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The reconstruction of the thermal history of folded and thrust units is crucial to define the pattern of tectonic loading and the time-space evolution of an orogen where tectonic exhumation processes occurred at shallow crustal levels. In the present study, a well-constrained reconstruction of the thermal maturity in the axial zone of the southern Apennines has been achieved by the combined use of different thermal indicators in diagenesis. The major results are: (i) documentation of a jump in thermal maturity from the Apenninic Platform derived tectonic unit (from immature to early mature stages of hydrocarbon maturation) to the Lagonegro Basin derived tectonic units (late diagenetic zone); (ii) documentation of along-strike slighter variations in the Lagonegro units, concerning thermal maturity (thus maximum burial temperatures). This can be related to changes in amounts of tectonic burial and erosion/exhumation because of the lack of cylindricity of contractional structures; (iii) recognition of an independent thermal evolution of the allochthonous chain compared with the Apulian Platform tectonic unit with Mt Alpi area (in the late mature stage of hydrocarbon generation) interpreted as a sector of localized, intense exhumation within the External Zone of the orogen.Terra Nova, 17, 56–65, 2005 [ABSTRACT FROM AUTHOR]

Abstract: Several tectonic processes have been proposed to be important in the Alpine to the recent evolution of the Polish Outer Carpathians, i.e., Paleogene–Neogene thrusting, post-thrusting extension, Quaternary reactivation of compression. This work tests the effect of these processes on exhumation of the wedge, in order to verify their timing and relative role in shaping the Polish Outer Carpathians. AFT, AHe and ZHe analyses were performed on samples collected along the study region. This allowed the reconstruction of their post-depositional minimum heating, depth of burial and timing of cooling and exhumation. After deposition samples from the innermost units were heated up to temperatures of ca. 60–120°C (ca. 4–9km), whereas samples from the outer units were heated to temperatures lower than 60°C (ca. 4km). Cooling and exhumation occurred progressively later from west to east (between ca. 25 and 10Ma in the western sector, between ca. 15 and 5Ma in the eastern sector). These results have been put in relationship with single structural features to understand the relative role of thrusts and normal faults. In the eastern sector of the study region samples at the footwall of significant normal faults show a higher degree of reset and younger ages than samples located at the hangingwall. This implies that, in this sector, extensional tectonics played an important role in exhumation. However, proper tectonic exhumation only had a minor role, the major exhumation mechanism being erosion, which is enhanced in the footwalls and reduced in the hangingwalls. In the western sector of the Polish Outer Carpathians only in few cases evidence of enhanced erosion to the footwall of major normal faults could be observed based on the present data. In this region the wedge exhumed mainly as a response to thrusting and normal faulting only played a minor role, locally modifying the pattern of erosion. Finally no major exhumation events occurred after Miocene, pointing to a minor relevance of recent compression. Unreset ZHe dates were used to estimate exhumation of source rocks through the ZHe PRZ and to outline the provenance of sediments forming the Polish Outer Carpathians. Exhumation occurred both in response to the Variscan (Late Devonian to Triassic) and Alpine (Late Jurassic to Early Paleocene) orogeneses, suggesting sedimentary provenance both from the southern margin and from the basement heights within the Outer Carpathian basin. [Copyright &y& Elsevier]

Unraveling the deformation pattern characterizing the transition from final oceanic subduction stages to early stages of deformation of a foreland continental margin is crucial for a better understanding of the geodynamic processes taking place at convergent plate boundaries. In particular, the combined role of internal wedge dynamics and continental-margin architecture in controlling the tectonic evolution of an accretionary complex during its final emplacement onto the foreland continent is discussed in this study. To this purpose, we conducted integrated structural, stratigraphic, and low-temperature thermochronometric analyses on the Ligurian accretionary complex units exposed in the Campania region (Italy) and on continental-margin successions located in their footwall, as well as on related foredeep and wedge-top basin deposits. Our results point out a series of late early Miocene (Burdigalian) shortening events, also involving buttressing of the accretionary wedge against the crustal ramp of the foreland continental margin. Emplacement of the overthickened accretionary complex onto the distal part of the continental margin was followed by horizontal extension and wedge thinning, aiding the development of wedge-top depocenters. Extension may have been either related to reduced subduction rates during the middle Miocene, or to a period of subduction erosion (known to have occurred in the Northern Apennines in the same time frame). Early Miocene NW-SE shortening recorded by Ligurian accretionary complex units was completely unrelated to later (late Miocene to Pleistocene) NE-directed thrusting in the Apennines, which was coeval with backarc extension in the Tyrrhenian Sea. Therefore, our results emphasize the occurrence of a major discontinuity in the Neogene geodynamic evolution of the Southern Apennines, the tectonic history of which may be clearly subdivided, from a kinematic point of view, into pre- and syn-Tyrrhenian backarc extension stages. [ABSTRACT FROM AUTHOR]