238-10 Siliciclastic Influence and Taphonomic Variability in Late Pleistocene Coral Reefs at Three Sites in Jamaica

Session: Recent Advances and New Voices in Marine and Coastal Geoscience

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The syn- and post-depositional taphonomic features of late Pleistocene coral reefs in Jamaica offer a unique lens through which past reef environments and dynamics can be reconstructed. This study examines the impact of siliciclastic sediment input on the preservation and development of late Pleistocene coral reef systems at three Jamaican localities: Treasure Beach, Port Morant Harbour, and Rio Bueno. These sites represent contrasting sedimentological and geomorphic settings, providing a framework to examine spatial variability in reef accretion and diagenesis.

Ninety-five coral samples (336 slabs) and 17 thin sections were analyzed to characterize four key taphonomic features- encrustation, bioerosion, sediment occlusion, and dissolution. Quantitative image analysis using ImageJ and multivariate statistics (NMDS and PERMANOVA) was employed to identify patterns across reef zones and depositional settings. Six distinct taphonomic facies and sequences were defined, capturing the variability in syn- and post-mortem processes affecting coral preservation.

Crest-associated biofacies across all sites consistently exhibit high encrustation and low bioerosion, indicative of stable, low-productivity environments. In contrast, backreef and lagoonal facies show pronounced taphonomic divergence. Port Morant Harbour reefs are heavily influenced by fine siliciclastic influx, leading to high sediment occlusion, micritization, dissolution, and poor water quality post-mortem. Rio Bueno reefs, in a more carbonate-dominated setting, show stronger bioerosion and reduced sediment occlusion, implying longer residence times in the taphonomically active zone and higher primary productivity. Treasure Beach exhibits distinct infilling of reef frameworks by angular siliciclastic sands, likely signalling the end of the Last Interglacial Warm Period.

These findings highlight the role of siliciclastic input as a key control on coral taphonomy, reef preservation, and accretion dynamics in late Pleistocene systems. The integration of taphonomic indicators with sedimentological context offers new insight into reef response to environmental stressors during the Last Interglacial, with implications for interpreting fossil reef records and predicting the vulnerability of modern reefs to shifting sediment regimes.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8465

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