Abstract: This report demonstrates that the stratigraphic, compositional and textural data are sufficient to easily distinguish the four major granitic rock types in the area. This is an essential first step in exploration for intrusion-related mineral occurrences since the known occurrences are associated with only two of the four granitic rock types.

The four granitic rock types distinguished are: Mid-Jurassic pink quartz monzonite, Mid-Cretaceous biotite quartz monzonite, Upper Triassic-Lower Jurassic hornblende granodiorite, and Lower Tertiary smoky quartz granites. The latter two intrusives are associated with significant mineralization.

The copper-iron skarn deposits in Upper Triassic banded limestone are associated with Upper Triassic granodiorite. The nature of the Upper Triassic granodiorite distinguishes it from porphyry copper-bearing granitic rocks of similar age in British Columbia. The Upper Triassic granodiorite batholiths in the Yukon Crystalline Terrane are not a good prospect for porphyry-type mineralization. The polymetallic nature and the alteration associated with the Lower Tertiary subvolcanic rocks suggest they have good potential for porphyry copper mineralization of the Casino type.

Authors: Morrison, G.W.

Map Scale: 1 : 0

NTS Mapsheet(s): 105D

Citation: Morrison, G.W., 1976, Granitic rocks and associated mineral deposits of the Whitehorse Map-Area, Yukon Territory. In: Mineral Industry Report 1975, Yukon Territory, EGS 1976-15, W.D. Sinclair, J.A. Morin, D.B. Craig, and M. Marchand (eds), Indian and Northern Affairs, Northern Natural Resources and Environment Branch, p. 14-20.

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