Using stable oxygen isotope dual-inlet isotope-ratio mass spectrometry to elucidate uranium transport and mixed Th/U calcite formation ages at the seminal Devils Hole, Nevada, natural laboratory.

Rationale: Vein calcite in Devils Hole has been precipitating continuously in oxygen-isotope equilibrium at a constant temperature for over 500 000 years, providing an unmatched δO paleoclimate time series. A substantial issue is that coeval calcite (based on matching δO values) has uranium-series ages differing by 12 000 years.

Methods: An unparalleled high-accuracy δO chronology series from continuously submerged calcite was used to correct the published uranium-series ages of non-continuously formed calcite in two cores, cyclically exposed by water-table decline during glacial-interglacial transitions.

Equilibrated Gas and Carbonate Standard-Derived Dual (Δ47 and Δ48) Clumped Isotope Values.

Carbonate clumped isotope geochemistry has primarily focused on mass spectrometric determination of 47 CO for geothermometry, but theoretical calculations and recent experiments indicate paired analysis of the 47 (COO) and 48 (COO) isotopologues (referred to as and ) can be used to study non-equilibrium isotope fractionations and refine temperature estimates. We utilize 5,448 and 3,400 replicate measurements of carbonate samples and standards, and 183 and 195 replicate measurements of gas standards from 2015 to 2021 from a multi-year and multi-instrument data set to constrain and values for 27 samples and standards, including Devils Hole cave calcite, and study equilibrium -, -temperature, and -temperature relationships. We compare results to previously published findings and calculate equilibrium regressions based on data from multiple laboratories.

Insights on Geochemical, Isotopic, and Volumetric Compositions of Produced Water from Hydraulically Fractured Williston Basin Oil Wells.

Tracing produced water origins from wells hydraulically fractured with freshwater-based fluids is sometimes predicated on assumptions that (1) each geological formation contains compositionally unique brine and (2) produced water from recently hydraulically fractured wells resembles fresher meteoric water more so than produced water from older wells. These assumptions are not valid in Williston Basin oil wells sampled in this study. Although distinct average Ra/Ra ratios were found in water produced from the Bakken and Three Forks Formations, average δH, δO, specific gravity, and conductivity were similar but exhibited significant variability across five oil fields within each formation.

USGS44, a new high-purity calcium carbonate reference material for δ C measurements.

Rationale: The stable carbon isotopic (δ C) reference material (RM) LSVEC Li CO has been found to be unsuitable for δ C standardization work because its δ C value increases with exposure to atmospheric CO . A new CaCO RM, USGS44, has been prepared to alleviate this situation.

Methods: USGS44 was prepared from 8 kg of Merck high-purity CaCO .

Food Matrix Reference Materials for Hydrogen, Carbon, Nitrogen, Oxygen, and Sulfur Stable Isotope-Ratio Measurements: Collagens, Flours, Honeys, and Vegetable Oils.

An international project developed, quality-tested, and measured isotope-delta values of 10 new food matrix reference materials (RMs) for hydrogen, carbon, nitrogen, oxygen, and sulfur stable isotope-ratio measurements to support food authenticity testing and food provenance verification. These new RMs, USGS82 to USGS91, will enable users to normalize measurements of samples to isotope-delta scales. The RMs include (i) two honeys from Canada and tropical Vietnam, (ii) two flours from C3 (rice) and C4 (millet) plants, (iii) four vegetable oils from C3 (olive, peanut) and C4 (corn) plants, and (iv) two collagen powders from marine fish and terrestrial mammal origins.