Unnamed Occurrence (ARDF - IL003; near hill 1759), Bristol Bay Mining District, Lake and Peninsula Borough, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - IL003; near hill 1759)	- not defined -
Bristol Bay Mining District	Mining District
Lake and Peninsula Borough	Borough
Alaska	State
USA	Country

Location: This occurrence is at an elevation of about 1,700 feet on the north side of the Koktuli River. It is on or near hill 1759 in the SW1/4 sec. 20, T. 4 S., R. 36 W., Seward Meridian. The location was reported by Northern Dynasty Minerals (2003); the map site is probably accurate within 0.5 mile.
Geology: This occurrence is the site of porphyry copper-type mineralization of unknown extent and grade. The area near the occurrence was mapped as undivided volcanic rocks of Tertiary age (Detterman and Reed, 1980). More recent studies suggest that the area may instead be underlain by relatively fine-grained phases of a granodiorite-tonalite batholith of Late Cretaceous (about 90 Ma) age exposed immediately to the north and west of the copper occurrence. The occurrence is in a north-trending lobe in the southern part of a 90- square-kilometer (34.8-square-mile) area of sulfide mineralization delineated by an IP/chargeability anomaly (Northern Dynasty Minerals, 2003). This anomalous area includes the Pebble Copper deposit (IL007), about 9. 5 miles to the northeast; the 38 Porphyry deposit (IL004), 3.5 miles to the east-southeast; and the 37 Skarn deposit (IL002), 1.7 miles to the south. Assuming that this occurrence is similar to the Pebble Copper deposit, it is probably hosted by porphyritic to equigranular, relatively fine-grained phases of the granodiorite-tonalite batholith. Sulfide minerals almost certainly include pyrite and chalcopyrite and probably molybdenite. Development of secondary potassium feldspar and biotite characterizes the mineralized rocks of the area (Bouley and others, 1995).
Workings: The occurrence is in a north-trending lobe of sulfide mineralization delineated by regional geophysical surveys conducted by Cominco (Bouley and others, 1995) and Northern Dynasty Minerals (2003). Reconnaissance followup of a geophysical anomaly revealed porphyry copper mineralization at this site, which was staked in 2002 as an extension to the main Northern Dynasty claim block. To date (2003), the prospect has not been drilled.
Age: Probably Late Cretaceous, about 90 Ma.
Alteration: Potassic.

Commodities (Major) - Cu; (Minor) - Ag?, Au?, Mo?
Development Status: None
Deposit Model: Probably porphyry copper-gold deposit, or possibly porphyry copper-molybdenum d

Other Databases

Link to USGS - Alaska:	IL003

Other Regions, Features and Areas containing this locality

References