Taurus

Prospect, Active

Alternative names

East Taurus
West Taurus

Commodities and mineralogy

Main commodities Au; Cu; Mo
Ore minerals azurite; chalcocite; chalcopyrite; covellite; magnetite; molybdenite; pyrite
Gangue minerals fluorite; quartz; sericite; tourmaline

Geographic location

Quadrangle map, 1:250,000-scale TC
Quadrangle map, 1:63,360-scale C-1
Latitude 63.6474
Longitude -141.263
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Taurus prospect has two main centers of interest, West Taurus and East Taurus. Most of the work has been done at East Taurus at the coordinates of for this site. West Taurus is about 3,000 meters to the west. East Taurus is about 12.5 miles east-southeast of Prindle Volcano and about 0.6 mile northwest of the center of section 36, T. 22 N., R. 21 E.

Geologic setting

Geologic description

From 1970, when Taurus was discovered during a reconnaissance geochemical survey, to 1996, a succession of companies, notably International Minerals and Chemical Corp., Duval Minerals, Rioamex, City Services Minerals Corp., Noranda, and Cross Canada, explored the property with mapping and sampling, ground and aerial geophysical surveys, several geochemical programs, and by 30 drill holes (Harrington, 2010). By 1996, Taurus East had become the focus of interest and 8 holes were drilled there. In 2008, Senator Minerals Inc. drilled 3 more holes at East Taurus that totaled 3,179 feet. As of early 2011, Senator Minerals holds the property (Senator Minerals, Inc., 2011).
The Taurus property has two main centers of porphyry-type mineralization, West Taurus and East Taurus (Harrington, 2010). The property is underlain in part by a metamorphic basement complex possibly of Late Precambrian or early Paleozoic age that consists of biotite gneiss, augen gneiss, biotite schist, and quartzite, intruded by Cretaceous granodiorite (Foster, 1970). Two Early Tertiary stocks who outcrop areas roughly coincide with East and West Taurus intrude the metamorphic rocks and the granodiorite. Secondary biotite in one intrusion has been dated by K-Ar methods at 57 +/- 2 Ma (Nokleberg and others, 1995).
Two major faults have been identified. The Tourmaline fault strikes northeasterly and appears to have left-lateral movement with a possible displacement of up to 6.5 kilometers. The McCord Creek fault trends east across the claims. Porphyry intrusions, which host the mineralization at East and West Taurus, are near the McCord Creek fault, suggesting that the fault controlled their emplacement. Many northeast trending lineaments have been interpreted using satellite images and topographic maps (Leriche, 1995, p. 452).
The Taurus porphyry copper mineralization appears to be related to widespread, small bodies of early Tertiary, quartz monzonite porphyry, quartz latite, feldspar-quartz porphyry, intrusive breccia, quartz porphyry and dacite porphyry. Intrusive breccia crops out along the southern border of an altered, Late Cretaceous granodiorite pluton on the eastern side of the property. Quartz monzonite porphyry occurs along the southern contacts of the altered granodiorite, and intrusive breccia is in the central part of the property (Leriche, 1995; Harrington, 2010)).
The East Taurus ore body consists of an upper leached cap underlain by supergene and hypogene zones. The leached cap is up to 150 feet thick and shows pervasive argillic alteration due to groundwater leaching. The leached cap shows pervasive silicification, and quartz-sericite, and quartz-magnetite alteration. The supergene and hypogene zones are marked by phyllic, silicic, propylitic, and potassic alteration (Leriche, 1995, Harrington, 2010).
Mineralization in the leached cap at East Taurus consists of minor remnant pyrite, chalcopyrite, and molybdenite in quartz stockworks and silicified zones. The supergene zone varies in thickness from 70 to 150 feet and contains chalcocite, covellite, pyrite, chalcopyrite, and molybdenite. The chalcocite is in fractures and in quartz veinlets. In the lower hypogene zone, pyrite, chalcopyrite, and molybdenite are disseminated along fractures and in the center of quartz veinlets (Leriche, 1995).
Some notable intercepts in the 2008 drilling at East Taurus are: 1) 772 feet of 0.309 percent copper, 0.036 percent molybdenum, and 0.245 grams of gold per tonne; 2) 179 feet of 0.258 percent copper, 0.026 percent molybdenum, and 0.149 grams of gold per tonne; 57 feet of 0.232 percent copper, 0.004 percent molybdenum, and 0.015 grams of gold per tonne (Harrington, 2010). The mineralization at East Taurus is open in all directions as well as below the deepest 1,400-foot drill hole.
Mineralization in the West Taurus area consists of pyrite and subordinate chalcopyrite, covellite, chalcocite, malachite, and azurite. Molybdenite is found in quartz-filled fractures in sericitically altered, quartz latite. Chalcopyrite and molybdenite are in fracture fillings near the Tourmaline and McCord Creek faults (Leriche, 1995, p. 454).
In 1993, Noranda indicated that the East Taurus zone contained a reserve of 23 million tons with an average grade of 0.3 percent copper and 0.039 percent molybdenum (Leriche, 1995). The 1996, 2008, and earlier drilling provided sufficient information for an estimate to modern standards of the size of the deposit. Harrington (2010) estimated that East Taurus has an inferred mineral resource of 75.2 million tons with an average grade of 0.275 copper, 0.032 percent molybdenum, and 0.166 gram of gold per tonne.
Geologic map unit (-141.265236325152, 63.6470844579402)
Mineral deposit model Porphyry Cu-Mo-Au deposit (Cox and Singer, 1986; model 21a).
Mineral deposit model number 21a
Age of mineralization Secondary biotite from one of the stocks associated with the mineralization has been dated by K-Ar techniques methods as 57 +/- 2 Ma (Nokleberg and others, 1995).
Alteration of deposit The leached cap, which is up to 150 feet thick, shows pervasive argillic alteration due to groundwater leaching. Other alteration types in the leached cap consist of pervasive silicification, quartz-sericite, and quartz-magnetite alteration. Supergene and hypogene zones are accompanied by phyllic, silicic, propylitic, and potassic alteration (Leriche, 1995, p. 453).

