Geology of the late Miocene south-eastern Volterra Basin (Northern Apennines, Italy)

We present a 1:10,000 scale geological map for the south-eastern sector of the Volterra Basin (Northern Apennines, Italy), together with supporting stratigraphic-structural data. The Volterra Basin consists of a major structural depression within the Northern Apennines hinterland, NNW-SSE-oriented and filled with more than 2000 m of late Miocene-Quaternary deposits. Its south-eastern sector is classically considered as a type area for late Tortonian non-marine strata, here mapped and refined in terms of internal stratigraphy adopting a scheme of depositional and lithostratigraphic units. Stratigraphic assessments helped in redefining the character of the lower boundary of the non-marine succession, as well as in mapping a newly recognized angular unconformity. Deformation structures affecting the basin fill include blind normal faults rooted to a deep detachment, outcrop-scale transtensional faults and clusters of gentle folds. Faults and folds appear to be kinematically linked. Our structural observations largely agree with those present in the literature, supporting a model of post-orogenic crustal stretching.