Inversion structures in a foreland domain: Seismic examples from the Italian Adriatic Sea

Abstract

Positive structural inversion within foreland domains ahead of thrust belts can create structures with significant hydrocarbon potential in mature and underexplored areas. Within this context, the Adriatic region represents a well-established hydrocarbon province constituting a foreland domain bounded by the Apennines, Southern Alps, and Dinaric fold-and-thrust belts. Newly reprocessed regional 2D seismic data and a renewed exploration interest in the area motivate a reappraisal of the regional structure and stratigraphy of the deformed Central Adriatic region of Italy (i.e., the Mid-Adriatic Ridge). Here, we developed and discussed examples of inversion structures that have different structural styles. The structural interpretations displayed on time-to-depth converted profiles had been validated by 2D structural-kinematic balancing and forward modeling. Our aim was to better define the geometry, style, and timing of the analyzed inversion-related folds. Positive inversion structures appeared locally as asymmetric harpoon-shaped anticlines riding over high-angle blind thrusts. More commonly, inversion structures were symmetric anticlines formed above conjugate faults. Retrodeformed cross sections showed that positive inversion involved symmetric graben and asymmetric half-graben that originated during the Triassic and Jurassic. That these inversion structures developed during basement-involved thrusting, as suggested for the Adriatic in general, was consistent with forward modeling. Regionally, the contractional structures belonging to the Mid-Adriatic Ridge can be explained in terms of intraplate deformation that chiefly acted through reactivation of Mesozoic normal faults.