Estimating uplift of clay-filled extensional basins through the porosity-depth curve: the case of the Radicofani Basin (Italy)

Clayey Pliocene sediments of Southern Tuscany represent one of the best examples to study the effects of compaction and erosion. Pliocene sediments were deposited through all Southern Tuscany producing piles of clastic deposits more than 1000 m thick. Since middle Pliocene all Southern Tuscany underwent uplift and erosion deeply affected these sediments. They are now preserved in tectonic depressions bounded by normal faults, such as the uplifted Pliocene Radicofani Basin. Here compressibility oedometric tests on undisturbed near surface samples have been performed in order to reconstruct the sedimentation and erosion paths in this basin. Results lead us to determine the void index-effective load relation (i.e. virgin curve) and the derived porosity-depth relation. Based on these data, the amount of erosion for the Radicofani Basin was estimated. Finally, the amount of uplift was computed considering the depth of sedimentation, the topographic data and the amount of erosion. The total uplift in the basin, ranges between 0.8 and 2 km in the eastern and western sides, respectively. This differential uplift did not significantly modify the structural features of the basin.