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Allegro, G.L., 1987

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Bibliographic Reference

Allegro, G.L., 1987, The Gilmore Dome tungsten mineralization, Fairbanks mining district, Alaska: University of Alaska Fairbanks, M.S. thesis, 150 p., illust., maps, 7 folded maps.

Abstract

Scheelite in the Fairbanks mining district, Alaska, occurs in small, discontinuous, stratabound bodies along the northern flank of the Gilmore Dome intrusive up to 3 km away from intrusive contacts within late Precambrian greenschist facies marble, calc-silicate marble, and calcareous quartzite. Detailed studies of these prospects have led to the conclusion, based on gangue mineralogy, structural control, cross-cutting features, and age of mineralization, that the scheelite is of metasomatic origin. Scheelite occurs in pyroxene (Hd90-40) - garnet (Gr82-70) skarn, ferro-actinolite hornblende + quartz + calcite retrograde skarn, and muscovite + biotite + chlorite altered zones. Skarns are localized in calcareous horizons cut by veins, felsic dikes, and faults. Marble hosted skarns have higher tungsten ) gold grades and show spatial zoning from proximal garnet to distal pyroxene. Amphibole and white mica from skarns have ages consistent with the cooling age of Gilmore Dome pluton (85-91 Ma). These skarns are similar to other tungsten skarns worldwide.

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