Barium isotopes in mid-ocean ridge hydrothermal vent fluids: A source of isotopically heavy Ba to the ocean
نویسندگان
چکیده
Abstract Mid-ocean ridge (MOR) hydrothermal vent fluids are enriched with dissolved barium, but due to barite (BaSO4) precipitation during mixing between Ba-bearing and SO4-bearing seawater, the magnitude of Ba input ocean remains uncertain. Deep-ocean isotopes show evidence for non-conservative behavior, which might be explained by isotopically heavy Ba. In this study we present first isotope data in mid-ocean particles from systems on Mid-Atlantic Ridge (Rainbow 36°N TAG 26°N), East Pacific Rise (EPR9–10°N 13°N) Juan de Fuca (MEF ASHES). The display a wide range concentrations 0.43 97.9??mol/kg ?138/134Ba values ?0.26 +0.91‰, modified relative initial composition barite. Calculated endmember fluid values, prior precipitation, ?0.17 +0.09‰, consistent observed oceanic basalts pelagic sediments. Water-rock interaction at depth crust appears occur without fractionation. During subsequent venting preferentially removes light fractionation factor ?138/134Bahyd-barite-fluid?=??0.35?±?0.10‰ (2SE, n?=?2). Based knowledge saturation effective component that mixes seawater after has completed can calculated: ?138/134Bahyd?=?+1.7?±?0.7‰ (2SD). This value is heavier than deep waters may explain waters. These new constraints compositions enable Atlantic assessed ?3–9% Barium used as tracer reconstruct history inputs SO4 past.
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ژورنال
عنوان ژورنال: Geochimica et Cosmochimica Acta
سال: 2021
ISSN: ['1872-9533', '0016-7037']
DOI: https://doi.org/10.1016/j.gca.2020.09.037