Southern Apennines: structural setting and tectonic evolution

Davide Scrocca

The Southern Apennines thrust belt, a roughly NW-SE oriented segment of the Apennines, is located in the hanging wall of a W-directed and E-retreating subduction of the Apulo-Adriatic lithosphere. The accretionary prism migrated from west to east since the Early Miocene being followed by coeval extensional tectonics which, progressively, cross-cut the thrust-sheets.

The development of the Southern Apennines accretionary prism occurred through the off-scraping and incorporation at the subduction zone of the Meso-Cenozoic passive margin sedimentary covers, which overlay the subducted Apulo-Adriatic crystalline basement, and the associated foredeep deposits.

Beneath the mountain chain the Apulian platform shallow water carbonates are deformed to shape a buried antiformal stack, whose structure at depth is poorly constrained by the available data. As a consequence, both thick- and thin-skinned models have been proposed. In these contrasting models significant differences regard: i) the shortening in the accretionary prism (particularly within the buried Apulian thrust units), and ii) the degree of involvement of the lower plate basement (i.e., the Apulian crystalline basement).

However, although it remains possible that the upper few kilometres of the Apulian basement could have been involved in thrusting, an integrated analysis of documented tectonic, geophysical and geochemical features shows that the thin-skinned model is generally more consistent with the available data.

In the preferred thin-skinned model, the total shortening of the allochthonous units (i.e., Apennine and Apulian Carbonate platforms and Lagonegro basin) is estimated to be greater than 280-300 km, while about 90 km of shortening can be attributed to the Apulian thrust units.