Geology and geochronometry of the Scheelite Dome tungsten-bearing skarn property, Yukon Territory

CIM Bulletin, Vol. 75, No. 838, 1982

V.M. KURAN, C.I. GODWIN and R.L ARMSTRONG, The University of British Columbia, Department of Geological Sciences, Vancouver, B.C.

The Scheelite Dome tungsten-bearing skarn property, central Yukon Territory, is in metasediments in contact with a quartz monzonite intrusion. Contact metamorphism to biotite-muscovite-andalusite hornfels and calc-silicate hornfels is superimposed on low-grade regionally metamorphosed rocks represented by quartz-mica pelitic schist and muscovite-biotite pelitic schist.Metasediments are likely Precambrian in age, even though Rb-Sr whole-rock analyses indicate an early Paleozoic age (511 ±41 Ma); this apparently too young radiometric age is due to partial loss of radiogenic strontium during regional metamorphism. The minimum age of the quartz monzonite intrusion is Cretaceous at 90.4±2.6 Ma (K-Ar on biotite) and its initial S7Sr/S6Sr ratio is 0.7121. The high initial ratio of the intrusion is due to the addition of radiogenic strontium from the 'metasedimentary country rocks and perhaps an underlying older basement.Scheelite-pyrrhotite-chalcopyrite mineralization occurs in diopside-zoisite skarn pods within the calc-silicate hornfels near the quartz monzonite intrusion. The source for lithophile tungsten is probably the same as for the granitic magma, namely Precambrian sialic basement.

Mots Clés: Economic geology, Geochronometry, Scheelite Dome property, Tungsten, Skarn, Petrology, Yukon Territory.