Seismic Reflection of Offshore Faults in the Singapore Strait: Implications for Fault Architecture and Basin Formation

The Singapore Strait is located at the tectonic transition zone between the eastern Indochina-East Malaya Block and western Sibumasu block. Recent studies have examined the structural architecture and tectonic evolution of its bedrock, but there is uncertainty regarding the younger deformation. Moreover, limited fault exposures inland make it difficult to determine the full extent of structural geology. Mapping offshore faults and understanding their structural evolution are crucial for assessing marine geohazards, infrastructure development, coastal management, and fostering a comprehensive understanding of Southeast Asia’s complex geological framework.

To investigate the offshore faults distribution and their geometric features in the Singapore Strait, we acquired single-channel seismic reflection profiles and multibeam bathymetric data. The integration of seismic reflection, bathymetric, and gravity anomaly data elucidates the position, continuity, and configuration of the offshore faults in the Singapore Strait. Faults and folds orientated NW-SE are mostly located in western Singapore, whereas the eastern region is characterised by a network of buried channels. In the western area, predominant ENE-WSW, NW-SE, and N-S striking fault structures are in accord with a dextral shear that had developed in the Mesozoic. However, we observed some faults that contradict the dextral strike-slip PDZ (e.g., NW-SE strike-slip and (N)NE-(S)SW thrust). Moreover, a potential half graben boundary fault along the southwestern island delineates the western and eastern regions, where the isopach thickness map of the late Quaternary strata exhibits an increase in thickness towards this boundary fault. This evidence indicates a possible fault reactivation during the latest Cenozoic tectonic history.