Abstract: Between the Swift and Nisutlin rivers, unmetamorphosed granite to ultramafic intrusions of four ages (from Permian through Cretaceous) span the amalgamation of Cassiar Platform with Yukon-Tanana and Cache Creek terranes. The mid-Permian granitic Ram Stock and two plutons cutting the Sylvester Allochthon lie at the edge of the Dorsey Complex, a remnant of an ancient passive margin succession that underlies the volcanic arcs of Yukon-Tanana Terrane. Middle Jurassic, locally foliated granodiorite to gabbro intrusions are metaluminous, and high in Sr and low in Ti compared to the Cretaceous suite. These `I-type volcanic arc plutons may be the remnants of an overlapping arc correlative with the Quesnel Terrane. The Cretaceous (113 to 98 Ma) meta- to peraluminous granites are late orogenic incipient `A-type plutons from highly fractionated F- and Cl-rich magmas. These generated extensive hydrothermal systems that produced tin, tungsten, molybdenum and beryl occurrences.

Authors: Liverton, T., Mortensen, J.K. and Roots, C.F.

Keywords: igneous petrology

NTS Mapsheet(s): 105A, 105B, 105C, 105D

Citation: Liverton, T., Mortensen, J.K., and Roots, C.F., 2005. Character and metallogeny of Permian, Jurassic and Cretaceous plutons in the southern Yukon-Tanana Terrane. In: Yukon Exploration and Geology 2004, Emond, D.S., Lewis, L.L., and Bradshaw, G.D. (eds.), Yukon Geological Survey, p. 147-165.

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