Preliminary Interpretation of Magnetic Anomalies Over the Waimangu, Waiotapu, Waikite and Reporoa Geothermal Areas, New Zealand

Abstract

The Waimangu, Waiotapu, Waikite and Reporoa geothermal areas are situated on the eastern side of the Taupo Volcanic Zone m) in the central North Island of New Zealand. An airborne magnetic survey at c. 760 m RSL (m respect to sea level) over the study area showed a complex pattern of residual magnetic anomalies reflecting a complex magnetic structure where thermally demagnetized volcanic rocks occur together with old, reversely magnetized rocks. Two outcrops of reversely magnetized rocks are marked by prominent negative residual anomalies. Preliminary interpretation of the magnetic data indicates that hydrothermally demagnetized rocks occur beneath the Waiotapu and the SW part of the Waimangu geothermal fields. Residual magnetic anomalies over the Reporoa geothermal field are not indicative for demagnetized rocks.