# Armadillo Formation

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Geological formation in British Columbia

Armadillo Formation Stratigraphic range: 6.9–6.1 Ma PreꞒ Ꞓ O S D C P T J K Pg N Basaltic lava flows of the Armadillo Formation are exposed in Sezill Creek valley Type Geological formation[1] Unit of Mount Edziza volcanic complex[2] Underlies Ice Peak Formation, Spectrum Formation, Big Raven Formation, Nido Formation[1] Overlies Little Iskut Formation, Raspberry Formation[1] Lithology Primary Alkali basalt, comendite, trachyte[1] Location Coordinates 57°30′N 130°36′W / 57.5°N 130.6°W / 57.5; -130.6[2] Region British Columbia[1] Country Canada[1] Type section Named for Armadillo Peak[1] Named by Souther et al.[3] Year defined 1984[3] Paleogeological map showing the inferred maximum extent of the Armadillo Formation at the end of the Armadillo eruptive period

The **Armadillo Formation** is a [stratigraphic unit](/source/Stratigraphic_unit) of [Miocene](/source/Miocene) age in northwestern [British Columbia](/source/British_Columbia), Canada.

## Name

The Armadillo Formation takes its name from [Armadillo Peak](/source/Armadillo_Peak), a volcanic peak east of [Raspberry Pass](/source/Raspberry_Pass) in the middle of the [Mount Edziza volcanic complex](/source/Mount_Edziza_volcanic_complex).[1][4]

## Geology

The Armadillo Formation has a volume of 159 km3 (38 mi3), making it the most voluminous of the 13 [geological formations](/source/Geological_formation) comprising the Mount Edziza volcanic complex.[2] It [conformably](/source/Conformably) overlies the [Little Iskut Formation](/source/Little_Iskut_Formation), as well as the [Raspberry Formation](/source/Raspberry_Formation). It is overlain by the [Ice Peak Formation](/source/Ice_Peak_Formation), [Nido Formation](/source/Nido_Formation), Spectrum Formation and [Big Raven Formation](/source/Big_Raven_Formation).[1]

The Armadillo Formation consists of [volcanic rocks](/source/Volcanic_rock) of both [felsic](/source/Felsic) and [mafic](/source/Mafic) compositions. They are the products of a long period of [bimodal volcanism](/source/Bimodal_volcanism), having issued from multiple eruptive centres. The felsic rocks include [trachyte](/source/Trachyte) and [comenditic](/source/Comenditic) [rhyolite](/source/Rhyolite) which form [pyroclastic](/source/Pyroclastic_rock) deposits, [lava domes](/source/Lava_dome) and lava flows. [Basalt](/source/Basalt) is the main mafic rock of the Armadillo Formation and forms lava flows.[1]

[K–Ar dating](/source/K%E2%80%93Ar_dating) of the Armadillo Formation has yielded ages of 10.2 ± 1.4 million years for comendite, 6.9 ± 0.3 million years and 6.1 ± 0.1 million years for comenditic [ash flows](/source/Ash_flow), 6.9 ± 0.3 million years for comenditic [glass](/source/Volcanic_glass) and 6.5 ± 0.2 million years, 6.3 ± 0.5 million years, 6.2 ± 0.1 million years and 6.1 ± 0.2 million years for [hawaiite](/source/Hawaiite).[1] The first age is anomalously old and most likely results from excessive atmospheric [argon](/source/Argon).[3]

## See also

- [Volcanism of the Mount Edziza volcanic complex](/source/Volcanism_of_the_Mount_Edziza_volcanic_complex)

## References

1. ^ [***a***](#cite_ref-Souther_1-0) [***b***](#cite_ref-Souther_1-1) [***c***](#cite_ref-Souther_1-2) [***d***](#cite_ref-Souther_1-3) [***e***](#cite_ref-Souther_1-4) [***f***](#cite_ref-Souther_1-5) [***g***](#cite_ref-Souther_1-6) [***h***](#cite_ref-Souther_1-7) [***i***](#cite_ref-Souther_1-8) [***j***](#cite_ref-Souther_1-9) [***k***](#cite_ref-Souther_1-10) [Souther, J. G.](/source/Jack_Souther) (1992). The Late Cenozoic Mount Edziza Volcanic Complex, British Columbia. *[Geological Survey of Canada](/source/Geological_Survey_of_Canada)* (Report). Memoir 420. Canada Communication Group. pp. 32, 61, 71, 246, 267. [doi](/source/Doi_(identifier)):[10.4095/133497](https://doi.org/10.4095%2F133497). [ISBN](/source/ISBN_(identifier)) [0-660-14407-7](https://en.wikipedia.org/wiki/Special:BookSources/0-660-14407-7).

