|Quadrangle map, 1:250,000-scale||NM|
|Quadrangle map, 1:63,360-scale||C-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This record is a summary description of the lode and placer deposits of the Nome mining district. The district has been variously defined. For the purposes of this summary, it comprises all of the Nome B-1 and C-1 quadrangles and parts of the Nome C-2, D-1, and D-2 quadrangles (Bundzten and others, 1994). The region encompassed by these quadrangles includes all the important placer gold deposits in what historically has been called the Nome mining district; it also includes the most important lodes that gave rise to the placer deposits and essentially all the production assigned to the Nome mining district by Bundtzen and others (1994) and Koschmann and Bergendahl (1968). The map location is approximately at the head of the richest alluvial placers and at the south end of the main lode belt that fed the placer deposits. It is in the NW1/4SW1/4 section 36, T. 10 S., R. 33 W., Kateel River Meridian. The district includes the Nome placer field (NM251), an area of composite alluvial and beach placers (NM252), and the main beach and marine abrasion placers (NM253). Specific placer deposits throughout this region are described separately.|
The country rocks in the Nome mining district as defined by Bundtzen and others (1994) consist of three main lithostratigraphic units: an upper unit of chlorite- and albite-rich mafic schist, local marble, and calc-schist; a middle unit of massive and platy marble, graphitic mica and quartz schist, felsic schist, and chlorite-rich metaturbidite schist; and a lower unit of garnet and graphitic schist, albite-chlorite schist, quartz schist, paragneiss, and iron-rich biotite schist. These three units are correlated, from the top down, with the Casadepaga Schist of Smith (1910) and Moffit (1913), the 'mixed unit 'of Till and others (1986), and the Solomon Schist of Smith (1910) and Moffitt (1913). The relations of the three units are complex; locally they appear to be in thrust contact with each other; elsewhere, apparently different units may be metamorphic equivalents. In general, however, they form a mappable, apparently stratigraphic, sequence of rocks. For the purpose of describing the dominant type of lode deposit, the apparent stratigraphic sequence can be used. The principal lode gold deposits have a ductile-brittle structural history. The oldest lodes are rich in arsenopyrite and albite; they occur in ductilly deformed, concordant and fold-controlled deposits. These deposits appear to grade into the sheeted-vein deposits that sharply cut metamorphic rocks and that contain most of the lode gold in the district.
Structurally, the district is divided into two provinces. The southern and most important province has an antiformal structure modified by relatively late faults that strike north-northeast to northeast. From east to west, the main northeast faults are the composite Anvil Creek fault, the Rodine fault, the Penny River fault, and the Aurora Creek fault (Bundzten and others, 1994). The core of the antiformal structure lies west of Snake River; it trends generally north. As mapped in a more detailed industry study (1:12,000 to 1:24,000 scale), the antiformal axis is displaced by the Rodine and other faults. The apparently oldest rocks are exposed at lower elevations in Boulder Creek, along lower Twin Mountain Creek, and in Bangor Creek. Bundtzen and others (1994) mapped a slightly foliated metadiorite or metagabbro in or near the core of the antiform in Bangor Creek. The northern province includes the Mount Distin area and the area north of Stewart River. There the major structures are aligned more nearly east-west, subparallel to the uplift axis of the arch of the Kigluaik Mountains to the north (see Hummel, 1962 [MF 247]).
The main belt of lode deposits extends north-northwest for about 5 miles from Bonanza Hill through Glacier and Rock Creeks to the Goodluck Gulch deposit (NM202). Within the belt, most of the mineralized structures strike northeast.Placer deposits formed in a complex fluvial and coastal marine environment. High-level placers, such as the High Bench at the Dexter divide (NM246), formed early in the erosional history of the district, perhaps in an early Nome glacial event (Hopkins and others, 1960; Nelson and Hopkins, 1972). Somewhat later, erosion of lodes and older placers formed alluvial deposits, as at Anvil Creek (NM236), in or near the modern drainages. Complex deposits formed where ancient auriferous drainages flowed into ancestral Norton Sound. Beach strand-line and related offshore deposits formed by abrasion and reworking of deposits in the strand and offshore marine environment (Metcalfe and Tuck, 1942). The richest placer gold deposits, including those on the coastal plain, have been reworked extensively, are proximal to their bedrock sources, or both. The development of all placer gold deposits in the region that are at elevations of 250 feet or less was probably influenced by fluctuations in sea level in the late Pliocene and in the Pleistocene.
