Kinematics and Timing of Brittle-Ductile Shearing of Mylonites along the Bok Bak Fault, Peninsular Malaysia

Study on the Bok Bak fault in Peninsular Malaysia reveals it to be a predominantly dextral brittle–ductile strike slip fault zone. This fault zone is characterized by gentle to sub-horizontal NE stretching lineation. The deformation occurred in a brittle–ductile domain. 40 Ar/ 39 Ar radiometric dating of biotite from the mylonite assigns an age of 136.1 ± 1.4 Ma. This age is the first reported radiometric dating of the Bok Bak fault, suggesting that the fault affected Sundaland prior to the collision between India and Asia, and therefore indicates an early faulting in the Malay Peninsula.