Investigation of the spatio-temporal relationship between normal faulting and arc volcanism on million-year time scales

Abstract

The spatio-temporal evolution of normal faulting and submarine volcanism during the Mid-Miocene to Recent (<16 Ma) in the Taranaki Basin, New Zealand, provides insights into the processes driving rifting and volcanism. In the Taranaki Basin high sedimentation rates have led to the blanketing and preservation of mainly submarine volcanic edifices and normal faults. Volcanic activity gradually migrated southward along the basin and contrasts with the punctuated migration of normal faulting in the same direction. Gradual southward migration of volcanism since c . 16 Ma has been attributed to progressive steepening and SE rollback of the subducting Pacific Plate. Similarly, the location and NE–SW strike of Late Miocene and younger normal faults mainly west of the North Island appear to have been controlled by the location and NE–SW strike of the underlying subducting plate. Stepwise changes in the locus of faulting at c . 8, 4 and 2 Ma could have been triggered by increases in the rates of vertical-axis rotation of the North Island associated with changes in plate convergence rates and southward migration of the rotation pole. The disparate spatio-temporal migration histories of subduction-related faulting and volcanism indicate that, over time scales of millions of years and distances of tens of kilometres, neither process controls the timing, location and rates of activity of the other.