Waiareka-Deborah volcanic field
| Waiareka-Deborah volcanic field | |
|---|---|
| Stratigraphic range: | |
| Type | Igneous |
| Overlies | Rakaia Terrane |
| Area | 890 square kilometres (340 sq mi) |
| Lithology | |
| Primary | Sub-alkaline basalt and basaltic andesite |
| Location | |
| Coordinates | 45°00′S 170°18′E / 45.0°S 170.3°E |
| Region | Otago |
| Country | New Zealand |
| Type section | |
| Named for | Waiareka Valley, inland from Oamaru |
The Waiareka-Deborah volcanic field is a group of sub-alkaline basalt to basaltic andesite composition volcanics, most of which erupted about 34 million years ago. There is a range of determined ages by various methods and sites although most have very similar timings. At Bridge Point one deposit has an age of 39.5 ± 1.8 and another 34.3 ± 0.5 million years ago. They are found near Oamaru, South Island New Zealand, and are small Surtseyan volcanoes that erupted originally on a submerged continental shelf.
The former term, the Waiareka-Deborah volcanic group should not be used as any alkali basalt volcanoes in this group and all of those in the former Waiareka volcanic field are now assigned to the Dunedin volcanic group and its monogenetic volcanic field.