Controls of upwelling and emplacement: the response of the envelope: balloons, pistons and reality

Abstract

It is most unlikely that magmatism is ever a tectonically passive event; melting is initiated, the site of intrusion selected, upwelling motivated and the arrival in the upper crust controlled, all in response to crustal movements. In the broadest sense magmatism is always syntectonic, especially so if account is taken of the whole process time involved in the melting, assembly, intrusion and cooling. Unfortunately, even with the best of outcrop maps, geophysically controlled for the third dimension, we can only observe the arrival stage of this emplacement process, though structural studies of both the pluton and envelope can provide the clues for unravelling the ascent history.