|
|
|
|
|
| Monna, F; Lancelot, J; Bernat, M; Mercadier, H. |
| Geochronological data (Pb-210) Obtained on four sediment cores, coupled with geochemical analysis, X-ray radiography, meteorological data and stratigraphical observations, made it possible to provide a recent and coherent sedimentary history of the Thau basin (Herault, France). Cluster analysis of major elements isolates some horizons presenting a strong terrigenous signature, which are also identified by X-ray. These strata, characterized by high Al, Fe, Ti and K contents, are the consequence of the exceptional flood which occurred in September 1875. This event serves to calibrate the radiochronological data, which are limited at 100 years. Cores located close to the continental and fluviatile inputs accurately record the flood horizon. Measured... |
| Tipo: Text |
|
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20422/18089.pdf |
| |
|
|
| 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 |
| |
|
| |
|
|
|
