Alkaline Rocks and Carbonatites of the World

Setup during HiTech AlkCarb: an online database of alkaline rock and carbonatite occurrences

Aiyansh Volcano/Teax Cone


Occurrence number: 
British Columbia
Longitude: -128.89944, Latitude: 55.11085

Aiyansh/Tseax is a volcano associated with a lava flow located in north-western British Columbia, Canada. It is the southernmost volcanic centre of the Northern Cordillera Volcanic Belt, currently lying dormant with its last eruption occurring in the 18th century. Structurally the volcano itself features a horseshoe shaped outer cone, with an inner tephra cone and a satellite cone located ~150-200 m to the north. The lava flow field covers ~36 km2, mostly following the Tseax River and Nass Valleys. The lava flow field can be split into four flow events belonging to a single eruption: the first two being phenocryst-poor pahoehoe and the latter two being phenocryst-rich ‘a‘ā. All eruptives are nepheline-normative basanite/tephrite to trachybasalt. Whole rock and mineral (olivine, plagioclase, oxides) geochemical data can be found in Sutherland-Brown (1969), Le Moigne (2020), Gallo (2018).

1749 ± 130 CE radiocarbon dating of carbonised wood, between 1675-1778 AD from indigenous Nisga people’s oral histories (Le Moigne et al., 2020)
GALLO, R., 2018. History and dynamics of explosive volcanism at Tseax Cone, British Columbia. Undergraduate Research, University of British Columbia. LE MOIGNE, Y., 2020. Investigating Canada’s deadliest volcanic eruption and mitigating future hazards. Doctoral thesis, Simon Fraser University, Canada and Université Clermont Auvergne, France. LE MOIGNE, Y., WILLIAMS-JONES, G., RUSSELL, K. & QUANE, S., 2020. Physical volcanology of Tseax Volcano, British Columbia, Canada. Journal of Maps Vol 16 No. 2 pp 363-375. SUTHERLAND-BROWN, A., 1969. Aiyansh lava flow, British Columbia. Canadian Journal of Earth Sciences 6 pp 1460-1468
Fig. 1 Map of Aiyansh lava flows and cones (Le Moigne et al., 2020, Fig 4.a)
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