title: Glendonite-Like Carbonate Aggregates from the Lower Ordovician Koporye Formation (Russian Part of the Baltic Klint): Detailed Mineralogical and Geochemical Data and Paleogeographic Implications
metadata.name: dc.contributor.author
metadata.value: Ершова, Виктория Бэртовна
metadata.lang: -
metadata.name: dc.date.accessioned
metadata.value: 2020-09-08T16:52:17Z
metadata.lang: -
metadata.name: dc.date.available
metadata.value: 2020-09-08T16:52:17Z
metadata.lang: -
metadata.name: dc.date.issued
metadata.value: 2019
metadata.lang: -
metadata.name: dc.identifier.uri
metadata.value: http://hdl.handle.net/11701/19297
metadata.lang: -
metadata.name: dc.description.abstract
metadata.value: Stellate and plate-like carbonate bodies, traditionally called anthraconites, are found
  throughout the Baltic-Ladoga Klint in bituminous shale of the Koporye Formation (Tremadocian,
  Lower Ordovician). Although this time interval is usually considered as a greenhouse, there is some
  evidence for the existence of at least temporary cold conditions during the Cambrian–Ordovician.
  However, the origin of anthraconites is still strongly debated.We studiedthemineralogical, petrographic,
  cathodoluminescence, geochemical, and isotopic characteristics of anthraconites from five sections of
  the Russian part of the Baltic paleobasin. A close similarity between the morphological, petrographic,
  cathodoluminescence, and isotopic characteristics of the studied anthraconites with those of
  glendonites allow us to suggest that these bodies formed in a similar paleo-environment and
  should be considered as pseudomorphs of the mineral ikaite. The oxygen and carbon isotope ratios
  reveal that ikaite precipitation occurred in low-temperature conditions on the seafloor. The carbon
  isotopic values reveal influence of inorganic seawater carbon along with organic matter decomposition
  and/or methane oxidation during ikaite-glendonite transformations. The oxygen isotopic composition
  significantly changed after deposition due to meteoric diagenesis. We propose that the studied
  Tremadocian anthraconites formed under a region of upwelling, where cold phosphate-rich deep
  waters rose to the relatively shallow part of the Baltic paleobasin, providing favorable conditions for
  ikaite precipitation. Based on our cathodoluminescence study, we suggest that ikaite was transformed
  to calcite over several stages during diagenesis. Mineralogical studies also reveal that primary calcite
  was transformed to sulfate (gypsum) or dolomite during late superimposed processes.
metadata.lang: en_GB
metadata.name: dc.language.iso
metadata.value: en
metadata.lang: en_GB
metadata.name: dc.publisher
metadata.value: MDPI
metadata.lang: en_GB
metadata.name: dc.title
metadata.value: Glendonite-Like Carbonate Aggregates from the Lower Ordovician Koporye Formation (Russian Part of the Baltic Klint): Detailed Mineralogical and Geochemical Data and Paleogeographic Implications
metadata.lang: en_GB
metadata.name: dc.type
metadata.value: Article
metadata.lang: en_GB
resources.filename: Mikhaylova-et-al-2019-Min.pdf
resources.url: https://dspace.spbu.ru/bitstream/11701/19297/1/Mikhaylova-et-al-2019-Min.pdf
resources.format: Adobe PDF
resources.size: 5,7 MB