This work deals with an integrated geomorphological and chemical–physical study of “calanchi” landforms intwo sites (Ottosalme and Catalfimo) of NW Sicily (southern Italy), developed on dominant silty-clay deposits.The calanchi fronts are characterized by different morphological features and dominant geomorphic processes.Sharp knife-edged ridges and concentrated water runoff dominate at Ottosalme, and smoother landformsaffected by mass movements (mud flows and translational slides) prevail at Catalfimo. We focused on somegeochemical and physical parameters such as pH, total dissolved salts, sodium adsorption ratio (SAR), porosity,plastic and liquid limits as possible causes of the above differences, with special emphasis on their role indiscriminating the behavior of peculiar microforms, such as a weathered outer crust and the correspondinginner massive portion (unweathered substrate). Our results show that the main chemical–physical featuresof calanchi morphologies and microforms often display no clear correlations with respect to those reportedin the existing literature, pointing to a higher complexity of patterns and behaviors. In particular, all samplesconsist of dispersive material (SAR values>10), but a more plastic and liquid behavior at Catalfimo can explaina higher occurrence of landslides and smoother morphology than at Ottosalme. Higher SAR values atOttosalme well explain the dominance of concentrated water erosion. The chemical behavior of the studiedmicroforms is better described by pH being alkaline with higher values in the inner substrate than theouter crust, and appears to minimize the effects of all other parameters and their responses to other externalcontrolling factors. Lower SAR values in the crust suggest that clay dispersivity is not the prominent factorcontrolling its surface detachment and mobility downslope, which is more likely promoted by its higher porosityand consequent water absorption than the inner portion, with changes in the saturation state, shearstrength and water pressure.
|Numero di pagine||13|
|Stato di pubblicazione||Published - 2012|
All Science Journal Classification (ASJC) codes
- Earth-Surface Processes