Unnamed (between Curtis Hills and Bruce Hills)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Cu; Pb
Other commodities Cr; Fe; Ti
Gangue minerals ankerite; calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale MF
Quadrangle map, 1:63,360-scale D-1
Latitude 58.96
Longitude -136.25
Nearby scientific data Find additional scientific data near this location
Location and accuracy Poorly-defined northwest-trending area between the Curtis Hills and Bruce Hills. It is north of Plateau Glacier and south of Burroughs Glacier. The area is approximately 2 to 3 miles long and 1 mile wide. The coordinates are for the approximate midpoint of the area. The site is location number 73 of Kimball and others (1978) and number 23 of MacKevett and others (1971).

Geologic setting

Geologic description

The area is underlain by schist, hornfels, and marble derived mainly from sedimentary rocks of Paleozoic age. The sedimentary rocks were metamorphosed by the intrusion of a granitic batholith of Cretaceous age (Brew and others, 1978). The metasedimentary rocks are cut by mafic dikes and lie between the granitic Curtis and Bruce Hills. The area has recently been denuded by melting of the Plateau and Burroughs Glaciers.
The mineral occurrences of the area are mainly low-sulfide quartz-calcite-ankerite veins that formed on the contacts of mafic dikes that cut the metasedimentary rock. Grab samples of various occurrences contained as much as 300 ppm lead, 700 ppm copper, and 15 ppm silver (MacKevett and others, 1971, location 23, table 9; Kimball and others, 1978, location 73, p. C316-317). Other elements, including chromium, iron, and titanium, are locally geochemically anomalous in the veins; these elements possibly were contained in or contributed to the veins by the mafic dikes. Titanium content exceeded 1 percent in one sample and was 1 percent in several others.
Veins of the area could be distal structures to a buried contact zone between granite and the metasedimentary rocks.
Geologic map unit (-136.251881225129, 58.9596005688375)
Mineral deposit model Distal low-sulfide quartz-carbonate veins: Possible trace element contribution from mafic dike hosts.
Age of mineralization Cretaceous or younger.
Alteration of deposit Propylitic?

Production and reserves

Workings or exploration No workings. MacKevett and others (1971, location 23) found as much as 700 ppm copper and chromium and 1 percent titanium in iron-stained vein zones along mafic dikes. Kimball and others (1978, p. C316-317) reported 300 ppm lead and 15 ppm silver in a 0.3 foot thick quartz-calcite vein and more than 1 percent titanium in one wider (5 ft.) chip sample.
Indication of production None

Additional comments

The vein deposits are typical distal quartz-carbonate veins locally enriched in lead, copper, and silver. Prospecting closer to the granitic intrusives of the Bruce and Curtis Hills might find richer vein deposits, possibly transitional into copper and copper-molybdenum-bearing deposits.
The site is in Glacier Bay National Park and Preserve.

References