Raspberry Formation

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

Raspberry Formation
Stratigraphic range: 11.4–5.5 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation[1]
Unit of	Mount Edziza volcanic complex[2]
Underlies	Little Iskut Formation[1] Armadillo Formation[1]
Overlies	Stikinia[1]
Lithology
Primary	Alkali basalt, hawaiite[1]
Location
Coordinates	57.5°N 130.6°W / 57.5; -130.6[2]
Region	British Columbia[1]
Country	Canada[1]
Type section
Named for	Raspberry Pass[1]
Named by	Souther et al., 1984[3]

Naming

The Raspberry Formation takes its name from Raspberry Pass, a mountain pass cutting through the central portion of the Mount Edziza volcanic complex.^[1][4]

Geology

The Raspberry Formation has a volume of 119 km³ (29 cu mi), making it the third most voluminous geological formation comprising the Mount Edziza volcanic complex.^[1][2] It varies in elevation from less than 1,310 m (4,300 ft) along the Mess Creek Escarpment to 1,740 m (5,710 ft) near Armadillo Peak.^[1]

The Raspberry Formation is overlain conformably by the Little Iskut Formation. An erosion surface separates the Raspberry Formation from the overlying Armadillo Formation and younger geological formations. Rocks of the Stikinia terrane underlie the Raspberry Formation.^[1]

The Raspberry Formation consists of flat-lying alkali basalt and hawaiite flows. These flows are rusty brown and are interbedded with reddish-brown to yellow or orange scoria.^[1] The Raspberry Formation represents three overlapping Miocene shield volcanoes.^[2]

K–Ar dating has yielded ages of 11.4 ± 1.5 million years, 8.4 ± 0.4 million years and 6.4 ± 0.3 million years for Raspberry hawaiite and 6.1 ± 0.4 million years and 5.5 ± 0.1 million years for Raspberry alkali basalt.^[1]

See also

• Volcanism of the Mount Edziza volcanic complex

References

1. Souther, J. G. (1992). The Late Cenozoic Mount Edziza Volcanic Complex, British Columbia. Geological Survey of Canada (Report). Memoir 420. Canada Communication Group. pp. 3, 32, 47, 61, 249, 267. doi:10.4095/133497. ISBN 0-660-14407-7.
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. p. 10. ISBN 0-612-25005-9.
3. "Raspberry Formation". Lexicon of Canadian Geologic Units. Government of Canada. Retrieved 2023-08-04.
4. "Raspberry Pass". BC Geographical Names. Archived from the original on 2021-10-19. Retrieved 2023-04-17.