The application of airborne geophysics to epithermal gold exploration in Eastern Misima Island, Papua New Guinea

Abstract

Misima Island is situated 625 km east southeast of Port Moresby in Papua New Guinea. A detailed airborne magnetic and radiometric survey was carried out over the eastern portion of the island which contains the Umuna epithermal gold deposit.The purpose of the survey was to improve the understanding of surface and underlying geology and assist the regional mineral exploration of the area.In situ magnetic susceptibility measurements were taken within the survey area to determine the magnetic properties of the various Palaeocene-Miocene metasedimentary sequences and Miocene porphyritic felsic intrusives.The interpretation of the airborne magnetic data was constrained by susceptibility measurements, magnetic modelling and regional geological mapping. Computer processing included the use of reduction to the pole and pseudo gravimetric transforms.Variable density and type of vegetation cover on the island limited previous interpretations of the airborne radiometric data. The data was reprocessed using principal components analysis of the potassium and total count radiometric data.