Toward a Cenozoic history of atmospheric CO ₂

Science · 2023 · 186 citations

• Environmental science
• Astrobiology
• Geology

thresholds in biological and cryosphere evolution.

InterCarb: A Community Effort to Improve Interlaboratory Standardization of the Carbonate Clumped Isotope Thermometer Using Carbonate Standards

Geochemistry Geophysics Geosystems · 2021 · 328 citations

• Geology
• Geochemistry
• Mineralogy

(I-CDES) values for Intercarb-Carbon Dioxide Equilibrium Scale.

Carbonate clumped isotope analysis (Δ ₄₇ ) of 21 carbonate standards determined via gas‐source isotope‐ratio mass spectrometry on four instrumental configurations using carbonate‐based standardization and multiyear data sets

Rapid Communications in Mass Spectrometry · 2021 · 33 citations

• Computer Science
• Chemistry
• Mineralogy

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 by treating some standards as anchors (working standards) and the remainder as unknowns (consistency standards). RESULTS: We show that different acid digestion systems and mass spectrometer models yield indistinguishable results when instrument drift is well characterized. For linearity correction, mixed gas-and-carbonate standardization or carbonate-only standardization yields similar results. No difference is observed in the use of three or eight working standards for the construction of transfer functions. CONCLUSIONS: values are reported for 21 carbonate standards on both the absolute reference frame (ARF; also refered to as the Carbon Dioxide Equilibrated Scale or CDES) and the new InterCarb-Carbon Dioxide Equilibrium Scale (I-CDES) reference frame, facilitating intercomparison of data from a diversity of labs and instrument configurations and restandardization of a broad range of sample sets between 2006, when the first carbonate measurements were published, and the present.

Reconstructing Environmental Temperature, Humidity, & δ 18 O Precipitation from Stable & Clumped Isotope Compositions of Global Land Snails

AGU Fall Meeting Abstracts · 2020

• Environmental science
• Ecology
• Atmospheric sciences

Reduced evaporation rates primarily led to growth of glacial Lake Bonneville

AGU Fall Meeting Abstracts · 2020

• Environmental science
• Geology
• Oceanography

Massive formation of early diagenetic dolomite in the Ediacaran ocean: Constraints on the “dolomite problem”

Proceedings of the National Academy of Sciences · 2020 · 145 citations

• Geology
• Geochemistry
• Paleontology

O values of diagenetic fluids, rare earth element plus yttrium compositions, and petrographic observations of these dolostones are consistent with an early diagenetic origin in a rock-buffered environment. We thus propose that a precursor precipitate from seawater was subsequently dolomitized during early diagenesis in a near-surface setting to produce the large volume of dolostones in the Doushantuo Formation. Our findings suggest that the preponderance of dolomite in Paleozoic and Precambrian deposits likely reflects oceanic conditions specific to those eras and that dolostones can be faithful recorders of environmental conditions in the early oceans.

Braiding Water Knowledge

AGU Fall Meeting Abstracts · 2020 · 1 citations

• Computer Science
• Computer Science
• Environmental science