Integrated sedimentological and micropaleontological study of 16 cores and 137 piezocone penetration tests, approximately 40 m deep, in the Comacchio area enables the documentation of the depositional history of southeastern Po Plain in the last 30 ka, in response to fluctuating sea-level. Sedimentation within an alluvial plain was the dominant feature across the entire study area during the pronounced sea-level fall which culminated in the last glacial maximum. Thin lowstand fluvial sediments form the lower part of a shallow incised valley identified above the last glacial maximum unconformity, whereas a characteristic paleosol separates the last glacial alluvial plain deposits from the overlying post-glacial deposits in the interfluves. Transgressive and highstand deposits show a well developed stacking pattern of retrogradational (coastal-plain and estuarine) and progradational (deltaic) facies. Detailed reconstruction of transgressive paleogeography shows evolutionary features which can be useful for refined interpretation of coeval and ancient analogs. At relatively early stages of transgression (10.5-9 ka BP) sedimentation in a coastal plain was restricted to the incised valley, whereas non-deposition and pedogenesis took place on the interfluves. With rising sea-level (9-6 ka BP) a wave-dominated, barred estuary developed in coincidence of the former topographic low. At peak transgression, after filling up of the estuarine systems with coastal, behind-barrier sediments, wide areas outside the valleys were flooded, aggradation extended onto the interfluve unconformity, and a shallow-marine depositional environment developed across most of the study area. The depositional history during the subsequent highstand phase was dominated by progradation of the early Po River delta, and reflects the complex interplay between high-frequency sea-level fluctuations, climate, subsidence, and autocyclic processes (distributary channel avulsion and delta lobe abandonment).
Facies architecture and latest Pleistocene-Holocene depositional history of the Po Delta (Comacchio area), Italy.
2003
Abstract
Integrated sedimentological and micropaleontological study of 16 cores and 137 piezocone penetration tests, approximately 40 m deep, in the Comacchio area enables the documentation of the depositional history of southeastern Po Plain in the last 30 ka, in response to fluctuating sea-level. Sedimentation within an alluvial plain was the dominant feature across the entire study area during the pronounced sea-level fall which culminated in the last glacial maximum. Thin lowstand fluvial sediments form the lower part of a shallow incised valley identified above the last glacial maximum unconformity, whereas a characteristic paleosol separates the last glacial alluvial plain deposits from the overlying post-glacial deposits in the interfluves. Transgressive and highstand deposits show a well developed stacking pattern of retrogradational (coastal-plain and estuarine) and progradational (deltaic) facies. Detailed reconstruction of transgressive paleogeography shows evolutionary features which can be useful for refined interpretation of coeval and ancient analogs. At relatively early stages of transgression (10.5-9 ka BP) sedimentation in a coastal plain was restricted to the incised valley, whereas non-deposition and pedogenesis took place on the interfluves. With rising sea-level (9-6 ka BP) a wave-dominated, barred estuary developed in coincidence of the former topographic low. At peak transgression, after filling up of the estuarine systems with coastal, behind-barrier sediments, wide areas outside the valleys were flooded, aggradation extended onto the interfluve unconformity, and a shallow-marine depositional environment developed across most of the study area. The depositional history during the subsequent highstand phase was dominated by progradation of the early Po River delta, and reflects the complex interplay between high-frequency sea-level fluctuations, climate, subsidence, and autocyclic processes (distributary channel avulsion and delta lobe abandonment).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
