Using Mg Isotopes to Estimate Natural Calcite Compositions and Precipitation Rates During the 2010 Eyjafjallajökull Eruption

Pogge von Strandmann, Philip A.E.; Olsson, Jonas; Luu, Tu-Han; Gislason, Sigurður R.; Burton, Kevin W.

doi:10.3389/feart.2019.00006

Using Mg Isotopes to Estimate Natural Calcite Compositions and Precipitation Rates During the 2010 Eyjafjallajökull Eruption

Pogge von Strandmann, Philip A.E.; Olsson, Jonas; Luu, Tu-Han; Gislason, Sigurður R.; Burton, Kevin W.

Authors

Philip A.E. Pogge von Strandmann

Jonas Olsson

Tu-Han Luu

Sigurður R. Gislason

Professor Kevin Burton kevin.burton@durham.ac.uk
Professor

Abstract

Chemical weathering of silicate rocks is a key control on the long-term climate, via drawdown of atmospheric CO2. Magnesium isotopes are increasingly being used to trace weathering, but are often complicated by several coincident fractionating processes. Here we examine Mg isotope ratios of waters stemming from beneath lava flows from the 2010 Eyjafjallajökull eruption. Travertine calcite was observed directly precipitating from these high-TDS (total dissolved solids) waters, and were also sampled. This system therefore provides the opportunity to study natural Mg isotope fractionation by calcite. Riverine δ26Mg increase from −2.37 to +0.43% with flow distance, as isotopically light travertine precipitates (δ26Mg = −3.38 to −3.94%). The solution Mg isotope ratios also co-vary with pH, calcite saturation indices and Sr/Ca ratios, strongly indicating that they are dominantly controlled by carbonate precipitation. Using experimental isotopic fractionation factors and the measured δ26Mg values, we can predict the compositions of the precipitated travertines that are within uncertainty of the directly measured travertines. Hence, in some systems, Mg isotopes can be used to quantify carbonate precipitation.

Citation

Pogge von Strandmann, P. A., Olsson, J., Luu, T., Gislason, S. R., & Burton, K. W. (2019). Using Mg Isotopes to Estimate Natural Calcite Compositions and Precipitation Rates During the 2010 Eyjafjallajökull Eruption. Frontiers in Earth Science, 7, Article 6. https://doi.org/10.3389/feart.2019.00006

Journal Article Type	Article
Acceptance Date	Jan 17, 2019
Online Publication Date	Feb 1, 2019
Publication Date	Feb 1, 2019
Deposit Date	Mar 7, 2019
Publicly Available Date	Mar 7, 2019
Journal	Frontiers in Earth Science
Publisher	Frontiers Media
Peer Reviewed	Peer Reviewed
Volume	7
Article Number	6
DOI	https://doi.org/10.3389/feart.2019.00006

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Copyright Statement
Copyright © 2019 Pogge von Strandmann, Olsson, Luu, Gislason and Burton. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.