Lithium isotopes in dolostone as a palaeo-environmental proxy – An experimental approach

Isaac John Kell Duivestein, Holly Taylor, Juraj Farkas, Anthony Dosseto, Martin Dietzel

Publikation: Beitrag in einer FachzeitschriftArtikelForschungBegutachtung

Abstract

Lithium (Li) isotopes in marine carbonates have considerable potential as a proxy to constrain past changes in silicate weathering fluxes and improve our understanding of Earth’s climate. To date the majority of Li isotope studies on marine carbonates have focussed on calcium carbonates. Determination of the Li isotope fractionation between dolomite and a dolomitizing fluid, would allow us to extend investigations to deep times (i.e., Precambrian) when dolostones were the most abundant marine carbonate archives. Dolostones often contain a significant proportion of detrital silicate material, which dominates the Li budget, thus pre-treatment needs to be designed so that only the isotope composition of the carbonate-associated Li is measured. This study aims to serve two main goals: (1) determining the Li isotope fractionation between Ca-Mg carbonates and solution and (2) to develop a method for leaching the carbonate-associated Li out of dolostone while not affecting that contained within the detrital portion of the rock. We synthesized Ca-Mg carbonates at high temperature (150 to 220 °C) and measured the Li isotope composition (δ7Li) of precipitated solids and their respective reactive solutions. The relationship of the Li isotope fractionation factor with temperature was obtained: 10#푙푛훼'()*+,-. = −(2.45 ± 8.29)×<8= >? 42 + (5.8 ± 1.3) Competitive nucleation and growth between dolomite and magnesite were observed during the experiments, however, without notable effect of their relative proportion on the apparent Li isotope fractionation. We found that Li isotope fractionation between precipitated solid and solution is much greater for Ca-Mg carbonates than for Ca carbonates. If the seawater temperature can be estimated independently, the above equation could be used in conjunction with the Li isotope composition of dolostones to derive those of the precipitating solutions and hence make inferrals about the past oceanic Li cycle.
Originalspracheenglisch
Seiten (von - bis)635-646
FachzeitschriftClimate of the Past
Jahrgang15
DOIs
PublikationsstatusVeröffentlicht - Apr 2019

Fingerprint

dolostone
lithium
isotope
carbonate
fractionation
dolomite
silicate
magnesite
calcium carbonate
nucleation
Precambrian
weathering

Dies zitieren

Lithium isotopes in dolostone as a palaeo-environmental proxy – An experimental approach. / Kell Duivestein, Isaac John; Taylor, Holly; Farkas, Juraj; Dosseto, Anthony; Dietzel, Martin.

in: Climate of the Past, Jahrgang 15, 04.2019, S. 635-646.

Publikation: Beitrag in einer FachzeitschriftArtikelForschungBegutachtung

Kell Duivestein, Isaac John ; Taylor, Holly ; Farkas, Juraj ; Dosseto, Anthony ; Dietzel, Martin. / Lithium isotopes in dolostone as a palaeo-environmental proxy – An experimental approach. in: Climate of the Past. 2019 ; Jahrgang 15. S. 635-646.
@article{d87423b7326340ceaa459396e33149a2,
title = "Lithium isotopes in dolostone as a palaeo-environmental proxy – An experimental approach",
abstract = "Lithium (Li) isotopes in marine carbonates have considerable potential as a proxy to constrain past changes in silicate weathering fluxes and improve our understanding of Earth’s climate. To date the majority of Li isotope studies on marine carbonates have focussed on calcium carbonates. Determination of the Li isotope fractionation between dolomite and a dolomitizing fluid, would allow us to extend investigations to deep times (i.e., Precambrian) when dolostones were the most abundant marine carbonate archives. Dolostones often contain a significant proportion of detrital silicate material, which dominates the Li budget, thus pre-treatment needs to be designed so that only the isotope composition of the carbonate-associated Li is measured. This study aims to serve two main goals: (1) determining the Li isotope fractionation between Ca-Mg carbonates and solution and (2) to develop a method for leaching the carbonate-associated Li out of dolostone while not affecting that contained within the detrital portion of the rock. We synthesized Ca-Mg carbonates at high temperature (150 to 220 °C) and measured the Li isotope composition (δ7Li) of precipitated solids and their respective reactive solutions. The relationship of the Li isotope fractionation factor with temperature was obtained: 10#푙푛훼'()*+,-. = −(2.45 ± 8.29)×<8= >? 42 + (5.8 ± 1.3) Competitive nucleation and growth between dolomite and magnesite were observed during the experiments, however, without notable effect of their relative proportion on the apparent Li isotope fractionation. We found that Li isotope fractionation between precipitated solid and solution is much greater for Ca-Mg carbonates than for Ca carbonates. If the seawater temperature can be estimated independently, the above equation could be used in conjunction with the Li isotope composition of dolostones to derive those of the precipitating solutions and hence make inferrals about the past oceanic Li cycle.",
author = "{Kell Duivestein}, {Isaac John} and Holly Taylor and Juraj Farkas and Anthony Dosseto and Martin Dietzel",
year = "2019",
month = "4",
doi = "10.5194/cp-15-635-2019",
language = "English",
volume = "15",
pages = "635--646",
journal = "Climate of the Past",
issn = "1814-9324",
publisher = "Copernicus Publications",

