Unnamed Occurrence (ARDF - NM022; near head of Windy Creek), Nome Mining District, Nome Census Area, Alaska, USAi

Regional Level Types
Unnamed Occurrence (ARDF - NM022; near head of Windy Creek)	- not defined -
Nome Mining District	Mining District
Nome Census Area	Census Area
Alaska	State
USA	Country

Location: The occurrence is on a steep ridge between the head of Windy Creek and an unnamed west-flowing tributary to the Cobblestone River. It is about 2.2 miles southwest of Mount Osborne. This is locality 113 of Hummel (1975). It is located within about 1,000 feet of the coordinates.
Geology: This pegmatite is an isolated occurrence north of the Thompson Creek orthogneiss, and its age is uncertain. Granite pegmatites are abundant in the Kigluaik Mountains, and others may be present near this occurrence. The pegmatites are noticeably radioactive; radioactivity measured on the ground with a scintillometer is as much as 500 counts per second or 3 to 5 times common background (Hawley and Associates, 1978, Section IV). Tourmaline and garnet are common accessory minerals, and the more radioactive pegmatites commonly contain smoky quartz. Beryl occurs in some of the pegmatite, including a body described by Moffit (1913, p. 25) about 1 mile west of the mouth of North Star Creek (NM046). Some granite pegmatites are within the Thompson Creek orthogneiss or appear to be spatially associated with it, particularly on its south or hanging wall side (Hummel, 1962 [MF 248]; Till, 1980). The Thompson Creek orthogneiss has been dated as latest Proterozoic (555 Ma, Amato and Wright, 1998), and some pegmatites may also be this age. However, metasedimentary rocks of the Kigluaik Mountains underwent granulite facies metamorphism and partial melting in the mid-Cretaceous and some pegmatites are crosscutting to local structure and are mid-Cretaceous in age (Throckmorton and Hummel, 1979; Till, 1983; Miller and Hudson, 1991; Hudson, 1994; Till and Dumoulin, 1994; Amato and others, 1994; Amato and Wright, 1997, 1998). The host rocks to this pegmatite are upper amphibolite facies metasedimentary rocks that are probably derived from Precambrian protolith (Sainsbury, 1972; Bunker and others, 1979; Till and Dumoulin, 1994). They are thought to have undergone regional high-pressure metamorphism along with many other rocks of Seward Peninsula in the Late Jurassic or Early Cretaceous (Sainsbury, Coleman and Kachadoorian, 1970; Forbes and others, 1984; Thurston, 1985; Patrick, 1988; Patrick and Evans, 1989; Armstrong and others, 1986; Hannula and McWilliams, 1995). Higher temperature metamorphism overprinted these rocks in conjunction with regional extension, crustal melting, and magmatism in the mid-Cretaceous (Throckmorton and Hummel, 1979; Till, 1983; Evans and Patrick, 1987; Leiberman, 1988; Patrick and Leiberman, 1988; Miller and Hudson, 1991; Miller and others, 1992; Dumitru and others, 1995; Hannula and others, 1995; Hudson and Arth, 1983; Hudson, 1994; Amato and others, 1994; Amato and Wright, 1997, 1998). Uplift of the higher temperature metamorphic rocks took place in the mid- to Late Cretaceous and in the Eocene (Calvert, 1992; Dumitru and others, 1995).
Workings: Reconnaissance uranium exploration including airborne radiometrics, stream sediment surveys, and ground traverses have been completed in the Kigluaik Mountains.
Age: Late Proterozoic or mid-Cretaceous; either the age of the Late Proterozoic Thompson Creek orthogneiss or mid-Cretaceous granulite facies metamorphism.

Commodities (Major) - Be, Th, U
Development Status: None
Deposit Model: Simple granite pegmatite with rudimentary zoning.

Other Databases

Link to USGS - Alaska:	NM022

Other Regions, Features and Areas containing this locality

References