Geological conditioning in the occurrence and evolution of mass movements in the Fitz Roy River watershed, Santa Cruz province

Abstract

In the Torre glacier watershed and along the Fitz Roy River valley, Southern Patagonian Andes, there are several mass movements as a consequence of the continuous loss of glacial conditions. From geomorphological detail analyses, we identified the recent and past mass movements, interpreted their origin and estimated the age related to the retreat of the Torre glacier for, finally, proposed what conditioning and triggering factors caused these movements. Among the movements identified stands out a megalandslide, with approximately 115 million of m³, developed from the south slope of the valley. From the analysis, we interpreted a lithological-structural control as the main conditioning factor, attributing a probable seismic event, which occurred in the Pleistocene-Holocene, as the main triggering event. In addition, from the study of the identified mass movements, we evidenced the close relationship between the glacial retreat and its thinning, and activity of gravitational processes as a result of the relaxation of slopes. According to this, we revealed climate and geomorphological control as the main triggering factor in the development and initiation of these movements. Finally, understanding geomorphological evolution in this area is important for the future evaluation of the existing geological risks.