Transition from slab roll-back to slab break-off in the central Apennines, Italy: Constraints from the stratigraphic and thermochronologic record

Stratigraphic and thermochronologic data are used to study the processes that shaped the topography of the central Apennines of Italy. These are part of a major, active mountain belt in the center of the Mediterranean area, where several subduction zones control a complex topography. The Apennines were shaped by contraction at the front of the accretionary wedge overlying the subducting Adria microplate followed by extension at the wedge rear in response to eastward slab roll-back. In the central Apennines, intermontane extensional basins on the western flank rise eastward toward the summit. We contribute with new data consisting of 28 (U-Th-Sm)/He and 10 fission track ages on apatites to resolve a complex pattern of thermal histories in time and space, which we interpret as reflecting the transitional state of the orogen, undergoing a two-phase evolution related to initial slab retreat, followed by slab detachment. Along the Tyrrhenian coast, we document cooling from depths ≥3–4 km occurring between 8 and 5 Ma and related to the opening of marine extensional basins. Post–5 Ma, a broader region of the central Apennines exhibits cooling from variable depths, between
GSA Bulletin, 134 (7-8)
ISSN:0016-7606
ISSN:1943-2674