Volcanism of the Mount Edziza volcanic complex

Volcanism of the Mount Edziza volcanic complex
Volcanism of the Mount Edziza volcanic complex
	Satellite imagery of Mount Edziza and the surrounding snow-covered Big Raven Plateau
	Location in British Columbia
	Coordinates: 57°30′N 130°36′W / 57.5°N 130.6°W
Location	British Columbia, Canada
Range	Tahltan Highland
Geology	Basalt, trachyte, mugearite, rhyolite, trachybasalt, tristanite, benmoreite

The Mount Edziza volcanic complex (MEVC) in British Columbia, Canada, has a long history of volcanism that spans more than 7 million years. It occurred during five cycles of magmatic activity, each having produced less volcanic material than the previous one. Volcanism during these cycles has created several types of volcanoes, including cinder cones, stratovolcanoes, subglacial volcanoes, shield volcanoes and lava domes. The approximately 1,000-square-kilometre (400-square-mile) volcanic plateau forming the base of the MEVC owes its origin to successive eruptions of highly mobile lava flows. Volcanic rocks such as basalt, trachybasalt, benmoreite, tristanite, mugearite, trachyte and rhyolite were deposited by multiple eruptions of the MEVC; the latter seven rock types are products of varying degrees of magmatic differentiation in underground magma reservoirs. At least 10 distinct flows of obsidian were produced by volcanism of the MEVC, some of which were exploited by indigenous peoples in prehistoric times to make tools and weaponry. Renewed volcanism could produce explosive eruptions and block local streams with lava flows.

The first magmatic cycle between 7.5 and 6 million years ago is represented by the Raspberry, Little Iskut and Armadillo geological formations, each of which is the product of a different eruptive period. Three distinct periods of eruptive activity also characterized the second magmatic cycle between 6 and 1 million years ago; they are represented by the Nido, Spectrum and Pyramid geological formations. The third magmatic cycle about 1 million years ago is represented by the Ice Peak, Pillow Ridge and Edziza geological formations, each of which is also the product of a distinct eruptive period. Three distinct periods of eruptive activity also characterized the fourth magmatic cycle between 0.8 and 0.2 million years ago which are represented by the Arctic Lake, Klastline and Kakiddi geological formations. The fifth magmatic cycle began at least 20,000 years ago and may be continuing to the present; a single distinct eruptive period of this magmatic cycle is represented by the Big Raven Formation.

^ Edwards, Benjamin Ralph (1997). Field, kinetic, and thermodynamic studies of magmatic assimilation in the Northern Cordilleran Volcanic Province, northwestern British Columbia (PhD thesis). University of British Columbia. pp. 6, 10, 11. ISBN 0-612-25005-9.
^ Yagi, Kenzo; Souther, Jack Gordon (1974). "Aenigmatite From Mt. Edziza, British Columbia, Canada" (PDF). American Mineralogist. 59. Mineralogical Society of America: 820. Archived from the original (PDF) on 2021-04-01. Retrieved 2021-09-27.
^ "A 502" (Topographic map). Telegraph Creek, Cassiar Land District, British Columbia (3 ed.). 1:250,000. 104 G (in English and French). Department of Energy, Mines and Resources. 1989. Archived from the original on 2021-05-02. Retrieved 2021-09-25.
^ Souther, J. G.; Hickson, C. J. (1984). "Crystal fractionation of the basalt comendite series of the mount Edziza volcanic complex, British Columbia: Major and trace elements". Journal of Volcanology and Geothermal Research. 21 (1). Elsevier: 79. Bibcode:1984JVGR...21...79S. doi:10.1016/0377-0273(84)90017-9. ISSN 0377-0273.

[Edwards-1] Edwards, Benjamin Ralph (1997). Field, kinetic, and thermodynamic studies of magmatic assimilation in the Northern Cordilleran Volcanic Province, northwestern British Columbia (PhD thesis). University of British Columbia. pp. 6, 10, 11. ISBN 0-612-25005-9.

[2] Yagi, Kenzo; Souther, Jack Gordon (1974). "Aenigmatite From Mt. Edziza, British Columbia, Canada" (PDF). American Mineralogist. 59. Mineralogical Society of America: 820. Archived from the original (PDF) on 2021-04-01. Retrieved 2021-09-27.

[HR-3] "A 502" (Topographic map). Telegraph Creek, Cassiar Land District, British Columbia (3 ed.). 1:250,000. 104 G (in English and French). Department of Energy, Mines and Resources. 1989. Archived from the original on 2021-05-02. Retrieved 2021-09-25.

[LR-4] Souther, J. G.; Hickson, C. J. (1984). "Crystal fractionation of the basalt comendite series of the mount Edziza volcanic complex, British Columbia: Major and trace elements". Journal of Volcanology and Geothermal Research. 21 (1). Elsevier: 79. Bibcode:1984JVGR...21...79S. doi:10.1016/0377-0273(84)90017-9. ISSN 0377-0273.

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