Post-orogenic volcanics(Group D sites)

Abstract

The five sites descibed in this chapter include examples of the small-volume extrusives and intrusives that developed after the emplacement of the main granite plutons of the Cornubian batholith. Their locations are shown in Figure 6.1. Volcanism occurred during the prevalence of the ‘red-bed’ environment of the late Carboniferous and the early Permian Periods; it includes the mixed volcanics of the Exeter Volcanic ‘Series’, as well as suprabatholithic rhyolite lavas which were fed by late granite porphyry dykes. The volcanics of this period are often referred to as being Permian in age, although recalculated isotopic age dates suggest that they could also represent late Carboniferous activity. These volcanics represent the last remnant of magmatic activity that developed largely after continent-continent collision in a post-orogenic, tectonic setting.