Development patterns of fringing and barrier reefs in New Caledonia (southwest Pacific) |
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| Institution: | 1. Post-graduate Program in Zoology, Universidade Federal do Paraná, Centro Politécnico, Caixa Postal 19020, 81531-980 Curitiba, PR, Brazil;2. Post-graduate Course on Estuarine and Ocean Systems (PGSISCO), Universidade Federal do Parana, Caixa Postal 61, 83255-976 Pontal do Paraná, PR, Brazil;3. Centro de Estudos do Mar, Universidade Federal do Paraná, Caixa Postal 61, 83255-976 Pontal do Paraná, PR, Brazil;4. Zoology Department, Universidade Federal do Paraná, Centro Politécnico, Caixa Postal 19020, 81531-980 Curitiba, PR, Brazil;1. Marine Ecology Research Center, First Institute of Oceanography of State Oceanic Administration, Qingdao 266061, China;2. Xiamen Huaxia University, Xiamen 361024, China;3. Laboratory of Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China;4. Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China;1. Scottish Association for Marine Science, Oban PA37 1QA, UK;2. British Geological Survey, The Lyell Centre, Edinburgh EH14 4AP, UK;3. Department of Geography, University of Durham, Durham DH1 3LE, UK |
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| Abstract: | In New Caledonia, core data indicate that the fringing reefs grew during the last interglacial and the Holocene, while the barrier reefs developed during several high sea level stands of the Quaternary. These growth periods are archived in a 128-m-long core from Ilot Amédée, offshore of Nouméa. Directly upon the peridotitic substrate (reached at 126.50 m), a basal unit comprising abundant rhodoliths, molluscs and rare corals is characteristic of the pioneer stage of barrier reef development. Above it, a severely calcitized unit contains corals, molluscs and abundant micritic levels. Then, a sequence punctuated by several minor discontinuities and by a downward increase in diagenetic alteration is found. At 47 m core depth, a unit, which is thought to be related to isotopic stages 7 and 9, contains thin beds of coralgal frameworks and muddy detritus. The 125 ka-old reef, from 14 to 37 m core deep, is predominantly composed of biocalcarenites and rare coral colonies. Finally, the Holocene reef is composed of sands and scarce coral buildups. Drilling results indicate that the distributional patterns of the 125-ka-old reef bodies around New Caledonia express an increasing tendency of island subsidence northward, southwestward and more markedly seaward, mainly controlled by isostatic readjustments and margin collapse. |
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