Long- to short-term denudation rates in the southern Apennines: geomorphological markers and chronological constraints

Abstract

Age constraints of geomorphological markers and consequent estimates of long-to short-term denudation rates from southern Italy are given here. Geomorphic analysis of the valley of the Tanagro River combined with apatite fission track data and radiometric dating provided useful information on the ages and evolution of some significant morphotectonic markers such as regional planated landscapes, erosional land surfaces and fluvial terraces. Reconstruction of paleotopography and estimation of the eroded volumes were perfomed starting from the plano-altimetric distribution of several orders of erosional land surfaces surveyed in the study area. Additional data about denudation rates related to the recent and/or active geomorphological system have been obtained by estimating the amount of suspended sediment yield at the outlet of some catchments using empirical relationships based on the hierarchical arrangement of the drainage network. Denudation rates obtained through these methods have been compared with the sedimentation rates calculated for two adjacent basins (the Pantano di San Gregorio and the Vallo di Diano), on the basis of published tephrochronological constraints. These rates have also been compared with those calculated for the historical sediment accumulation in a small catchment located to the north of the study area, with long-term exhumation data from thermochronometry, and with uplift rates from the study area. Long-and short-term denudation rates are included between 0.1 and 0.2 mm/yr, in good agreement with regional data and long-term sedimentation rates from the Vallo di Diano and the Pantano di San Gregorio Magno basins. On the other hand, higher values of exhumation rates from thermochronometry suggest the existence of past erosional processes faster than the recent and present-day exogenic dismantling. Finally, the comparison between uplift and denudation rates indicates that the fluvial erosion did not match the tectonic uplift during the Quaternary in this sector of the chain. The axial zone of the southern Apennines should therefore be regarded as a landscape in conditions of geomorphological disequilibrium.

Long-term geomorphological evolution of the axial zone of the Campania-Lucania Apennine, southern Italy: a review

“…As above reported, apatite fission-track data from rocks belonging to different tectonic units of the axial zone of the southern Apennines Mazzoli et al 2008) indicate a concordant final cooling age of ca 2.5-2.6 Ma (average value, Gioia et al 2011a;Schiattarella et al 2013), suggesting a widespread exhumation during the Late Pliocene. Since apatite passed the closure temperature isotherm at about 2.5 Ma, a considerable (~2 km) exhumation/denudation was needed to reach the surface.…”

“…Relative and absolute dating of the summit palaeosurface indicated that it developed in the Late Pliocene, but the planation process was still active during the Early Pleistocene (Gioia et al 2011a;Schiattarella et al 2013). The morphological de-activation of a land surface is achieved when it undergoes to a significant tectonic hanging and acquires the condition of relict landform.…”

Denudation processes and landforms map of the Camastra River catchment (Basilicata – South Italy)

“…This complex geological framework accounts for the presence of a variety of lithologies, different in age, composition and lithotechnical properties. Taking into consideration the geological map of Bonardi et al (1988) The geomorphological setting of the study area is strongly controlled by geological and structural conditions (Gioia, Martino, & Schiattarella, 2011). In fact, the distribution of the lithological units, with respective geotechnical properties, influence the slope dynamics and the nature of the geomorphic processes.…”

Age constraints and denudation rate of a multistage fault line scarp: an example from Southern Italy

“…4), representing a remnant of a regional planation surface, late Pliocene -early Pleistocene in age (Schiattarella et al, 2003Boenzi et al, 2004;Gioia et al, 2011).…”

“…8b) and the reworking of the pre-existing upper Pliocene -lower Pleistocene summit land surface (palaeosurface or "Paleosuperficie" Auctt., S1 after Schiattarella et al, 2003, cf. age constrain in Gioia et al, 2011); -third stage: both the regional uplift at about 1.2 Ma ("Emilian" tectonic stage, cf. Ruggieri et al, 1984), responsible for the displacement of the palaeosurface, and the instauration of a humid climate regime, favouring the fluvial erosion, promoted the vertical incision by streams of the morpho-structural low previously created; successively, the lateral planation of the valley in a steady-state fluvial condition, produced an erosional glacis in the shaly Lagonegro-type units of the downthrown block (Fig.…”