Cited by 15Geochemistry and Elemental AnalysisPaleontology and Stratigraphy of FossilsGeology and Paleoclimatology Research

Assessment of Factors Controlling Clumped Isotopes and δ18O Values of Hydrothermal Vent Calcites

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Kluge, Tobias, John, Cédric M., Boch, Ronny, Kele, Sándor·2018·Geochemistry, Geophysics, Geosystems

Abstract

The clumped isotope composition of CaCO 3 (Δ 47) is a geochemical proxy that can provide mineral formation temperatures and, together with measured carbonate δ 18 O, inferred fluid δ 18 O values. Under natural conditions, carbonates form within a relatively wide pH range and varying growth rates which are typically not reflected in laboratory‐based calibrations (mostly ∼pH 8, moderate growth rates). A pH and growth‐rate dependence is known for oxygen isotopes and was also postulated for clumped isotopes. Theoretical predictions suggest that Δ 47 values could lie between the carbonate equilibrium value and the value inherited from the dissolved inorganic carbon (predicted offset: +0.04‰ pH < 4 and −0.025‰ at high pH > 12). Here we test whether pH (in addition to temperature) is recorded in the carbonate clumped isotope composition using modern calcites from natural travertine‐forming streams and scales precipitated in pipes of deep geothermal wells from Italy, Hungary, and Turkey (pH: 6.1–7.5, T: 33–100°C). Although a comparison of all samples with expected equilibrium values in this pH range and known formation temperatures reveals only an insignificant Δ 47 offset (0.006 ± 0.004‰, 1SE, n = 9), the clumped isotope values of samples with the highest growth rates (0.014 ± 0.007‰, 1SE, n = 5) are consistent with the theoretical prediction attributable to pH of 0.01‰. Similarly, deviations in δ 18 O of up to −2‰ follow a growth‐rate dependence. This field‐based study shows that pH‐related effects are mostly small for Δ 47 in the subsurface environment at lower pH and that high mineral growth rates control the magnitude of this disequilibrium.

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Crossref · 10.1029/2017gc006969

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  • Mineral precipitation occurring over a period of months removes the possibility of any pH-related disequilibrium effect being recorded in carbonate clumped isotope values.

    “Mineral precipitation occurring over a period of months removes the possibility of any pH-related disequilibrium effect being recorded in carbonate clumped isotope values (Hill et al., 2014;Kluge et al., 2018;Tripati et al., 2015).”

    From Reconstructing the temperature and origin of CO2 mineralisation in CarbFix calcite using clumped, carbon and oxygen isotopes (2024) · cites this paper as Kluge et al., 2018

    Section 5 (Discussion) says that carbonate scales growing at 1–10 mm per year should have the potential to record isotopic disequilibrium. Section 5.4 (Implications) makes preservation depend on growth rate relative to isotope equilibration, pH, and temperature—not on a categorical months-long cutoff. No page numbers are available in our copy. (LLM, conf=0.85)

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  • The equilibration time for oxygen isotopes in DIC and water with a pH and temperature of monitoring well fluids at the pump depth (8.5 at 45°C) is 1-2 h.

    “This is because the equilibration time for oxygen isotopes in DIC and water with a pH and temperature of monitoring well fluids at the pump depth (8.5 at 45 • C) is 1-2 h (Kluge et al., 2018;Uchikawa and Zeebe, 2012;Watkins et al., 2013).”

    From Reconstructing the temperature and origin of CO2 mineralisation in CarbFix calcite using clumped, carbon and oxygen isotopes (2024) · cites this paper as Kluge et al., 2018

    Section 5.4 (page unavailable) says oxygen-isotope equilibration between DIC species and water depends on pH and temperature, and becomes slower as pH rises. Our copy does not give a 1–2-hour equilibration time at pH 8.5 and 45°C or relate that estimate to monitoring-well fluids at pump depth. (LLM, conf=0.84)

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Research works printed but not linked: 1

  1. Mook, W. G. (2000). Environmental isotopes in the hydrological cycle: Principles and applications. In W. G. Mook (Ed.), Introduction, theory, methods, review. IHP-V: Technical documents in hydrology (Vol. 1, No. 39). Paris, France: UNESCO.

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Authors
Kluge, T., John, C. M., Boch, R., & Kele, S.
Affiliations
  • Heidelberg University (DE)
  • Imperial College London (GB)
  • Graz University of Technology (AT)
  • Institute for Geological and Geochemical Research (HU)
Corresponding author
Kluge, Tobias
Venue
Geochemistry, Geophysics, Geosystems
Published
2018-06
Volume
19
Issue
6
Pages
1844-1858
ISSN
1525-2027 (ISSN-L)
OpenAlex
W2800140460
Cited by
14
References
96
Citations by year
2024: 1 · 2023: 2 · 2022: 2 · 2021: 3 · 2020: 2 · 2019: 2 · 2018: 2
FWCI
1.86
Type
journal article
Language
en
Open access
Locations
  • Geochemistry Geophysics Geosystems (publishedVersion)
  • Spiral (Imperial College London) (submittedVersion)
Funders
  • Hungarian Academy of Sciences and the Hungarian Scientific Research Fund (OTKA 101664, KH 125584)
  • NKFIH
Topics
  • Physical Sciences › Earth and Planetary Sciences › Geochemistry and Petrology › Geochemistry and Elemental Analysis
  • Physical Sciences › Earth and Planetary Sciences › Paleontology › Paleontology and Stratigraphy of Fossils
  • Physical Sciences › Earth and Planetary Sciences › Atmospheric Science › Geology and Paleoclimatology Research
Keywords
clumped isotopes, pH dependence, growth rate (crystal and thin-film growth), travertine, oxygen isotopes

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