ASPETTI MORFOTETTONICI DELL’EVOLUZIONE GEOMORFOLOGICA DELLA VALLE DEL MELANDRO (APPENNINO CAMPANO-LUCANO)

Abstract

C. Martino & M. Schiattarella, Morphotectonics and Quaternary geomorphological evolution of the Melandro Valley,
southern Apennines, Italy. (IT ISSN 0394-3356, 2006).
The target of this study is to furnish new data on the morphotectonic setting of a key-area of the southern Italian Apennines, the valley
of Melandro River, by means of both geomorphological and structural analyses. Further, a fruitful attempt of morphostratigraphic cor- relation of several orders of sub-horizontal land surfaces and flat summit landscapes with other similar geomorphic features on a regional scale has been done. The age attribution of such features to sufficiently constrained Pliocene and Pleistocene time intervals
allowed the calculation of the regional and local uplift rates and the reconstruction of the morphotectonic history of the study area. The Melandro River basin is a tectonic depression located in the axial zone of the south-Apennines chain, a fold-and-thrust belt strongly uplifted and fragmented by neotectonics and therefore characterized by many Quaternary longitudinal and transversal morphostructural depressions.
The uplift rates have been estimated using geomorphological, stratigraphical and structural data. Geomorphic data consist essentially
of elevation values, ages and arrangement of erosional gently dipping land surfaces and other morphotectonic indicators. The morphostructural evolution of the Melandro River basin is characterized by stages of uplift alternated with slack periods in which the erosional surfaces developed. In particular, four generations of land surfaces have been detected on the basis of both field survey and map analysis. The age of these surfaces have been defined on the basis of morphostratigraphic relationships with the Pliocene and
Quaternary deposits. Specifically, the oldest surface was sculptured also in the marine Pliocene deposits whereas the intermediate surface cuts the continental lower Pleistocene sediments filling the main depression. The youngest surface is late Pleistocene in age, as verified for similar terraces in adjacent areas. The uplift rates have been calculated on the basis of the difference in height between the absolute (sea level) or local (present-day talweg) erosion base levels and the several generations of land surfaces. Further, in this study we also calculated the stage (or partitioned) uplift on the basis of the difference in height between a given order of land surfaces and that immediately younger, aiming to consider the behaviour trend in specific time intervals. The trend of stage uplift is characterized by two increments: the first during the upper part of the early Pleistocene and the second during the late Pleistocene.
New data permitted us to restore the palaeomorphology of the different land surfaces and, by comparing them with present-day longitudinal stream profiles, to formulate suitable hypotheses on the genetic environments of these ancient erosional flat landscapes. In particular, the older surfaces seem to be generated at the sea level by marine erosion, whereas the younger ones show a continental origin, maybe related to cold periods of the Pleistocene, and were altered under warm-humid climatic conditions, as deduced from the presence of peculiar weathering fronts and as suggested by correlations with the global sea-level changes.