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Carbon stable isotope (δ 13 C) and elemental (TOC, TN) geochemistry in saltmarsh surface sediments (Western Brittany, France): a useful tool for reconstructing Holocene relative sea‐level
Author(s) -
Goslin Jérôme,
Sansjofre Pierre,
Van VlietLanoë Brigitte,
Delacourt Christophe
Publication year - 2017
Publication title -
journal of quaternary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.142
H-Index - 94
eISSN - 1099-1417
pISSN - 0267-8179
DOI - 10.1002/jqs.2971
Subject(s) - holocene , geology , salt marsh , total organic carbon , isotopes of carbon , diagenesis , sea level , oceanography , sedimentary rock , marsh , δ13c , radiocarbon dating , context (archaeology) , physical geography , paleontology , stable isotope ratio , geochemistry , environmental chemistry , ecology , wetland , chemistry , geography , physics , quantum mechanics , biology
Providing a dense network of Holocene relative sea‐level (RSL) records still faces some challenges, such as the paucity of microfossil assemblages within some Holocene sedimentary sequences. Recently, the isotopic (δ 13 C) and elemental geochemistry [total organic carbon (TOC), total nitrogen (TN) and C/N ratios] of saltmarsh sediments has showed potential for RSL reconstruction. This study presents the results of new δ 13 C, TOC and TN measurements obtained on surface sediments of two marshes of the Brittany region (France). Overall, the distribution of δ 13 C, TOC, TN and C/N values shows clear dependencies with elevation. Sediments from above and below the high tide level show contrasting TN contents. Clustering analyses identified three elevation‐dependent groups, characterized by specific values of δ 13 C, TOC and TN. The use of this geochemical reference for RSL reconstruction is tested on a core retrieved from one of the marshes. The sea‐level index points obtained plot in good accordance with the microfauna‐based RSL positions previously obtained in the region. Some diagenetic losses in TN are observed between modern and Holocene sediments. This does not appear to be harmful to the accuracy of the RSL reconstructions but suggests that C/N ratios may be unreliable palaeoenvironmental proxies in this specific context.