Abstract: In this contribution, we present new U-Pb age data for ten intrusive units that bracket the timing of polymetallic mineralization occurring within the Northern Freegold Resources Ltd. (NFR), Freegold Mountain project area. Polymetallic mineralization occurring in the Tinta zone predates trachytic dykes (~109 Ma) and represents the earliest phase of mineralization recognized on the Freegold Mountain property thus far. Feldspar porphyry dykes that intrude the Revenue zone are correlative to the Nucleus zone feldspar porphyry dykes, and yield ages of ~105-104 Ma, indicating that the structural corridor in which Au mineralization occurred was active from at least this time. Furthermore, monzodiorite was emplaced at ~107 Ma within the Revenue zone. An ~97 Ma aplitic dyke that intrudes porphyritic granite of the Stoddart intrusion predates ~94 Ma Mo-Cu-W mineralization. Andesitic dykes (~77 Ma) that crosscut the Stoddart porphyry and rhyolitic dykes (~75 Ma) intruding the Revenue zone, represent Carmacks-age volcanism in the region. These new age data indicate that economically important mineralizing events took place over a period of at least 40 Ma.

Authors: Bineli Betsi, T. and Bennett, V.

Keywords: Northern Freegold, Stoddart intrusion

NTS Mapsheet(s): 115I

Citation: Bineli Betsi, T. and Bennett, V., 2010. New U-Pb age constraints at Freegold Mountain: Evidence for multiple phases of polymetallic mid- to Late Cretaceous mineralization. In: Yukon Exploration and Geology 2009, MacFarlane, K.E., Weston, L.H. and Blackburn, L.R. (eds.), Yukon Geological Survey, p. 57-84.

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