Cape Darby Occurrence, Council Mining District, Nome Census Area, Alaska, USAi

Regional Level Types
Cape Darby Occurrence	Occurrence
Council Mining District	Mining District
Nome Census Area	Census Area
Alaska	State
USA	Country

Location: This occurrence is on the east coast of Golovin Bay. It is on a sea cliff 3.3 miles southeast of Golovin Mission and 4.1 miles northeast of Cape Darby. This is occurrence 136 of Cobb (1972, MF 445; 1978, OF 78-181).
Geology: West (1953) collected slope wash or detrital material from a small drainage at this locality. A heavy mineral concentrate obtained from the sample material (concentration ratio approximately 1,200:1) contained 0.049 percent equivalent uranium. The minerals identified in this concentrate included allanite, scheelite, monazite, fluorite, hematite, ilmentite, magnetite, epidote, biotite, and zircon. The bedrock here is an amphibolite facies, metasedimentary assemblage that forms a regional selvage between the Darby pluton to the east the the Kachauik pluton to the west (Miller and others, 1972; Till and others, 1986). The Darby pluton, is a large mid-Cretaceous granodiorite and granite body that has elevated background levels of uranium and thorium (Miller an Bunker, 1976; Johnson and others, 1979; Till and others, 1986). The Kachauik pluton is a composite syenite to granodiorite body, locally cut by nepheline syenite dikes, that is slightly older than the Darby pluton ( 99.9 +/- 3 Ma; Miller and others, 1972; Miller, 1972; Miller and Bunker, 1976). Parts of the Kachauik pluton contain U, Th, and REE mineralization near nepheline syenite dikes (Miller and others, 1976). Many of the minerals identified in the heavy mineral concentrate from this location are known accessory minerals in the Darby pluton.
Workings: The reconnaissance sampling by West (1953) is the only work known in the area.
Age: Mid-Cretaceous?; K/Ar ages for the Darby pluton are 88.3 +/- 1.5 and 92.8 +/- 2.6 Ma (Berry and others, 1976). A K/Ar age for the Kachauik pluton is 99.9 +/- 3 Ma (Miller and others, 1972; Miller and Bunker, 1976).

Commodities (Major) - REE, U, W
Development Status: No
Deposit Model: Disseminated; the heavy mineral concentrate is from a sample of detrital materia

Other Databases

Link to USGS - Alaska:	SO001

Other Regions, Features and Areas containing this locality

References