Bulletin of the Geological Society of Malaysia, Volume 65, June 2018, pp. 1 – 12
JX Nippon Oil & Gas Exploration (Deepwater Sabah) Limited, Kuala Lumpur, Malaysia
*Corresponding author email address: email@example.com
Abstract: NW Sabah is dominated by numerous structural trends of tightly folded and thrusted Miocene to Pleistocene sediments forming the Sabah deepwater fold-thrust belt, resulting from the complex interaction between gravitational forces and compressional tectonics. The timing of structuration and deformation of most of the toe-thrust features is recorded by the Shallow-Regional Unconformity (SRU), which separates the pre- and post-kinematic phases of the structural development. A good understanding of the timing of the structural development is paramount in the analyses of sedimentary fairways and depositional patterns. The pre-kinematic phase is likely to result in an unconfined depositional setting, while structurally influence syn- and post-kinematic depositional phases tend to deflect turbidite sand fairways, and trap turbiditic sand in between ridges forming ponded turbidites. This study aims to provide further support for the semi-qualitative understanding of the various deformational episodes experienced in the “L-B-P” structural trend, from the oldest studied sequence, the Kinarut interval to the seabed, in a temporal and spatial framework. A quantitative analysis of the deformation profiles was conducted to observe the 3D structural evolution and its effect on the sedimentary patterns, supported by amplitude analysis and spectral decomposition mapping. The basic principal of line balance restoration is employed to unravel the deformation history of the “L-B-P” structures, with the fundamental assumption that a geological section will restore at any particular moment in time to an unstructured section according to the law of superposition and horizontality. Structures are examined by calculating the rate of shortening at different geological times over a number of line-sections. This quantitative analysis has shown that the structuration and deformation history of the “L-B-P” structures are varied along the structural trend. These variations in turn play a significant role in controlling sediment fairway distribution patterns and impact on the selection of exploration reservoir objectives.
Keywords: deformation, Miocene, NW Sabah, structural kinematics, toe-thrust