Gli effetti della neotettonica sull'evoluzione dei sistemi carsici ipogei: esempi dalle Alpi Apuane (Toscana)

Abstract

In the Alpi Apuane area, the evolution of endokarst systems was controlled by neotectonics events. The most important effect is the negative movement of the hydrologic base level as the consequence of the uplift of the massif. Where there are no geostructural obstacles, the lowering of base level causes the deepening of the piezo-metric level; because a karst system tends to develop a conduit-network close to the elevation of piezometric level, variations in the uplift rate cause a differential vertical development of karst conduits. Neotectonics interacted with the evolving endokarst systems. Some karst systems lost their water source because of surface or subterranean captures due to neotectonic events, whereas normal or strike-slip faults acted as underground watersheds, rearranging water drainage pattern of carbonate massifs. Evidence of recent or active tectonic movements are observable in many caves as shear surfaces cutting a subterranean conduit. Sometime this is due to faulting, but mostly the movements are the effect of spreading by slope tectonics along pre-existing surfaces (bedding or joints).