Part 6. Present plate boundary seismic, volcanic and kinematic processes: The volcanic rocks associated with a complex plate boundary

Abstract

Given that the plate tectonic model (Le Pichon et al., 1973) is a valid working hypothesis that has operated during the Phanerozoic; then one should be able to use the data that are available on the abundance, composition and distribution of volcanic rocks as pointers to the various tectonophysical regimes that have operated in this segment of time. At present most of the major tectonic events that are observed at the surface of our planet are considered to be related to a relatively simple world-wide kinematic pattern; and it is claimed that along most major plate boundaries there is a relatively simple relationship between volcanism and tectonism. While this is true of most major plate boundaries some boundaries are complex. As most of these complex boundaries leave a relatively permanent record of their former existence in the geologic history of the continents, it is important to attempt to explain their origin and evolution. New Zealand lies astride a complex plate boundary and the tectonic diversity and complexity of the New Zealand crustal unit is regarded as a response of the continental crustal rocks of this area to the significant changes that are taking place in the kinematic character of this plate boundary.