Age accuracy and resolution of Quaternary corals used as proxies for sea level |
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| Institution: | 1. College of Oceanography, Hohai University, Nanjing 210098, China;2. College of Marine Science and Technology, China University of Geosciences, Wuhan 430074, China;3. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Science, Nanjing, 210008, China;4. Department of Earth and Environmental Sciences, Milano-Bicocca University, Piazza della Scienza 4, 20126 Milano, Italy;5. Institut für Geologie, Universität Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany;6. State Key laboratory of Marine Geology, Tongji University, Shanghai 200092, China;7. Institute of Geology, Chinese Academy of Geological Sciences, Baiwanzhuang street 26, 10037 Beijing, China;8. China National Offshore Oil Corporation Ltd, Beijing 100010, China |
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| Abstract: | The accuracy of global eustatic sea level curves measured from raised Quaternary reefs, using radiometric ages of corals at known heights, may be limited by time-averaging, which affects the variation in coral age at a given height. Time-averaging was assessed in uplifted Holocene reef sequences from the Huon Peninsula, Papua New Guinea, using radiocarbon dating of coral skeletons in both horizontal transects and vertical sequences. Calibrated 2σ age ranges varied from 800 to 1060 years along horizontal transects, but weighted mean ages calculated from 15–18 dates per horizon were accurate to a resolution within 154–214 yr. Approximately 40% of the variability in age estimate resulted from internal variability inherent to 14C estimates, and 60% was due to time-averaging. The accuracy of age estimates of sea level change in studies using single dated corals as proxies for sea level is probably within 1000 yr of actual age, but can be resolved to ≤ 250 yr if supported by dates from analysis of a statistical population of corals at each stratigraphic interval. The range of time-averaging among reef corals was much less than that for shelly benthos. Ecological time-averaging dominated over sedimentological time averaging for reef corals, opposite to patterns reported from shelly benthos in siliciclastic environments. |
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