Unraveling Multiple Thermotectonic Events Accommodated by Crustal\u2010Scale Faults in Northern Iberia, Spain: Insights From K-Ar Dating of Clay Gouges

Large-scale faults in the continental crust are significant features that control the evolution of sedimentary basins and intraplate mountain chains. Deciphering their evolution is a significant task because faults slip and reactivate in a variety of geological settings. In this work, clay gouges of two major orogen-scale, long-lived faults in northern Iberia, the Río Grío and Vallès-Penedès Faults, were investigated by X-ray diffraction and K-Ar isotopic analysis. Illite polytype determinations of 44 subfractions (from