fractures. (W.T. Ellis, oral communication, 2001). Downhill to the west along this trend, the dunite is intruded by variably serpentinized olivine gabbro. A copper-stained, sulfide-bearing serpentinized zone is present at one location along the poorly exposed gabbro contact. The sulfide minerals range from a trace to 2 percent disseminated chalcopyrite, pentlandite, pyrrhotite, and magnetite. Strong large-loop electromagnetic geophysical conductors were detected on three surveyed lines.
Float sample contained up to 0.39 percent nickel, 0.24 percent copper, 0.09 percent cobalt, 216 parts per billion (ppb) palladium, and 295 ppb platinum. A rock grab sample from the prospect assayed 0.25 percent nickel, 0.48 percent copper, 68 ppb palladium, and 95 ppb platinum. The 250-foot drill hole failed to intersect significant mineralization at one of the stronger geophysical anomalies.Bittenbender and others (2007) examined and sampled the prospect in 2002. A sample with copper sulfides and copper staining from a contact zone between a gabbro dike and serpentinized dunite contained 2,430 parts per million (ppm) copper, 578 ppm zinc, 31 ppm chromium, 70 ppm nickel, 1.3 ppb platinum, and 2 ppb palladium. A sample of dunite contained 455 ppm chromium, 1,910 ppm nickel, 21 ppb platinum, and 19 ppb palladium.
|Geologic map unit||(-145.933260159085, 63.3259830608631)|
|Mineral deposit model||Nickel-copper-PGE mineralization in a differentiated mafic-ultramafic complex.|
|Age of mineralization||Genetically related to the emplacement of a Late Triassic mafic-ultramafic complex.|
|Alteration of deposit||Local silicification and serpentinization of dunite and gabbro.|
|Workings or exploration||The area was staked by American Copper and Nickel Company ACNC in 1995 but the Hail Creek prospect was not discovered until 1998 when their exploration followed up a reconnaissance large-loop geophysical survey and an anomalous float sample (W.T. Ellis, oral communication, 2001). A 250-foot hole was drilled in 1998 but failed to intersect mineralization. Examined and sampled by the Bureau of Land Management in 2002.|
|Indication of production||None|
Bittenbender, P.E., Bean, K.W., Kurtak, J.M., and Deininger, James Jr., 2007, Mineral assessment of the Delta River Mining District area, east-central, Alaska: U.S. Bureau of Land Management, Alaska Technical Report 57, 675 p.
Nokleberg, W. J., Aleinikoff, J. N., Dutro, J. T., Lanphere, M. A., Silberling, N. J., Silva, S. R., Smith, T. E., and Turner, D. L., 1992, Map, tables, and summary of fossil and isotopic age data, Mount Hayes Quadrangle, eastern Alaska range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1996-D, 43 p., 1 sheet, scale 1:250,000.
Nokleberg, W.J., Aleinikoff, J. N., Lange, I. M.; Silva, S. R., Miyaoka, R. T., Schwab, C. E., Zehner, R. E., Bond, G. C., Richter, D. H., Smith, T. E., and Stout, J. H., 1992, Preliminary geologic map of the Mount Hayes quadrangle, eastern Alaska Range, Alaska: U.S. Geological Survey Open-File Report 92-594, 39 p. 1 sheet, scale 1:250,000.
Nokleberg, W.J., Lange, I.M., Roback, R.C., Yeend, Warren, and Silva, S.R., 1991, Map showing locations of metalliferous lode and placer mineral occurrences, mineral deposits, prospects, and mines, Mount Hayes quadrangle, eastern Alaska Range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1996-C, 42 p., 1 sheet, scale 1:250,000.
|Reporters||W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS); D.J. Grybeck (Contractor, USGS)|
|Last report date||5/13/2012|