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Cenozoic sea level and the rise of modern rimmed atolls

June 1, 2016

Sea-level records from atolls, potentially spanning the Cenozoic, have been largely overlooked, in part because the processes that control atoll form (reef accretion, carbonate dissolution, sediment transport, vertical motion) are complex and, for many islands, unconstrained on million-year timescales. Here we combine existing observations of atoll morphology and corelog stratigraphy from Enewetak Atoll with a numerical model to (1) constrain the relative rates of subsidence, dissolution and sedimentation that have shaped modern Pacific atolls and (2) construct a record of sea level over the past 8.5 million years. Both the stratigraphy from Enewetak Atoll (constrained by a subsidence rate of ~ 20 m/Myr) and our numerical modeling results suggest that low sea levels (50–125 m below present), and presumably bi-polar glaciations, occurred throughout much of the late Miocene, preceding the warmer climate of the Pliocene, when sea level was higher than present. Carbonate dissolution through the subsequent sea-level fall that accompanied the onset of large glacial cycles in the late Pliocene, along with rapid highstand constructional reef growth, likely drove development of the rimmed atoll morphology we see today.

Publication Year 2016
Title Cenozoic sea level and the rise of modern rimmed atolls
DOI 10.1016/j.palaeo.2016.03.018
Authors Michael Toomey, Andrew Ashton, Maureen E. Raymo, J. Taylor Perron
Publication Type Article
Publication Subtype Journal Article
Series Title Palaeogeography, Palaeoclimatology, Palaeoecology
Index ID 70182742
Record Source USGS Publications Warehouse
USGS Organization Eastern Geology and Paleoclimate Science Center