Dr Graham Leslie is a Senior Mapping Geologist with the British Geological Survey (BGS) who has also taught, trained, and mentored students and researchers in a number of UK universities. He brings over 30 years of experience in primary mapping, structural geology and geophysics. Graham provided leading geological input to the 3D geological model and geological review of Singapore undertaken by BGS on behalf of the Geological Office of BCA between 2012 and 2014. He has continued to develop that role in the new work with BCA, integrating recently acquired GI and outcrop data into an up-to-date geological understanding of subsurface Singapore, and to revision of the stratigraphical and structural frameworks.
Singapore’s geology is dominated by late Permian to Triassic arc magmatism that is partly contemporaneous with a broadly Upper Triassic, marine and fluvial, volcano-sedimentary inner forearc succession that we now assign to the Jurong and Sentosa groups. These strata were deformed into a NE-vergent pattern of inclined asymmetrical folds during collisional accretion tectonics in the latest Triassic to early Jurassic Indosinian Orogeny. Accretion drove progressive shortening and rotated earlier formed folds, culminating in the development of a large-scale NE-vergent, NE-facing fold and SW-dipping thrust system that includes the Murai Thrust structure. The subduction-related magmatic complex represented by the Central Singapore Granite pluton and its associated mafic rocks probably acted as a backstop to thrusting at this time. Two distinct early Cretaceous sedimentary successions (Berriasian and Barremian respectively) overstep the collisional tectonic structures. Subsequently, a (?Cenomanian) régime of dextral shear stress generated fault sets and fractures trending mostly NE-SW and ENE-WSW, along with subsidiary (N)NW-(S)SE and N-S sets that include the Bukit Timah and Nee Soon faults.