2. A regional study of sequence geometry and structural control of the Darai and Foreland
Basin megasequences, Papuan Basin foreland
Norman Nele and Simon A. Kawagle
Earth Sciences Division, SNPS, University of Papua New Guinea
Email: skawagle@upng.ac.pg
______________________
Abstract
The Papuan Basin occupies the southern part of the island of New Guinea, and comprises a fold and
thrust belt that coincides with the southern flank of the central mountain ranges, and a foreland basin that
extends southward from the mountain ranges. Within PNG, the foreland basin occupies the lowlands of
the Fly-Strickland plains, and extends offshore into the Gulf of Papua. The fold belt runs in a northwest-
southeast direction and hosts the current producing oil and gas fields in PNG. Oil has been produced
from the Papuan Basin since 1992 from structures within the fold belt. Although commercial gas and
condensate have been discovered in the foreland (e.g. Stanley, Douglas, Elevala and Ketu), no
commercial oil has been found.
A regional scale study, which involved an analysis and interpretation of existing industry multi-channel
seismic reflection data from three vintages from within the foreland of the Papuan Basin has delineated
sequences, which are correlatable to previously documented Darai and Foreland Basin megasequences of
the Papuan Basin. Depth structure and isopach maps of the sequences show thickness variations
reflecting strong tectonic influences on sedimentation.
Results indicate that a northwest-trending spur or anticline correlating with the Komewu, Kiunga, Kaliem
and Baliem or 3KB Trend influenced sequence geometry and sedimentation. Northeast-trending
lineaments, developed in Early Mesozoic are the major structures that are orthogonal to the NW-trending
3KB Trend. They bound localised sediment troughs. These lineaments are not related to formation of
structures in the Papuan Basin foreland. These, probably are related to pre-existing structures or zones of
weakness in the Palaeozoic basement and reactivated as transfer zones during the Mesozoic extension, as
documented elsewhere in the Papuan Basin.
Keywords: Papuan Basin, Darai, Foreland basin, megasequences.
