Unnamed (near Tsirku Glacier )

Occurrence, Probably inactive

Commodities and mineralogy

Main commodities Ag; Au; Cu; Pb; Zn
Other commodities Ba; Co
Ore minerals chalcopyrite; galena; pyrite; pyrrhotite; sphalerite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale SK
Quadrangle map, 1:63,360-scale B-4
Latitude 59.32
Longitude -136.45
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is located in the headwaters of the Tsirku River, 0.7 miles east of the Alaska-Canada border and 0.6 miles north of the Tsirku Glacier at an elevation of 2,500 feet. It is in the NW1/4, section 35, T. 29 S., R. 53 E. of the Copper River Meridian. It is shown as number 156 of Still and others (1984) which is at the approximate center of an area of anomalously high samples that includes map numbers 149 to 168.

Geologic setting

Geologic description

According to Still and others (1984): 'Float and bedrock samples contain up to 6.2% zinc, 2.33% copper, 1.18% lead, 450 ppm cobalt, 49.84 ppm silver, 0.30 ppm gold, 1.13% barium, 200 ppm tin, 400 ppm arsenic, 300 ppm nickel, and 900 ppm bismuth. The samples include: 'pyrrhotite bearing quartz vein in slate', 'quartz boulder with 0.1 foot pyrrhotite band', 'massive pyrrhotite boulder with sparse quartz', 'altered volcanic boulder with massive sphalerite, chalcopyrite and galena(?)', and '70% silica, 30% sulfides - pyrrhotite, chalcopyrite and sphalerite.' Bedrock in the area is Paleozoic slate, metavolcanics. and limestone near a Cretaceous diorite, quartz diorite and granodiorite pluton (MacKevett and others, 1974).
The nature of this occurrence is unclear. It is probably either a polymetallic quartz-sulfide vein(s) or a volcanogenic, massive sulfide. If it is a vein(s), then it is probably Cretaceous based on the age of nearby intrusives (MacKevett and others, 1974). If it is a volcanogenic massive sulfide occurrence, then it is probably Late Triassic like the Windy Craggy and Greens Creek massive sulfide deposits (Still, 1984 [OF 118-84]; Newberry and others, 1997).
Geologic map unit (-136.451873018667, 59.3196485420606)
Mineral deposit model Unknown, but probably either a polymetallic quartz-sulfide vein or a Besshi- or Kuroko-type volcanogenic massive-sulfide occurrence (Cox and Singer, 1986; models 22c, 24b, 28a).
Mineral deposit model number 22c?, 24b?, 28a?
Age of mineralization If it is a quartz-sulfide vein, it is probably Cretaceous, based on the age of nearby intrusives (MacKevett and others, 1974). If it is a volcanogenic massive sulfide, it is probably Late Triassic like the Windy Craggy and Greens Creek massive-sulfide deposits nearby (Still, 1984 (OFR 118-84); Newberry and others, 1997)
Alteration of deposit Altered volcanics are mentioned but not described (Still and others, 1984).

Production and reserves

Indication of production None

References