Kantishna Hills lode deposits

Mines, Inactive

Commodities and mineralogy

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale C-2
Latitude 63.5542
Longitude -150.8915
Nearby scientific data Find additional scientific data near this location
Location and accuracy
This record is a summary description of numerous lode deposits in the Kantishna Hills, especially those in a belt that trends east-northeast from Alpha Ridge, across Quigley Ridge and the south flank of Wickersham Dome, to Kankone Peak. The belt includes the two largest precious-metal lode mines of the Kantishna Hills--the Little Annie No. 2 (MM115) and the Banjo (MM097). The area also includes several of the richest placer deposits in the Kantishna Hills, summarized in record MM084.
For this record, the site is at the approximate center of the belt of lode deposits. It is at an elevation of about 3200 feet on the ridge about a mile east of Wickersham Dome and about 0.1 mile north of the Banjo mine (called the Red Top mine on the 1954/1978 edition of the USGS Mt. McKinley C-2 topographic map).
The major mines are briefly described in several publications, chiefly those of Cobb (1972 [MF 366], 1980 [OFR 80-363]), MacKevett and Holloway (1977), Bundtzen (1981), and Thornsberry, McKee, and Salisbury (1984).

Geologic setting

Geologic description

The Kantishna Hills area of lode deposits described in this record conforms closely to the central part of an antiform, an upwarp that can be traced east-northeast from Eldorado Creek to at least Kankone Peak (Wells, 1933). This structure is informally called the Kantishna antiform. Rocks exposed in the antiform's crestal region belong mainly to the lower Paleozoic Spruce Creek sequence (Bundtzen, 1981, p. 50). Regionally, the Spruce Creek rocks structurally overlie the Precambrian Birch Creek Schist, but along the crest of the antiform, they appear to be downfaulted into Birch Creek Schist along high-angle faults (Bundtzen, 1981). Spruce Creek rocks crop out continuously across strike from Eldorado Creek to Canyon Creek. The sequence appears to be 500 to 1000 meters thick and to consist chiefly of gray slate and phyllite, chloritic phyllite and semischist, light-colored metafelsite, quartz-feldspar phyllite, and micaceous marble. Bundtzen (1981, p. 40) divided the sequence into two main units: one consists mainly of metafelsite, quartz-feldspar schist, and chlorite-rich phyllite and semischist; the other is mainly graphitic phyllite and semischist and marble. Bundtzen (1981, p. 40) referred to the Spruce Creek rocks as 'ore-zone rocks' because 'many quartz-carbonate-sulfide veins in the Kantishna mining district . . . are hosted in them.' The Spruce Creek sequence is regionally metamorphosed to greenschist grade, and appears to have undergone only one main period of deformation. Birch Creek rocks have been deformed at least twice and probably were regionally metamorphosed to amphibolite grade before being retrograded to lower greenschist grade.
Rocks corresponding to Spruce Creek lithologies were mapped by Wells (1933), Morrison (1964), and Hawley and Associates (1978), but were included by them in the Birch Creek Schist. Bundtzen (1981) was the first to distinguish the Spruce Creek sequence in the Kantishna district. The sequence was also mapped separately by Thornsberry, McKee, and Salisbury (1984).
There are mainly two types of lode deposits in the Kantishna Hills area: gold-bearing, relatively low-sulfide, quartz-arsenopyrite-(scheelite) veins; and silver-bearing, sulfide-rich, galena-sphalerite-tetrahedrite-pyrite-chalcopyrite veins. This subdivision, first proposed by Wells (1933), was used by Bundtzen, Smith, and Tosdal (1976), and by Bundtzen (1981) to characterize the deposits. The veins occupy mostly high-angle faults. The area also contains stratabound deposits.
Quartz is the dominant gangue mineral in the gold-bearing veins. Quartz and siderite are the most abundant gangue minerals in the silver-bearing veins. A few sulfide minerals, including arsenopyrite, galena, pyrite, and sphalerite tend to be dominant in most veins, but the area-wide mineral suite is large and complex and less-common minerals locally predominate. Tetrahedrite and its silver-rich analogue freibergite are locally important, as are ruby silver and related minerals such as polybasite and pearceite. Boulangerite and jamesonite ocur widely in the complex silver-rich deposits. Scheelite is common, especially in the gold-rich veins. Cassiterite is rare. Some minerals are known only from float: rhodonite is common in float in Glenn Creek (MM108); its lode source is unknown. There is little evidence of extensive supergene enrichment in the Kantishna Hills, but sulfate-charged ground waters form melanterite and rare native sulfur in veins opened by mining. Thin, surface-oxidized zones are mainly composed of limonite and, depending on primary mineral composition, may contain azurite, malachite, cerrusite, and stibiconite.
The fault-controlled, precious-metal-bearing veins in the district formed after regional metamorphism, probably nearly synchronous with upwarping of the Kantishna antiform. The deposits herein are assumed to be Eocene, inferred from an isotopically-dated mineralized quartz porphyry plug and mineralized bimodal dikes at the Bonnell prospect (MM030).
Geologic map unit (-150.893786456014, 63.5536950566972)
Mineral deposit model Polymetallic silver-rich veins and low-sulfide gold-quartz veins (Cox and Singer, 1986; models 22c, 36a).
Mineral deposit model number 22c, 36a
Age of mineralization Based on radiometric dating, Bundtzen and Turner (1979, p. 26, 28-30) proposed that the schistose basement rocks in the Kantishna district were metamorphosed in pre-Jurassic time and overprinted by mid-Cretaceous greenschist-grade regional metamorphism. The epigenetic deposits, chiefly mineralized quartz veins and their alteration envelopes, postdate the Cretaceous regional metamorphism and may be roughly synchronous with lower Tertiary plutonism. Four dates, three from dikes and one from a quartz porphyry plug at the Bonnell prospect (MM030) have Eocene (about 50 to 48 Ma) minimum emplacement ages. The quartz porphyry and the dikes are mineralized, indicating that the deposits are no older than Eocene. The deposits herein are assumed to be Eocene, and this age is extrapolated to apply to all epigenetic lode deposits in the Kantishna district. The Eocene age is roughly contemporaneous with eruption of the Teklanika Volcanics in the Mt. McKinley (Denali) Park area (Gilbert, Ferrell, and Turner, 1976).
Alteration of deposit Surface oxidation of iron, copper, lead, and antimony minerals.

