Geomorphic constraints on uplift history in the Aspromonte Massif, southern Italy

Abstract

The landscape morphology of the Aspromonte Massif, southern Italy, shows hanging low-relief surfaces that correlate with uplifted landsurfaces which are preserved all around the massif. The drainage network has deeply incised the high-standing low-relief landscapes, seen here as being the remnants of phases of relief smoothing prior to strong uplift that has affected the area since the Middle Pleistocene. GIS-aided estimation of the rock volumes eroded since the late Early Pleistocene indicate high variability in denudation rates between the gently rolling landscapes and the river valleys. In this framework, longitudinal river profiles are examined for 42 river channels to constrain multiple non-equilibrium conditions and to reconstruct the long-term uplift history of the massif. Most profiles consist of three/four segments separated by knickpoints and suggest a complex incision pattern. Longitudinal profiles reveal two upper, low gradient channel segments, a zone of steep channels further down the low relief landsurface margin, and a very steep lower channel segment, particularly in the western quadrant. Upper channel segments correspond to the Relict Landscape (RLandscape – a high-standing landsurface on top of the massif) and the Hanging Landscape (HLandscape – a landsurface surrounding the RLandscape), respectively. Steeper middle and lower segments are the result of two-phase river incision that is linked to changes in regional uplift rates, and, subordinately, to rock strength properties. Indeed, analysis of river longitudinal profiles could indicate, initially, relatively slow Aspromonte uplift during the early Pleistocene and, then, pulses of rapid uplift during the Middle-Late Pleistocene. Multi-segment river longitudinal profiles are, therefore, evidence of the transient landscapes of Aspromonte in response to pulsed massif uplift.