Pliocene-Quaternary transpressional evolution of the Anzi-Calvello and Northern S. Arcangelo basins (Basilicata, Southern Apennines, Italy) as a consequence of deep-seated fault reactivation

In this paper we report the results of a study of the Plio-Pleistocene Anzi -Calvello Basin and the northern sector of the S. Arcangelo Basin (Southern Apennines, Italy). Our work suggests that the evolution of the Anzi-Calvel lo Basin is related to the activity of a deep-seated, roughly NNE-trending, dextral transpressional fault zone ("Camastra Transcurrent Fault Zone", CT FZ). Structural control of sedimentation by this structure is indicated by the geometry of the unconformity-bounded stratigraphic units as well as by the deformation of the basin fill. En-echelon N-S-trending thrusts, N- to N E-trending dextral transpressional faults, and NW- to NNW-striking folds af fecting the substratum, constitute the surface response to lateral displace ment along the CTFZ. The S. Arcangelo Basin is bounded to the north by a de ep-seated, roughly WNW/NW-trending, sinistral transpressional structure ("V alsinni Lateral Ramp", VLR) that terminates northwestward against the CTFZ. At the surface, the VLR is dominated by back thrusts and by transpressiona l fault zones. The VLR has been interpreted as the sinistral lateral ramp o f the large-scale Valsinni thrust anticline and it is inferred to have stro ngly controlled local deposition within the S. Arcangelo Basin. The deep-seated structures (CTFZ and VLR) probably represent reactivated pr e-existing normal and transfer faults affecting the rigid Apulian Platform that were generated during passive margin evolution, as well as during the flexural bending of the Apulian lithosphere. During the Pliocene-Pleistocen e, these structures were reactivated as lateral ramps accommodating the thr usting within the Apulian Platform. Transpression along the lateral ramps i n the Apulian Platform propagated upwards through the nappe pile, giving ri se to a complex surface structural pattern and the local development of flo wer-like structures. (C) 2000 Elsevier Science Ltd. All rights reserved.