Production and reserves

Workings or exploration Exploration in the Kantishna district began shortly after the discovery of placer deposits in about 1905 (Prindle, 1906, 1907, 1911). Several rich deposits found before 1916 were actively prospected but had negligible recorded production (Capps, 1919). A short period of mining occurred in the early 1920s after discovery of rich mineral deposits at the Little Annie (MM115), Red Top (MM118) and Alpha (MM021) mines (Davis, 1923, Moffit, 1933, Wells, 1933). A spurt of mining accompanied development of the Banjo mine (MM097) just before WW II. A final stage occurred in the 1970s and early 1980s after the price of gold was freed and before litigation that terminated most mining in the Kantishna Hills area.
Indication of production Yes; medium
Production notes Including 120 tons of low-grade ore mined in 1923, the production of bonanza-grade silver-rich ores from 1920 to 1923 totaled 1,655 tons that contained 257,965 ounces of silver, 449 ounces of gold, and 504,760 pounds of lead (Bundtzen, 1981, table 12). The production from the Banjo mine from 1938 to 1942 totaled 13,603 tons of ore that contained 7113.8 ounces of silver and 6259.9 ounces of gold. This ore also contained considerable lead. Small quantities of high-grade gold and silver ore were produced at the Wieler (Parky) deposit (MM098) after World War II.

Additional comments

The Kantishna lode area is in Denali National Park and Preserve. Although many of the deposits have been known for decades, their remoteness has precluded extensive exploration. Geologic work by Bundtzen, Smith, and Tosdal (1976), Hawley and Associates (1978), and Thornsberry, McKee, and Salisbury (1984) identified geologic types of deposits not known to early prospectors, including volcanogenic and sedimentary-exhalative deposits, that are largely unexplored.

References

References

Bundtzen, T.K., 1981, Geology and mineral deposits of the Kantishna Hills, Mt. McKinley quadrangle, Alaska: M. S. Thesis, University of Alaska, College, Alaska, 238 p.
Morrison, D. A., 1964, Geology and ore deposits of Kantishna and vicinity, Kantishna district, Alaska: College, AK, University of Alaska, M. S. Thesis, 109 p.
Reporters C.C. Hawley
Last report date 2/9/2001