An integrated Geological-Geophysical approach for recognizing the major tectono-stratigraphic units of the 350 – Penne Sheet (CARG Project)

The relaunch of the CARG Project has created new opportunities and challenges. One of the main objectives in the ongoing 350–Penne Sheet is to enhance our understanding of the tectono-stratigraphic evolution of the Mio-Pliocene Foreland Basin System in the Abruzzo Apennines. A key strategy to tackle this challenge involves detecting the primary tectono-stratigraphic units into which the basin has been divided during the Plio-Quaternary thrusting. To achieve this goal, we performed a 1:10.000 scale fieldwork in a key area located in the central portion of the Sheet. The survey aimed to assess the southward continuity of the successions of the Laga and Cellino Fms., described and mapped in the adjacent 339-Teramo Sheet. This preliminary investigation highlighted both analogies and differences, and led to the identification of new potential lithostratigraphic units, such as formations, facies associations and key-horizons. The geological map obtained reveals the internal structure of the major thrust sheets, although the precise locations of some thrust traces remain uncertain, due to the poor exposures. The turbiditic origin and compositional similarity of both Laga and Cellino Fms., make it challenging their distinction if based only on the lithostratigraphic criteria. It is important to note that, in this preliminary phase of the project, results from biostratigraphic and petrographic analyses are not yet available. We then attempted to differentiate the major thrust faults from the minor splays by integrating field data with subsurface investigation. In this context, the interpretation of publicly available seismic lines from the Vi.D.E.P.I. Project was a crucial resource. After calibrating the seismic data with three exploitation wells and integrating it with surface geological information, we gained insights that helped to pinpoint the likely location of the surface thrusts and proposed an initial subdivision of tectono-stratigraphic units. Although a complete subsurface model is not explicitly expected for the 350 Sheet, our work demonstrates how seismic interpretation can contribute to: i) identify the connections between buried structures and outcropping ones; (ii) highlight regional-scale master faults considering the associated amount of slip; and, (iii) support the surface interpretation of the main stratigraphic tops, especially where they display a clear seismostratigraphic evidence.