Impacts of Hikurangi Plateau subduction on the origin and evolution of the Alpine Fault

摘要

The Alpine Fault has traditionally been interpreted as a plate boundary through continental lithosphere, with attendant widespread deformation. But recent three-dimensional imaging of deep crustal structure has shown that the habitat of the fault is dominated by strong, large igneous province (Hikurangi Plateau) lithosphere, producing a much narrower deformation zone. The fault formed at c. 23Ma as a subduction-transform edge propagator (STEP fault). STEP fault propagation stopped at c.15Ma, and motion on the fault renewed at c. 7Ma, when the fault linked with the Marlborough fault system. If the 480km offset of geological terranes across the fault occurred only during these two episodes, this implies an average strike-slip rate close to that in the Late Quaternary. The current pattern of convergence along the fault is dominated by the 16 degrees mismatch between the strikes of the STEP fault and the converging plateau.