Communications Earth & Environment (Oct 2023)

Fibrous dolomite formation at a Miocene methane seep may reflect Neoproterozoic aragonite-dolomite sea conditions

  • Yang Lu,
  • Carsten Paulmann,
  • Boriana Mihailova,
  • Thomas Malcherek,
  • Daniel Birgel,
  • Matthias López Correa,
  • Zhiyong Lin,
  • Liuyi Lu,
  • Yvonne Milker,
  • Jörn Peckmann

DOI
https://doi.org/10.1038/s43247-023-01021-y
Journal volume & issue
Vol. 4, no. 1
pp. 1 – 8

Abstract

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Abstract Fibrous dolomite widely formed in Neoproterozoic marine sedimentary environments, but apparently disappeared in the Phanerozoic. Here, fibrous dolomite is recognised in a Miocene methane seep limestone (Marmorito, Italy) by synchrotron X-ray diffraction, length slow crystal optics and primary zonation under cathodoluminescence, which is unexpected. Low δ13C values and their negative correlation with MgCO3 contents indicate a formation driven by highly alkaline pore waters and catalysis of dissolved sulphide generated by sulphate-driven anaerobic oxidation of methane. Cementing cavities of reefal carbonate, Neoproterozoic fibrous dolomite might have formed under sulphate-reducing conditions like Quaternary reef microbialites. Since the cavities of Neoproterozoic reefs were restricted microenvironments, the formation of fibrous dolomite was possibly favoured by catalysis similar to its Miocene seep counterpart. Our findings reinforce the concept of penecontemporaneous dolomite formation by sulphide catalysis and contribute to our understanding of the environmental conditions of the Neoproterozoic.