Strontium isotopes and rare-earth element geochemistry of hydrothermal carbonate deposits from Lake Tanganyika, East Africa

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doi: 10.1016/S0016-7037(99)00294-X
Authors:Barrat, J. A.; Boulègue, J.; Tiercelin, J. J.; Lesourd, M.
Author Affiliations:Primary:
Université d'Angers, Faculté des Sciences, Angers, France
Other:
Université de Paris, France
Institut Universitaire Européen, France
CNRS, France
Volume Title:Geochimica et Cosmochimica Acta
Source:Geochimica et Cosmochimica Acta, 64(2), p.287-298. Publisher: Pergamon, Oxford, International. ISSN: 0016-7037
Publication Date:2000
Note:In English. 25 refs.; illus., incl. 4 tables, sketch map
Summary:Two sub-lacustrine hydrothermal fields occur along the Zaire side of the N basin of Lake Tanganyika; the Cape Banza field includes > 70 active vents with aragonitic chimneys, pyrite and greigite on the walls of pipes and fractures, and fluids emitted at 65-103°C. Analyses are presented of the aragonites for REE and Sr isotopes, and of surface waters and hydrothermal fluids for HCO3, H4SiO4, SO4 and seven elements. The results are used to compare the signatures of fluids with those of the aragonites associated with the vents. The Sr isotopic compositions of the chimneys indicate that they precipitated from a mixture of lake water and a few % of the hydrothermal end-member fluid. External-wall aragonites and the carbonate-depositing fluid show similar REE patterns indicating equilibrium. Internal-wall carbonates are richer in REE than the external wall samples with the excess being hosted by unidentified impurities. There is no significant biological effect on the incorporation of REE in corals, based on the similar homogeneous partition coefficients for REE between the present samples and coral aragonite. [R.K.H.]
Sections:Geochemistry
Subsections:Minerals and ores
Subjects:Alkaline earth metals; Aragonite; Carbonates; Computer programs; Data processing; Fluid phase; Geochemistry; Hydrology; Hydrothermal vents; Isotope ratios; Isotopes; Lacustrine environment; Limnology; Metals; Phase equilibria; Rare earths; SEM data; Sr-87/Sr-86; Stable isotopes; Strontium; Surface water; Thermal waters; Trace elements; Africa; Central Africa; Congo Democratic Republic; East African Lakes; Kivu Congo Democratic Republic; Lake Tanganyika; Cape Banza; WATRA2
Coordinates:S040400 S040300 E0291500 E0291400
Abstract Numbers:00M/3870
Record ID:2000019157
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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