|Geologic map unit||(-165.397003721261, 64.5768346275509)|
|Mineral deposit model||The principal deposit types in the region are: low-sulfide Au-quartz veins, simple Sb deposits, Kuroko massive sulfide, and alluvial placer Au (Cox and Singer, 1986; models 36a, 27d, 28a, and 39a).|
|Mineral deposit model number||36a, 27d, 28a, 39a|
|Age of mineralization||The lode gold deposits are mid-Cretaceous, and the placer gold deposits are Quaternary. The lode gold deposits at Bluff have been determined to be 109 Ma (Ford and Snee, 1996); more widespread radiometric dating of lode gold deposits is needed.|
|Alteration of deposit||Extensive alteration, mainly albitization and sulfidization, accompanied early ductile lode mineralization. Arsenopyrite was the main introduced sulfarsenide. Later alteration during the brittle stage includes sericitization, silicification, and ankeritization.|
|Workings or exploration||
Major alluvial placer gold deposits in the Nome mining district were discovered in September and October of 1898 by John Brynteson, Jafet Lindeberg, and Erik O. Lindblom. The men were supported by an active Scandinavian community based at Golovin, who mainly came to the region for the Swedish Covenant Church, and by several Eskimos, including Gabriel Adams and Constantine Uparazuck. A mining district was formed in October, 1898, by Brynteson, Lindeberg, Lindblom, A.N. Kittlesen, Johan Tornensis, a Saami, and Gabe Price, who represented Charles D. Lane, an experienced mining man. Many of the best alluvial placers were located in 1898. In 1899, gold was discovered on Present Beach (NM255) at Nome. A.H. Brooks of the U.S. Geological Survey then predicted that buried beach placer deposits would be found, a prediction that proved accurate when Second Beach (NM256) was discovered in 1902. The Third beach (NM258) was discovered in 1904. The placers were first exploited mainly by hydraulic methods, and major ditches were constructed to support these operations. Some shallow thawed deposits were mined successfully by small dredges. In the 1920s, after invention of the cold-water thawing process, large dredges were brought into the country by Wendell P. Hammon, whose interests were later consolidated by the U.S. Smelting, Refining, and Mining Company. The more important references for the early history of the Nome mining district are Brooks and others, (1901), Collier and others (1908), Moffit (1913), Metcalfe and Tuck (1942), and Spence (1996).Lode exploration began shortly after discovery of the placers, but that was not significant until the 1980s when geologist R.V. Bailey reopened old workings in Rock Creek (NM207) and discovered sheeted veins in upper Snow Gulch (NM223). His work was followed up by Placer Dome, Newmont Mining Company, and Kennecott Exploration Company. In 1999, the assets of the successors to the U.S. Smelting, Refining, and Mining Company were acquired by Novagold Resources. This company is proceeding with hardrock exploration and has plans to continue placer mining.
|Indication of production||Yes|
|Reserve estimates||Drill-indicated gold resources, which approximate reserves when gold is about 350 to 400 dollars per ounce in 2000 dollars, are on the order of 2,500,000 ounces including 1 million ounces offshore, 1 million ounces in placers onshore, and more than 500,000 ounces in lodes on shore, mainly at Rock Creek. The onshore placer resources are in several deposits including some amenable to open-pit mining and others that could be dredged if thawing is economic.|
|Production notes||The Nome mining district is the second most important placer district in Alaska. From 1898 to 1993, more than 4,800,000 ounces of gold (150 metric tonnes) were produced, essentially all by placer methods and mostly from complex alluvial deposits or buried beach deposits (Bundtzen and others, 1994, table 4; Metcalfe and Tuck, 1942). This production estimate exceeds the nearly 3,600,000 ounces reported by Koschmann and Bergendahl (1968) for the district through 1959 that excludes years 1931 to 1946; the 1930s were important producing years. The district is also estimated to have produced more than 550,000 ounces (17.54 metric tonnes) of silver (Bundtzen and others, 1994, table 4). Very small amounts of stibnite and scheelite were also produced.|
|MRDS Number||D002178; M047043|
Brooks, A.H., Richardson, G.B., Collier, A.J., and W.C. Mendenhall, 1901, A reconnaissance in the Cape Nome and adjacent gold fields of Seward Peninsula, Alaska, in 1900: U.S. Geological Survey Special Publication, p. 1-185, maps.
Bundtzen, T.K., Reger, R.D., Laird, G.M., Pinney, D.S., Clautice, K.H., Liss, S.A., and Cruse, G.R., 1994, Progress report on the geology and mineral resources of the Nome mining district: Alaska Division of Geological and Geophysical Surveys, Public Data-File 94-39, 21 p., 2 sheets, scale 1:63,360.
Collier, A.J., Hess, F.L., Smith, P.S., and Brooks, A.H., 1908, The gold placers of parts of Seward Peninsula, Alaska, including the Nome, Council, Kougarok, Port Clarence, and Goodhope precincts: U.S. Geological Survey Bulletin 328, 343 p.
Ford, R.C., and Snee, L.W., 1996, 40Ar/39Ar thermochronology of white mica from the Nome district, Alaska--The first ages of lode sources to placer gold deposits in the Seward Peninsula: Economic Geology, v. 91, p. 213-220.
Hopkins, D.M., MacNeil, F.S. and Leopold, E.B., 1960, The coastal plain at Nome, Alaska, A late Cenozoic type section for the Bering Sea region, in Chronology and climatology of the Quaternary: International Geological Congress, 21st, Copenhagen, Proceedings, Part 4, p. 46-57.
Hummel, C.L., 1962, Preliminary geologic map of the Nome C-1 quadrangle, Seward Peninsula, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-247, 1 sheet, scale 1:63,360.
Koschmann, A.H., and Bergendahl, M.H., 1968, Principal gold producing districts of the United States: U.S. Geological Survey Professional Paper 610, 283 p.
Metcalfe, J.B., and Tuck, Ralph, 1942, Placer gold deposits of the Nome district, Alaska: Report for U.S. Smelting, Refining, and Mining Co., 175 p.
Moffit, F.H., 1913, Geology of the Nome and Grand Central quadrangles, Alaska: U.S. Geological Survey Bulletin 533, 140 p.
Nelson, C.H., and Hopkins, D.M., 1972, Sedimentary processes and distribution of particulate gold in the northern Bering Sea: U.S. Geological Survey Professional Paper 689, 27 p., 1 plate.
Smith, P.S., 1910, Geology and mineral resources of the Solomon and Casadepaga quadrangles, Seward Peninsula, Alaska: U.S. Geological Survey Bulletin 433, 234 p.
Spence, C.C., 1996, The northern gold-fleet, Twentieth century gold-dredging in Alaska: Urbana, University of Illinois Press, 303 p.
|Reporters||C.C. Hawley and Travis L. Hudson|
|Last report date||7/10/2000|