Distribution:

Mount Edziza and northern plateau; Ice Peak, Armadillo Peak and central plateau; Spectrum Range and plateau south of Raspberry Pass (Souther, 1988).

Lithology:

It consists almost entirely of alkali olivine basalt and hawaiite plus a small volume of comenditic trachyte pumice that is assigned to the Sheep Track Member (Souther, 1992). Postglacial eruption of Big Raven basalt from clusters of vents on the north and south flanks of Mount Edziza and from single vents elsewhere within the complex produced the fields of blocky lava, tephra plumes, and scores of small pyroclastic cones. These deposits are products of the fifth, and youngest, cycle of activity. The predominant lithology is fine-grained, vesicular hawaiite with 10% to 20% phenocrysts of calcic plagioclase and lesser pyroxene and olivine phenocrysts in a groundmass of calcic plagioclase, clinopyroxene, glass, and opaques. Alkali olivine basalt and picrite occur locally as minor, olivine-rich phases (Souther et al., 1984).

Relationship:

The Big Raven Formation is a unit of the Mount Edziza Complex. It disconformably overlies the Klastline, Kakiddi and Arctic Lake formations (Souther, 1988).

Other Citations:

Mihalynuk et al., 1996.

References:

Mihalynuk, M., Bellefontaine, K., Brown, D., Logan, J., Nelson, J., Legun, A. and Diakow, L., 1996. Digital Geology, NW British Columbia (94/E, L, M; 104/F, G, H, I, J, K, L, M, N, O, P; 114/I, O, P); Ministry of Energy, Mines and Petroleum Resources, Open File 1996-11.

Souther, J.G., 1971a. Telegraph Creek map-area, British Columbia; Geological Survey of Canada, Paper 71-44, 38 p.

Souther, J.G., 1988. Geology, Mount Edziza volcanic complex, British Columbia; Geological Survey of Canada, "A" Series Map no. 1623A, 2 sheets.

Souther, J.G., 1992. The Late Cenozoic Mount Edziza Volcanic Complex, British Columbia; Geological Survey of Canada, Memoir 420, 329 p.

Souther, J.G., Armstrong, R.L., and Harakal, J., 1984. Chronology of the peralkaline, late Cenozoic Mount Edziza Volcanic Complex, northern British Columbia, Canada; Geological Society of America Bulletin, March 1984, Vol. 95, Issue 3, pp. 337-349.