235 D7. General Topics in Geochemistry and Metamorphic Petrology (Posters)

Wednesday, 12 October 2022
9:00 AM - 1:00 PM
Exhibit Hall F

WECSIP: ANALYZING STABLE ISOTOPES IN PRECIPITATION TO CREATE A PRELIMINARY LOCAL METEORIC WATER LINE FOR GRAND JUNCTION, CO

Paper number: 235-19
Program: Technical Sessions
Time: 9:00 AM – 1:00 PM

Authors

Abstract

By using isotopic ratios of δ18O and δ2H in meteoric water, precipitation samples can be ‘fingerprinted’ to find their vapor source. Geochemical analysis of meteoric water can give insight into several different atmospheric processes such as Rayleigh fractionation and distillation. For each sample, isotopic data is plotted against the global meteoric water line (GMWL) and analyzed to determine the general latitude, elevation, and climate associated with the regional vapor sources. Grand Junction is a semi-arid location seasonally affected by monsoons in Western Colorado, which is located in the northeast region of the Colorado Plateau. Using isotopic precipitation data collected from 2020-2021 from multiple sources in the Grand Valley, a preliminary trend line called the local meteoric water line (LMWL) was created. The slope of this line is δ2H=7.27(δ18O)+2.91, which is similar to slopes of other LMWL from localities which are also mid latitude and experience monsoons. These localities, Gunnison, CO and Lanzhou City, China represent previously studied areas with seasonal variation in their isotopic ratios of δ18O and δ2H. This study assesses seasonal differences in isotopic ratios from locality to locality and provides general climatic patterns found in these latitudinally and climatically similar regions.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-383457

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