Kinematics of the Demon Fault: Implications for Mesozoic strike-slip faulting in eastern Australia

The Demon Fault is a north-striking, dextral strike-slip fault that displaces Carboniferous to Middle Triassic rock units in eastern Australia. We present results from aeromagnetic gridded data, satellite images, digital elevation models, and field observations, which provide constraints on the geometry and kinematics of the Demon Fault. The fault can be subdivided into four steeply dipping segments (DF1 to DF4) with oblique reverse-dextral kinematics. Earlier NW-striking faults, which affected Early and Middle Triassic magmatic rocks, are displaced by the Demon Fault, implying that activity along the Demon Fault has occurred during the latest Middle Triassic or later. The amount of dextral offset along the different parts of the Demon Fault is decreased towards the south. This suggests that either different segments have experienced different histories of reactivation, or that deformation toward the south has partitioned into minor splays, which operated as reverse faults and resulted in a lesser dextral displacement. We propose that the Demon Fault and other sub-parallel faults operated in conjunction with the development of basins in eastern Australia from Late Triassic to Early Cretaceous. The pattern of minor faults and their kinematics indicate that recent activity along the Demon Fault has occurred during dextral transpression, which we attribute to mid-Cretaceous contractional deformation, or possibly even Cenozoic deformation associated with collisional processes at the northern boundary of the Australian plate.