Tectonic and environmental evolution of Quaternary intramontane basins in Southern Apennines (Italy): insights from paleomagnetic and rock magnetic investigations

摘要

Southern Apennines is characterized by active extensional tectonics with NE–SW stretching\uddirection. The seismicity of the region is very well understood and continuously monitored. In\udcontrast, the onset of extensional tectonics is chronologically poorly constrained. The aim of\udthis study is that to give important constraints on the development of extensional regime and\udthe onset of the continental deposition during Quaternary in Southern Apennines.\udWe report the results of palaeomagnetic and rock magnetic analyses from four Quaternary\udsmall intramontane basins in the PicentiniMountains (Southern Apennines). The sedimentary\udsequences are located at different altitudes, from 600 to 1200 m a.s.l., and were deposited in\udfluvial-lacustrine environments. We sampled 29 sites in clays and lacustrine limestones from\udTizzano, Piano del Gaudo and Acerno basins and in red palaeosoils and matrix-supported\udconglomerates from the Iumaiano basins. In the clay and limestones samples magnetite,\udtitano-magnetite, hematite and iron-sulphide have been recognized as the main magnetic\udcarriers, whereas magnetite and hematite characterize the Iumaiano conglomerates and red\udsoils. Palaeomagnetic results have been integrated with published radiometric data in order to\udconstrain the age of each sedimentary basins. Sites from the Iumaiano basin, which represents\udthe substrate of the Tizzano and Piano del Gaudo basins, show a reverse polarity and therefore\udhave been attributed to the lower Matuyama chron. In contrast, palaeomagnetic data from\udTizzano basin show a transition from reversed to normal polarity along the exposed section,\udwhich has been interpreted as the Matuyama/Brunhes transition. Sites from Acerno and Piano\uddel Gaudo basins show a normal polarity, which, according to radiometric and pollen data,\udhave been correlated to the Brunhes epoch. On the base of such results we discuss the tectonostratigraphic\udevolution of the basins and the role of extensional tectonics in this portion of the\udSouthern Apennine during the Quaternary.