THE LONG SEDIMENTARY SUCCESSION OF THE VALLE GIUMENTINA BASIN (ABRUZZO, CENTRAL ITALY): NEW EVIDENCE FROM STRATIGRAPHIC STUDIES AND ELECTRICAL RESISTIVITY TOMOGRAPHY (ERT)

Abstract

We carried out a multidisciplinary study on the sedimentary succession of Valle Giumentina, a small intermountain basin located in the Central Apennine. Studied in the 1950s, this 70 m-thick succession, including nine Palaeolithic occupation layers, was considered to be of Rissian and Würmian age. However, recent 40Ar/39Ar geochronological and tephrochronological investigations constrained the sedimentary history of the whole succession to the MIS 15-MIS 12 interval (Villa et al. 2016). Geophysical investigations (Electrical Resistivity Tomography) allow detecting the contact between bedrock and Quaternary infilling of the basin. No master fault was identified along the flank of the basin, suggesting that tectonics played a marginal role in the formation and evolution of the basin. Indeed, the basin sedimentary processes appear to be mainly climate-driven, with the deposition of glacio-fluvial sediments during colder glacial periods of MIS 14 and MIS 12 and alluvial sedimentation and/or pedogenesis processes active during warmer interglacial (MIS 15 and MIS 13) and interstadial phases (during MIS 12). Based on the available chronological data, the capture of the basin by a tributary stream of the San Bartolomeo canyon and its definitive extinction, occurred in MIS 12 glacial; i.e., when the uplift of the Apennine chain induced the reorganisation of the regional drainage system and the capture of almost all the lakes hosted in the intermountain basins.