Abstract
<title>Abstract</title> <p>Felsic igneous plutons dominate Earth’s upper continental crust, yet their assembly dynamics and magma solidification kinetics remain poorly constrained. To advance on these issues, we investigated the hypabyssal ~760 m thick Beauvoir granite (France) which was emplaced as a series of 18 stacked magma sheets. Using thermo-kinetic simulations consistent with petrological and microstructural observations, here we show that the composite pluton was emplaced and solidified over ~10 kyr, with an average volumetric construction rate ranging from ~2.1.10-4 to ~3.4.10-2 km3.yr-1. Individual magma sheet solidification times ranged from decades to millennia. Rapid magma solidification resulted in disequilibrium three-grain junction geometries, while localised skeletal crystal habits bear witness to an early period of high magma undercooling related to sill emplacement. Our results highlight the value of integrating thermal modelling with microstructural observations to reconstruct magma storage histories, and extend the use of dihedral angles to felsic magmas, offering a new tool for probing solidification dynamics in granitic systems.</p>