Nucleation of low-angle normal faults within the carbonates of the Lagonegro succession (Southern Apennines, Italy)

Low-Angle Normal Faults (LANF) consist of shallow dipping extensional faults, which form a mechanical paradox currently debated by researches. LANF are generally interpreted as either rotated pre-existing tectonic structures or large-scale landslides phenomena. In Southern Apennines, in several cases, LANF have been interpreted as thrust remnants or klippen, although several LANF have been documented by means of geological mapping and structural analysis (D'ARGENIO et alii, 1986; FERRANTI et alii, 1995, 1999; BUCCI et alii, 2009). In any case, the role of these structures, in the evolution of the apenninic chain, is still uncertain. In this note we present the preliminary result of a systematic structural analysis carried out along natural exposures, and some road cuts, along which the Calcari con Selce Fm. (Lagonegro succession) crops out. The study area is located close to the Pignola village, nearby the city of Potenza (Basilicata Region, Italy). The attitude of the planar elements is studied in relation to the attitude of bedding, in order to investigate their cut-off angles. Furthermore, we document the abutting and crosscutting relationship among the various sets of pressure solution seams, joints, sheared pressure solution seams and joints to decipher their relative timing of deformation and possible re-activation during burial, folding and extensional deformation. The work is aimed at gaining new data to understanding the mechanism of LANF nucleation within stratified and folded limestone rocks.