Section 35

Location: Alaska, United States (63.640, -142.264 approx.)

Commodities: beryllium; niobium; thorium; uranium; zirconium; rare earth elements

Deposit model: Th-REE veins · carbonatite deposits

Geology

The Section 35 prospect is in the outer portion of the Mount Fairplay pluton whose outcrop area is about 4 miles in diameter (Adams, 2009). The pluton is a Late Cretaceous to early Tertiary alkaline complex with well-developed ring structures. It intrudes biotite schist and gneiss, probably of Mississippian and older age and bimodal felsic and mafic volcanic rocks, probably of Late Cretaceous age. The Mount Fairplay complex was emplaced in three phases between 59 and 67 Ma: 1) an early alkaline ring phase that consists of diorite and several syenite units on the north side of the complex; 2) a later alkaline ring phase that consists of several syenite units and perthosite on the south side of the complex; and 3) a calc-alkaline core phase that consists of hornblende-biotite quartz monzonite. The Section 35 occurrence is in a protoclastic hornblende-biotite syenite on the south side of the complex. (Adams (2009))

Exploration and site history

• Exploration — Various companies explored near Mt. Fairplay, 1970–1990 (Adams (2009))
• Discovery — occurrence identified in sampling of area formations, 2006–2009 (Adams (2009))

Record imported from USGS USMIN ver. 4.0 (June 2019). Developments after that date appear on facility records, not here; see the methodology.