37 Skarn Prospect, Bristol Bay Mining District, Lake and Peninsula Borough, Alaska, USAi

Regional Level Types
37 Skarn Prospect	Prospect
Bristol Bay Mining District	Mining District
Lake and Peninsula Borough	Borough
Alaska	State
USA	Country

Location: The 37 Skarn prospect is about 0.5 mile south of the Koktuli River at an elevation of about 1,000 feet. The prospect is about 3.8 miles west-northwest of Sharp Mountain near the center of W1/2 sec. 32, T. 4 S., R. 36 W., Seward Meridian. The location of the prospect is shown by Northern Dynasty Minerals (2003) and is accurate within 0.5 mile.
Geology: The 37 Skarn prospect is in granodiorite and calcic metasedimentary rocks near the south contact of an Upper Cretaceous granodiorite batholith (Detterman and Reed, 1980). The deposit consists of pyrite, chalcopyrite, and magnetite in garnet-epidote(?)-quartz skarn. Relatively high gold assays suggest that it may also contain native gold. The prospect is in the southwest part of a sulfide-rich area delineated by a 90-square-kilometer (34.8-square-mile) IP/chargeability anomaly (Northern Dynasty Minerals, 2003). The sulfide-rich area also includes the Pebble Copper (IL007) and 38 Porphyry (IL004) deposits. The 37 Skarn deposit was discovered in 2002 and has been explored mainly by a few drill holes and by geochemical (soil) and geophysical surveys. The deposit is open to the northeast, where there is a strong copper-gold anomaly in soil, and farther to the east, where there is a magnetic anomaly (Northern Dynasty Minerals, 2003). Five holes were drilled in 2002 (Northern Dynasty Minerals, 2003), and some intercepts returned significant gold and copper values. Drill hole 37 had a 258-foot intercept which averaged 1 gram of gold per tonne and 0.4 percent copper; this intercept contained a 21.5 foot zone which assayed 3.63 grams of gold per tonne and 1.73 percent copper. The copper-gold soil anomaly notheast of the prospect has not yet (2003) been tested by drilling.
Workings: The deposit was discovered by Northern Dynasty Minerals during their evaluation of a 34.8-square-mile, sulfide-rich area marked by an IP/chargeability anomaly. They drilled five holes in 2002. The deposit is open to the northeast and east, where there are untested gold-copper-in-soil and magnetic anomalies (Northern Dynasty Minerals, 2003).
Age: Probably Late Cretaceous, about 90 Ma.
Alteration: Contact metasomatism: replacement of calcic host rocks by sulfides, magnetite, garnet, quartz, and epidote(?).

Commodities (Major) - Cu; (Minor) - Ag, Au
Development Status: None
Deposit Model: Copper-gold skarn; probably related to porphyry copper-gold deposit (Cox and S

Other Databases

Link to USGS - Alaska:	IL002

Other Regions, Features and Areas containing this locality

References