Morphology of the Belize barrier reef as indicator for Atlantic sea-level changes during the last glacial cycle

Mixed carbonate-siliciclastic margins such as the Belize Barrier Reef provide sensitive archives of glacio-eustatic variability because reef accretion, erosion, and sediment supply respond directly to sea-level fluctuations. This study investigates the geomorphological imprints of relative sea-level change along more than 100 km of the Belize Barrier Reef margin using high-resolution multibeam bathymetry. The new bathymetric dataset provides deeper insight into reef-margin morphology and identifies constructional and erosional paleo-sea-level indicators. Ridge-crest lineaments and reef-wall notches were used for statistic depth distributions from ten along-strike sectors, which reveal laterally persistent elevation clusters that correspond to distinct paleo-sea-level positions. Ridge-crest lineaments show a dominant concentration near ~20 m water depth, interpreted as a period of reduced early Holocene sea-level rise, or even possible MIS 5 stillstands, whereas widespread notch horizons at ~80–85 m and ~ 100–105 m record prolonged late Pleistocene stillstands preceding and approaching the Last Glacial Maximum. The absence of systematic vertical offsets between sectors indicates negligible neotectonic deformation along the margin. Results demonstrate that reef-margin morphology preferentially preserves intervals of slow or stable sea-level change, while phases of rapid transgression leave limited geomorphic imprint. High-resolution bathymetry thus provides a powerful tool for reconstructing sea-level histories from steep carbonate margins and establishes the Belize Barrier Reef as a key reference archive for late Quaternary sea-level dynamics.