| Raspberry Formation | |
| Type: | Geological formation[1] |
| Period: | Miocene |
| Prilithology: | Alkali basalt, hawaiite |
| Namedfor: | Raspberry Pass |
| Namedby: | Souther et al., 1984[2] |
| Region: | British Columbia |
| Country: | Canada |
| Coordinates: | 57.5°N -130.6°W[3] |
| Unitof: | Mount Edziza volcanic complex |
| Underlies: | Little Iskut Formation Armadillo Formation |
| Overlies: | Stikinia |
The Raspberry Formation is a stratigraphic unit of Miocene age in northwestern British Columbia, Canada.
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]
The Raspberry Formation has a volume of 119km3, making it the third most voluminous geological formation comprising the Mount Edziza volcanic complex.[1] [3] It varies in elevation from less than 1310m (4,300feet) along the Mess Creek Escarpment to 1740m (5,710feet) 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.[3]
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]