Impact of thrust-ridge development on deepwater sedimentary systems as illustrated by 3D seismic data offshore NW Sabah

NW Sabah deepwater fold and thrust belt (FTB) started with the subduction of the Dangerous Ground microcontinental plate under Borneo because of the opening of the South China Sea occurred approximately 32 Ma to 15 Ma. In the study area, the deformation of the FTB is characterized by large wavelength synclines in the SW and short wavelength thrusting in the NE. In such context, variable deepwater sedimentation feedback mechanisms may be recognized due to the interplay between controlling factors such as sedimentation rate, tectonic activity, nature of sediments, sea level cyclicity, basin physiography and slope rugosity. The seabed morphology of NW Sabah deepwater FTB demonstrates classical architectural elements of lower trench-slope basins with well-developed shelf-attached or detached canyons mass-transport complexes (MTCs), as well as turbidite lobes and channels, sometimes axial (i.e. parallel to the trench). This study integrates (1) the 15,000 km2 offshore Sabah TGS multiclient 3D broadband seismic megasurvey with bin spacing of 12.5 x 12.5 m and 3 ms of vertical sampling and (2) twenty-three wells drilled in the study area. The detailed and extensive 3D seismic geomorphology analysis of syn-tectonic strata within the intra-slope basins demonstrates the close interaction between sedimentation and deformation along the margin. Gravity-driven deposits may be organized into sequences of (1) incised canyons (2) MTCs (3) turbidites and (4) hemi / or pelagic shale related to tectonic pulses and uplift at the thrust ridges. Transport directions vary through time with syn-tectonic sedimentation either being sourced from the forelimb and / or backlimb settings of the thrusts. The detailed understanding of syn-tectonic sedimentary processes within trench-slope basins can provide new insights into deep-water sediment distribution in complex compressive margins and improve reservoir prediction.