Polyphase extensional basins: interplay between tectonics and sedimentation in the Neogene Siena-Radicofani Basin (Northern Apennines, Italy)

Abstract Rift-basins are the shallow effects of lithosphere-scale extensional processes often producing polyphase faulting. Their sedimentary evolution depends on mutual interplay between tectonics, climate, and eustasy. Estimating role each factor is generally a challenging issue. This paper focused tectono-sedimentary Neogene Siena-Radicofani Basin, structural depression located in inner Northern Apennines. Since Miocene, this basin developed after prolonged first as bowl-shaped depression, later reorganized into half-graben structure due to activation high-angle normal faults Zanclean. At that time contained coeval continental marine settings controlled by faulting caused development local coarse-grained depositional systems. These were investigated to: (i) discriminate influences tectonics climate sedimentation patterns, (ii) provide detailed constraints fault activity. The analysed successions deposited an interval 5.08 4.52 Ma, when climate-induced highstand phase occurred throughout Mediterranean. However, evidence relative sea-level drops registered record, associated with increased accommodation space sediment supply. Such base-level fluctuations not connected changes, suggesting control along margins.