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| Bernat, M; Loubet, M; Baumer, A. |
| Phosphates from the Nauru atoll lie on a karstic structure developed at the expenses of a coral reef. These formations are fluorapatites low in carbonate, with less fluorine than common marine carbonate-fluorapatites (CFA). At least one of the deposits is from the last interglacial era (Th-230-U-234 dating). Rare Earth spectra seems to be affected by the dissolution-precipitation reactions leading to the formation of the carbonate-fluorapatite. But U and Sr isotopic ratios support the marine origin of most of these formations, except for one result, which give a Nd-143/Nd-144 ratio indicating a slight volcanic influence. Our results and the literature reports favorise the hypothesis that these phosphates originate from the endo-upwelling of phosphorus rich... |
| Tipo: Text |
Palavras-chave: PHOSPHATES ATOLLS ISOTOPES U; TH; SR. |
| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/00102/21374/18974.pdf |
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