Patterns and controls of disequilibrium isotope effects in speleothems: Insights from an isotope-enabled diffusion-reaction model and implications for quantitative thermometry

Guo, Weifu; Zhou, Chen

doi:10.1016/j.gca.2019.07.028

Cited by 54 publications

(71 citation statements)

References 110 publications

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“…Most carbonates in our study exhibit systematic departures from the clumped isotope equilibrium line (Eqs. (1-3)) that are consistent with the model predictions 26,27 , supporting that CO 2 absorption and CO 2 degassing reactions are the primary drivers for the observed departures from isotopic equilibrium (Fig. 3a).…”

Section: Discussionsupporting

confidence: 80%

“…However, as the forward reaction progresses and the product concentration increases, the backward reaction will become more and more significant until the forward and backward reaction rates become identical and the isotopic equilibrium is attained again (Fig. 3a) 26,27 . The exact pattern and extent of these disequilibrium effects during CO 2 absorption and CO 2 degassing depend on several parameters 26,27 , such as solution temperature, pH, the isotopic compositions of the gaseous CO 2 and the solution, and for calcifying organisms, carbonic anhydrase activity that facilitates the interconversion between dissolved carbon dioxide and bicarbonate ( Fig.…”

Section: Discussionmentioning

confidence: 99%

“…(4) and (5)), increases the saturation state of calcium carbonate and leads to carbonate precipitation 6,27,41,42 . In the early stages of CO 2 degassing, carbonate Δ 47 values are expected to show a negative offset and Δ 48 values to show a positive offset from equilibrium 27 (Fig. 3a, Supplementary Data 5).…”

Section: Discussionmentioning

confidence: 99%

“…Projecting the measured carbonate isotope composition to the equilibrium Δ 47 and Δ 48 line (Eq. (3)) along these predicted linear kinetic trajectories, shall yield their actual formation temperatures, unbiased by kinetic effects 26,27 . Specifically, this leads to temperature estimates of 34(±9)°C, 2(±7)°C, 1(±5)°C, and 34(±6)°C for the synthetic speleothem, the stalagmite, the cold-water coral, and the warm-water coral, respectively (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…(2) To model the isotopic composition of the synthetic speleothem, simulations were constructed using the IsoCave model 27 , based on the conditions of the laboratory experiment 55…”

Section: Methodsmentioning

confidence: 99%

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Dual clumped isotope thermometry resolves kinetic biases in carbonate formation temperatures

et al. 2020

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Surface temperature is a fundamental parameter of Earth's climate. Its evolution through time is commonly reconstructed using the oxygen isotope and the clumped isotope compositions of carbonate archives. However, reaction kinetics involved in the precipitation of carbonates can introduce inaccuracies in the derived temperatures. Here, we show that dual clumped isotope analyses, i.e., simultaneous Δ 47 and Δ 48 measurements on the single carbonate phase, can identify the origin and quantify the extent of these kinetic biases. Our results verify theoretical predictions and evidence that the isotopic disequilibrium commonly observed in speleothems and scleractinian coral skeletons is inherited from the dissolved inorganic carbon pool of their parent solutions. Further, we show that dual clumped isotope thermometry can achieve reliable palaeotemperature reconstructions, devoid of kinetic bias. Analysis of a belemnite rostrum implies that it precipitated near isotopic equilibrium and confirms the warmer-than-present temperatures during the Early Cretaceous at southern high latitudes.

