Defining an absolute reference frame for ‘clumped’ isotope studies of CO2

Dennis, Kate J.; Affek, Hagit P.; Passey, Benjamin H.; Schrag, Daniel P.; Eiler, John M.

doi:10.1016/j.gca.2011.09.025

Cited by 549 publications

(841 citation statements)

References 22 publications

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“…For example, one possible source of inconsistency is the purification of sample gases. This step is carried out in some laboratories by transferring the gas with a He‐flow through a gas chromatograph with a Porapak® column (e.g., Ghosh, Garzione, et al, 2006; Passey et al, 2010) or by forcing the CO 2 to diffuse through a tube filled with Porapak, via freezing from one cold finger to another (e.g., Dennis et al, 2011; Meckler et al, 2014). One possible issue is the temperature at which the Porapak trap is cooled.…”

Section: The Absolute Reference Framementioning

confidence: 99%

“…The Nu Perspective (Nu Instruments, Wrexam, UK), on the other hand, does not show strongly negative backgrounds, but their absence needs to be verified regularly. In contrast, heated gas line‐based correction requires the averaging of measurements over multiple days or even weeks, as the construction of a heated gas line requires multiple measurements of heated gases with widely different compositions or of a large number of gases with variable compositions (e.g., Dennis et al, 2011; Huntington et al, 2009). Therefore, background changes cannot be immediately detected using heated gases.…”

Section: Carbonate Standards For Optimized Data Correction and Linkagmentioning

confidence: 99%

“…After considering and assessing the importance of the largest analytical sources of uncertainty, we propose that currently the best avenue for improved interlaboratory comparability is to use a suite of carbonate standards across laboratories. These carbonate standards should be firmly anchored to the interlaboratory absolute standardization scheme or carbon dioxide equilibrium scale (CDES), which is a scale the clumped isotope community has developed to standardize clumped isotope values among laboratories (Dennis et al, 2011). In this study we demonstrate that a carbonate‐based standardization method allows for much better interlaboratory comparability than the current standardization based on heated and equilibrated gases.…”

Section: Introductionmentioning

confidence: 99%

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Reducing Uncertainties in Carbonate Clumped Isotope Analysis Through Consistent Carbonate‐Based Standardization

Bernasconi

Müller

Bergmann

et al. 2018

Geochem Geophys Geosyst

222

380

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About a decade after its introduction, the field of carbonate clumped isotope thermometry is rapidly expanding because of the large number of possible applications and its potential to solve long‐standing questions in Earth Sciences. Major factors limiting the application of this method are the very high analytical precision required for meaningful interpretations, the relatively complex sample preparation procedures, and the mass spectrometric corrections needed. In this paper we first briefly review the evolution of the analytical and standardization procedures and discuss the major remaining sources of uncertainty. We propose that the use of carbonate standards to project the results to the carbon dioxide equilibrium scale can improve interlaboratory data comparability and help to solve long‐standing discrepancies between laboratories and temperature calibrations. The use of carbonates reduces uncertainties related to gas preparation and cleaning procedures and ensures equal treatment of samples and standards. We present a set of carbonate standards of diverse composition, discuss how they can be used to correct for mass spectrometric biases, and demonstrate that their use significantly improves the comparability among four laboratories. We propose that the use of these standards or of a similar set of carbonate standards will improve the comparability of data across laboratories.

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Section: The Absolute Reference Framementioning

confidence: 99%

Section: Carbonate Standards For Optimized Data Correction and Linkagmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reducing Uncertainties in Carbonate Clumped Isotope Analysis Through Consistent Carbonate‐Based Standardization

Bernasconi

Müller

Bergmann

et al. 2018

Geochem Geophys Geosyst

222

380

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“…Purified CO 2 was transferred to the mass spectrometer, and simultaneously analyzed for d 18 O, d 13 C, and D 47 . D 47 values were corrected for acid fractionation using an empirically derived acid fractionation offset of 0.092‰ (Henkes et al, 2013;Defliese et al, 2015), and are reported on the absolute reference frame (Dennis et al, 2011). D 47 values were converted to temperatures (see Supplementary Information) using a variety of calibrations, (Ghosh et al, 2006;Eagle et al, 2013;Zaarur et al, 2013;Tang et al, 2014;Defliese et al, 2015), which have been adjusted to a common acid fractionation reference frame (Defliese et al, 2015 Kim and O'Neil (1997).…”

Section: Stable Isotopic Analysis Of Lake Carbonatesmentioning

confidence: 99%

Evaporation induced 18O and 13C enrichment in lake systems: A global perspective on hydrologic balance effects

