Unnamed (Ferndale Creek)

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Pb; Zn
Other commodities Cu; Sn
Gangue minerals clay minerals; iron oxides; quartz

Geographic location

Quadrangle map, 1:250,000-scale BN
Quadrangle map, 1:63,360-scale D-6
Latitude 65.83
Longitude -164.54
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is on a flat ridge crest at an elevation of 2,220 feet; it overlooks the headwaters of Hot Springs Creek and Ferndale Creek (a tributary to Humbolt Creek, Hudson, 1979, Plate 1). It is one mile north of the continental divide and 2,000 feet east of outcrops of the Oonatut Granite Complex (Hudson, 1979).

Geologic setting

Geologic description

A very fine-grained granite dike trends N 80 W west and intrudes hornfels in the country rocks to the Oonatut Granite Complex here (Hudson, 1979). This dike and adjacent country rocks have been altered and rust-stained soils, rock fragments, and small gossan fragments are localized along the trend of the dike. The presence of slickensided rock fragments in the soils suggests that the dike was emplaced along a fault that has had recurring movement. Twelve composite grab samples of soil, altered rocks, and gossan fragments collected across the altered zone contain up to 150 ppm Ag, 10,000 ppm As, 200 ppm Cd, 500 ppm Cu, greater than 20,000 ppm Pb, greater than 10,000 ppm Zn, and 700 ppm Sn. Gold was not determined (Hudson, 1979, p. 26). The length of the altered zone that was sampled is about 1,000 feet. This altered zone is interpreted to have developed above buried parts of the Oonatut Granite Complex and to be related to its crystallization. The Oonatut Granite is part of the western Seward Peninsula tin granite suite (Hudson and Arth, 1983) and the polymetallic character of this mineralization may be reflective of the lead-zinc zone in tin deposit systems (Hudson, 1979).
Geologic map unit (-164.542716057859, 65.829283672506)
Mineral deposit model Sulfide veining or impregnations in hornfels and granite dike
Age of mineralization Probably Late Cretaceous; this occurrence is thought to be related to emplacement and crystallization of the Oonatut Granite Complex. K/Ar ages for the Oonatut Granite Complex are about 70 my (Hudson, 1979).
Alteration of deposit Iron-oxide staining and bleached discoloration are common; some clay development is probably present.

Production and reserves

Workings or exploration Shallow hand-dug prospect pits may be present.
Indication of production None