AuthorsA. Lavecchia, S. Clark, F. Beekman, S. A. P. L. Cloetingh and E. Burov
TitleThermal perturbation, mineral assemblages and rheology variations induced by dyke emplacement in the crust
AfilliationScientific Computing
Project(s)No Simula project
StatusPublished
Publication TypeJournal Article
Year of Publication2016
JournalTectonics
Volume35
PublisherAGU
Abstract

We constructed a thermo-mechanical model to examine the rheology variations in a two-layered crustal section, resulting from the intrusion of a sequence of basaltic dykes. The mineralogical assemblage can change in space and time as the result of temperature-induced metamorphism. We adopted typical intracontinental lithologies, with a temperature and melt dependent rheology, and paid particular attention to determine how different mineral assemblages and reaction kinetics during metamorphism may influence the thermo-mechanical behavior of the crust, in terms of differential stress values. We have investigated: 1) a quartz-feldspathic crust (QF), 2) a crust whose mineralogical assemblage approximates estimations of average chemical composition occurring in literature (CC), and 3) a micaschists crust (MS).

Our model shows that temperature profiles are weakly influenced by metamorphism, with negligible variations in the T-t paths. The results indicate that the intrusion-induced changes in the crustal rheology are strongly dependent on mineralogical assemblage variation. The strength of a dyke aureole in the upper crust increases during dyke emplacement; this may cause migration of later dykes and influence the dyke spacing. In contrast, the strength of a dyke aureole in the lower crust decreases during dyke emplacement. Fast kinetics results in a ductile lower crust in proximity of the dykes, whereas slower kinetics leads to the formation of partial melts and subsequent switch from ductile to brittle behavior. Lithology exerts a dominant role on the quantity of melt produced, with higher volume percentages occurring in the MS case study. Produced melts may migrate and support acidic volcanic activity.

URLhttp://onlinelibrary.wiley.com/doi/10.1002/2016TC004125/full
DOI10.1002/2016TC004125

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