Chathenda Creek; Johnson Creek Prospect, Chisana Mining District, Valdez-Cordova Census Area, Alaska, USAi

Regional Level Types
Chathenda Creek; Johnson Creek Prospect	Prospect
Chisana Mining District	Mining District
Valdez-Cordova Census Area	Census Area
Alaska	State
USA	Country

The prospect is in the Wrangell-St. Elias National Preserve.
Location: This prospect is on the north bank of Chathenda Creek about 0.9 mile upstream from the mouth of Salt Creek and 1.2 miles downstream from Bonanza. The site is in the SW1/4 of section 34, T. 4 N., R. 19 E. of the Copper River Meridian. This is locality 39 of Richter and others (1975). Cobb and Richter (1980) included this prospect under the name 'Chathenda Cr.'. It is located to within a few hundred feet.
Geology: This prospect consists of gold-bearing quartz-pyrite veins, some of which contain marcasite. The veins are in a zone up to 10 feet wide of mineralized, volcanic and diorite country rocks (Capps, 1916; Pilgrim, 1931, p. 66-68). The mineralized zone strikes N 65 W and dips 78 S. Gold values of 0.01 and 0.10 ounce of gold per ton were reported by Pilgrim (1931). A chip sample across 5 feet of limonite-stained, fine-grained, volcanic rock contained 1.5 parts per million (ppm) silver, 1,500 ppm chromium, 500 ppm copper, and 300 ppm lead (Richter and Matson, 1970 [OFR 70-275]). The host rocks are volcanic and volcaniclastic rocks of the Cretaceous, Chisana Formation (Richter and Jones, 1973). These volcanic rocks are intruded by the mid-Cretaceous, Chisana pluton about 1,000 feet north of the prospect. The Chisana pluton varies from clinopyroxene diorite to monzonite and has been dated by K/Ar methods as 110 +/- 3.0 Ma (Richter, Lanphere, and Matson, 1975).
Workings: There are open cuts and two short adits in this area (Capps, 1916). A number of small gold-bearing quartz-pyrite lodes occur in mineralized volcanic country rock of the Cretaceous, Chisana Formation on the north side of Chathenda Creek (also see NB092 and NB093). By 1940 a large group of claims had been staked in this area but exploration, including trenches and some short adits, was unsuccessful.
Age: Mid-Cretaceous? The deposit may be related to emplacement of the Chisana pluton which has a K/Ar date of 110 +/- 3.0 Ma (Richter, Lanphere, and Matson, 1975).
Alteration: Pyrite and quartz veining and replacement(?); oxidation has produced abundant iron-staining.

Commodities (Major) - Au, Cu
Development Status: None
Deposit Model: Polymetallic veins (Cox and Singer, 1986; model 22c)

Other Databases

Link to USGS - Alaska:	NB080

Other Regions, Features and Areas containing this locality

References