Combining AIRSAR data of Huon peninsula and Hawaii MR1 data of Huon Gulf, Papua New Guinea, for studies of tectonic and sedimentary processes

Abstract

Two swaths of airborne synthetic aperture radar (AIRSAR) imagery, acquired over the southern Huon Peninsula, Papua New Guinea, have been digitally merged with aerial photogrammetric topography and with Hawaii MR] acoustic side‐scan imagery and bathymetry of the adjacent seabed of Huon Gulf. This example of land‐sea integration provides a means of examining relationships between tectonic lineaments and sediment transport pathways on land and on the subjacent seabed. Imaging methods and geometries dictate both the regions covered and the information content of the data. The principal limitations in merging the two data sets arise because the coastal and inner shelf zone, in water depths less than 500 m, is inaccessible to the imaging techniques that were used. Indirect methods allow some inferences to be made about the geomorphology of this zone, using surface sound channel data and sea surface imagery. The area examined is part of an active tectonic collision zone in which the northern margin of the Australian plate is being subducted beneath the South Bismarck plate. The edge of the South Bismarck plate has been uplifted 4,000 m since the late Pliocene, forming the Finisterre Range on Huon Peninsula. The record of relative emergence and submergence is seen in subaerially exposed Quaternary marine sediments and in drowned carbonate reefs. The merged radar and sonar imagery clearly indicate rapid erosion and deformation, both on land and under water. The imagery shows details of sediment transport and depositional systems, which are generating large terrestrial fluvial/alluvial plains, coastal fan deltas, and submarine channel deposystems. Fault structures and outcrops of bedrock units are clearly delineated both on land and on the seabed. These observations help explain patterns of onshore and submarine outcrops in terms of interactions between modern offshore sedimentation patterns and progressive deformation.