Ptarmigan Creek

Prospect, Undetermined

Commodities and mineralogy

Main commodities Au
Ore minerals gold

Geographic location

Quadrangle map, 1:250,000-scale LC
Quadrangle map, 1:63,360-scale C-5
Latitude 60.6
Longitude -154.7
Nearby scientific data Find additional scientific data near this location
Location and accuracy The location appears to include the whole of Ptarmigan Creek. Individual prospects not delineated. Location plotted as approximate midpoint of Ptarmigan Creek. Location could extend up to 13 km both upstream and downstream.

Geologic setting

Geologic description

Brooks (1913) reported encouraging placer gold results from benches along Ptarmingan Creek. Ptarmigan Creek drains a diverse group of rocks: sedimentary rocks (unit KJs), volcanic rocks (unit Tv), plutonic rocks (unit TKi6), and the Chilikadrotna Greenstone. The Chilikadrotna Greenstone is a Late Silurian unit of weakly metamorphosed basalt, andesite, chert, limestone, and tuffaceous sedimentary rocks. Fossils from a limestone lens in the Chilikadrotna Greenstone suggest an early Late Silurian age (Bundtzen and others, 1979). Nelson and others (1983) described the unit KJs as interbedded lithic graywacke, silty sandstone, black shale , and local conglomerate. Irregular quartz segregations and veinlets are locally present. Small diorite bodies (unit TKi6) intrude these sedimentary rocks. One diorite pluton yielded a potassium-argon age on hornblende of 69.4 +/- 2.1 m.y. (Eakins and others, 1978) Adjacent to some of the larger igneous bodies are narrow contact aureoles of pelitic hornfels. Unit Tv includes: rhyolitic breccia, ash-flow tuff, flows, and intrusive rocks and subordinate mafic to intermediate flows. Potassium-argon ages for unit Tv range from 56.2 to 62.7 m.y. indicating a Tertiary age for these rocks (Eakins and others, 1978).
Geologic map unit (-154.702249719638, 60.5993238838221)
Mineral deposit model Placer Au (Cox and Singer, 1986; model 39a)
Mineral deposit model number 39a
Age of mineralization The placer gold is Quaternary, the source of gold could come from a variety of rocks with diverse ages.
Alteration of deposit Not applicable

Production and reserves

Workings or exploration Unknown
Indication of production Undetermined
Reserve estimates No reserves
Production notes No production

Additional comments

Cobb (1976) indicates that the location of the creek is not given, and because no other mention of the creek occurs, the report is suspect.

References

MRDS Number A106369

References

Reporters D.P. Bickerstaff (USGS)
Last report date 6/15/1998