Early diagenesis of foraminiferal calcite under anoxic conditions:A case study from the Landsort Deep, Baltic Sea (IODP Site M0063)
| Autor: | N. B. Quintana Krupinski, Inda Brinkmann, K.L. Knudsen, Helena L. Filipsson, Marit-Solveig Seidenkrantz, Jeroen Groeneveld, A. Somogyi, Per Persson, Sha Ni |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Calcite
010504 meteorology & atmospheric sciences biology Elphidium Geochemistry Trace element Geology Authigenic 010502 geochemistry & geophysics biology.organism_classification 01 natural sciences Anoxic waters Diagenesis Foraminifera chemistry.chemical_compound chemistry 13. Climate action Geochemistry and Petrology Carbonate 14. Life underwater 0105 earth and related environmental sciences |
| Zdroj: | Ni, S, Quintana Krupinski, N B, Groeneveld, J, Persson, P, Somogyi, A, Brinkmann, I, Knudsen, K L, Seidenkrantz, M S & Filipsson, H L 2020, ' Early diagenesis of foraminiferal calcite under anoxic conditions : A case study from the Landsort Deep, Baltic Sea (IODP Site M0063) ', Chemical Geology, vol. 558, 119871 . https://doi.org/10.1016/j.chemgeo.2020.119871 Chemical Geology |
| DOI: | 10.1016/j.chemgeo.2020.119871 |
| Popis: | The chemical composition of foraminiferal calcite is widely used for studying past environmental conditions and biogeochemistry. However, high rates of microbial organic matter degradation and abundant dissolved metal sources in sediments and pore waters may impede the application of foraminifera-based proxies due to formation of secondary carbonates or other authigenic minerals on and/or inside of foraminiferal tests. Secondary carbonate precipitation severely alters the bulk foraminiferal geochemistry and can be difficult to eliminate through standard foraminiferal trace element cleaning procedures. We present results showing the mineral composition and formation sequence of diagenetic coatings on foraminiferal tests formed under extreme anoxic conditions in the Baltic Sea's deepest basin (the Landsort Deep, IODP Exp. 347, Site M0063). Our study focuses primarily on the diagenetic carbonates present on and in the tests of the low-oxygen tolerant benthic foraminiferal species Elphidium selseyensis and Elphidium clavatum. We applied various geochemical and imaging methods to ascertain the diagenesis processes and the authigenic mineral formation sequence on foraminifera. The authigenic carbonates were enriched in Mn, Mg, Fe and Ba, depending on the environmental redox conditions when the authigenic carbonates were precipitated. Concentrations of redox-sensitive elements such as Mn and Fe were particularly elevated in bottom waters and sedimentary pore waters under oxygen-depleted conditions in the Landsort Deep, resulting in formation of carbonates with highly elevated Mn and Fe contents. In addition to Mn- and Fe carbonates, several other types of authigenic minerals also formed on and in the foraminiferal chambers, including authigenic calcite, and non-carbonate accessory minerals. The formation sequence reveals the redox sensitivities of different elements and the preferential sequence of oxidants used by the microbes during organic matter oxidation and secondary redox reactions. This study provides a case study of extreme early diagenesis of foraminiferal calcite and may serve as a valuable guide when interpreting foraminiferal trace element records from low oxygen environments. |
| Databáze: | OpenAIRE |
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