Rationale: Clumped isotope geochemistry examines the pairing or clumping of heavy isotopes in molecules and provides information about the thermodynamic and kinetic controls on their formation. The first clumped isotope measurements of carbonate minerals were first published 15 years ago, and since then, interlaboratory offsets have been observed, and laboratory and community practices for measurement, data analysis, and instrumentation have evolved. Here we briefly review historical and recent developments for measurements, share Tripati Lab practices for four different instrument configurations, test a recently published proposal for carbonate-based standardization on multiple instruments using multi-year data sets, and report values for 21 different carbonate standards that allow for recalculations of previously published data sets.Methods: We examine data from 4628 standard measurements on Thermo MAT 253 and Nu Perspective IS mass spectrometers, using a common acid bath (90 C) and small-sample (70 C) individual reaction vessels. Each configuration was investigated

Carbonate clumped isotope thermometry is a tool for paleotemperature reconstruction (Eiler, 2011) in the geosciences which is based on temperature dependent equilibrium constants for internal isotope exchange reactions in carbonate minerals (Ghosh et al., 2006;Schauble et al., 2006). For minerals that form in isotopic equilibrium, the frequency with which rare, heavy isotopes in carbonate minerals are bonded to each other (instead of bonded to much more common light isotopes) relative to a stochastic (random) distribution is proportional to precipitation temperature (Ghosh et al., 2006;Schauble et al., 2006).There are multiple clumped isotopologues containing paired heavy isotopes in carbonate minerals that can potentially be used for geothermometry. The abundance of the dominant m/z 63 isotopologue ( 13 C 18 O 16 O 2 ) forms the basis of the most widely used thermometer. The acid digestion of minerals containing carbonate ion groups with m/z 63 yields m/z 47 CO 2 , which can be measured by isotope ratio mass spectrometry (Ghosh et al., 2006). Theory predicted that the lower abundance m/z 48 CO 2 isotopologue derived from acid digestion of m/z 64 ( 12 C 18 O 2 16 O) carbonate ion groups could be used for geothermometry (

Rationale: Carbonate clumped isotope geochemistry has primarily focused on mass spectrometric determination of mass-47 CO 2 for geothermometry, but theoretical calculations indicate paired analysis of the mass-47 ( 13 C-18 O-16 O) and mass-48 ( 12 C-18 O-18 O) isotopologues (denoted with Δ 47 and Δ 48 notation) can be used to study nonequilibrium isotope fractionations and refine temperature estimates. We are one of two labs currently utilizing paired Δ 47 and Δ 48 measurements to study equilibrium and kinetic isotope effects in carbonates. Additional work is needed on different instruments to define standard Δ 48 values against equilibrated gases and evaluate Δ 48 values using carbonate transfer functions. Methods: We determined Δ 47 and Δ 48 of standards using isotope ratio mass spectrometry during the time interval of 2015-2021 on a Thermo Fischer MAT 253 mass spectrometer with a common acid bath digestion system and two Nu Instruments Perspective mass spectrometers with common acid bath and individual reaction vessel digestion systems. A total of 5,581 Δ 47 and 4,212 Δ 48 measurements of carbonates, and 183 Δ 47 and 195 Δ 48 measurements of gas standards are used from robust correction intervals over multiple years. We report statistical methods for data screening and quality assurance.

Elemental ratios in biogenic marine calcium carbonates are widely used in geobiology, environmental science, and paleoenvironmental reconstructions. It is generally accepted that the elemental abundance of biogenic marine carbonates reflects a combination of the abundance of that ion in seawater, the physical properties of seawater, the mineralogy of the biomineral, and the pathways and mechanisms of biomineralization. Here we report measurements of a suite of nine elemental ratios (Li/Ca, B/Ca, Na/Ca, Mg/Ca, Zn/Ca, Sr/Ca, Cd/Ca, Ba/Ca, and U/Ca) in 18 species of benthic marine invertebrates spanning a range of biogenic carbonate polymorph mineralogies (low-Mg calcite, high-Mg calcite, aragonite, mixed mineralogy) and of phyla (including Mollusca, Echinodermata, Arthropoda, Annelida, Cnidaria, Chlorophyta, and Rhodophyta) cultured at a single temperature (25°C) and a range of pCO2 treatments (ca. 409, 606, 903, and 2856 ppm). This dataset was used to explore various controls over elemental partitioning in biogenic marine carbonates, including species-level and biomineralization-pathway-level controls, the influence of internal pH regulation compared to external pH changes, and biocalcification responses to changes in seawater carbonate chemistry. The dataset also enables exploration of broad scale phylogenetic patterns of elemental partitioning across calcifying species, exhibiting high phylogenetic signals estimated from both uni- and multivariate analyses of the elemental ratio data (univariate: λ = 0–0.889; multivariate: λ = 0.895–0.99). Comparing partial R2 values returned from non-phylogenetic and phylogenetic regression analyses echo the importance of and show that phylogeny explains the elemental ratio data 1.4–59 times better than mineralogy in five out of nine of the elements analyzed. Therefore, the strong associations between biomineral elemental chemistry and species relatedness suggests mechanistic controls over element incorporation rooted in the evolution of biomineralization mechanisms.