Search

How tectonic forcing, expressed as base level change, is encoded in the stratigraphic and geomorphic records of coupled source-to-sink systems remains uncertain. Using sedimentological, geochronological and geomorphic approaches, we describe the relationship between transient topographic change and sediment deposition for a low-storage system forced by rapid rock uplift. We present five new luminescence ages and two terrestrial cosmogenic nuclide paleo-erosion rates for the late Pleistocene Pagliara fan-delta complex and we model corresponding base level fall history and erosion of the source catchment located on the Ionian flank of the Peloritani Mountains (NE-Sicily, Italy). The Pagliara delta complex is part of the broader Messina Gravel-and-Sands lithostratigraphic unit that outcrops along the Peloritani coastal belt as extensional basins have been recently inverted by both normal faults and regional uplift at the Messina Straits. The deltas exposed at the mouth of the Pagliara River have constructional tops at ca. 300 m a.s.l. and onlap steeply east-dipping bedrock at the coast to thickness between ca. 100 and 200 m. Five infrared-stimulated luminescence (IRSL) ages collected from the delta range in age from ca. 327 to 208 ka and indicate a vertical long-term sediment accumulation rate as rapid as ca. 2.2 cm/yr during MIS 7. Two cosmogenic 10Be concentrations measured in samples of delta sediment indicate paleo-erosion rates during MIS 8-7 near or slightly higher than the modern rates of ca. 1 mm/yr. Linear inversion of Pagliara fluvial topography indicates an unsteady base level fall history in phase with eustasy that is superimposed on a longer, tectonically driven trend that doubled in rate from ca. 0.95 to 1.8 mm/yr in the past 150 ky. The combination of footwall uplift rate and eustasy determines the accommodation space history to trap the fan-deltas at the Peloritani coast in hanging wall basins, which are now inverted, uplifted and exposed hundreds of metres above the sea level. [ABSTRACT FROM AUTHOR]

The evolution of subduction forearcs as archived in the tectonic and geomorphic record serves to constrain geodynamic models of many convergent plate margins. This paper presents geomorphic stream channel metrics and river longitudinal profile modeling to assess geodynamic models describing the late Cenozoic horizontal translation of a Mediterranean forearc. The northern flank of Sicily is drained by roughly parallel north‐flowing streams arranged across the hypothesized west‐to‐east migration path of the Calabrian forearc high. These streams present a snapshot of current geomorphic processes driven by spatiotemporal variations in crustal deformation, including river incision and landscape steepness. A stream power rule‐based numerical modeling of the fluvial response time and knickpoint migration provides an independent prediction for the history of rock uplift associated with the translating forearc over the past ∼4 Myr. The results serve as a test for two, crustal wave versus transform‐fault, end‐member geodynamic models for the Calabrian forearc evolution, suggesting that our modeling supports the former. The river profile modeling shows that northern Sicily rivers experienced two pulses of time‐transgressive rock uplift that progressively sweeps west to east. This analysis suggests the most rapid contemporary rock uplift rates are focused in NE‐Sicily, where the forearc is currently located and where Pleistocene marine terraces indicate the highest rock uplift rates. These results are consistent with the west‐to‐east passage of a forearc high embedded in the subduction wedge, followed by a dynamic wave of rock uplift in its wake similar to what has been proposed for slab windows in other plate boundary settings. Key Points: River long‐profile inversions show that northern Sicily experienced two time‐transgressive base level falls since 4 MaThe base level fall pulses are related to the transit of the Calabrian forearc high during the opening of the Tyrrhenian BasinRelationships and feedbacks between tectonic forcing and geomorphic response are documented [ABSTRACT FROM AUTHOR]

During the Mw 4.9 earthquake of December 26, 2018, an 8 km long arc‐shaped coseismic fracture belt formed along the southeastern flank of Etna Volcano (Sicily, Italy). We performed prompt field mapping of the 2018 coseismic fracture field, integrated with structural measurements in about 600 sites. The fracture belt comprises a northern, 3‐km‐long N130° striking segment, and a southern, 5‐km‐long N150°–170° portion. Along the former segment our data document a dextral shear zone, geometrically and kinematically coherent with the focal mechanism of the earthquake and indicating N170‐oriented compression. This shear zone shows a distinctive ground signature affecting lava flows of different ages, suggesting progressive growth of the structure through repeated coseismic cycles. The coseismic strain migrated to the NNW‐oriented segment, along which the strike‐slip deformation changed into N100–120°‐trending extension. The deformation along this segment is derived from the reactivation of a Late Quaternary tectonic boundary separating two adjacent compressional and extensional domains. The overall coseismic deformation is the result of these two different kinematics, consistent with the long‐term dynamics of both adjacent domains. The growth rate of recent cumulative morphotectonic features along the remobilized NNW‐striking fault demonstrates that the structure is still deforming at a rate comparable to the long‐period estimate. Our study points out that the 2018 seismic event, even if triggered by volcano‐tectonic processes, represents the expression of the composite regional dynamics, which are well constrained by large scale geodetic data. Key Points: The study is based on field mapping of the 2018 Mount Etna coseismic fracture field and on 600 structural in situ measurementsWe compared the kinematics along the composite coseismic fracture belt to the Late Quaternary regional kinematicsThe seismic event is coherent with the active dynamics at the regional scale [ABSTRACT FROM AUTHOR]