Pleasant Creek

Prospects, Active

Commodities and mineralogy

Main commodities Pb; Zn
Other commodities Ag; As; Co; Cu; Sb
Ore minerals galena; pyrite; sphalerite
Gangue minerals quartz; serpentine

Geographic location

Quadrangle map, 1:250,000-scale CY
Quadrangle map, 1:63,360-scale A-1
Latitude 65.177
Longitude -141.053
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Pleasant Creek prospects are located in the central and southwest portion of T. 4 N., R. 33 E., of the Fairbanks Meridian. They have an irregular boundary and cover about 6 square miles. The easternmost boundary is the Canadian border, and they do not encompass VABM Pack. Coordinates are for the northernmost prospect, in section 16, T. 4 N., R. 33 E., of the Fairbanks Meridian. The location is accurate. These prospects are located within Doyon Limited selected or conveyed land.

Geologic setting

Geologic description

Rock units in the prospect area are of Late Precambrian age and include a thick unit of basalt and redbeds with an interlayered sequence of massive carbonate rocks and conglomerate (DiMarchi and others, 1993). Carbonate rocks include the Pack Formation, a massive dolomite that lies unconformably over the Pleasant Creek Formation of dolomitic limestone, quartzite, and shale. Numerous facies changes and iron-rich zones characterize the prospect area. All of the units are folded along a northeast-trending anticlinal structure which is probably sympathetic to the larger scale Cathedral Creek arch. The prospect area also contains numerous northeast-trending thrust faults and two major high-angle faults, having displacements of 700 to 1,500 feet. A northeast-trending andesite dike swarm cuts across all of the map units in the area (DiMarchi and others, 1993).
The prospect hosts two types of breccia: (1) areally extensive collapse breccias related to karsting in the carbonate units; and (2) an areally limited breccia related to faulting along the margins of the andesite dikes. Small iron oxide gossans along the breccias may increase with depth. Silicification and quartz veining are common in both breccia types, and serpentine is found rarely in fractures in the dolomite (DiMarchi and others, 1993). Mineralization at Pleasant Creek consists of a breccia body of unrotated dolomite fragments coated with pyrite in an open-space-fill matrix of coarse dolomite and massive pyrite; very fine grained, light colored sphalerite infilling brecciated pyrite; and late galena cubes (Andres and others, 1977).
Soil sampling, rock sampling, and geologic mapping programs have been conducted at the Pleasant Creek prospects (DiMarchi and others, 1993).
Geologic map unit (-141.055359279015, 65.1767295533029)
Mineral deposit model Plutonic-related Pb-Zn?, Carbonate-hosted Zn? (Cox and Singer, 1986; model 32b)
Mineral deposit model number 32b?
Alteration of deposit The alteration at the Pleasant Creek prospects includes serpentinization, silicification, and quartz veining.

Production and reserves

Workings or exploration Soil sampling, rock sampling, and geologic mapping programs have been conducted at the Pleasant Creek prospects (DiMarchi and others, 1993).
Indication of production None

Additional comments

This property lies on Doyon, Limited selected or conveyed land. For more information, contact Doyon, Limited. This site is within the Yukon-Charley Rivers National Preserve.

References

MRDS Number 10307408

References

Andrews, Tom, Bigelow, C.G., Fernette, J.P., Jirik, R., Kretschmar, U., Kretschmar, D., Lessman, J., McOuat, M., Martin, W., Ruzicka, J., Sandrock, G., Skyllingstad, P., Yinger, M., 1977, 1976 Annual progress report, Doyon project volume 1a, blocks 1, 4, 5, 7, 8: Anchorage, Alaska, WGM, Inc., p. 7-1 to 7-23. (Report held by Doyon, Limited, Fairbanks, Alaska.)
DiMarchi, J.J., Weglarz, T.B., Adams, D.D., Hubert, J.A., and West, A.W., 1993, 1993 annual report--Reconnaissance program, Doyon option lands: ASA Inc., 120 p. (Report held by Doyon, Limited, Fairbanks, Alaska.)
Schmidt, J.M., 1997, Shale-hosted Zn-Pb-Ag and barite deposits of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral deposits of Alaska, 1997: Economic Geology Monograph 9, p. 35-65.
Reporters C.E. Cameron (ADGGS)
Last report date 4/7/2000