Modificazioni geomorfiche controllate dalla deposizione di travertino

Abstract

Travertines are freshwaters-deposited carbonate rocks that form self-regulating systems able to modify the morphological features of their depositional sites. Travertine deposition is controlled by the complex interaction among physical, chemical and biological factors, and by the environmental modifications resulting from sedimentation. Ultimately, travertine sedimentary organization is controlled by continued feed-back loops among processes and products which increase the complexity of depositional system over time. Geomorphic modifications controlled by travertines are manly due to early lithification and rapid upward growth characterizing these deposits. Owing to these features travertine deposition transforms original slopes into gently inclined flat areas (travertine terraces) limited downhill by steeper slopes, eventually evolving into subverticai escarpments. The latter, which may simulate erosionai terraces, develop as the process of encrustation significantly decreases downcurrent, and do not correlate with the lowering of base level. Travertine systems may develop either along longitudinal profiles of rivers, laterally constrained by steep-sided valleys (Barrage Travertine Systems), transforming the river into a series of lakes connected by waterfalls (e. g. Plitvice, Croatia) or downstream along slopes (Slope Travertine Systems). These latter form wedge-shaped sedimentary bodies with thickest accumulation downstream, transforming the original water flow into a system of suspended channels and ponds, which eventually evolve into very shallow lakes behind waterfalls (e. g. Rocchetta-al-Volturno, Volturno River Spring).