Saddle

Prospect, Active

Commodities and mineralogy

Geographic location

Quadrangle map, 1:250,000-scale CA
Quadrangle map, 1:63,360-scale B-5
Latitude 65.4648
Longitude -161.3861
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospect is just east of Weather Ridge in the saddle at the divide between the head of the Kiwalik River and the western headwater tributary to Quartz Creek. It at an elevation of about 1,210 feet, about 0.5 mile north-northwest of the center of section 28, T. 1 N., R. 13 W.

Geologic setting

Geologic description

The Saddle 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 Linus's initial work relied heavily on soil geochemistry and surface sampling. The Saddle prospect is similar to most of the rest of the deposits along the Kiwalik trend. As described by Adams (2007), there are several types of mineralization, many occurring together: 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.
The Saddle prospect was discovered by Linus in 2005 (Adams, 2007). It is in the east contact zone of the quartz monzonite pluton; the rocks at the surface are a volcanic assemblage of andesitic and dacitic rock and interbedded epiclastic rocks. The rocks are widely chloritized and locally tourmalinated, silicified, and carbonatized. Seven samples collected at the surface contained less than 10 to 2,580 parts per billion (ppb) gold, 0.45 to 250 parts per million (ppm) silver, 5.6 to 12,300 ppm arsenic, 0.6 to 30.3 ppm bismuth, 44.9 to 194 ppm copper, 2.4 to 19.6 ppm molybdenum, 66.40 to 13,700 ppm lead, 19 to 418.1 ppm antimony, 13.7 to 105.3 ppm tin, 0.3 to 12 ppm thorium, 0.2 to 3.2 ppm uranium, 1.2 to 42.6 ppm tungsten, and 354 to 17,100 ppm zinc. In 2006, Linus drilled one hole to a depth of 499 feet. The upper portion of the hole was was in dacitic tuff and siltstone, followed by andesitic tuff that is altered to biotite-tourmaline hornfels at depth. The middle portion is largely in altered granodiorite. The bottom portion is mostly in biotite-tourmaline hornfels but the bottom of the hole is in granodiorite. Hornfelsing and tourmalination increased dramatically with depth. The drill hole intersected two zones of sulfide-tourmaline-quartz veins with various assemblages of sulfides, mainly pyrrhotite, galena, sphalerite, and arsenopyrite. Some of the better intercepts were 50 feet with 3.9 ppm silver, 1, 722 ppm lead, 15.43 ppm tungsten, and 6,652 ppm zinc; 10 feet with 60 ppb gold, 0.7 ppm silver, 13.2 ppm thorium, and 6.85 ppm uranium; and 10 feet with 46.5 ppm gold, 2.1 ppm silver, 960 ppm lead, 14.5 ppm thorium, 8 ppm uranium, and 8,093 ppm zinc.
Geologic map unit (-161.388742641592, 65.4641249974627)
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.
Age of mineralization Cretaceous or younger based on the age of the host rocks.
Alteration of deposit The rocks are widely chloritized and locally tourmalinized, silicified, and carbonitized. In one drill hole, hornfelsing and tourmalization increased dramatically with depth.

Production and reserves

Workings or exploration 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 one hole to a depth of 499 feet.
Indication of production None

References

References

Adams, D.D., 2007, Geologic report on the Granite Mountain property, Koyuk Mining District, Candle B-5 and C-5 quadrangles, west-central Alaska: Unpublished Technical Report for the Linus Gold Corp., 71 p. (posted on www.sedar.com on February 8, 2008).
Reporters D.J. Grybeck (Port Ludlow, WA)
Last report date 6/5/2008