T139 Celebrating Dr. John W. Valley's Contributions to Isotope Geochemistry and Beyond, from the Hadean to the Holocene II

Monday, 23 October 2017
1:30 PM - 5:30 PM
Skagit 2

CONTINUOUS, HIGH-RESOLUTION MEASUREMENTS OF Δ17O OF H2O

Paper number: T139-3
Program: Technical Sessions
Time: 1:55 PM – 2:10 PM

Authors

Abstract

The measurement of Δ17O, the deviation in δ17O from the global meteoric water line, ln(δ17O+1) – 0.528ln(δ18O+1), offers considerable potential for separating the various influences on water isotope variations recorded in polar ice cores. The availability of Δ17O measurements has been limited by the time-consuming nature of analysis by isotope-ratio mass spectrometery (IRMS) method, which requires conversion of H2O to O2 by flourination. Laser spectroscopy has made it possible to measure Δ17O without the flourination step. Such measurements remain challenging because existing instruments are subject to calibration drift and sample-to-sample memory. Nevertheless, when careful protocols are followed, reliable and routine measurements can be achieved, competitive with IRMS. Furthermore, laser spectroscopy instruments can be coupled with continuous flow analysis (CFA) systems to provide very-high-resolution ice core measurements. Here, we show the first continuous record of Δ17O ever obtained from an ice core. We coupled a CFA system with a Picarro L214Oi instrument to analyze a 1750-m long ice core from the South Pole, with sub- centimeter resolution for δ17O, δ18O and δD. Data averaging yields an effective resolution for Δ17O of 50 cm, with better than 10 per meg precison.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-305495

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