T83 Advances in Non-Traditional Stable Isotope Measurements and Utility as Proxies in Modern and Paleo-Settings I

Monday, 16 October 2023
8:00 AM - 12:00 PM
335

HIGH TEMPERATURE CONVERSION–METHANATION–FLUORINATION: A NOVEL METHOD FOR HIGH-PRECISION TRIPLE OXYGEN ISOTOPE MEASUREMENTS

Paper number: T83-9
Program: Technical Sessions
Time: 9:50 AM – 10:05 AM

Authors

Abstract

In most natural systems, triple oxygen isotope anomalies (denoted Δ'17O) vary by small amounts on the order of 10s of ppm, necessitating very high-precision measurements (≤ 10 ppm 1σ) of Δ'17O to extract a clear signal. Such analytical precisions have been difficult to achieve for several materials such as organics, sulfates, and nitrates, leaving them unexplored for small Δ'17O variations. We have developed a novel method that enables high-precision measurements in a diverse range of materials including but not limited to phosphates, sulfates, organics, nitrates, carbonates, silicates, and waters. The method uses a three-step process to first convert sample oxygen to oxygen in CO via high temperature conversion (HTC; commonly referred to as TC/EA). Next, oxygen in CO is converted to oxygen in H2O by a methanation process. Finally, the oxygen in water is converted to molecular oxygen (O2) by fluorination and analyzed via dual-inlet isotope ratio mass spectrometry. Here we present results from Δ'17O measurements of standard reference materials of various material types (listed above), reporting analytical precisions that approach shot-noise limits (5 ppm 1σ) for all materials.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-391489

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