290 Delta Evolution from Rivers to the Shelf: Past, Present and Future Perspectives for Society

The session focuses on deltas and adjacent depositional environments from fluvial systems to the continental shelf. Research on modern, ancient or extraterrestrial deltas that emphasize their importance to our society is welcome.

Wednesday, 22 October 2025
1:30 PM - 5:30 PM
HBGCC, 303AB

Post-LGM Evolution of Cuspate Delta Systems on the Northeastern Sardinian Continental Shelf (Italy) and Coastal Implications

Paper number: 290-5
Program: Technical Sessions
Time: 2:27 PM – 2:42 PM

Authors

Abstract

A high-resolution geomorphological survey of the continental shelf of northeastern Sardinia (Italy) has revealed a variety of submerged landforms associated with the evolution of deltaic and coastal depositional systems from the Last Glacial Maximum (LGM) to the early Holocene. The survey integrated multibeam bathymetry, side-scan sonar, and remotely operated vehicle (ROV) imagery, enabling detailed mapping and stratigraphic interpretation of key morphological features across the shelf. During the LGM, when sea level stood approximately 130 meters below its present position, fluvial systems extended across the exposed shelf, forming cuspate delta systems near the shelf edge. As sea level rose during the post-LGM period, these deltas were gradually drowned, leading to significant changes in sediment transport and deposition. Importantly, this transgressive phase was not continuous but interrupted by at least three relative stillstands, during which beach ridges and well-developed backshore lagoons formed along paleo-shorelines. These ridges, composed of cemented sandstones exhibiting beachface cross-bedding, are interpreted as transgressive shoreline deposits. Based on their depth and morphology, they are correlated with major climatic cooling events such as the Older Dryas (~17–15 ka), Younger Dryas (~12.9–11.6 ka), and the 8.2 ka cold event. These markers constrain paleo-shoreline positions and illustrate how rapid climate shifts shaped shelf morphology. They improve regional sea-level reconstructions and provide useful analogues for understanding sedimentary responses to sea-level change in similar coastal systems.

 

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-413319

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