| Whangārei volcanic field | |
|---|---|
| Puhipuhi-Whangarei volcanic field | |
| Map of surface volcanics centred on the Whangārei volcanic field. 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 of the Tangihua Complex in Northland Allochthon, arc basalts, arc ring basalts, dacite, andesite (shades of red), basaltic andesite, rhyolite, (ignimbrite is lighter shades of violet), and plutonic. White shading is selected caldera features. | |
| Highest point | |
| Coordinates | 35°40′S 174°17′E / 35.66°S 174.28°E / -35.66; 174.28 |
| Geology | |
| Rock age | late Pliocene to Quaternary 22.6–0.31 Ma PreꞒ Ꞓ O S D C P T J K Pg N |
| Mountain type | Volcanic field |
| Rock type(s) | basaltic and dacicitic intra-plate monogenetic |
| Last eruption | 260 ka |
The Whangārei volcanic field (Puhipuhi-Whangarei volcanic field) is an area of intra-plate monogenetic volcanism located near the city of Whangārei, North Island, New Zealand. It was last active between 260,000 to 319,000 years ago and continues to be potentially active as a low-velocity seismic zone in the crust exists beneath Whangārei, which is interpreted to be a body of partial melt. This mantle source has been coupled to the lithosphere for about 8 million years. As the field has potentially been active at low frequency for millions of years, with 100,000 years or more between events it might best be regarded as dormant. The recent vents active in the last million years include some dacite in composition. Composition details are freely available for most of the field but many vents do not have ages.
Geology
Volcanics
These volcanoes are part of the eastern Northland volcanic belt which includes the monogenetic Kaikohe-Bay of Islands volcanic field and the volcanoes of the Whangārei Heads and the Hen of the Hen and Chickens Islands which are not part of the field. Rather the volcanoes of the Whangārei Heads are usually related to the now extinct predominantly andesitic Taurikura volcanic complex and its caldera, although the close proximity, overlap in time, and dacite eruptive centres possibly reflects a continuum.
Non-volcanics and tectonics
The hilly landscape to the west of Whangārei is from uplifted Waipapa Terrane greywacke deposits from ocean floor sediments first laid down several hundred millions ago off the coast of Gondwanaland. There are some coal measures, sandstone, and limestone from late Eocene and Oligocene (Te Kuiti Group) sediments laid on top of the greywacke basement. On top of these contributing to many hills are often more clay like deposits originally from the floor of the Pacific Ocean of 80-25 million years ago. About 25 million years ago these deep-sea sediments were uplifted as the Northland Allochthon. There are no known active faults in Northland Historic faults are believed, due to volcanic alignment, to have been permissive to the surface volcanism of the last 25 million years, with the Whangārei Harbour fault being a prominent example.
List of volcanoes
References
- ^ Shane, Phil; Coote, Alisha (2018). "Thermobarometry of Whangarei volcanic field lavas, New Zealand: Constraints on plumbing systems of small monogenetic basalt volcanoes". Journal of Volcanology and Geothermal Research. 354: 130–139. doi:10.1016/j.jvolgeores.2018.02.013. ISSN 0377-0273.
- ^ Smith, Ian E. M.; Cronin, Shane J. (2021). "Geochemical patterns of late Cenozoic intraplate basaltic volcanism in northern New Zealand and their relationship to the behaviour of the mantle". New Zealand Journal of Geology and Geophysics. 64 (2–3): 201–212. doi:10.1080/00288306.2020.1757470. S2CID 219440898.
- "Project: The evolution of basaltic volcanism in Northland in space and time Earthquake Commission Grant (project 09/U585)" (PDF). Retrieved 22 January 2023.
- Horspool, N. A.; Savage, M. K.; Bannister, S. (2006). "Implications for intraplate volcanism and back-arc deformation in northwestern New Zealand, from joint inversion of receiver functions and surface waves". Geophysical Journal International. 166 (3): 1466–1483. doi:10.1111/j.1365-246X.2006.03016.x. S2CID 85512500.
- GNS:NZ active fault database
- ^ Hayward, Bruce W.; Black, Philippa M.; Smith, Ian E. M.; Ballance, Peter F.; Itaya, Tetsumaru; Doi, Masako; Takagi, Miki; Bergman, Steve; Adams, Chris J.; Herzer, Richard H.; Robertson, David J. (2001). "K-Ar ages of early Miocene arc-type volcanoes in northern New Zealand". New Zealand Journal of Geology and Geophysics. 44 (2): 285–311. doi:10.1080/00288306.2001.9514939. S2CID 128957126.
- ^ Beetham, R. D.; McSaveney, M.; Dellow, G.; Rosenberg, M.; Johnston, D.; Smith, W. (2004). "A review of natural hazards information for Northland Region" (PDF). Retrieved 23 January 2023.
- ^ Hayward, Bruce; Isaac, Mike; Miller, Keith; Spörli, Bernhard (2002). "Introduction to Whangarei geology" (PDF). Geological Society of New Zealand. p. 27. Archived from the original (PDF) on 4 March 2009.
- ^ NZ TopoMap:Hikurangi
- ^ GNS:1:250000 geological map NZ
- ^ NZ TopoMap:Whakapara
- ^ NZ TopoMap:Apotu
- ^ NZ TopoMap:Parakiore
- ^ NZ TopoMap:Hurupaki
- "Mount Parihaka name corrected". 19 July 2005. Archived from the original on 20 January 2009. Retrieved 14 August 2008.
- ^ NZ TopoMap:Mount Parihaka
- ^ NZ TopoMap:Maungakaramea
- ^ NZ TopoMap:Maungatapere
- ^ NZ TopoMap:Onerahi