ScienceDirect The influence of hydrothermal activity on the Li isotopic signature of rivers draining volcanic areas

• Published in: Procedia Earth and Planetary Science
• Main Authors: Henchiri, S., Clergue, C., Dellinger, M., Gaillardet, J., Louvat, P., Bouchez, Julien
• Other Authors: Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: Li isotopes; rivers; silicate weathering; volcanic islands; hydrothermal activity; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; Iceland
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-01516076; https://hal-insu.archives-ouvertes.fr/insu-01516076/document; https://hal-insu.archives-ouvertes.fr/insu-01516076/file/procedia-earth-henchiri-2014-10-223.pdf; https://doi.org/10.1016/j.proeps.2014.08.026

International audience We explore the geochemistry and the isotopic composition of lithium (δ 7 Li) of rivers draining volcanic islands (Guadeloupe, Iceland, Java, Martinique and Sao Miguel) with a specific focus on continental hydrothermal activity. Our preliminary results reveal a global-scale trend between δ 7 Li and the elemental ratio Li/Na in rivers draining volcanic islands. We suggest that this trend results from a mixture between waters with low δ 7 Li and high Li/Na, inherited from high-temperature water rock interactions, and waters with low Li/Na and high δ 7 Li, in which Li is controlled by the neoformation of clays during low-temperature chemical weathering in basaltic soils. This latter process can be described by a simple isotope fractionation model, consistent with reported values for isotopic fractionation factors between secondary weathering products and water. These data highlight the important potential role of continental high-temperature weathering processes on the oceanic budget of lithium.