Elevated marine terraces from Eleuthera (Bahamas) and Bermuda: sedimentological,petrographic and geochronological evidence for important deglaciation events during the middle Pleistocene |
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Institution: | 1. Université des Antilles, Campus Fouillole, Laboratory L.a.R.G.E., 97159 Pointe-à-Pitre Cedex, French West Indies (FWI), France;2. Aix Marseille Université, CNRS, IRD, Coll France, CEREGE, Centre Saint Charles, 3, Place Victor Hugo, 13331 Marseille Cedex 3, France;1. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430074, China;2. School of Earth Sciences, University of Bristol, BS8 1RJ, UK;3. Department of Geology, University of Cincinnati, Cincinnati, OH 45221-0013, United States;4. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China;1. Geography, College of Life and Environmental Sciences, University of Exeter, Amory Building, Rennes Drive, Exeter EX4 4RJ, UK;2. Biosciences, College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK;1. Department of Geological Sciences, California State University Fullerton, 800 N. State College Blvd., Fullerton, CA 92834, United States;2. Chemistry and Earth Science, Los Angeles City College, 855 N. Vermont Ave, Los Angeles, CA 90029, United States |
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Abstract: | Sedimentological, petrographic and geochronological (uranium series and amino acid racemization dating) study of middle Pleistocene deposits from the archipelagos of Bermuda and The Bahamas revealed the occurrence of marine terraces of possible stage 11 age at +2, +7 and over 20 m above mean sea level. Considering the tectonic stability of the investigated regions, these elevated deposits likely correspond to three discrete, higher than present sea levels during this time period, which is regarded by many as the warmest interglacial of the late Quaternary. It follows that warmer than present climatic conditions might profoundly modify water distribution between the cryosphere and the oceans. The punctuated nature of our stratigraphy further suggests that future deglaciation might not be a smooth process, but could be marked by rapid ice-sheet breakdown leading to abrupt, meter-scale sea-level rises. Given the long period of warm climate and stable sea level of the past few thousands of years and CO2 loading of the atmosphere, the probability of a rapid eustatic rise must be seriously considered. |
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