Abstract: Magmatism in the Nahanni region, which defines the eastern extent of the Tintina Gold Province, is generally associated with tungsten mineralization and/or gold-copper-antimony-bismuth-lead-zinc metal occurrences. Intrusions are subalkaline, granitic to granodioritic, and contain several types of textural variations and highly evolved phases. The intrusions range from large composite batholiths to small stocks with associated felsic dykes and veins. Initial U-Pb and Ar-Ar geochronology reveals ages of 97.5-95 Ma with short (0.5-1.5 m.y.) cooling periods, although the intrusion associated with the Cantung tungsten-skarn orebody cooled over a relatively long period (3 m.y.). Magmatism in the area has been interpreted as crustally derived, however, the rare earth element primitive-mantlenormalized profile revealed negative niobium, tantalum and titanium anomalies suggesting an arctype setting. Furthermore, the granites lack volumetrically significant, primary peraluminous mineralogies characteristic of S-type granites.

Authors: Rasmussen, K.L., Mortensen, J.K., and Falck, H.

Keywords: magmatism

NTS Mapsheet(s): 105H, 105I

Citation: Rasmussen, K.L., Mortensen, J.K., and Falck, H., 2006. Geochronological and lithogeochemical studies of intrusive rocks in the Nahanni region, southwestern Northwest Territories and southeastern Yukon. In: Yukon Exploration and Geology 2005, Emond, D.S., Bradshaw, G.D., Lewis, L.L., and Weston, L.H. (eds.), Yukon Geological Survey, p. 287-298.

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