Carbonate Precipitation Induced by Serpentinization on the Mid-Atlantic Ridge
Zusammenfassung der Projektergebnisse
The major outcome of this project is the documentation of the variety of environmental conditions under which carbonate minerals form in different lithologies of the ocean crust. We have been able to show that the mineralogy of carbonate minerals, their crystal fabrics, element patterns, as well as isotopical compositions reflect the different modes of their formation. Carbonate precipitation was found to occur from water with a composition similar to that of seawater, from seawater affected from conductive heating, and from hydrothermal fluid after conductive cooling. We are confident that these mechanisms are widespread in the ocean floor, yet it cannot be excluded that the actual diversity of modes of carbonate formation is even greater. This study yielded only circumstantial evidence for an involvement of microbial activity in carbonate formation. With more serpentinites with secondary carbonates hopefully becoming available in the future, this shortcoming will possibly be overcome by the analysis of the lipid biomarker content of the respective carbonate phases. Such rocks with substantial secondary mineralisation are known from the Mariana Arc and the Lost City vent field. Another promising approach is the study of on-shore ophiolitic complexes like those in Oman, where serpentinites are exposed and active serpentinization is still going on, producing hydrogen and methane.
Projektbezogene Publikationen (Auswahl)
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(2006) Carbonate formation in serpentinized peridotites: A new aspect of the serpentinization process. DMG-Sektionstreffen Geochemie, Kiel
Eickmann B, Peckmann J
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(2006) Carbonate formation induced by serpentinization: Preliminary results. Annual meeting of the German Mineralogical Society, Hannover
Eickmann B, Peckmann J
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(2007) Authigenic carbonates in ultra mafic-hosted hydrothermal systems at the Mid-Atlantic Ridge. Annual meeting of the Geologische Vereinigung, Bremen
Eickmann B, Peckmann J
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(2007) Petrography, geochemistry and isotope characteristics of authigenic carbonates from the Mid-Atlantic Ridge. Goldschmidt Conference, Köln
Eickmann B, Peckmann J
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(2008) The hidden biosphere: Cryptoendolithic life in Devonian pillow basalt. International Geological Congress, Oslo
Eickmann B, Bach W, Kiel S, Reitner J, Peckmann J
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(2008) The hidden biosphere: Cryptoendolithic life in Devonian pillow basalt. International Kalkowsky Meeting, Göttingen
Eickmann B, Bach W, Kiel S, Reitner J, Peckmann J
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(2009) Authigenesis of carbonate minerals in modern and Devonian ocean-floor hard rocks. The Journal of Geology X17, 307-323
Eickmann B, Bach W, Peckmann J
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(2009) Evidence for widespread cryptoendolithic life in Devonian pillow basalts of Variscan orogens, Germany. Palaeogeography, Palaeoclimatology, Palaeoecology 283, 120-125
Eickmann B, Bach W, Kiel S, Reitner J, Peckmann J
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(2009) Geochemical constraints on the modes of carbonate precipitation in peridotites from the Logatchev Hydrothermal Vent Field and Gakkel Ridge. Chemical Geology 269, 97-105
Eickmann B, Bach W, Rosner M, Peckmann J
