Mapping Sub-Surface Geology from Magnetic Data in the Hides area, Western Papuan Fold Belt, PNG

Abstract

SUMMARYHorizon mapping using magnetic data was conducted over a part of the Western Papuan Fold Belt, in an area of rugged terrain, where the geological structures are of relatively low complexity. Energy spectral analysis was used to detect magnetic susceptibility contrasts that were laterally merged to form magnetic interfaces corresponding to horizons derived from seismic and well data.Numerous magnetic interfaces were detected corresponding to: magnetic layers within the Darai Limestone, top of Ieru Formation, intra-Ieru and deeper intra-sedimentary boundaries. These mapped sedimentary surfaces form an anticlinal structure which plunges towards the south-east. A major thrust fault, mapped from magnetic data using automatic curve matching, truncates the anticline in the south-west. Sedimentary magnetic layers were mapped on both sides of this fault. The results obtained from the interpretation of the magnetic data are consistent with structures mapped from seismic and well data.

Mapping sub-volcanic geology using magnetic data

“…This magnetic field was subtracted from the TMI data and the resultant magnetic field of the sub-volcanic crust was computed (Figure 8). Such a resultant magnetic field, if computed over a sedimentary basin, can be further analysed and interpreted using the Horizon Mapping technique discussed in Kivior et al, 2015 and2018. This would allow mapping of multiple sub-volcanic sedimentary horizons and structures.…”