The funding provided for the mapping of sheet no. 310 ‘Nocera Umbra’ of the geological map of Italy on 1:50.000 scale, enabled the execution of a 60 m deep borehole (Plestia1) aimed at characterising the filling deposits of the depocentral area of the Colfiorito basin, an intermontane tectonic depression filled during the Quaternary by continental deposits. The stratigraphic sequence in this basin was unknown and the activity of the border fault that must have developed it is debated. The sediments were examined using a multidisciplinary approach, through lithostratigraphic, paleomagnetic, palynological, petrological and micro-paleontological analyses. The entire sequence analysed consists of fine sediments, silts and clays from a lacustrine environment. These sediments showed stable magnetization, characterised by normal magnetic polarity. Pollen analyses have highlighted vegetation development attributable to climatic fluctuations corresponding to MIS 5d - MIS 2. Petrological analyses highlighted the presence of two volcanic tephra. The first is located at a depth of 58.67 m and corresponds to a Flegrean eruption occurred 109.3 ± 1.0 ka. The second is located at a depth of 38.80 m and could correspond to the eruptive phase of the Lazio volcanic complex (87.6 - 85.06 ka). Micro-palaeontological analyses focused on the distribution of ostracods. A radiocarbon dating to ostracod shells extracted from sediments at a depth of 8.90 m yielded an age of 26103 ± 215 cal BP. The analyses carried out provided evidence to associate the sequence crossed by the Plestia1 borehole with the Late Pleistocene. The Colfiorito basin must have experienced an average subsidence of approximately 0.6 mm/year during the last 110 ka. Examined the recent seismic crisis of 1997-98 that affected this area, it is possible to associate the Colfiorito basin's border fault with a steadily activity from the Late Pleistocene to the present day.
Stratigraphic and morphotectonic advances in the Colfiorito basin (Umbria-Marche Apennines) from the new Plestia1 borehole / Silvani, F., Di Rita, F., Magri, D., Uda, L., Spadoni, G., Monaco, L., Giaccio, B., Mazzini, I., Porreca, M., Mirabella, F., Melelli, L., Pazzaglia, F., Barchi Massimiliano, R.. - (2026). (Lotti 2026: cento anni di ricerche geologiche in Umbria Spoleto, Umbria ).
Stratigraphic and morphotectonic advances in the Colfiorito basin (Umbria-Marche Apennines) from the new Plestia1 borehole
Di Rita Federico;Magri Donatella;Uda Lorenzo;Spadoni Giorgia;Mazzini Ilaria;
2026
Abstract
The funding provided for the mapping of sheet no. 310 ‘Nocera Umbra’ of the geological map of Italy on 1:50.000 scale, enabled the execution of a 60 m deep borehole (Plestia1) aimed at characterising the filling deposits of the depocentral area of the Colfiorito basin, an intermontane tectonic depression filled during the Quaternary by continental deposits. The stratigraphic sequence in this basin was unknown and the activity of the border fault that must have developed it is debated. The sediments were examined using a multidisciplinary approach, through lithostratigraphic, paleomagnetic, palynological, petrological and micro-paleontological analyses. The entire sequence analysed consists of fine sediments, silts and clays from a lacustrine environment. These sediments showed stable magnetization, characterised by normal magnetic polarity. Pollen analyses have highlighted vegetation development attributable to climatic fluctuations corresponding to MIS 5d - MIS 2. Petrological analyses highlighted the presence of two volcanic tephra. The first is located at a depth of 58.67 m and corresponds to a Flegrean eruption occurred 109.3 ± 1.0 ka. The second is located at a depth of 38.80 m and could correspond to the eruptive phase of the Lazio volcanic complex (87.6 - 85.06 ka). Micro-palaeontological analyses focused on the distribution of ostracods. A radiocarbon dating to ostracod shells extracted from sediments at a depth of 8.90 m yielded an age of 26103 ± 215 cal BP. The analyses carried out provided evidence to associate the sequence crossed by the Plestia1 borehole with the Late Pleistocene. The Colfiorito basin must have experienced an average subsidence of approximately 0.6 mm/year during the last 110 ka. Examined the recent seismic crisis of 1997-98 that affected this area, it is possible to associate the Colfiorito basin's border fault with a steadily activity from the Late Pleistocene to the present day.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
