Effect of growth rate and pH on Li isotope fractionation during its incorporation in calcite

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F22%3A00000167" target="_blank" >RIV/00025798:_____/22:00000167 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/pii/S0016703722000795" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0016703722000795</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.gca.2022.02.014" target="_blank" >10.1016/j.gca.2022.02.014</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Effect of growth rate and pH on Li isotope fractionation during its incorporation in calcite

Popis výsledku v původním jazyce

Lithium isotope compositions were determined for synthetic calcite and fluid, reported in Füger et al. (2019). Calcite wasprecipitated at 25 C, and mineral growth rate and pH varied within the range of 10-8.1 < rp (mol m-2 s-1) < 10-7.2 and6.3 < pH < 9.5, respectively. At pH = 8.25 ± 0.15, the D7Licalcite-fluid = d7Licalcite - d7Lifluid value of -2.76 ± 0.22per mille(n = 4) was yielded when calcite growth rate was lower than ~ 10-7.7 (mol m-2 s-1). As calcite growth rate increased,D7Licalcite-fluid values progressively decreased to about -4.5per mille. The dependence of Li isotope fractionation on calcite growthrate is described by the surface reaction kinetic model developed by DePaolo (2011). In this model the equilibrium and kineticisotope fractionation factors obtain values of -2.7 ± 0.1per mille and -8.8 ± 0.1per mille, respectively. In addition, for experiments performedunder similar surface-normalized growth rate of 10-7.7±0.2 (mol m-2 s-1) a significant decrease in D7Licalcite-fluid frompH 9.5 to 6.3 was observed. These variations of D7Licalcite-fluid as a function of pH for experiments performed under lowdegrees of solution saturation with respect to calcite point towards the incorporation of two or more Li-bearing species inthe solid phase. Thus, the Li isotope composition of the solid reflects the abundance of these species, which depends on solutionpH and fluid composition.Overall the results of this study suggest that both calcite growth rate and pH are parameters that can significantly affect themeasured Li isotope fractionation between calcite and fluid. The high sensitivity of D7Licalcite-fluid to calcite growth rateobserved in this study suggests that a high variability of d7Licalcite in natural samples, such as foraminifera, brachiopods,and speleothems can be expected in natural environments. The implications for the potential use of elemental and isotopefractionation of Li during calcite formation are discussed in the light of reconstruction of paleo-environmental conditions.

Název v anglickém jazyce

Effect of growth rate and pH on Li isotope fractionation during its incorporation in calcite

Popis výsledku anglicky

Lithium isotope compositions were determined for synthetic calcite and fluid, reported in Füger et al. (2019). Calcite wasprecipitated at 25 C, and mineral growth rate and pH varied within the range of 10-8.1 < rp (mol m-2 s-1) < 10-7.2 and6.3 < pH < 9.5, respectively. At pH = 8.25 ± 0.15, the D7Licalcite-fluid = d7Licalcite - d7Lifluid value of -2.76 ± 0.22per mille(n = 4) was yielded when calcite growth rate was lower than ~ 10-7.7 (mol m-2 s-1). As calcite growth rate increased,D7Licalcite-fluid values progressively decreased to about -4.5per mille. The dependence of Li isotope fractionation on calcite growthrate is described by the surface reaction kinetic model developed by DePaolo (2011). In this model the equilibrium and kineticisotope fractionation factors obtain values of -2.7 ± 0.1per mille and -8.8 ± 0.1per mille, respectively. In addition, for experiments performedunder similar surface-normalized growth rate of 10-7.7±0.2 (mol m-2 s-1) a significant decrease in D7Licalcite-fluid frompH 9.5 to 6.3 was observed. These variations of D7Licalcite-fluid as a function of pH for experiments performed under lowdegrees of solution saturation with respect to calcite point towards the incorporation of two or more Li-bearing species inthe solid phase. Thus, the Li isotope composition of the solid reflects the abundance of these species, which depends on solutionpH and fluid composition.Overall the results of this study suggest that both calcite growth rate and pH are parameters that can significantly affect themeasured Li isotope fractionation between calcite and fluid. The high sensitivity of D7Licalcite-fluid to calcite growth rateobserved in this study suggests that a high variability of d7Licalcite in natural samples, such as foraminifera, brachiopods,and speleothems can be expected in natural environments. The implications for the potential use of elemental and isotopefractionation of Li during calcite formation are discussed in the light of reconstruction of paleo-environmental conditions.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2022

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Geochimica et Cosmochimica Acta

ISSN

0016-7037

e-ISSN

—

Svazek periodika

323

Číslo periodika v rámci svazku

April 15

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

15

Strana od-do

276-290

Kód UT WoS článku

000831742200009

EID výsledku v databázi Scopus

2-s2.0-85126269822