Dunedin Volcano

The Dunedin Volcano is an extensively eroded multi-vent shield volcano that was active between 16 and 10 million years ago.[1] It originally extended from the modern city of Dunedin, New Zealand to Aramoana about 25 km away. Extensive erosion has occurred over the last 10 million years and Otago Harbour now fills the oldest parts of the volcano.[2][3] The remnants of the volcano form the hills around Otago Harbour (including Mount Cargill, Flagstaff, Saddle Hill, Signal Hill, and Otago Peninsula). Volcanism began in a shallow marine environment. The volcano became larger with flows of basalt and minor trachyte creating the bulk of the volcano. The final phase of eruptions are preserved as phonolite domes around Mount Cargill.

Dunedin Volcano
Stratigraphic range: 16-10 Mya
TypeIgneous
OverliesWaipuna Bay Formation
Lithology
PrimaryBasalt, trachyte, phonolite and breccia
Location
Coordinates45.848°S 170.636°E / -45.848; 170.636
RegionOtago
CountryNew Zealand
Type section
Named forDunedin
A layer of scoria covered by a basalt lava flow at Taiaroa Head

Traces of the old Dunedin Volcano are best seen in the Dunedin Botanic Garden's geology walk,[4] the cliffs at Aramoana and the geomorphology of Mount Cargill which has preserved lava domes. Basaltic columns are also to be found as prominent features above Second Beach at St Clair and at Blackhead.

The Dunedin Volcano was originally centred on Quarantine Island (centre of the image) and is now highly eroded. There is speculation that it may have been up to 1000m high.[5]

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See also

References
  1. McDougall, Ian; Coombs, D. S. (1973). "Potassium-argon ages for the Dunedin volcano and outlying volcanics". New Zealand Journal of Geology and Geophysics. 16 (2): 179–188. doi:10.1080/00288306.1973.10431451. ISSN 0028-8306.
  2. "New Zealand Stratigraphic Lexicon". GNS Science.
  3. "Volcano Fact Sheet" (PDF). www.gns.cri.nz. GNS Science.
  4. "A city born of fire and rock". Otago Daily Times Online News. 19 November 2018. Retrieved 10 January 2019.
  5. "Volcano Fact Sheet" (PDF). www.gns.cri.nz. GNS Science.


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