ABSTRACT
For a long period through the later Paleozoic and Mesozoic, convergence and subduction beneath the Zealandia margin of Gondwana caused terrane accretion and generated the Median Batholith. At ~100 Ma, in the mid-Cretaceous, subduction ceased and extension began. Figure 9.1 (from Tulloch et al., 2009) is a reconstruction for a time soon after Gondwana breakup. From then until ~20 Ma, the structure of the New Zealand region remained more or less the same and was based around an inactive subduction zone with its extinct arc (the Median Batholith). These two features, along with the Eastern and Western province terranes, were more or less straight, not bent into a reverse-S shape as they are today. This remained the case until the Early Miocene, when changes in relative plate motion led to renewed convergence, the development of the Alpine fault, and massive deformation of New Zealand geography.
