GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.1 GNGTS 2023 This work investigates a small-scale lacustrine basin ( Fig. 1B and 1C ) in the upper Nure Valley drainage system, dominated by the ophiolitic substrate the Mt. Ragola massif (1712 m a.s.l.) and strongly deformed clayey complexes belonging to Ligurides Auctt .. A multidisciplinary approach (i.e., analysis of historical archives, geophysical surveys, geognostic soundings, radiocarbon dating, geological and geomorphological mapping) was applied to reconstruct the tectonic-climatic evolution of this sector of the northern Apennines during the Holocene. Fig. 1 (A) Tectonic sketch map and geological cross-section of the Northern Apennines with location of the study area (red box). The main structural landforms and topographic lineament recognized in the lake Moo plain extracted from (B) high-resolution orthophotography and (C) DEM, respectively. Modified from Segadelli et al. (2022). In particular, this study allowed us to confute the glacial origin classically proposed for this lacustrine basin, instead revealing that a combination of relatively recent sedimentary, gravitational, and (neo)tectonic processes played a major role in the morphological reshaping of the study area. The resultant physiographic scenario, which is preconditioned by the subsurface geological architecture, is mainly driven by lithological/mechanical contrast and reworking/reactivation of inherited structures. In the last 10 Kyrs, three main processes were responsible for the morphological reshaping of the area (Fig. 2): (1) A deep-seated slope gravity deformation started between 9672-9501 B.P., that subsequently continued during the Holocene Climatic Optimum due to tectonic uplift, unroofing, and lateral valley unloading; (2) The recent activity of a fault system, which post-dates the deep-seated gravity movement, that seems to be related to the reactivation of previous tectonic structures, responsible for the segmentation and lateral compartmentalization of the deep-seated gravity movement;