CARATTERI MORFOTETTONICI DELL’AREA DEL VALICO DI PRESTIERI E DEI MONTI DI LAURIA (APPENNINO MERIDIONALE)

Abstract

: D. Gioia & M. Schiattarella, Morphotectonics of the Valico di Prestieri area and adjacent Lauria Mts (southern
Appennines). (IT ISSN 0394-3356, 2006).
Lauria-Castelluccio Mountains, located to the west of the Mercure basin and separated by it from the Pollino Ridge, form a morphostructural high of the Calabria-Lucania border, southern Italy, made of Mesozoic shallow-water carbonates, whose evolution has been strongly controlled by Quaternary tectonics. To the south of the ridge, a 15 km-long narrow depression, named Valico di Prestieri, is filled by continental Pleistocene deposits organized in several sedimentary bodies.
In this paper, the stratigraphic and morphostructural picture of the Quaternary deposits and surrounding areas is widely discussed and, in the end, a reconstruction of Miocene to Pleistocene tectonic and morpho-evolutionary sequences is proposed. The original contractional structure – built on during late Miocene to Pliocene time-span – has been dismembered by Pleistocene strike-slip and normal faulting along a N120°- striking shear zone. Several episodes of both tectonic crisis and quiescence have been recognized. During the quiescence periods, sculpture of erosional land surfaces and deposition of sedimentary bodies with gently dipping tops (alluvial fans and flood), both related to the different past base levels of the trough, took place. The use of such features as morphotectonic markers – whose ages have been deduced by morphostratigraphic correlations with the close Mercure River and Sinni River basins – allowed the estimation of the regional and local uplift rates and the calculation of the slip rates of the main high-angle faults. Regional uplift rates are settled on a value of about 1 mm/yr, whereas the local rates are nearly coincident with the magnitude of the fault slip rates, reaching the highest values (about 0,5-0,6 mm/yr) at the passage between early and middle Pleistocene, in correspondence of the beginning of the extensional tectonics with NE-SW oriented tensile axis.
The amount of Quaternary denudation due to fluvial erosion, calculated on the base of bedrock incision rates, is clearly less than tectonic burial (several km) suffered by the Mesozoic formations of the Lauria Mts and surrounding areas. Therefore, it is necessary to invoke alternative mechanisms of exhumation, such as tectonic erosion or denudation, that may adequately justify also the presence of lowangle normal or oblique faults, surveyed at Mt. La Spina and Mt. Zaccana and probably Pliocene in age.