Sulfur isotope fractionation between aqueous and carbonate-associated sulfate in abiotic calcite and aragonite
Journal Article
·
· Geochimica et Cosmochimica Acta
- Weizmann Inst. of Science, Rehovot (Israel)
- California Inst. of Technology (CalTech), Pasadena, CA (United States); Univ. de Lorraine (France)
- SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)
- California Inst. of Technology (CalTech)
Sulfate (SO42–) incorporated into calcium carbonate minerals enables measurements of sulfur (S) isotope ratios in carbonate rocks. This Carbonate Associated Sulfate (CAS) in marine carbonate minerals is thought to faithfully represent the S isotope composition of the seawater sulfate incorporated into the mineral, with little or no S isotope fractionation in the process. However, comparison between different calcifying species reveals both positive and negative S isotope fractionation between CAS and seawater sulfate, and a large range of S isotope ratios can be found within a single rock sample, depending on the component measured. To better understand the isotopic effects associated with sulfate incorporation into carbonate minerals, we precipitated inorganic calcite and aragonite over a range covering more than two orders of magnitude of sulfate concentration and precipitation rate. Coupled measurements of CAS concentration, S isotope composition and X-ray absorption near-edge spectra (XANES) permit characterization and explanation of the observed dependence of S isotope fractionation between CAS and aqueous sulfate (CAS-SO42– isotope fractionation) on sulfate concentration and precipitation rate. In aragonite, the CAS-SO42– isotope fractionation is 1.0 ± 0.3‰ and independent of the sulfate (and CAS) concentration. In contrast, we note the CAS-SO42– isotope fractionation in calcite covaries strongly with the sulfate concentration and weakly with the precipitation rate, between values of 1.3 ± 0.1 and 3.1 ± 0.6‰. We suggest that the correlation between aqueous sulfate concentration and CAS-SO42– isotope fractionation in calcite reflects a dependence of the equilibrium S isotope fractionation on the concentration of CAS, through the effect of the sulfate impurity on the carbonate mineral’s energetic state.
- Research Organization:
- SLAC National Accelerator Laboratory, Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)
- Sponsoring Organization:
- European Research Council (ERC); USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC02-76SF00515
- OSTI ID:
- 1637646
- Alternate ID(s):
- OSTI ID: 1775796
- Journal Information:
- Geochimica et Cosmochimica Acta, Journal Name: Geochimica et Cosmochimica Acta Journal Issue: C Vol. 280; ISSN 0016-7037
- Publisher:
- Elsevier; The Geochemical Society; The Meteoritical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Relative growth rates and compositions of aragonite and MG calcite cements in seawater: effects of temperature and sulfate
Morphological and crystallographic controls in the replacement of calcite and aragonite by cerussite and otavite
Carbonate “clumped” isotope signatures in aragonitic scleractinian and calcitic gorgonian deep-sea corals
Conference
·
Mon Dec 31 23:00:00 EST 1984
· Geol. Soc. Am., Abstr. Programs; (United States)
·
OSTI ID:6643240
Morphological and crystallographic controls in the replacement of calcite and aragonite by cerussite and otavite
Journal Article
·
Mon Nov 14 19:00:00 EST 2022
· Geochimica et Cosmochimica Acta
·
OSTI ID:2426384
Carbonate “clumped” isotope signatures in aragonitic scleractinian and calcitic gorgonian deep-sea corals
Journal Article
·
Sun Dec 11 19:00:00 EST 2016
· Biogeosciences (Online)
·
OSTI ID:1335183