Back to search
Munnecke et al., 2023

The origins and transformation of carbonate mud during early marine burial diagenesis and the fate of aragonite: A stratigraphic sedimentological perspective

Munnecke, A., Wright, V. P., Nohl, T.
DOI
DOI10.1016/j.earscirev.2023.104366
Year2023
JournalEarth-Science Reviews
Volume239
Pages104366
Typearticle in journal
LanguageEnglish
Id47292

Abstract

The current understanding of the origins of modern carbonate muds and their early stages of transformations are reviewed. The fine-grained nature of such sediments makes them susceptible to intensive structural and chemical alteration at relatively shallow burial depths driven especially by mineral instability under microbially mediated reactions within the sediment associated with the decay of organic matter. Whereas the transformation of high Mg calcite (HMC) to low magnesian calcite (LMC) generally takes place incongruently and in situ, that of aragonite is predominantly via congruent dissolution. The loss of aragonite produces a huge potential flux of carbonate which is translocated within the sediment. Parallel to studies on Quaternary sediments, investigations in the stratigraphic record have shown that in low-energy settings the transformation of the aragonite component leads to the formation of diagenetic bedding (such as limestone-marl-alternations or LMAs), and related bipartite lithologies, some types of hardgrounds, secondary carbonate mudrocks, and to the significant modification of the original skeletal biota. There are uncertainties such as the exact sources for the precursor aragonite, where the released carbonates reprecipitate in the shallow sediment column, how much carbonate (and hence carbon) is back-fluxed to the water column, how this affects palaeoenvironmental proxies, and the environmental distributions of these processes. The evidence from the stratigraphic record, from settings where organic matter was able to accumulate promoting these transformations, is that these changes in carbonate-rich sediments took place very early, at shallow (decametre or less) burial depths, affecting what we now see from the micron to the outcrop scale. The complexity and inter-relationships of these fundamental processes has received more attention in recent years, though their implications still seem remarkably undervalued.

Last change: 13.11.2023
KIKNATARCSARVTÜ Loodusmuuseumi geokogudEesti Loodusmuuseumi geoloogia osakond
All materials in the portal are for free usage according to CC BY-SA , unless indiated otherwise.
Portal is part of natianal research infrastructure and geoscience data platform SARV, hosted by TalTech.
Open Book icon by Icons8.