Gossan

Prospect, Active

Commodities and mineralogy

Geographic location

Quadrangle map, 1:250,000-scale CA
Quadrangle map, 1:63,360-scale B-5
Latitude 65.4201
Longitude -161.353
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Gossan prospect is at an elevation of about 780 feet on the south end of Gossan Ridge. It is about 3.7 miles west-southwest of the top of Granite Mountain and about 0.5 mile north-northwest of the center of section 9, T. 1 S., R. 13 W., of the Kateel River Meridian. The location is accurate.

Geologic setting

Geologic description

As initially described by Miller and Elliott (1969) this prospect is near the border of the mid-Cretaceous Quartz Creek pluton, a hook-shaped, quartz monzonite body at least 16 miles long and up to a mile wide. The pluton is surrounded by an alteration zone 2 to 5 miles wide that is marked by numerous mineral occurrences along the entire length of the pluton. The alteration zone is in Jurassic-Cretaceous andesitic volcanic and sedimentary rocks. Fine-grained dikes of varying composition cut the andesite near the pluton.
In 2005, the Linus Gold Corp. began work in the area and by 2006 had staked 176 Alaska (state) claims that covered this prospect and others along the 'Kiwalik trend' of mineralization that roughly coincides with the Quartz Creek pluton and its alteration zone. Exposures are poor in the area and their initial work relied heavily on soil geochemistry and surface sampling. As described by Adams (2007), there are several types of mineralization, many occurring together, along the Kiwalik trend: 1) sulfide-tourmaline-quartz veins with galena, sphalerite, and pyrite and locally minor arsenopyrite, pyrrhotite, chalcopyrite, and molybdenite; 2) disseminated pyrite and arsenopyrite in hairline veinlets that also locally contain sparse galena, stibnite, and bismuthinite; 3) sulfide-rich veins and veinlets with various assemblages of pyrite, pyrrhotite, chalcopyrite, arsenopyrite, sphalerite, galena, stibnite, molybdenite, and pyrargyrite, 4) pyrite-chlorite-calcite-quartz veins, 5) sulfide-quartz veins and stockworks with pyrite, pyrrhotite, arsenopyrite, galena, stibnite, sphalerite, chalcopyrite, and scheelite, and 6) fluorite-molybdenite-galena-pyrite-uranothorianite veinlets and disseminations. There are several distinct types of alteration: 1) phyllic, 2) silicification, 3) carbonate, 4) argillic, 5) propylitic, 6) tourmalinization, 7) alunitic, and 8) potassic. Gossans with remnant galena and sphalerite are found locally.
In 2006, Linus drilled 2 holes at the Gossan prospect where the surface is mostly rubble crop of andesite, basalt, dacite, epiclastic rocks, and gossan. The rocks at the surface and in the drill holes are characterized by pervasive propylitic alteration of the mafic volcanic rocks, quartz-sericite+/-carbonate alteration of the dacite, and irregular zones of silicification, carbonate alteration, and sericitization of the massive syenite that was intersected at a depth of 880 feet in one hole. The drill holes intersected several types of mineralization: 1) multiple 2- to 20-meter-thick zones of disseminated sulfides and veinlets in interlayered dacite, andesite tuff, and siltstone; 2) ubiquitous disseminated pyrite and pyrite-chlorite -actinolite-calcite-quartz veinlets; 3) sulfide-tourmaline-quartz veins, veined breccias, and massive tourmaline replacement in zones less than one meter thick; and 4) sulfide-rich veins and breccias in several zones. The sulfides include variable amounts of arsenopyrite, pyrite, galena, and stibnite. The best intercept in the two drill holes was 5 feet that contained 204 parts per billion gold; many intercepts contained significant values in silver, bismuth, molybdenum, copper, thorium, uranium, lead, and antimony.
Geologic map unit (-161.355638937155, 65.419424110927)
Mineral deposit model Disseminated and veined, Ag-As-Au-Bi-Cu-Mo-Pb-Sb-Th-U mineralization in several styles that occurs widely for 16 miles along the altered border zone of a Cretaceous quartz monzonite pluton.
Age of mineralization Cretaceous of younger based on the age of the host rocks.
Alteration of deposit The rocks in the drill holes at the Gossan prospect are characterized by pervasive propylitic alteration of the mafic volcanic rocks, quartz-sericite+/-carbonate alteration of the dacite, and irregular zones of silicification, carbonate alteration, and sericitization of syenite.

Production and reserves

Workings or exploration The prospect was discovered by the U.S. Geological Survey in the late 1960s (Miller and Elliott, 1969). It was subsequently examined by several companies. In 2005, the Linus Gold Corp. began work in the area and by 2006 had staked 176 Alaska (state) claims that covered this project and others along the 'Kiwalik trend' that roughly coincides with the Quartz Creek pluton and its alteration zone. Exposures are poor in the area and their initial work relied heavily on soil geochemistry and surface sampling. In 2006, Linus drilled two holes on the Gossan prospect.
Indication of production None

References