Clough and Roe reported in 1990 on the history, geology, and coal resources of northwestern Alaska to supplement the information entered into the National Coal Resource Data System. A detailed final report encompassing ADGGS coal studies in northwest Alaska and utilizing the database management and graphics capabilities of NCRDS is in preparation.
Coal (and lignite) in northwestern Alaska occurs within Lower Mississippian, Cretaceous, and Tertiary rocks. Coal quality and the extent of coal resources depends largely ontheir geologic age and tectonic setting. The oldest and highest rank coals (bituminous to semianthracite) of the Lower Mississippian rocks exposed on Cape Lisburne are in a structurally complex setting making resource estimates unreliable.
The thickest individual coal beds (up to 100 ft thick) are also the youngest and lowest in rank (lignite) occurring in numerous isolated Tertiary basins scattered across Seward Peninsula, St. Lawrence Island and Norton Sound to Kobuk River areas. Many of these basins are undergoing Cenozoic subsidence and their relationship to one another is poorly understood. The best resources of coal in both known areal extent and high quality (subbituminous to high volatile C and B) occur in Cretaceous rocks in the region extending north of the Brooks Range.
Between 1980 and 1985 the ADGGS' Northwest Alaska Coal Project examined occurrences of lignite to bituminous coal in northwestern Alaska to consider the practicality of coal as an alternative energy source for the 28 villages in the region. The 13 most promising sites (Fig. 1) were investigated by geologists from ADGGS and U.S. Bureau of Land Management (BLM) and are (from north to south):
1) Cape Beaufort-Deadfall Syncline;
2) Cape Lisburne;
3) Kallarichuk River;
4) Hockley Hills;
5) Singauruk River;
6) Chicago Creek;
7) Turner Creek;
8) Sinuk River;
9) Wilson Creek;
10) Grouse Creek;
11) Koyuk;
12) Unalakleet; and
13) St. Lawrence Island.
Beginning in 1981, Requests for Proposals (RFPs) for subcontractors to conduct test-drilling at six sites (Cape Beaufort, Chicago Creek,
Sinuk River, Koyuk, Unalakieet, and St. Lawrence Island) were solicited from drilling companies and consulting geologists. Drill site and coal occurrence studies included drill-hole coring and lithologic/geophysical logging; field examinations and trenching of coal outcrops; and stratigraphic section measuring where feasible.
Coal quality analyses (proximate and some ultimate) were performed on samples collected from outcrops and drill hole cores and cuttings. These analyses along with stratigraphic thickness of coal beds, cross-sections and detailed maps were utilized for entry into the NCRDS. The distribution of coal-bearing rocks, locations of coal mines, and ADGGS field investigations and drilling sites are shown on Plate 1.
Reports on the Northwest Alaska Coal Project written by ADGGS geologists and its subcontractors, and BLM geologists are:
Alaska Division of Geological and Geophysical Surveys (1982);
Callahan and Eakins (1986) C.C. Hawley and Associates (1983,1985);
Clough and others (1982% 1982b);
Eakins (1986);
Eakins and Clough (1982);
Haga (1984);
Ramsey and others (1986);
Renshaw (1981, 1982, 1983);
Retherford (1986);
Plangraphics (1983); and
Stevens Exploration Management Corporation (1982).
Additional State of Alaska funded products on northwestern Alaska coal are:
Arctic Slope Consulting Engineers (1984,1986);
Dames and Moore (1980);
Denton and others (1986); and
Grinage and Gillen (1986).
Geology, coal bed thickness and coal quality information was also obtained from the following sources:
Barnes (1967% 1967b);
Barnes and Hudson (1977);
C.C. Hawley and Associates (1977% 1977b, 1977~);
Callahan and Sloan (1978);
Cass (1959);
Collins (1958);
Martin and Callahan (1978);
Miller and others (1972);
Patton (1967);
Patton and Csjetey (1980);
Patton and Miller (1968);
Patton and others (1968);
Rao (1980);
Rao and Smith (1983);
Sainsbury (1974,1975);
Sainsbury and Hudson (1972);
Tailleur (1965);
Tailleur and Brosge (1976); and
U.S. Bureau of Mines (1979).
The authors concluded that The diverse quantity and quality of coal in northwestern Alaska (Figs 13 and 14) is directly related to disparate depositional settings and ages. The most abundant high quality coal resources are the Cretaceous coal found at Cape Beaufort and to the north. The likelihood that these resources will be mined by both surface and underground techniques is high. A mining plan developed by Arctic Slope Regional Corporation for the Deadfall Syncline proposes mining 300,000 tons of coal per year for local use and export and would employ more than 300 workers.
The second most abundant coal resource in the region exists in the Tertiary-age basins on Seward Peninsula where very thick coal beds of limited areal extent occur. A mining plan for Chicago Creek developed by C.C. Hawley and Associates would open pit mine 50,000 short tons of coal per year for 30 years out of demonstrated resources of 3,429,000 short tons to supply a power plant in Kotzebue.
Other Tertiary coal deposits with limited potential under current market conditions include the Death Valley-Boulder Creek basin where a 175-ft-thick bed of
subsurface coal and a 35 ft-thick-coal in outcrop at Grouse Creek is known. Undiscovered Tertiary coal on Seward Peninsula may be considerable.
The most difficult to extract yet highest quality coal in the region is the Mississippian-age coal at Cape Dyer on the Lisburne Peninsula. Coal here is up to
semianthracite in rank but is structurally complicated due to local and regional tectonics. The high rank and near tide-water location may provide incentive for further exploration by industry and government.
Coal in northwestern Alaska, as throughout the state, is low in total sulfur and generally low in pyritic sulfur which is of great importance in light of new and future coal-burning regulations. The demand for low-sulfur coal is expected to rise in the United States and worldwide. The 125 northwestern Alaska coal Point IDS and 231 coal quality analyses entered into NCRDS (to date) provides an accurate database file of known low-sulfur coal resources in the region. It is our hope that the currently available AKSTRAT and USALYT files will be utilized by the public, Federal and state agencies, and industry seeking information on the coal resources of northwestern Alaska.
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