TOWARD MAGMATIC SOURCE MODELS FOR NGAKURU GRABEN, TAUPO RIFT, NEW ZEALAND

Abstract

A thermo-mechanical code is used to model heat transfer in the ductile region below the Taupo Rift constrained by crustal resistivities derived from MT measurements. We investigate how magmatic fluid and heat are transported to the upper, brittle crust and affected by underplating, fluid flux from the subduction system beneath the rift, and thinning of inherited basement in the rift. We show that intrusion and underplating of melt within and below the brittle crust are necessary to attain sufficient heat-flow at the base of the permeable brittle crust. These results are used to inform more detailed models of fluid flow through the Ngakuru graben fault system which aim to explain the presence of surface hydrothermal activity throughout this system during the last 30 kyr.