Armadillo Formation

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Armadillo Formation
Stratigraphic range: 6.9–6.1  Ma
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Armadillo Formation.png
Paleogeological map showing the inferred maximum extent of the Armadillo Formation at the end of the Armadillo eruptive period
Type Geological formation [1]
Unit of Mount Edziza volcanic complex [2]
UnderliesIce 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′N130°36′W / 57.5°N 130.6°W / 57.5; -130.6 [2]
Region British Columbia [1]
CountryCanada [1]
Type section
Named for Armadillo Peak [1]
Named by Souther et al., 1984 [3]

The Armadillo Formation is a stratigraphic unit of Miocene age in northwestern British Columbia, Canada.

Contents

Naming

The Armadillo Formation takes its name from Armadillo Peak, a volcanic peak east of Raspberry Pass in the middle of the Mount Edziza volcanic complex. [1] [4]

Geology

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

The Armadillo Formation consists of volcanic rocks of both felsic and mafic compositions. They are the products of a long period of bimodal volcanism, having issued from multiple eruptive centres. The felsic rocks include trachyte and comenditic rhyolite which form pyroclastic deposits, lava domes and lava flows. Basalt is the main mafic rock of the Armadillo Formation and forms lava flows. [1]

K–Ar 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, 6.9 ± 0.3 million years for comenditic 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. [1] The first age is anomalously old and most likely results from excessive atmospheric argon. [3]

See also

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Gnu Butte is a butte in Cassiar Land District of northwestern British Columbia, Canada. It is located southeast of Telegraph Creek on the northwestern side of Raspberry Pass. The western and southern sides of the butte are surrounded by Raspberry Creek while the eastern and northern sides of the butte are surrounded by Flyin Creek. Gnu Butte lies on the Tahltan Highland between Mess Lake and Mowdade Lake in Mount Edziza Provincial Park. It bears a resemblance to flat-topped hills in parts of Africa, hence its name.

Artifact Ridge is a mountain ridge extending southeast from the eastern side of the Mount Edziza volcanic complex in northwestern British Columbia, Canada. It is bounded on the north by Bourgeaux Creek valley, on the south by Artifact Creek valley, on the east by the Little Iskut River valley and on the west by the Kitsu Plateau. The ridge is at the southeastern end of Mount Edziza Provincial Park and gets its name from the knapping of obsidian tools and points by early Tahltan hunters. Destell Pass cuts north–south through the westernmost end of Artifact Ridge.

Idiji Ridge is a mountain ridge extending east of Tencho Glacier on the southern flank of Mount Edziza in northwestern British Columbia, Canada. It is bounded on the south by a valley containing an unnamed creek, on the east by Tennaya Creek valley and on the north by cirques extending east of Ice Peak. Idiji Ridge takes its name from the adjacent Idiji Glacier; Idiji means "it thunders" in the Tahltan language.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 Souther, J. G. (1992). The Late Cenozoic Mount Edziza Volcanic Complex, British Columbia. Geological Survey of Canada (Report). Memoir 420. Canada Communication Group. pp. 32, 61, 71, 246, 267. doi: 10.4095/133497 . ISBN   0-660-14407-7.
  2. 1 2 3 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. p. 10. ISBN   0-612-25005-9.
  3. 1 2 "Armadillo Formation". Lexicon of Canadian Geologic Units . Government of Canada . Retrieved 2023-08-04.
  4. "Little Iskut River". BC Geographical Names . Archived from the original on 2021-09-30. Retrieved 2023-06-28.