1. ^ [***a***](#cite_ref-Edwards_2-0) [***b***](#cite_ref-Edwards_2-1) [***c***](#cite_ref-Edwards_2-2) 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](/source/University_of_British_Columbia). p. 10. [ISBN](/source/ISBN_(identifier)) [0-612-25005-9](https://en.wikipedia.org/wiki/Special:BookSources/0-612-25005-9).

1. ^ [***a***](#cite_ref-LCGU_3-0) [***b***](#cite_ref-LCGU_3-1) [***c***](#cite_ref-LCGU_3-2) ["Armadillo Formation"](https://weblex.canada.ca/html/000000/GSCC00053000458.html). *[Lexicon of Canadian Geologic Units](/source/Lexicon_of_Canadian_Geologic_Units)*. [Government of Canada](/source/Government_of_Canada). Retrieved 2023-08-04.

1. **[^](#cite_ref-4)** ["Little Iskut River"](https://web.archive.org/web/20210930231839/https://apps.gov.bc.ca/pub/bcgnws/names/9205.html). *[BC Geographical Names](/source/BC_Geographical_Names)*. Government of British Columbia – B.C. Geographical Names Office (BCGNO). Archived from [the original](https://apps.gov.bc.ca/pub/bcgnws/names/2478.html) on 2021-09-30. Retrieved 2023-06-28.

v t e Mount Edziza volcanic complex Cinder cones The Ash Pit Cache Hill Camp Hill Cinder Cliff Cocoa Crater Coffee Crater Eve Cone Exile Hill Icefall Cone Kana Cone Keda Cone Klastline Cone Mess Lake Cone Moraine Cone Nahta Cone Outcast Hill Ridge Cone Sidas Cone Sleet Cone Source Hill Storm Cone Thaw Hill Triplex Cones Twin Cone Walkout Creek centres Williams Cone Subglacial volcanoes Pillow Ridge Tennena Cone Tsekone Ridge Wetalth Ridge Central volcanoes Armadillo Peak Mount Edziza Ice Peak Spectrum Range Lava domes Glacier Dome IGC Centre Nanook Dome Pharaoh Dome The Pyramid Sphinx Dome Triangle Dome Lava fields Desolation Lava Field Mess Lake Lava Field Snowshoe Lava Field Plateaus Arctic Lake Plateau Big Raven Plateau Kitsu Plateau Ridges Artifact Ridge Cartoona Ridge Idiji Ridge Obsidian Ridge Pillow Ridge Sorcery Ridge Tsekone Ridge Wetalth Ridge Yagi Ridge Mountain passes Destell Pass Raspberry Pass Bluffs Koosick Bluff Ornostay Bluff Glaciers Idiji Glacier Tenchen Glacier Tencho Glacier Tennaya Glacier Streams Artifact Creek Ball Creek Bourgeaux Creek Chakima Creek Crayke Creek Elwyn Creek Flyin Creek Gerlib Creek Kadeya Creek Kitsu Creek Little Iskut River More Creek Nagha Creek Nido Creek Pyramid Creek Raspberry Creek Sezill Creek Shaman Creek Sorcery Creek Stewbomb Creek Tadekho Creek Taweh Creek Tenchen Creek Tennaya Creek Tsecha Creek Walkout Creek Stratigraphic units Armadillo Formation Big Raven Formation (Sheep Track Member) Edziza Formation Ice Peak Formation Kakiddi Formation Klastline Formation Little Iskut Formation Nido Formation (Tenchen Member) Pyramid Formation Raspberry Formation Other Cartoona Peak Gnu Butte Mess Creek Escarpment Volcanism of the Mount Edziza volcanic complex

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Adapted from the Wikipedia article [Armadillo Formation](https://en.wikipedia.org/wiki/Armadillo_Formation) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Armadillo_Formation?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.