Styx River Occurrence, McGrath Mining District, Bethel Census Area, Alaska, USAi

Regional Level Types
Styx River Occurrence	Occurrence
McGrath Mining District	Mining District
Bethel Census Area	Census Area
Alaska	State
USA	Country

Location: This occurrence is at an elevation of about 4,000 feet on a small east tributary to the upper Styx River. The map site is just within the north boundary of the NW 1/4 section 30, T 17 N, R 21 W, of the Seward Meridian. It is locality 14 of Cobb (1972, MF-412; 1976, OFR 76-485) and locality 26 of Gamble and others (1989). The location is probably accurate to within one quarter of a mile.
Geology: Reed and Elliott (1970) reported that iron-stained and altered intrusive rocks are present along about 200 feet of this creek. The altered rocks consist dominantly of quartz and sericite with minor potassium feldspar and altered biotite. These rocks generally contain less than one percent sulfide minerals, including pyrite, sphalerite, and galena, that are disseminated and in quartz veins as much as 2 inches wide. Sphalerite and galena also occur as thin veinlets and disseminations in felsite. Shear zones in the altered intrusions are also mineralized with sulfides. Besides zinc and lead values, rock samples contain as much as 15 ppm silver and 300 ppm molybdenum. The altered intrusive rocks are probably Late Cretaceous or Tertiary parts of the Alaska-Aleutian Range batholith (Reed and Lanphere, 1973).
Workings: Reconnaissance surface observation and sampling has been completed in this area (Reed and Elliott, 1970).
Age: Late Cretaceous or Tertiary? Mineralized granitic rocks in this area are commonly Late Cretaceous or Early Tertiary parts of the Alaska-Aleutian Range batholith (Reed and Elliott, 1970; Reed and Lanphere, 1973).
Alteration: Quartz-sericite-pyrite replacement and veining.

Commodities (Major) - Ag, Mo, Pb, Zn
Development Status: None
Deposit Model: Polymetallic veins? or porphyry Cu-Mo? (Cox and Singer, 1986, model 22c and 21

Other Databases

Link to USGS - Alaska:	LH020

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References