Abstract: Recent discoveries of at least two types of volcanogenic massive sulphide (VMS) deposits hosted in varying terranes have greatly expanded the mineral potential of the Yukon Territory. Kuroko style deposits at Kudz Ze Kayah and Wolverine are hosted by an Early Mississippian felsic metavolcanic and carbonaceous sedimentary package within the Yukon-Tanana Terrane in the Finlayson Lake area. The massive sulphide lenses at Wolverine have spectacular grades and constitute a geological resources, as of November 1996, of 5,311,000 tonnes with 1.81 g/t Au, 359.1 g/t Ag, 1.41% Cu, 1.53% Pb and 12.96% Zn. New discoveries at the Fyre Lake and Ice properties continue to expand the volcanic hosted massive sulphide potential of the Finlayson Lake area. Fyre Lake is a copper-cobalt-gold Besshi-type deposit hosted by chlorite schist. Towards the end of the season DDH 65 at Fyre Lake intersected 31.3 m of 2.29% Cu, 0.53 gpt Au and 0.07% Co. The enigmatic, ""Cyprus-type"", Ice occurrence has copper-cobalt mineralization in mafic volcanic rocks that are interpreted to belong to the Slide Mountain Terrane. The last hole of the season, DDH IC96-34 intersected 20.56 m of massive pyrite, chalcopyrite and bornite with grades of 5.2% Cu, 0.6 gpt Au, 25 gpt Ag and 0.6% Co. Prior to discovery of Ice, volcanic hosted massive sulphide mineralization was unknown in the Slide Mountain Terrane in the Yukon.

The Yukon-Tanana and Slide Mountain Terranes are not restricted to the Finlayson Lake area but cover a considerable portion of the Yukon Territory. West of Dawson the Yukon-Tanana Terrane contains several exhalite occurrences in the Devono-Missisippian Nasina Assemblage and the Permian Klondike Schist. Devono-Mississippian strata in the Yukon-Tanana Terrane may correlate with similar aged units in the Pelly-Cassiar Platform and Selwyn Basin where there are several massive sulphide occurrences. The Marg Deposit occurs at the northern edge of the Selwyn Basin; the MM, Bnob and Chzerpnough properties are hosted by extension related, pyritic, brecciated, felsic metavolcanic rocks within the Pelly-Cassiar Platform. The Yukon-Tanana Terrane extends westward into the Delta District of Alaska where there are at least 26 stratiform and replacement massive sulphide deposits and occurrences. Strata potentially correlative with the Yukon-Tanana Terrane hosts several volcanogenic massive sulphide deposits and occurrences in northern British Columbia.

Authors: Hunt, J.A.

Map Scale: 1 : 0

NTS Mapsheet(s): 106C, 106D, 116B, 116C

Citation: Hunt, J.A., 1997. Massive Sulphide Deposits in the Yukon-Tanana and Adjacent Terranes. In: Yukon Exploration and Geology 1996, Roots, C.F. (edt), Indian & Northern Affairs Canada/Department of Indian & Northern Development: Exploration & Geological Services Division, 35-45.

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