Stratigraphic constraints on the late Miocene-Pleistocene evolution of the North Island Fault System and axial ranges in the central Hikurangi subduction margin, New Zealand

摘要

The North Island Fault System (NIFS), coincides with North Island's axial ranges, accommodating crustal strain associated with the Hikurangi subduction margin. Detailed geological mapping along c. 80 km of the NIFS constrains uplift/subsidence and displacement patterns since c. 12 Ma. Uplift within the NIFS area and/or vertical displacement on faults occurred at 12-10, 7-6.5, 5-4.5, 3.5-3.0, 2.5-2, and post-1 Ma. Each deformation episode was associated with vertical offsets across the NIFS of 300-500 m (total c. 5 km). Total dextral strike-slip across the NIFS since 5 Ma is 20 km. Little of the relative plate motion is accommodated on the NIFS (10%) or in the upper plate (20%), the majority occurring on the subduction interface. The tectonic evolution of North Island is best explained by reconstructions incorporating vertical axis block rotations and 30 km strike-slip distributed across the entire margin on multiple discrete structures.