Fort Hamlin Hills pluton occurrence, Yukon Flats Mining District, Yukon-Koyukuk Census Area, Alaska, USAi

Regional Level Types
Fort Hamlin Hills pluton occurrence	Occurrence
Yukon Flats Mining District	Mining District
Yukon-Koyukuk Census Area	Census Area
Alaska	State
USA	Country

Occurrence consists of a single strongly anomalous sample. Sample number 181 (Barker and Foley, 1986) contained 308 ppm Sn, 1,102 ppm Rb, 29 ppm Ta, and 16 ppm W.

Location: The occurrence is located about 24 miles west of Stevens Village along a high (approximately 2500-foot level) ridge in the Fort Hamlin Hills (sec. 29, T. 14 N., R. 11 W., of the Fairbanks Meridian). Location is accurate within a 1-mile radius.

Geology: This occurrence consists of a sample from a 5- to 8-ft.-wide tourmaline- and pyrite-bearing altered leucocratic, felsic dike which cuts biotite granite (Barker and Foley, 1986). The dike is variably stained brick-red and green and exposed for 50 feet along a north-trending strike. Alteration extends several feet into the granite, and secondary minerals in the dike and host granite include minor chlorite, sericite, tourmaline, hematite, and pyrite.

Age: The host dike cuts (and is probably related to) a biotite granite of the Fort Hamlin Hills pluton. The Fort Hamlin Hills pluton has not been dated, but its age is likely Cretaceous, based on ages of several compositionally similar plutons in the area which have ages ranging from 106 to 112 Ma (Barker, 1991).

Alteration: Secondary chlorite, sericite, tourmaline, hematite and pyrite.

Commodities (Major) - Rb, Sn; (Minor) - Ta, W

Development Status: None

Deposit Model: Sn veins(?) (Cox and Singer, 1986; model 15b)

Other Databases

Link to USGS - Alaska:	BV004

Other Regions, Features and Areas containing this locality

References