Horton

Defliese

Tripati

et al. 2016

Quaternary Science Reviews

141

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a b s t r a c tGrowing pressure on sustainable water resource allocation in the context of global development and rapid environmental change demands rigorous knowledge of how regional water cycles change through time. One of the most attractive and widely utilized approaches for gaining this knowledge is the analysis of lake carbonate stable isotopic compositions. However, endogenic carbonate archives are sensitive to a variety of natural processes and conditions leaving isotopic datasets largely underdetermined. As a consequence, isotopic researchers are often required to assume values for multiple parameters, including temperature of carbonate formation or lake water d 18 O, in order to interpret changes in hydrologic conditions. Here, we review and analyze a global compilation of 57 lacustrine dual carbon and oxygen stable isotope records with a topical focus on the effects of shifting hydrologic balance on endogenic carbonate isotopic compositions.Through integration of multiple large datasets we show that lake carbonate d 18 O values and the lake waters from which they are derived are often shifted by >þ10‰ relative to source waters discharging into the lake. The global pattern of d 18 O and d 13 C covariation observed in >70% of the records studied and in several evaporation experiments demonstrates that isotopic fractionations associated with lake water evaporation cause the heavy carbon and oxygen isotope enrichments observed in most lakes and lake carbonate records. Modeled endogenic calcite compositions in isotopic equilibrium with lake source waters further demonstrate that evaporation effects can be extreme even in lake records where d 18 O and d 13 C covariation is absent. Aridisol pedogenic carbonates show similar isotopic responses to evaporation, and the relevance of evaporative modification to paleoclimatic and paleotopographic research using endogenic carbonate proxies are discussed.Recent advances in stable isotope research techniques present unprecedented opportunities to overcome the underdetermined nature of stable isotopic data through integration of multiple isotopic proxies, including dual element 13 C-excess values and clumped isotope temperature estimates. We demonstrate the utility of applying these multi-proxy approaches to the interpretation of paleohydroclimatic conditions in ancient lake systems. Understanding past, present, and future hydroclimatic systems is a global imperative. Significant progress should be expected as these modern research techniques become more widely applied and integrated with traditional stable isotopic proxies.

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“…Gases with different bulk ␦ 18 O and ␦ 13 C ratios in quartz breakseals are heated to 1000 • C for two hours and then quenched at room temperature. These heated gases and 25 • C water-equilibrated gases are then purified and analyzed using the same protocol as sample gases, and used to construct the absolute reference frame and determine a non-linearity correction as described elsewhere (Dennis et al, 2011).…”

Section: Stable Isotope Analysis Standardization and Calculationsmentioning

confidence: 99%

Evolution of Neoproterozoic Wonoka–Shuram Anomaly-aged carbonates: Evidence from clumped isotope paleothermometry

Loyd

Corsetti

Eagle

et al. 2015

Precambrian Research

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a b s t r a c tThe Wonoka-Shuram Anomaly represents the largest negative carbon isotope excursion recognized in the geologic record and is associated with the emergence and diversification of metazoan life ca. 580 million years ago (Ma). The origin of the anomaly is highly debated, with interpretations ranging from primary to diagenetic, each having unique and potentially transformative implications for early life. Here, we apply carbonate clumped isotope thermometry to three sections expressing the anomaly in order to constrain mineral formation temperatures and thus directly calculate water oxygen isotope compositions (␦ 18 O w ) with which carbonate minerals equilibrated. With ␦ 18 O w known, it is possible to address previous hypotheses for the origin of the anomaly. In each section, precipitation temperatures correlate positively with reconstructed ␦ 18 O w . Previous hypotheses, based on the covariance of ␦ 18 O carb vs. ␦ 13 C carb (uncorrected for temperature effects), suggested a meteoric diagenetic origin for the anomaly. However, reconstructed ␦ 18 O w values do not covary with carbon isotope compositions (␦ 13 C carb ) within anomaly facies. Rather, the oxygen isotope and temperature data are consistent with carbonate recrystallization and equilibration under increasingly rock-buffered conditions. Based on simple modeling and comparison to modern formation fluids, recrystallization may have occurred in an environment far removed from the initial depositional or early diagenetic regime. In addition, although clumped isotope temperatures vary significantly and reach elevated values consistent with burial diagenesis, it is unclear to what degree, if at all, carbon isotope values were reset during recrystallization. Ultimately, these new data indicate that Wonoka-Shuram-aged carbonates experienced equilibration with fluids under increasingly closedsystem conditions. The clumped isotope data do not provide a means to distinguish previous hypotheses outright, but provide additional context for the evaluation of geochemical signatures within these ancient carbonate rocks.

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Defining an absolute reference frame for ‘clumped’ isotope studies of CO2

Cited by 549 publications

References 22 publications

Reducing Uncertainties in Carbonate Clumped Isotope Analysis Through Consistent Carbonate‐Based Standardization

Reducing Uncertainties in Carbonate Clumped Isotope Analysis Through Consistent Carbonate‐Based Standardization

Evaporation induced 18O and 13C enrichment in lake systems: A global perspective on hydrologic balance effects

Evolution of Neoproterozoic Wonoka–Shuram Anomaly-aged carbonates: Evidence from clumped isotope paleothermometry

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