Improvements in Drill-Core Headspace Gas Analysis for Samples from Microbially Active Depths

<div>Plot of <i>δ</i><sup>13</sup>C<sub>CH4</sub> vs. <i>δ</i><sup>13</sup>C<sub>CO2</sub> in coexisting gases. (a) Grey areas show fields relating to different gas sources and isotopic shifts resulting from production and oxidation (adapted from [<a href="/journals/geofluids/2018/2436814/#B50">50</a>]). The area indicated by the dashed rectangle is enlarged in (b). (b) Solid arrow indicates a methane oxidation trend for samples with 350 m groundwater; dashed arrow indicates the trend for samples with 50 m groundwater.</div>

Geofluids

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Figure 6

Figure 6: Improvements in Drill-Core Headspace Gas Analysis for Samples from Microbially Active Depths 