Tectonics and melting in intra-continental settings

Abstract

Most of the geodynamic theories of deformation aswell asmetamorphismandmelting of continental lithosphere are concentrated on plate boundaries and are dominated by the effects of subduction upon deformation of the margins of continental lithospheric blocks. However, it is becoming increasingly apparent that suture zones, or mobile belts, presumably representing fossil subduction zones, or other types of pre-deformation which occur far from present plate boundaries, play a key role in intra-continental deformation. In such zones, the crust is strongly sheared and the mantle lithosphere is metasomatized. Reworking of such settings reveals a surprisingly large range of instabilities that develop in compressed lithosphere with lateral heterogeneities inherited from previous deformational processes. Structural complexity arises,which is sensitive to lithospheric age and tectonic setting. This complexity influences localization of deformation, topographic evolution, melt generation, and melt generation, ascent and emplacement. In this paper, using fully coupled petrological–thermomechanical modeling, various tectonic responses are correlated with magmatic events in intra-continental settings and are compared to observed intra-cratonic orogenies and magmatic events.