Unnamed Prospect (ARDF - TE056; on western side of Brooks Mountain), Port Clarence Mining District, Nome Census Area, Alaska, USAi

Regional Level Types
Unnamed Prospect (ARDF - TE056; on western side of Brooks Mountain)	- not defined -
Port Clarence Mining District	Mining District
Nome Census Area	Census Area
Alaska	State
USA	Country

Location: This area is along the west contact zone of the Brooks Mountain granite stock, about 0.8 mile north of the prospects on the southwest side of the stock (TE055). The prospect area is at an elevation of about 2,500 feet along and immediately west of the continental divide. This locality was not shown separately by Cobb and Sainsbury (1972) but some relevant references were summarized by Cobb (1975) under the name 'Brooks Mtn.'.
Geology: Brooks Mountain granite stock is a 1 by 2 mile composite intrusion just south and east of Brooks Mountain (elevation 2,898 feet), the highest part of the York Mountains. The country rocks to the Late Cretaceous (77.0 +/- 3.0 my; Hudson and Arth, 1983, p. 769) Brooks Mountain granite are Ordovician limestone and locally fine-grained, carbonaceous metaclastic rock of unknown but probable Paleozoic age. Tactite is common in marble nearby to the granite contact on the northwest and southwest sides of the stock (Sainsbury, 1969, plate 1). Hornfels is developed in the nearby metaclastic rocks. The granite is dominately seriate and prophyritic types (Hudson and Arth, 1983, p. 770) that are not known to be directly linked with significant tin metallization in the western Seward Peninsula tin belt; they are instead precusor-type granites (Hudson and Reed, 1997, figure 3). Tactite here contains much idocrase and some tourmaline. It forms irregular masses and green-colored seams along fractures in marble. Small cubes of galena are present in open vugs in the tactite. About 700 feet to the southeast, the Brooks Mountain granite contains 1 to 4 inch wide quartz-tourmaline veins along joints. Uranium (to 1% eU) is present in zuenerite associated with hematite coatings on vein and fracture surfaces (West and White, 1952).
Workings: Some surface pits have been dug here.
Age: The age of the mineralization is assumed to be similar to the age of the Brooks Mountain granite (77.0 +/- 3.0 my; Hudson and Arth, 1983, p. 769).
Alteration: Tactite in carbonate rocks, quartz-tourmaline veining in granite, and secondary oxide development.
Reserves: Not defined

Commodities (Major) - None; (Minor) - Pb, U
Development Status: None
Deposit Model: This is an area of variable contact metamorphism of Ordovician limestone by the

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Link to USGS - Alaska:	TE056

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References