Location of the Kaikohe - Bay of Islands volcanic centers. Modified from Johnson and others (1989) and Smith (1989).
The Northland Province includes the rocks of Kaikohe - Bay of Islands, Puhipuhi, and Whangarei volcanic centers. Volcanism began in the province about 2.3 million years ago. Volcanic features include remnants of lava flows that cap older layers of sedimentary rock, small plateaus made of stacks of lava flows, small lava cones, scoria cones, and lava flows that fill young valley systems (Johnson and others, 1989).
The Kaikohe - Bay of Islands volcanic centers are mostly basaltic in character and have no obvious tectonic relationship to the subduction zone to the south. Johnson and others (1989) consider the centers to be the result of intraplate volcanism. The chemistry of the rocks is distinctive from volcanic rocks at convergent and divergent plate boundaries. Peralkaline rhyolites have been described in the Kaikohe and Pungaere areas. Non-peralkaline rhyolites h ave been described in the Te Pene and Hurikuri areas.
The Kaikohe - Bay of Islands volcanic field has a single dated eruption, from the Te Puke vent, at 400 A.D. The date is from carbonized wood from beneath a young lava flow.
Sources of Information:
Ashcroft, J., 1986, The Kerikeri Volcanics: a basalt-pantellerite association in Northland, in, Smith, I.E.M., ed., Late Cenozoic Volcanism in New Zealand, Royal Society of New Zealand Bulletin, v. 23, p. 48-63.
Smith, I.E.M., 1989, New Zealand intraplate volcanism, North Island, in Johnson, R.W., Knutson, J., Taylor, S.R., eds., 1989, Intraplate volcanism in eastern Australia and New Zealand: Cambridge, England, Cambridge University press, p. 157-162.
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