Melt distribution beneath a young continental rift: The Taupo Volcanic Zone, New Zealand

Abstract

Taupo Volcanic Zone (TVZ) is a zone of intense volcanism and rifting associated with the subduction of the Pacific Plate beneath the continental crust of New Zealand's North Island. An image of the conductivity structure beneath the central part of the TVZ has been constructed using 2‐D inverse modeling of magnetotelluric data. A rapid increase in conductivity at a depth of 10 km beneath the TVZ, ∼3 km beneath the base of the seismogenic zone but well above the base of the quartzo‐feldspathic crust (∼16 km), is interpreted to mark the presence of an interconnected melt fraction (<4%) within the lower crust. Beneath the quartzo‐feldspathic crust the model shows a zone of increased conductivity on the eastern side of the TVZ consistent with an increased concentration of melt. At deeper levels the Pacific Plate is resistive compared with the overlying mantle.