EGU2020-4041
https://doi.org/10.5194/egusphere-egu2020-4041
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Multi-proxy study of cannon-ball concretions with glendonites from Paleogene-Neogene sediments of Sakhalin Island: implication for concretion growth and ikaite-calcite trans-formation

Kseniia Vasileva1, Victoria Ershova1, Oleg Vereshchagin1, Mikhail Rogov2, Marianna Tuchkova2, Yuriy Kostrov3, Eduard Khmarin3, and Boris Pokrovsky2
Kseniia Vasileva et al.
  • 1Saint Petersburg State University, Institute of Earth Sciences, Russian Federation (k.vasilyeva@spbu.ru, v.ershova@spbu.ru, o.vereshchagin@spbu.ru)
  • 2Geological Institute of RAS, Russian Federation ( russianjurassic@gmail.com, tuchkova@ginras.ru, pokrov@ginras.ru)
  • 3LLC RN-SakhalinNIPImorneft, Russian Federation (kos-geo@yandex.ru, Ekkhmarin@sakhnipi.ru)

The objects of the current study are glendonite pseudomorphs forming the central part of cannon-ball carbonate concretions found within Miocene terrigeneous sediments of Sakhalin island (easternmost part of Russia). Twelve samples of glendonites and host carbonate concretions were examined using optical and cathodoluminescence microscopy, EDX analysis, powder X-ray diffraction and isotopic analysis. The aim of the study is to determine the origin of the concretions and the relationships between the concretion and glendonite occurrence.

Glendonites and host cannon-ball concretions were found within terrigeneous sediments of Bora (Lower Miocene) and Vengeri (Upper Miocene) formations. These formations are composed of laminated sandstones, siltstones, argillites and siliceous rocks. Dropstones are often found within these sediments as well as cannon-ball carbonate concretions, some of them with glendonites in central part. 60-90% of the cannon-ball concretion is occupied by sandy limestone (with high-magnesium calcite) and occasionally contains dolomite and pyrite. Central part of the cannon-ball concretion is occupied by glendonite (single crystal-like or star-like cluster of crystals). Glendonites are composed of several calcite generations. Rosette-like calcite crystals (“ikaite-derived calcite”) are composed of low-magnesium calcite, they are non-luminescent. Needle-like calcite cement is composed of high-magnesium calcite or dolomite and show bright-yellow cathodoluminescence. The rest of the glendonite is occupied with low-magnesium radiaxial fibrous or sparry calcite with dark-red cathodoluminescence.

Isotopic ratios of glendonites are close to those of host concretions. For host concretions δ13С varies from -20.3 to -14.9 ‰PDB, δ18О varies from +1.7 to +2.7 ‰PDB; for glendonites δ13С varies from -18.1 to -1.9 ‰PDB, while δ18О varies from +0.7 to +3.4 ‰PDB.

Close mineralogical and isotopic composition of the studied glendonites and host cannon-ball concretions suggest they were formed in similar geochemical environment. Association of glendonite occurrence along with dropstones is an indicator of cold conditions, which is well-corresponding with view on glendonites as a proxy for cooling events. Cementation of surrounding sediment (formation of the cannon-ball concretions) and glendonite formation was simultaneous and occurred during early diagenesis in the sulfate-reduction zone. The source of calcium and magnesium ions was seawater (δ18О values are characteristic for seawater). Ikaite was replaced with low-magnesium calcite; the replacement was favored by organic matter decay (δ13C values are characteristic for organic matter). Cementation of the cannon-ball concretion with high-magnesium calcite occurred together with needle-like high-magnesium calcite growth in the glendonite with increasing concentration of magnesium due to calcite extraction from the pore water. The remaining pore space was subsequently filled with radiaxial fibrous or blocky sparry calcite during burial diagenesis.

The study is supported by RFBR, project number 20-35-70012.

How to cite: Vasileva, K., Ershova, V., Vereshchagin, O., Rogov, M., Tuchkova, M., Kostrov, Y., Khmarin, E., and Pokrovsky, B.: Multi-proxy study of cannon-ball concretions with glendonites from Paleogene-Neogene sediments of Sakhalin Island: implication for concretion growth and ikaite-calcite trans-formation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4041, https://doi.org/10.5194/egusphere-egu2020-4041, 2020

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  • CC1: Comment on EGU2020-4041, Madeleine Vickers, 04 May 2020

    Very interesting Miocene glendonites. What is the burial history of the section? Would it be possible to apply clumped isotope thermomtery and/or organic extraction with TEX86 temperature reconstructions?

    • CC2: Reply to CC1, Victoria Ershova, 04 May 2020

      Dear Madeleine, thank you for your comment.   We did not have RockEval data, but probably can find some  data from  previous papers . It would be interesting to apply  clumped isotope thermomtery and/or TEX86 temperature, but so far we do not have this equipment in house.

      Vika  Ershova 

      • CC3: Reply to CC2, Madeleine Vickers, 04 May 2020

        We have run clumped isotope analysis on Danish Eocene glendonites and got temerpatures of c. 5 C, which fits very well with what we understand about ikaite stabilisation temperatures. We are currently analysing glendonites from other localities and time periods to see if these low temperatures are always found or not (in fact I think we have some that Micha and Victoria provided from the Jurassic of Russia). We would be happy to run a pilot analysis of your miocene glendonites, if you were interested in collaboarting with us.

        • AC1: Reply to CC3, Kseniia Vasileva, 04 May 2020

          Thank you, Madeline for your offer. It would be great if we can collaborate on miocene glendonites and find out if studied glendonites preserved ikaite stabilization temperature during diagenesis.