Pleasant Creek Prospects, Black Mining District, Southeast Fairbanks Census Area, Alaska, USAi

Regional Level Types
Pleasant Creek Prospects	Group of Prospects
Black Mining District	Mining District
Southeast Fairbanks Census Area	Census Area
Alaska	State
USA	Country

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.
Location: 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.
Geology: 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).
Workings: Soil sampling, rock sampling, and geologic mapping programs have been conducted at the Pleasant Creek prospects (DiMarchi and others, 1993).
Alteration: The alteration at the Pleasant Creek prospects includes serpentization, silicification, and quartz veining.

Commodities (Major) - Pb, Zn; (Minor) - Ag, As, Co, Cu, Sb
Development Status: None
Deposit Model: Plutonic-related Pb-Zn?, Carbonate-hosted Zn? (Cox and Singer, 1986; model 32b)

Other Databases

Link to USGS - Alaska:	CY024

Other Regions, Features and Areas containing this locality

References