Observing silicic magma transport in dykes at depths of 8–19 km: Evidences from crustal xenoliths and numerical modelling

Within the context of magma transport processes in a dyke, this paper integrates petrography and thermodynamic modelling together with fluid dynamics to model the melting of the wall rock in three magma dykes at crustal depths from 8 to 19 km. Using this combination we explore the interaction between thermal and mechanical processes during silicic magma ascent, and the implications for the relative abundance of different crustal xenoliths erupted at the surface. We utilize a two-dimensional thermal model of dacitic magma injection and flow in dykes of different thickness, lengths and depths and associated partial melting of the wall rock, and compare the results with field examples from the Neogene Volcanic Province, SE Spain.The modelling results open the possibility to relate the range of observed xenoliths information (microstructures, size, distribution at the surface, P–T evolution) to their position in a transient thermal regime in the wall-rock of a magma conduit, and to the time spent immersed in magma. In addition, the effects of the modelled stress in the wall rock during magma ascent by the presence or absence of planar features in the xenoliths reveal that the stress patterns are independent of the dyke length and thickness.