Formation of amorphous calcium carbonate in caves and its implications for speleothem research

Attila Demény, Péter Németh, György Czuppon, Szabolcs Leél-Ossy, Máté Szabó, Katalin Judik, Tibor Németh, József Stieber

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Speleothem deposits are among the most valuable continental formations in paleoclimate research, as they can be dated using absolute dating methods, and they also provide valuable climate proxies. However, alteration processes such as post-depositional mineralogical transformations can significantly influence the paleoclimatic application of their geochemical data. An innovative sampling and measurement protocol combined with scanning and transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy is presented, demonstrating that carbonate precipitating from drip water in caves at ∼10 °C contains amorphous calcium carbonate (ACC) that later transforms to nanocrystalline calcite. Stable oxygen isotope fractionations among calcite, ACC and water were also determined, proving that ACC is 18O-depleted (by >2.4 ± 0.8‰) relative to calcite. This, in turn, has serious consequences for speleothem-based fluid inclusion research as closed system transformation of ACC to calcite may induce a negative oxygen isotope shift in fluid inclusion water, resulting in deterioration of the original compositions. ACC formation increases the speleothems' sensitivity to alteration as its interaction with external solutions may result in the partial loss of original proxy signals. Mineralogical analysis of freshly precipitating carbonate at the studied speleothem site is suggested in order to determine the potential influence of ACC formation.

Original languageEnglish
Article number39602
JournalScientific reports
Volume6
DOIs
Publication statusPublished - Dec 22 2016

ASJC Scopus subject areas

  • General

Fingerprint Dive into the research topics of 'Formation of amorphous calcium carbonate in caves and its implications for speleothem research'. Together they form a unique fingerprint.

  • Cite this

    Demény, A., Németh, P., Czuppon, G., Leél-Ossy, S., Szabó, M., Judik, K., Németh, T., & Stieber, J. (2016). Formation of amorphous calcium carbonate in caves and its implications for speleothem research. Scientific reports, 6, [39602]. https://doi.org/10.1038/srep39602