Buried volcano found in the Panmure Basin, New Zealand

A previously unknown volcano has been discovered in the Auckland volcanic field in the North Island of New Zealand. A team from the government-owned geophysical research company GNS Science and the University of Auckland have been drilling and analyzing core samples as part of an investigation of Auckland’s volcanic past. One of their drill cores revealed the presence of a scoria cone within the Panmure Basin, itself the mouth of a volcano that erupted around 28,000 years ago. Another drill core contained 2.6m of ash apparently erupted from nearby Mount Wellington some 9,200 years ago. From the GNS Science press release, 22 February 2008:

Scientists from both organisations, including Phil Shane, Ian Smith and Paul Augustinus of The University of Auckland, will now analyse the chemistry of the drill cores to determine the date and the source of each eruption. They will also try to determine the age of the scoria cone.

Project leader Graham Leonard, a volcanologist with GNS Science, said finding what appears to be a new volcanic cone inside  Panmure Basin was a very exciting result. 

‘Most of Auckland’s volcanoes have erupted only once, with the possible exception of  Rangitoto. We will now analyse the core to see if Panmure volcano should be added to the list’, Dr Leonard said.

It was also important to learn more about the Mount Wellington eruption, as it appeared to be the second most recent Auckland eruption, behind Rangitoto which erupted about 650 years ago.

The Auckland volcanic field is around 140km³ in extent and encompasses more than 50 maars, tuff rings, small lava shields and scoria cones formed over the past 140,000 years. The most recent eruptive activity, the Rangitoto eruption which formed Rangitoto Island, is believed to have taken place c.1350 AD.

Information
Smithsonian Institution Global Volcanism Program – summary information for the Auckland volcanic field (0401-02=)

News
Geologists find buried volcano inside Panmure Basin – GNS Science press release, 22 February 2008
New Auckland volcano discovered – NZ Herald, 22 February 2008
Buried volcano found in Panmure Basin – tvnz.co.nz, 22 February 2008
Buried volcano found in Panmure Basin – Radio New Zealand News, 22 February 2008