Unsteady base-level fall at river mouths generates knickpoints that migrate as a transient upstream through the drainage network, climbing at the same rate as long as the fluvial erosion process follows a detachment-limited stream power law. Here we demonstrate unsteady and nonuniform rock uplift using knickpoints as geomorphic markers in streams draining the eastern flank of the Peloritani Mountains (northeast Sicily), the footwall of an ~40-km-long offshore northeast-southwest-oriented normal fault where the uplift is documented by a flight of mapped and dated Pleistocene marine terraces. Using slope-area analysis on the major streams, we project the tops of prominent knickpoints down to the coast, intersecting the marine terraces, thus providing an age for that specific knickpoint and the paleo-longitudinal profile. We model the migration rate of those dated knickpoints to locally solve for the parameters in the detachment-limited stream power law, and apply the results to model the age of other knickpoints with no clear connection to marine terraces. In summary, we demonstrate that the eastern Peloritani Mountains have been nonuniformly uplifted in an along-strike elliptical pattern, consistent with the general model for the footwall of an active normal fault. A calculation of the long-term erosion rate by the volume beneath the dated paleo-longitudinal profiles reveals a tight positive nonlinear relationship with the modeled normalized channel steepness (k sn). Our analysis provides a method for using knickpoints as geomorphic markers in steep, rapidly eroding landscapes that commonly lack datable river terraces.
We here propose a new kinematic picture of central Sicily based on the results of detailed field mapping of the region, combined with structural analyses and the interpretation of the available literature subsurface data. Our study focused on the tectonic boundary of a structural depression, the Caltanissetta Trough, which is now filled with allochthonous terrains resting on the deep-seated inverted African palaeomargin units. Our data refer to the tectonosedimentary evolution of the thrust-top basins, from Late Tortonian to Quaternary times. The study points out the occurrence of regional E–W-oriented dextral shear zones, cutting the NE-oriented trends of the thrust belt. This new evidence would confirm the major role of the E–W trend in the tectonic inversion of the external portions of the Africa palaeomargin in Sicily. Our results could contribute to a better understanding of the location in Sicily of the tectonic lineaments accommodating the hundreds of kilometres of lateral displacement, caused by the Late Miocene–Quaternary Tyrrhenian Basin opening to the north of the island.
The tectonic setting of the Mediterranean basin features several convergent plate boundaries with small, highly arcuate subduction zones. Slabs in several of these subduction zones are rapidly rolling back (e.g., Doglioni, 1993), resulting in diverse kinematics of upper plate deformation, including paired compression and extensional fronts in overlying forearcs (Elter et al., 1975). The Calabrian Peninsula in southern Italy represents one such forearc where only the extensional domain is exposed above sea level today (D' Agostino et al., 2011;Tortorici et al., 1995). Calabria is widely thought to have rifted away from Sardinia 6 Ma, and rapidly translated eastward as the leading edge of a wave of the backarc extension that opened the
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