Dunedin volcanic group

Dunedin volcanic group
Stratigraphic range: Oligocene-Miocene (25–8 Ma)[1]
TypeIgneous
OverliesRakaia Terrane
Area7,800 square kilometres (3,000 sq mi)[1][2]
Lithology
PrimaryBasalt, trachyte, phonolite and breccia
Location
Coordinates45°39′S 170°18′E / 45.65°S 170.3°E / -45.65; 170.3
RegionOtago
CountryNew Zealand
Type section
Named forDunedin
Map
Map of selected surface volcanic features of the South Island centred on Otago. Clicking on the map enlarges it, and enables panning and mouseover of volcano name/wikilink and ages before present. Key for the volcanics that are shown with panning is:   basalt (shades of brown/orange),   monogenetic basalts,   undifferentiated basalts,   arc basalts,   arc ring basalts,   olivine (basalts shades of olive),   phonolite (pale salmon),   dacite,   andesite (shades of red),   basaltic andesite,   rhyolite, (ignimbrite is lighter shades of violet), and   plutonic or intusive (gray) - so dolerite/diabase/microgabbro will have shadings towards gray compared to erupted basalt.

The Dunedin volcanic group is a volcanic group that covers over 7,800 km2 (3,000 sq mi) of Otago in the South Island of New Zealand.[2] It is a recent[note 1] reclassification of the group previously known as the Waiareka-Deborah volcanic field due to common magma melt ancestries of the Dunedin Volcano[7] with the overlapping alkali basaltic monogenetic volcanic field.[1] Excluded from the group are a group of volcanics of different composition (sub-alkaline basalt to basaltic andesite) and older age (36.4 to 27.6 million years ago) near Oamaru, which have been given the name previously used for the Dunedin group.[8] The older Waiareka-Deborah volcanic field overlaps the new Dunedin volcanic group geographically; though Dunedin Volcano has been well studied from the 1880s since New Zealand's first school of geology was established at the University of Otago, detailed studies of north-central volcanoes such as the Crater near Middlemarch were done much later,[6][9] and high-quality composition studies still need to be done to properly classify many volcanics near Oamaru.

  1. ^ a b c d Scott, James M.; Pontesilli, Alessio; Brenna, Marco; White, James D. L.; Giacalone, Emanuele; Palin, J. Michael; le Roux, Petrus J. (2020). "The Dunedin Volcanic Group and a revised model for Zealandia's alkaline intraplate volcanism". New Zealand Journal of Geology and Geophysics. 63 (4): 510–529. Bibcode:2020NZJGG..63..510S. doi:10.1080/00288306.2019.1707695. S2CID 212937447.
  2. ^ a b Scanlan, Emma J.; Scott, James M.; le Roux, Petrus J. (2020). "Pyrometamorphosed Otago Schist xenoliths cause minor contamination of Dunedin Volcanic Group basanite". New Zealand Journal of Geology and Geophysics. 63 (4): 530–546. Bibcode:2020NZJGG..63..530S. doi:10.1080/00288306.2020.1767659. S2CID 219904459.
  3. ^ Pole, Mike (1993). "Nothofagus from the Dunedin Volcanic Group (Mid — Late Miocene), New Zealand". Alcheringa: An Australasian Journal of Palaeontology. 17 (1): 77–90. Bibcode:1993Alch...17...77P. doi:10.1080/03115519308619489.
  4. ^ Coombs, DS; Cas, RA; Kawachi, Y; Landis, CA; McDonough, WF; Reay, A (1986). Smith I.E.M. (ed.). Cenozoic volcanism in North, East, and Central Otago. In: Late Cenozoic volcanism in New Zealand. Vol. 23. Royal Society of New Zealand Bulletin. pp. 278–312.
  5. ^ Cite error: The named reference Coombs2008 was invoked but never defined (see the help page).
  6. ^ a b Németh, Károly (2001). Phreatomagmatic volcanism at the Waipiata Volcanic Field, Otago, New Zealand (Thesis).
  7. ^ 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. Bibcode:1973NZJGG..16..179M. doi:10.1080/00288306.1973.10431451. ISSN 0028-8306.
  8. ^ Scott, James M.; White, James D. L.; le Roux, Petrus J. (2020). "Intraplate volcanism on the Zealandia Eocene-Early Oligocene continental shelf: The Waiareka-Deborah Volcanic Field, North Otago". New Zealand Journal of Geology and Geophysics. 63 (4): 450–468. Bibcode:2020NZJGG..63..450S. doi:10.1080/00288306.2020.1785896. S2CID 221380814.
  9. ^ Németh, Károly; White, James D.L. (2009). "Miocene phreatomagmatic monogenetic volcanism of the Waipiata Volcanic Field, Otago, New Zealand: Field Guide".


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