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Article Dans Une Revue Applied Geochemistry Année : 2011

Boron isotope ratios of surface waters in Guadeloupe, Lesser Antilles

Pascale Louvat
Guillaume Paris
C. Dessert

Résumé

Large variations are reported in the B concentrations and isotopic ratios of river and thermal spring waters in Guadeloupe, Lesser Antilles. Rivers have d11 B values around 40‰ and B concentrations lower than 30 lg/L, while thermal springs have d11 B of 8–15‰ and B concentrations of 250–1000 lg/L. River samples strongly impacted by hydrothermal inputs have intermediate d11 B and B contents. None of these surface water samples have d11 B comparable to the local unweathered volcanic rocks (around 0‰), implying that a huge isotopic fractionation of 40‰ takes place during rock weathering, which could be explained by preferential incorporation of 10 B during secondary mineral formation and adsorption on clays, during rock weathering or in the soils. The soil-vegetation B cycle could also be a cause for such a fractionation. Atmospheric B with d11 B of 45‰ represents 25–95% of the river B content. The variety of the thermal spring chemical composition renders the understanding of B behavior in Guadeloupe hydrothermal system quite difficult. Complementary geochemical tracers would be helpful.

Dates et versions

hal-03945811 , version 1 (18-01-2023)

Identifiants

Citer

Pascale Louvat, Jérôme Gaillardet, Guillaume Paris, C. Dessert. Boron isotope ratios of surface waters in Guadeloupe, Lesser Antilles. Applied Geochemistry, 2011, 26, pp.S76-S79. ⟨10.1016/j.apgeochem.2011.03.035⟩. ⟨hal-03945811⟩
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