Production and reserves

Workings or exploration From 1970, when Taurus was discovered during a reconnaissance geochemical survey, to 1996, a succession of companies, notably International Minerals and Chemical Corp., Duval Minerals, Rioamex, City Services Minerals Corp., Noranda, Resource Associates of Alaska, and Cross Canada, explored the property with mapping and sampling, ground and aerial geophysical surveys, several geochemical programs, and by 30 drill holes (see Harrington, 2010 for the details of this work). By 1996, Taurus East had become the focus of interest and 8 holes were drilled there. In 2008, Senator Minerals Inc. drilled 3 more holes at East Taurus that totaled 3,179 feet. As of early 2011, Senator Minerals holds the property (Senator Minerals, Inc., 2011).
Indication of production None
Reserve estimates In 1993, Noranda indicated that the East Taurus zone contained a reserve of 23 million ton with an average grade of 0.3 percent copper and 0.039 percent molybdenum (Leriche, 1995). The 1996, 2008, and earlier drilling provided sufficient information for an estimate to modern standards of the size of the deposit. Harrington (2010) estimated that East Taurus has an inferred mineral resource of 75.2 million tons with an average grade of 0.275 copper, 0.032 percent molybdenum, and 0.166 gram of gold per tonne.
Production notes None.

Additional comments

See also the Pushbush prospect (TC024) and the ASARCO prospect (TC001).

References

MRDS Number A012535

References

Gill, R., 1977, Geology and mineral deposits of the southwest quarter of the Tanacross D-1 quadrangle, Alaska: Golden, Colorado School of Mines, M.Sc. thesis, 129 p.
Harrington, Edward, 2010, Technical report on the Taurus property, Fairbanks Recording District, Alaska, U.S.A.: Unpublished NI43-101 report for Senator Minerals Inc., 133 p. (posted on www.sedar.com, Jan. 4, 2011)
Leriche, P.D., 1995, Taurus copper-molybdenum porphyry deposit, east-central Alaska: in Schroeter, T.G., ed., Porphyry Deposits of the Northwestern Cordillera: Canadian Institute of Mining, Metallurgy, and Petroleum Special Volume 46, p. 451-457.
Nokleberg, W.J., Bundtzen, T.K., Brew, D.A., and Plafker, G., 1995, Metallogenesis and tectonics of porphyry copper and molybdenum (gold, silver) and granitoid-hosted gold deposits of Alaska, in Schroeter, Tom, ed., Porphyry deposits of the northwestern Cordillera: Canadian Institute of Mining and Metallurgy Special Volume 44, p. 103-141.
Reporters C.E. Cameron (ADGGS); D.J. Grybeck (Contractor, USGS)
Last report date 2/28/2011