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Sédimentation autour de Taiwan de 35000 ans à l'actuel: variations des sources (isotopes du Pb-Sr-Zn) et des conditions environnementales (isotopes du Cu-Zn)

Abstract : The Sr and Pb data of silicate fraction of marine sediments allow us to propose a model of present-day sedimentary input variations around Taiwan orogen: from South to North, we observe a progressive increase of Taiwan sedimentary contributions, which are then diluted, in the North-East of Taiwan, by Loess and Yangtze material. Moreover, this study reports the particular characteristics of Taiwan Zn isotopic compositions, since all the Taiwan samples present isotopic values heavier than those available in the literature for terrigenous material. This feature is also observed on marine sediments which result from Taiwan sedimentary inputs. These results suggest the possible use of Zn isotopes as tracer of material.
Significant variations of Sr-Pb (terrigenous) and Cu-Zn (carbonaceous) are recorded in the ODP core samples (Okinawa Basin) since 35ka. The Sr and Pb isotopic compositions highlight the strong influence of Chinese Loess contributions during the Younger Dryas-type event which suggests an intensification of the winter Asian monsoon. Accordingly, we suggest that the significant Cu and Zn fractionations recorded since 6.9ka reflect the preferential absorption of light isotopes by biological processes. Thus, the low values (similar to crustal signature) measured in the Younger Dryas samples are probably due to the replenishment of surface water by deep water during a period of strong trade winds, which have prevented the development of deep and permanent thermocline.
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https://tel.archives-ouvertes.fr/tel-00103456
Contributor : Yasmine Bentahila <>
Submitted on : Wednesday, October 4, 2006 - 2:43:23 PM
Last modification on : Friday, April 5, 2019 - 8:02:57 PM
Long-term archiving on: : Tuesday, April 6, 2010 - 6:09:44 PM

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Yasmine Bentahila. Sédimentation autour de Taiwan de 35000 ans à l'actuel: variations des sources (isotopes du Pb-Sr-Zn) et des conditions environnementales (isotopes du Cu-Zn). Géochimie. Université Montpellier II - Sciences et Techniques du Languedoc, 2006. Français. ⟨tel-00103456⟩

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