| Bennett Lake Volcanic Complex | |
|---|---|
| Elevation | 1,500 m (4,921 ft) |
| Location | |
| Location | British Columbia/Yukon, Canada |
| Range | Boundary Ranges, Coast Mountains |
| Geology | |
| Type | Caldera |
| Age of rock | 50 million years |
| Last eruption | Eocene |
The Bennett Lake Volcanic Complex (BLVC) is a huge 50 million year old extinct caldera complex that spans across the BC-Yukon border in Canada. The caldera complex is surrounded by granitic rocks containing pendants.
It is located near the eastern contact of the Coast Plutonic Complex and the Whitehorse Trough. There are thick series of pyroclastic and epiclastic rocks at the caldera. Remnants of this huge caldera complex are preserved near Bennett Lake in the Coast Mountains. The complex compose the Skukum Group.
The Bennett Lake Volcanic Complex was formed when the ancient Kula Plate was subducting under North America during the early Eocene period.[1] Cataclysmic eruptions from the Bennett Lake Volcanic Complex were from vents along arcuate fracture systems that spewed out about 850 km3 (200 cu mi) of glowing avalanches of pyroclastic rock called pyroclastic flows. Evacuation of the underlying magma chamber was followed by several stages of collapse to form two calderas, one nested inside the other, that produced an elliptical depression 19 km (12 mi) by 30 km (19 mi) across.[1] The calderas were from 200 m (656 ft) to 2,700 m (8,858 ft) deep. Volcanism continued for some time after the caldera collapse. High level andesite and rhyolite dykes and intrusive bodies crosscut volcanic flows and tuffs at all levels dyke swarms are emplaced along ring fractures and fault zones at the southwest edge of the caldera. Near the dying stages of the volcano, magma surged upward and arched the roof of the magma chamber into a broad dome with relief of about 1,500 m (4,921 ft).