Unraveling Multiple Thermotectonic Events Accommodated by Crustal‐Scale 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