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Climate and sea level variations in the Gulf of Lion : coupling stable and radiogenic isotopes proxies

Abstract : By its position, the Gulf of Lion is an ideal location for investigation of past ecological changes and processes affecting the sedimentary deposition. Previous work has highlighted the impacts of climatic and glacio-eustatic changes on the GoL stratigraphic organization, but also on terrestrial exports of organic matter.This isotopic study based on the organic carbon and nitrogen preserved in PRGL1-4 sediments highlights important rivers runoff during warm periods of the last 200 000 years.Regional intercomparison with terrestrial and marine records indicates that these river exports resulting from an increase of precipitation over the North Mediterranean borderland.Using PRGL1-4 location, out of Mediterranean cyclogenetic area, we suggest that these pluvial events occurred in response to enhance passage of North Atlantic atmospheric perturbation into the Western Mediterranean basin.Pyrite sulfur isotopes investigations over the last 500 kyr have also been done. The stratigraphic variations (up to 76‰) in the isotopic data reported here are among the largest ever observed in pyrite, and are in phase with glacial-interglacial sea level. These results suggest that there exist important but previously overlooked depositional controls on sedimentary sulfur isotope records. Two different mechanisms influencing the isotopic fractionation can explain the observed dataset: a climatic modulation of the bacterial activity, and / or (ii) a local sedimentary modulation involve during early diagenetic formation of pyrite in relation with the eustatic variations.
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https://tel.archives-ouvertes.fr/tel-01738260
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Submitted on : Tuesday, March 20, 2018 - 2:19:09 PM
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  • HAL Id : tel-01738260, version 2

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Virgil Pasquier. Climate and sea level variations in the Gulf of Lion : coupling stable and radiogenic isotopes proxies. Earth Sciences. Université de Bretagne occidentale - Brest, 2017. English. ⟨NNT : 2017BRES0094⟩. ⟨tel-01738260v2⟩

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