Sedimentary and biotic responses to climate-driven terrigenous input in the lower Priabonian of the South Pyrenean foreland basin (Centelles, Ebro Basin)

The lower Priabonian (SBZ 18b-c) La Tossa Formation in Centelles (south-eastern margin of the Ebro Basin) records an upward transition from the siliciclastic-dominated Centelles Sandstone to the carbonate-dominated Collsuspina Limestone, with an intervening mixed siliciclastic-carbonate interval. This long-term decline in terrigenous supply is interpreted to mark the onset of increasing aridity and seasonal climatic variability in the region during the early Priabonian. This aridification, also indicated by palaeobotanical and pedogenic records from the Iberian Peninsula, likely resulted from large-scale atmospheric reorganisation driven by Southern Hemisphere cooling and enhanced equatorial warming, which expanded subtropical dry belts. Through an integrated analysis of macro- and microfacies, combined with biostratigraphy and palaeoecology of larger foraminifera and coralline algae, this study reconstructs the facies architecture of a low-gradient homoclinal ramp. The results show a progressive ecological shift from larger foraminifera-dominated assemblages and cluster coral reefs to coralline algal-rich communities and frame-reef buildups, reflecting the influence of climate-mediated terrigenous fluxes on carbonate factory dynamics in a Priabonian shallow-marine platform.