Javascript är avstängt eller blockerat i din webbläsare. Detta kan leda till att vissa delar av vår webbplats inte fungerar som de ska. Sätt på javascript för optimal funktionalitet och utseende.

Webbläsaren som du använder stöds inte av denna webbplats. Alla versioner av Internet Explorer stöds inte längre, av oss eller Microsoft (läs mer här: * https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Var god och använd en modern webbläsare för att ta del av denna webbplats, som t.ex. nyaste versioner av Edge, Chrome, Firefox eller Safari osv.

Helena Filipsson, foto Erik Thor

Helena Filipsson

Professor

Helena Filipsson, foto Erik Thor

Early diagenesis of foraminiferal calcite under anoxic conditions : A case study from the Landsort Deep, Baltic Sea (IODP Site M0063)

Författare

  • S. Ni
  • N. B. Quintana Krupinski
  • J. Groeneveld
  • P. Persson
  • A. Somogyi
  • I. Brinkmann
  • K. L. Knudsen
  • M. S. Seidenkrantz
  • H. L. Filipsson

Summary, in English

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.

Avdelning/ar

  • Centrum för miljö- och klimatvetenskap (CEC)
  • Kvartärgeologi
  • Mikrobiologisk ekologi
  • MEMEG

Publiceringsår

2020-12-30

Språk

Engelska

Publikation/Tidskrift/Serie

Chemical Geology

Volym

558

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Geology

Status

Published

Projekt

  • Tracing marine hypoxic conditions during warm periods using a microanalytical approach
  • Lund University Centre for studies of Carbon Cycle and Climate Interactions

Forskningsgrupp

  • Microbial Ecology

ISBN/ISSN/Övrigt

  • ISSN: 0009-2541