Greisen (on Tin Creek)

Prospect, Inactive

Commodities and mineralogy

Main commodities Sn
Other commodities Ag; Cu; Pb; Zn
Ore minerals cassiterite
Gangue minerals fluorite; quartz; topaz; tourmaline; white mica

Geographic location

Quadrangle map, 1:250,000-scale TE
Quadrangle map, 1:63,360-scale B-5
Latitude 65.466
Longitude -167.121
Nearby scientific data Find additional scientific data near this location
Location and accuracy Tin Creek is an east tributary to Lost River whose confluence is located 4.5 miles upstream from the mouth of Lost River on the Bering Sea. The Gresien prospect is in the eastern part of the Tin Creek granite stock, a rounded hill in the headwaters of Tin Creek (Sainsbury, 1969). This rounded hill, between Tin Creek and its small north tributary, reaches elevations of just over 1,150 feet. This locality 10 of Cobb and Sainsbury (1972). Cobb (1975) summarized relevant references under the name 'Tin Cr., trib. Lost R.'.

Geologic setting

Geologic description

The headwaters of Tin Creek are in an area where a small stock of biotite granite, the Tin Creek stock (Sainsbury, 1969; Hudson and Arth, 1983) intrudes Ordovician limestone and dolomite. The Tin Creek stock covers a 1,000 by 2,000 foot area on the crest of the rounded hill between Tin Creek and its northern tributary. The south contact of the stock is irregular and includes granite offshoots, dikes, and apophyses in the bordering carbonate rocks. An eastern part of the Tin Creek granite stock is cut by parallel greisen sheets with peripheral alteration selvages. Seven samples of this greisen (Hudson, 1983) contained 525 to 3,020 ppm tin, 1,040 ppm to 1.7% lead, 8,400 to greater than 20,000 ppm fluorine, 550 to greater than 1,000 ppm arsenic, and 5 to 24 ppm silver. Copper (to 280 ppm) and zinc (to 3,630 ppm) are elevated in some of these samples and gold (5 ppb) was detected in four. The style of mineralization here is interpreted to be similar to that at depth in the Lost River Mine endogreisen prospect (TE050).
Geologic map unit (-167.123719465681, 65.4652255779414)
Mineral deposit model Tin greisen (Cox and Singer, 1986, model 15c)
Mineral deposit model number 15c
Age of mineralization The age of the mineralization is assumed to be related to the development of tin systems in the Lost River area and therefore Late Cretaceous, the age of the tin-mineralizing granites there (Hudson and Arth, 1983).
Alteration of deposit Typical greisen alteration with feldspar destruction and extensive replacement by quartz, topaz, and white mica in the host granite. Some quartz veining may be present in the cores of greisen zones. Tourmaline and fluorite are also present in altered rocks. Alteration selvages are less completely greisenized granite.

Production and reserves

Workings or exploration Little exploration has taken place here but some surface trenches or pits may be present.
Indication of production None
Reserve estimates Not defined

References

MRDS Number 10308407

References

Reporters Travis L. Hudson (Applied Geology)
Last report date 5/10/1998