}

TY - JOUR

T1 - Lithium isotopes in dolostone as a palaeo-environmental proxy – An experimental approach

AU - Kell Duivestein, Isaac John

AU - Taylor, Holly

AU - Farkas, Juraj

AU - Dosseto, Anthony

AU - Dietzel, Martin

PY - 2019/4

Y1 - 2019/4

N2 - Lithium (Li) isotopes in marine carbonates have considerable potential as a proxy to constrain past changes in silicate weathering fluxes and improve our understanding of Earth’s climate. To date the majority of Li isotope studies on marine carbonates have focussed on calcium carbonates. Determination of the Li isotope fractionation between dolomite and a dolomitizing fluid, would allow us to extend investigations to deep times (i.e., Precambrian) when dolostones were the most abundant marine carbonate archives. Dolostones often contain a significant proportion of detrital silicate material, which dominates the Li budget, thus pre-treatment needs to be designed so that only the isotope composition of the carbonate-associated Li is measured. This study aims to serve two main goals: (1) determining the Li isotope fractionation between Ca-Mg carbonates and solution and (2) to develop a method for leaching the carbonate-associated Li out of dolostone while not affecting that contained within the detrital portion of the rock. We synthesized Ca-Mg carbonates at high temperature (150 to 220 °C) and measured the Li isotope composition (δ7Li) of precipitated solids and their respective reactive solutions. The relationship of the Li isotope fractionation factor with temperature was obtained: 10#푙푛훼'()*+,-. = −(2.45 ± 8.29)×<8= >? 42 + (5.8 ± 1.3) Competitive nucleation and growth between dolomite and magnesite were observed during the experiments, however, without notable effect of their relative proportion on the apparent Li isotope fractionation. We found that Li isotope fractionation between precipitated solid and solution is much greater for Ca-Mg carbonates than for Ca carbonates. If the seawater temperature can be estimated independently, the above equation could be used in conjunction with the Li isotope composition of dolostones to derive those of the precipitating solutions and hence make inferrals about the past oceanic Li cycle.

AB - Lithium (Li) isotopes in marine carbonates have considerable potential as a proxy to constrain past changes in silicate weathering fluxes and improve our understanding of Earth’s climate. To date the majority of Li isotope studies on marine carbonates have focussed on calcium carbonates. Determination of the Li isotope fractionation between dolomite and a dolomitizing fluid, would allow us to extend investigations to deep times (i.e., Precambrian) when dolostones were the most abundant marine carbonate archives. Dolostones often contain a significant proportion of detrital silicate material, which dominates the Li budget, thus pre-treatment needs to be designed so that only the isotope composition of the carbonate-associated Li is measured. This study aims to serve two main goals: (1) determining the Li isotope fractionation between Ca-Mg carbonates and solution and (2) to develop a method for leaching the carbonate-associated Li out of dolostone while not affecting that contained within the detrital portion of the rock. We synthesized Ca-Mg carbonates at high temperature (150 to 220 °C) and measured the Li isotope composition (δ7Li) of precipitated solids and their respective reactive solutions. The relationship of the Li isotope fractionation factor with temperature was obtained: 10#푙푛훼'()*+,-. = −(2.45 ± 8.29)×<8= >? 42 + (5.8 ± 1.3) Competitive nucleation and growth between dolomite and magnesite were observed during the experiments, however, without notable effect of their relative proportion on the apparent Li isotope fractionation. We found that Li isotope fractionation between precipitated solid and solution is much greater for Ca-Mg carbonates than for Ca carbonates. If the seawater temperature can be estimated independently, the above equation could be used in conjunction with the Li isotope composition of dolostones to derive those of the precipitating solutions and hence make inferrals about the past oceanic Li cycle.

U2 - 10.5194/cp-15-635-2019

DO - 10.5194/cp-15-635-2019

M3 - Article

VL - 15

SP - 635

EP - 646

JO - Climate of the Past

JF - Climate of the Past

SN - 1814-9324

ER -