Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Johnston, S. T. Articles by Engebretson, D. C. Search for Related Content GeoRef GeoRef Citation

Yellowstone in Yukon: The Late Cretaceous Carmacks Group

¹ Canada/Yukon Geoscience Office, Box 2703 (F-3), Whitehorse, Yukon Y1A 2C6, Canada
² Geological Survey of Canada, 9860 West Saanich Road, P.O. Box 6000, Sidney, British Columbia V8L 4B2, Canada
³ Earth and Planetary Sciences, McGill University, Montreal, Quebec H3A 2A7, Canada
⁴ Department of Geology, Western Washington University, Bellingham, Washington 98225

The Late Cretaceous Carmacks Group, a thick subaerial volcanic succession that once covered much of southwest Yukon, was deposited on an uplifted terrane and is divisible into a lower fragmental unit and an upper flood basalt unit. Coeval hydrothermal activity resulted in widespread alteration and gold mineralization. The lavas are shoshonites, enriched in large ion lithophile and light rare earth elements, but depleted in high field strength elements. Ankaramitic absarokite flows in the upper Carmacks Group range up to 15 wt% MgO, requiring a high liquidus temperature (1400 °C at 1 bar, dry). High K₂O contents (>3%) of these magnesian lavas indicate that the potassic character of the volcanic suite was established in the mantle. Although previously interpreted as subduction related, the Carmacks Group was erupted during a Cordilleran-wide magmatic lull and lacks coeval calc-alkalic batholiths. The lavas are petrologically similar to plume-related Eocene to Pliocene potassic lavas of the western United States.

New paleomagnetic collections, combined with previous work, place the Carmacks Group 17.2° ± 6.5° (1900 ± 700 km) south of its present position relative to the craton during deposition, near the paleolocation of the Yellowstone hotspot. The spatial coincidence, similarity of tectonic setting, and lithologic similarity of the Carmacks Group and Yellowstone volcanic successions suggest that the Carmacks Group is the 70 Ma effusion of the Yellowstone hotspot. Subsequent northward displacement of the Carmacks Group is attributed to coupling with the Kula plate. Correlation of the Carmacks Group and the Yellowstone hotspot fixes the paleolatitude and the paleolongitude of the terranes of the northern Intermontane belt at 70 Ma.

This article has been cited by other articles:

				P. J. Haeussler, D. C. Bradley, R. E. Wells, and M. L. Miller Life and death of the Resurrection plate: Evidence for its existence and subduction in the northeastern Pacific in Paleocene-Eocene time Geological Society of America Bulletin, July 1, 2003; 115(7): 867 - 880. [Abstract] [Full Text] [PDF]

				A. H. PESLIER, D. FRANCIS, and J. LUDDEN The Lithospheric Mantle beneath Continental Margins: Melting and Melt-Rock Reaction in Canadian Cordillera Xenoliths J. Petrology, November 1, 2002; 43(11): 2013 - 2047. [Abstract] [Full Text] [PDF]

				J. M.G. Glen and D. A. Ponce Large-scale fractures related to inception of the Yellowstone hotspot Geology, July 1, 2002; 30(7): 647 - 650. [Abstract] [Full Text] [PDF]