Inversion tectonics

Studies on inversion tectonics are an important contribution to the thin- vs. thick-skinned debate. (Fig. 7 d, e). The outer zones of thrust belts are commonly characterized by pre-orogenic faults that control the geometry of thrusts and associated folds (Butler, 1989; McClay, 1989) and have been reactivated or partially translated by thrusts (Tavarnelli et al., 2004; Butler and Mazzoli, 2006). The role of pre-thrusting normal faults in the evolution of the Apennines has been investigated by several authors; such faults were either truncated by thrusts with a shortcut trajectory (sensu McClay, 1989; Coward, 1994) or reactivated with reverse kinematics (Butler, 1989; Scisciani et al., 2002; Tozer et al., 2002; Tavarnelli et al., 2004; Scisciani, 2009; Calamita et al., 2011). Contradictory styles of fault are linked to the same inversion event, and are related to the trend of pre-existing extensional faults with respect to the subsequent compressional NE-SW trending stress field (Calamita et al., 2011; Di Domenica et al., 2012). The N-S trending Ancona-Anzio pre-orogenic normal fault, which controlled the Mesozoic Adria paleomargin, was reactivated during the Neogene Period as an oblique thrust ramp (Fig. 5).