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…(2) To model the isotopic composition of the synthetic speleothem, simulations were constructed using the IsoCave model 27 , based on the conditions of the laboratory experiment 55…”

Section: Methodsmentioning

confidence: 99%

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Dual clumped isotope thermometry resolves kinetic biases in carbonate formation temperatures

et al. 2020

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Paired dual carbonate clumped isotopes (Δ47-Δ48) constrains kinetic effects and timescales in peridotite-associated springs at The Cedars, Northern California

Parvez

Matamoros

Rubi

et al. 2022

Preprint

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Eagle-Tripati LaboratoriesGuide for clumped isotope data quality assessment, including measurement flagging December 2022 J. Lucarelli and A. Tripati • Definitions:○ Data quality assessment: the process of assessing if data are reproducible, including identifying if there were statistical outliers that may arise due to incomplete sample digestion, voltage fluctuations, exchange with water, carousel not advancing properly, or other processes relating to sample reaction, purification, and measurement, etc., resulting in an erroneous measurement or non-representative value ○ Flagging: identifying a statistical outlier that you hypothesize is due to an erroneous measurement or is not representative of the sample, that you think should not be included in calculations.■ You need ≥3 replicates to begin flagging. ○ Outlier: an observation that statistically lies an abnormal distance from other values in a random sample from a population. ○ Exclusion: removal of an analysis from the population.■ Before excluding a replicate, talk to Aradhna/Rob and Ben about why it's being excluded -there may be a solution to the issue. ■ You must include detailed notes on the justification in both the run log and in Easotope, after discussion with Aradhna/Rob and Ben ○ Standard deviation: a measure of the amount of variation or dispersion of a set of values.A low standard deviation indicates that the values tend to be close to the mean (also called the expected value) of the set, while a high standard deviation indicates that the values are spread out over a wider range.

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Dual carbonate clumped isotopes (Δ47-Δ48) constrains kinetic effects and timescales in peridotite-associated springs at The Cedars, Northern California

Parvez

Lucarelli

Matamoros

et al. 2023

Preprint

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The Cedars is an area in Northern California with a chain of highly alkaline springs resulting from CO-charged meteorological water interacting with a peridotite body. Serpentinization resulting from this interaction at depth leads to the sequestration of various carbonate minerals into veins accompanied by a release of Ca and OH enriched water to the surface, creating an environment which promotes rapid precipitation of CaCO at surface springs. This environment enables us to apply the recently developed Δ-Δ dual clumped isotope analysis to probe kinetic isotope effects (KIEs) and timescales of CO transformation in a region with the potential for geological CO sequestration. We analyzed CaCO recovered from various localities and identified significant kinetic fractionations associated with CO absorption in a majority of samples, characterized by enrichment in Δ values and depletion in Δ values relative to equilibrium. Surface floes exhibited the largest KIEs (ΔΔ: 0.163‰, ΔΔ: -0.761‰). Surface floe samples begin to precipitate out of solution within the first hour of CO absorption, and the dissolved inorganic carbon (DIC) pool requires a residence time of >100 hours to achieve isotopic equilibria. The Δ/Δ slope of samples from the Cedars (-3.223±0.519; 1 SE) is within the range of published theoretical values designed to constrain CO hydrolysis-related kinetic fractionation (-1.724 to -8.330). The Δ/δO slope (-0.009±0.001) and Δ/δC slope (0.009±0.001) are roughly consistent with literature values reported from a peridotite in Oman of -0.006±0.002 and -0.005±0.002, respectively. The consistency of slopes in the multi-isotope space suggests the Δ-Δ dual carbonate clumped isotope framework can be applied to study CO-absorption processes in applied systems, including sites of interest for geological sequestration.

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Patterns and controls of disequilibrium isotope effects in speleothems: Insights from an isotope-enabled diffusion-reaction model and implications for quantitative thermometry

Cited by 54 publications

References 110 publications

Dual clumped isotope thermometry resolves kinetic biases in carbonate formation temperatures

Dual clumped isotope thermometry resolves kinetic biases in carbonate formation temperatures

Paired dual carbonate clumped isotopes (Δ47-Δ48) constrains kinetic effects and timescales in peridotite-associated springs at The Cedars, Northern California

Dual carbonate clumped isotopes (Δ47-Δ48) constrains kinetic effects and timescales in peridotite-associated springs at The Cedars, Northern California

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