|Quadrangle map, 1:250,000-scale||KC|
|Quadrangle map, 1:63,360-scale||C-6|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The approximate location of the Kingston prospect is at an elevation of about 100 feet, 0.1 mile inland from the southwest shore of Helm Bay, and about 1.4 miles from the mouth of the bay. The site is in section 19, T. 72 S., R. 88 E., of the Copper River Meridian. It corresponds to loc. 32 in Elliott and others (1978). The location is accurate within about 0.3 mile.|
The country rocks at this site are flyschlike metasedimentary rocks that gradationally intertongue with andesitic and basaltic metavolcanic rocks (Berg and others, 1988, p. 17-19). The strata were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time (Brew, 1996, p. 27). Their premetamorphic age is uncertain. Berg and others (1988, p. 17) state that they closely resemble Upper Jurassic to mid-Cretaceous marine flysch and volcanic rocks nearby on Gravina Island. Near Smugglers Cove, they are intruded by metadiorite that may be transitional to the metavolcanic rocks (Berg and others, 1988, p. 20).
The deposit consists of a quartz-fissure-vein stockwork 6-30 feet wide in chloritic schist (Brooks, 1902, p. 58). The largest vein observed by Brooks was 6 feet wide. Assays of the deposit made in the early 1900s reportedly showed gold values of $2.50-$600/ton (Au at $20.67/oz.).Fluid inclusion studies of quartz vein material from several of the Helm Bay lodes suggest that the veins formed at temperatures and pressures consistent with conditions during the Late Cretaceous greenschist-grade regional metamorphism (Maas and others, 1995, p. 184).
|Geologic map unit||(-131.968682991855, 55.6086372676745)|
|Mineral deposit model||Low-sulfide gold-quartz veins (Cox and Singer, 1986; model 36a)|
|Mineral deposit model number||36a|
|Age of mineralization||Late Cretaceous.|
|Workings or exploration||Assays of the deposit made in the early 1900s reportedly showed gold values of $2.50-$600/ton (Au at $20.67/oz.) (Brooks, 1902, p. 58).|
|Indication of production||None|
Berg, H.C., Elliott, R.L., and Koch, R.D., 1988, Geologic map of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Mineral Investigations Series Map I-1807, 27 p., scale 1:250,000.
Brew, D.A., 1996, Geologic map of the Craig, Dixon Entrance, and parts of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2319, 53 p., 1 sheet, scale 1:250,000.
Brooks, A.H., 1902, Preliminary report on the Ketchikan mining district, Alaska, with an introductory sketch of the geology of southeastern Alaska: U.S. Geological Survey Professional Paper 1, 120 p.
|Reporters||H.C. Berg, USGS|
|Last report date||6/30/1999|