Jim Prospect Confluence

Occurrence, Inactive

Alternative names

Jim River
Jim River Confluence

Commodities and mineralogy

Main commodities Au
Ore minerals gold; magnetite

Geographic location

Quadrangle map, 1:250,000-scale BT
Quadrangle map, 1:63,360-scale D-2
Latitude 66.7916
Longitude -150.7535
Nearby scientific data Find additional scientific data near this location
Location and accuracy These two placer-gold occurrences are along the Jim River. One is at the mouth of Prospect Creek (locally called the Jim Prospect Confluence). The second is in the canyon of Jim Creek about 6 miles downstream. The coordinates at at the Jim Prospect Confluence, just northwest of the center of section 26, T. 23 N., R. 15 W., of the Fairbanks Meridian, and about 0.5 mile southwest of Prospect Creek Camp.

Geologic setting

Geologic description

Fine placer gold, identified in panned concentrates occurs at two sites along Jim River (Kurtak and others, 2002). At the 'Jim Prospect Confluence', a panned -concentrate contained a single, very fine grained, gold particle, with abundant magnetite. An analysis of this concentrate indicated that it contained 1,590 ppb gold. Another placer sample from the same site contained 13 very fine gold particles and an analysis showed that it has a value of 0.0003 ounce of gold per cubic yard. At a site on Jim River about 6 miles downstream from the mouth of Prospect Creek, very fine gold flakes were observed in a panned-concentrate; an analysis showed a value of 1,230 ppb gold (Kurtak and others, 1999). Kurtak and others (1999) suspect that the gold is derived from the Jim River pluton, which crops out north of the Jim River canyon.
The rocks in the region are Triassic to Jurassic mafic volcanic and intrusive rocks, and mid-Cretaceous granitic, plutonic rocks (Patton and Miller, 1973). The rocks in the vicinity of the occurrences on the Jim River are altered volcanics, including pillow basalts (Kurtak and others, 2002). No bedrock was observed at the 'Jim Prospect Confluence' occurrence.
Geologic map unit (-150.756180387136, 66.7911460007658)
Mineral deposit model Placer Au (Cox and Singer, 1986; model 39a).
Mineral deposit model number 39a
Age of mineralization Quaternary.

Production and reserves

Workings or exploration In the 1970s, claims were located at the Jim Prospect Confluence occurrence, and the occurrence about 6 miles below Prospect Creek (BT008) the other site on the Jim River (Kurtak and others, 2002).
Indication of production None

References

Reporters J.M. Britton (Anchorage)
Last report date 8/1/2002