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Altered carbon cycling and trace-metal enrichment during the late Valanginian and early Hauterivian

Kuhn, Oliver ; Weissert, Helmut ; Föllmi, Karl ; Hennig, Susanne

In: Eclogae Geologicae Helvetiae, 2005, vol. 98, no. 3, p. 333-344

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    Title
    • Altered carbon cycling and trace-metal enrichment during the late Valanginian and early Hauterivian
    Author
    • Kuhn, Oliver. Shell China Exploration and Production Co., 100004, Bejing, P.R. China
    • Weissert, Helmut. Geological Institute, ETH Zurich, 8092, Zurich, Switzerland
    • Föllmi, Karl. Institut de Géologie, Université de Neuchâtel, 2007, Neuchâtel, Switzerland
    • Hennig, Susanne. Geological Institute, ETH Zurich, 8092, Zurich, Switzerland
    Document Type
    • Postprint
    Language
    • English
    Published in
    • Eclogae Geologicae Helvetiae, 2005, vol. 98, no. 3, p. 333-344. Birkhäuser-Verlag; www.birkhauser.ch
    Other Version
    OAI-PMH Identifier
    • oai:doc.rero.ch:318535
    Summary
    Abstract.: Carbonates of Valanginian age deposited in the Tethys and Atlantic Oceans show a distinct positive δ13C excursion (Δ δ13C = 1.5‰-2‰) in sections of the neritic, hemipelagic, and pelagic environment. This excursion records a major climate-induced perturbation of the global carbon system. The δ13C excursion is accompanied by enrichments in manganese (Mn) and iron (Fe). The correlation of the δ13C excursion with trends in Mn and Fe contents reflects changes in Valanginian paleoceanography and climate. Fe enrichment occurs mainly in terrestrial, platform, and shelf regions. In a basinal direction the Fe content decreases, whereas the Mn/Fe ratio increases. An increase in sedimentary Mn and Fe concentrations is related to elevated continental weathering rates and to widespread dys- or anoxia that favored metal deposition in Valanginian sediments. Various oceanographic changes (e.g., expansion of oxygen-minimum zones) resulting from increased continental runoff led to a strong remobilization and focused reprecipitation of metals in the oceans of the Valanginian stage