Detrital signatures of impending collision: The deep-water record of the Upper Cretaceous Bordighera Sandstone and its basal complex (Ligurian Alps, Italy)

摘要: Abstract Despite intensive research efforts and significant advances in the understanding of subduction obduction processes that affected several units which at present day compose Western Alps, paleogeographic evolution Alpine Tethys represents a debated topic geology. The role opposing continental margins (passive European margin active Adriatic margin) as source regions for Cretaceous siliciclastic turbidites bordering convergent system remains disputed. To address this question along Ligurian Alps transect, multi-proxy provenance analysis is applied to two terrigenous superimposed (Hauterivian-Campanian San Bartolomeo Fm. Campanian-Maastrichtian Bordighera Sandstone) Remo-Monte Saccarello Unit Flysch complex. Petrographic analyses characterize basal quartz-rich mature sandstones. By contrast, overlying Sandstone texturally compositionally immature first-cycle arkosic arenites. This change records sediment from stable craton into basement uplift setting, reflecting erosion granitoid plutons low-grade metamorphic basement. Geochronological data (U Pb detrital zircon ages) indicate virtually same terranes provided both formations. age spectra display peaks are compatible with well-documented magmatic pulses Southern Variscides Paleo-European margin. strong affinity clastic detritus rocks underlines importance lower plate passive supplying sand-rich turbidite systems prior arrival zone.