Non-linear response of the Golo River system, Corsica, France, to Late Quaternary climatic and sea level variations

Disentangling the impact of climatic and sea level variations on fluvio-deltaic stratigraphy is still an outstanding question in sedimentary geology and geomorphology. We used the Golo River system, Corsica, France, as a natural laboratory to investigate the impact of Late Quaternary climate and sea level oscillations on sediment flux from a catchment and on fluvio-deltaic stratigraphy. We applied a numerical model, PaCMod, which calculates catchment sediment production and transport and compared modeling output to the sedimentary record of the Golo alluvial-coastal plain, whose chronology was reinterpreted using new optical stimulated luminescence (OSL) ages on feldspars. Our modeling, OSL ages, and geomorphological results indicate that the two main phases of braidplain development in the Golo alluvial-coastal plain occurred during the cold-dry phases of MIS5 and during the late MIS4-early MIS3, as a consequence of high catchment erosion rates and low water discharge. Incision and sediment reworking occurred during sea level low stand periods (MIS4 and late MIS3-MIS2). High sediment flux pulses from the catchment outlet were generated during the Lateglacial and early Holocene, as a result of the release of sediments previously stored within the catchment and enhanced snowmelt. Our results suggest a non-linear response of the Golo River system to climatic and eustatic changes, caused by sediment storage within the catchment and geomorphological thresholds. This indicates that a direct comparison between palaeo-climate and stratigraphy is not possible without considering catchment sediment storage and sediment transport delays out of the catchment.