Tectonically driven exhumation of a young orogen: An example from the southern Apennines, Italy

Abstract

In many young orogens of the Mediterranean region, Quaternary tectonics and regional uplift are traditionally considered strictly correlated, but few data are actually available for precise calculations of uplift rates. Such quantitative studies are needed to define the relationships between local faulting and large-scale uplift, and to formulate correct hypotheses on the geodynamic scenario in which the regional raising occurred. In addition, data about burial depths of sediments or tectonic loadings suffered by sedimentary and low-grade metamorphic rocks are essential for comparisons with the uplift rates obtained in the same areas. Such comparisons between quite different data sources improve the comprehension and choice of the most reliable mechanism responsible for the regional uplift and exhumation. Uplift rates have been calculated for a large sector of the Lucanian Apennine (axial zone of the southern Italian Apennines), and also reviewed for the Calabrian arc (southern termination of the Italian peninsula), using both geomorphological observations (elevation values, ages, and arrangement of depositional and erosional land surfaces and other morphotectonic indicators) and stratigraphical and structural data (sea-level related facies, base levels, fault kinematics, and offset estimations). Such data have been compared with those derived from clay mineralogy of Mesozoic pelagic deposits (Lagonegro units), outcropping in the same sector of the chain, which give information on burial depths. The values of the Quaternary uplift rates of the southern Apennines axial zone vary from a minimum of 0.2 mm/yr near the town of Potenza to a maximum of ~1.2-1.3 mm/yr in Agri high valley, a severely deformed Quaternary intermontane basin, still tectonically active, in the Pollino Mountains, a carbonate ridge with elevation up to 2200 m above sea level (asl); intermediate values (0.5–0.7 mm/yr) have been calculated for the other studied areas. The erosion rate from a key area of the Lucanian Apennine, obtained from both quantitative geomorphic analysis and missing volumes calculations on a catchment basin as wide as 150 km2, has been estimated at 0.2 mm/yr for the middle Pleistocene to Holocene time span. Since in the upper part of that chronological interval erosion and uplift rates match well, the axial-zone landscape could have reached a fl ux steady-state during the late Pleistocene. Using geomorphological features and late Pliocene to Pleistocene deposits involved in the genesis of erosional and depositional land surfaces, similar rates (≈0.6 mm/yr) have been obtained for a quite large time span (~2 m.y.) in the Melandro basin and adjacent Maddalena Mountains. Therefore, during the last 2 m.y., the total uplift amount of the axial zone of the Lucanian Apennine is ~1.2–1.3 km, with local peaks of 1.5 km. On the other hand, the Mesozoic pelagic units experienced tectonic loading\ud of 4–5 km, as estimated by means of illite crystallinity (in the range 0.6–1.1 Δ°2θ), percentage of illitic layers in illite/smectite mixed...

Quantitative analysis of InSAR digital elevation models for identification of areas with different tectonic activities in southern Italy

“…Starting from the middle Pleistocene, another relevant uplift event occurred (D'Argenio et al, 1986;Brancaccio et al, 1991;Schiattarella et al, 2003). During the late Pleistocene the chain was characterized by stability of the Tyrrhenian belt and uplift of the axial zone of the chain, foredeep basin and foreland area (Cosentino and Gliozzi, 1988;Westaway, 1993;Bordoni and Valensise, 1998;Schiattarella et al, 2003Schiattarella et al, , 2006.…”

“…The usefulness of palaeosurfaces as a geomorphological signature of uplift in the southern Italian Apennines has been a hot issue for geomorphologists, geophysicists and geologists in the last decade (Amato and Cinque, 1999;Basili et al, 1999;Schiattarella et al, 2003Schiattarella et al, , 2006Ascione et al, 2003;Amato et al, 2003). The recognition of areas with different tectonic activity could be useful to define a relationship between local faulting and large-scale uplift.…”

Geomorphological, mineralogical, and geochemical evidence of Pleistocene weathering conditions in the southern Italian Apennines

“…Several authors identified two main uplift stages in the Early Pleistocene, and another relevant event was marked by uplift that occurred in the Middle Pleistocene (D'Argenio et al 1986;Brancaccio et al 1991;Schiattarella et al 2003). Finally, in the Late Pleistocene the chain was characterized by stability of the Tyrrhenian belt and uplift of the axial zone of the chain, the foredeep basin, and the foreland area (Westaway 1993;Bordoni & Valensise 1998;Schiattarella et al 2003Schiattarella et al , 2006.…”

“…4) -kaolinite is only observed in correlated levels within the Galestri Formation, where it exhibits a high crystallinity, and is totally absent in analogously correlated levels within the Scisti Silicei Formation (Di Leo et al 2002;Schiattarella et al 2003Schiattarella et al , 2006) -suggest that a more intense weathering period has also contributed to the formation of these weathered horizons and that a change to climate conditions typical of a mainly warm/humid climate occurred (Fig. 9).…”

New morphostratigraphic and chronological constraints for the Quaternary paleosurfaces of the Molise Apennine (southern Italy)

“…Brancaccio et al 1988;Bosi et al 1996;Amato & Cinque 1999;Basili et al 1999;Coltorti & Pieruccini 2000;Bartolini et al 2003, D'Alessandro et al 2003Boenzi et al 2004;Gioia & Schiattarella 2006;Schiattarella et al 2006). These paleosurfaces represent the remnants of gentlyrolling ancient landscapes, generated by fluvio-denudational processes, which are preserved at different altitudes above the local base levels of erosion.…”