Facies

, Volume 55, Issue 1, pp 103–114

Redox conditions during sedimentation of the Middle Jurassic (Upper Bajocian–Bathonian) clays of the Polish Jura (south-central Poland)

  • Michał Zatoń
  • Leszek Marynowski
  • Patrycja Szczepanik
  • David P. G. Bond
  • Paul B. Wignall
Original Article

DOI: 10.1007/s10347-008-0159-z

Cite this article as:
Zatoń, M., Marynowski, L., Szczepanik, P. et al. Facies (2009) 55: 103. doi:10.1007/s10347-008-0159-z

Abstract

Depositional redox conditions of the uppermost Bajocian–Bathonian (Middle Jurassic) ore-bearing clays of the Gnaszyn/Kawodrza area in the Polish Jura have been determined using an integrated geochemical (Th/U and U/Th ratios, degree of pyritisation (DOP), sulphur stable isotopes, biomarker analysis) and petrographic approach (measurements of pyrite framboid diameters, and microfacies analysis). The Th/U and U/Th ratios indicate that oxic conditions prevailed on the sea-floor during this interval, and 34S isotopes suggest open-system conditions. DOP values, however, are rather scattered, and may reflect oxic, dysoxic, or anoxic conditions. We consider that the DOP values result from reducing conditions within the sediment and the chemistry of the pore-waters, rather than true sea-floor redox conditions. Pyrite framboid populations also indicate that dysoxic conditions prevailed within the sediment, beneath an oxygenated water column. Biomarker data did not provide any evidence of water column stratification or anoxia during sedimentation of the Middle Jurassic clays.

Keywords

RedoxGeochemistryJurassicFramboidsOrganic matterPoland

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Michał Zatoń
    • 1
  • Leszek Marynowski
    • 1
  • Patrycja Szczepanik
    • 2
  • David P. G. Bond
    • 3
  • Paul B. Wignall
    • 3
  1. 1.Faculty of Earth SciencesUniversity of SilesiaSosnowiecPoland
  2. 2.Institute of Geological SciencesJagiellonian UniversityKrakówPoland
  3. 3.School of Earth and EnvironmentUniversity of LeedsLeedsUK