Late Mesozoic and Cenozoic wrench tectonics in eastern Australia: Insights from the North Pine Fault System (southeast Queensland)

Abstract

The North Pine Fault System (NPFS) in SE Queensland belongs to a series of NNW-striking sinistral faults that displaced Paleozoic to Cenozoic rock units in eastern Australia. We have studied the geometry and kinematics of the NPFS by utilizing gridded aeromagnetic data, digital elevation models, and field observations. The results indicate that all segments of the NPFS were subjected to sinistral reverse strike-slip faulting. Restorations of displaced magnetic anomalies indicate sinistral offsets ranging from ∼3.4 to ∼8.2km. The existence of a (possibly) Late Triassic granophyre dyke parallel to one of the fault segments, and the occurrence of NNW-striking steeply dipping strike-slip and normal faults in the Late Triassic-Early Cretaceous Maryborough Basin, indicate that the NPFS has likely been active during the Mesozoic. We propose that from Late Cretaceous to early Eocene, NNW-striking faults in eastern Australia, including the NPFS, were reactivated with oblique sinistral-normal kinematics in response to regional oblique extension associated with the opening of the Tasman and Coral Seas. This interpretation is consistent with the modeled dominant NNE- to NNW-directed horizontal tensional stress in the Eocene. The latest movements along the NPFS involved sinistral transpressional kinematics, which was possibly related to far-field contractional stresses from collisional tectonics at the eastern and northern boundaries of the Australian plate in the Cenozoic. This sinistral-reverse oblique kinematics of the NPFS in the Cenozoic is in line with ∼ESE to ENE orientations of the modeled maximum horizontal stress in SE Queensland.