A Geomorphic Examination of the Calabrian Forearc Translation

Abstract

AbstractThe 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.