Nome Coastal Plain

Mine, Active?

Commodities and mineralogy

Main commodities Au
Other commodities Ag; W
Ore minerals arsenopyrite; gold; ilmenite; magnetite; pyrite; scheelite
Gangue minerals garnet

Geographic location

Quadrangle map, 1:250,000-scale NM
Quadrangle map, 1:63,360-scale C-1
Latitude 64.5363
Longitude -165.4655
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Nome Coastal Plain is the area between the Nome uplands and the present beach along Norton Sound, between Cape Rodney to the west, and Cape Nome. It has a maximum width of about 3.5 miles at Nome. The width of the coastal plain gradually decreases eastward for 12 miles to Cape Nome. It includes both alluvial and marine gold placers, but the marine placers are by far the most important. The map location is at the approximate center of the most important deposits. It is at the midpoint of the boundary of sections 15 and 16, T. 11 S., R. 34 W., Kateel River Meridian. These coastal plain deposits include localities 129, 135, 137, 138, 139, 141, 142, and 143 of Cobb (1972 [MF 463], 1978 [OFR 78-93]).

Geologic setting

Geologic description

Pre-Pleistocene and Pleistocene marine and terrestrial sediments, especially near the major source areas of ancestral Snake River, Anvil Creek, and Nome River, contain small amounts of particulate gold. In the early days of the district, prospectors observed that they could obtain colors in sediments throughout the coastal plain (Brooks and others, 1901; Collier and others, 1908, plate X). Certain creeks cut only into the unconsolidated deposits. In those creeks, the gold disseminated in the terrestrial units and in marine sediments was locally concentrated into economic placer deposits by fluvial processes (Metcalfe and Tuck, 1942). Such creeks include Bourbon Creek (NM288), Lower Dry Creek (NM264), below Newton Gulch (NM266), Stevens Creek (NM274), Moss Creek (NM275), Laurada Creek (NM276), and Hastings Creek (NM298). All of these deposits are relatively young and were formed after marine transgression and deposition. Another class of coastal plain alluvial placer deposits formed before marine erosion. These deposits include the ancestral Anvil Creek (see Nome Placer Field, NM251), the Roxie placer and Newton Gulch (NM266). These streams cut headward into bedrock and flowed into the sea at the time Third Beach was formed. Subsequently, the channels were buried and preserved. Metcalfe and Tuck (1942, p. 26) also proposed that Evening Gulch, above the Sunset Creek (NM173) part of the Third Beach, is an old bedrock channel.
Another type of buried placer deposit exists in lower parts of Snake and Nome Rivers and in Otter Creek. The lower 2 miles of Snake River has cut 50 feet below sea level and about 30 feet into bedrock. This part of the Snake River, as well as lower Nome River and lower Otter Creek, contain thick alluvial deposits.
All of the shallow alluvial channels of the coastal plain, both in unconsolidated deposits and in schist bedrock, were discovered and mined in the early days of the Nome district. They had relatively minor production, although the ancestral Anvil Creek drainage was a main gold source for the marine deposits.
The most important deposits of the coastal plain are the Present, Second, and Third beach strandline deposits; also present are Intermediate, Monroeville, and Submarine beach deposits. Submarine Beach is the oldest deposit certainly known (Metcalfe and Tuck, 1942, p. 47). Metcalf and Tuck believed that Submarine Beach was an eroded beachline that formed when sea level stood at about 40 feet and when the coastal plain was rolling hills traversed by an ancestral Anvil Creek. As envisaged by these authors, 'The sea advanced landward, and the Submarine area with its gold concentration was left behind on the abrasion platform. The sea continued to erode into bedrock gold-bearing sources which included the old Anvil Creek channel . . . and as it advanced, it carried a gold concentration on the beach before it. Likewise as the sea continued to advance, its abrasion platform was progressively being lowered so that any gold on its abrasion platform, such as the Submarine concentration, was gradually carried to a lower elevation.' Continued sea advances partially eroded and redistributed concentrations at the Intermediate and Monroeville so called beaches. At the same time, gold continued to be brought from the landward end of the system by ancestral Anvil, Newton, and Dry Creeks, and complex alluvial-marine deposits formed where these creeks entered the sea.
Geologic map unit (-165.468082669576, 64.5355306731067)
Mineral deposit model Alluvial placer Au (Cox and Singer, 1986; model 39a); marine and complex placer deposits.
Mineral deposit model number 39a
Age of mineralization Pliocene and Pleistocene.

Production and reserves

Workings or exploration Exploration and production began with the discovery of Present Beach in 1899 and continued intermittently until 1998.
Indication of production Yes

References

MRDS Number A012956

References

Reporters C.C. Hawley and Travis L. Hudson
Last report date 7/10/2000