10 Undergraduate and Graduate Geoscience Student Showcase (Posters)

This is a hybrid oral-poster session. Presenters will submit one abstract for two presentations (3-minute lightning talk - morning, poster - afternoon). This will offer student presenters opportunities to practice a variety of science communication techniques. View the companion lightning talk session here.

Monday, 9 March 2026
9:00 AM - 5:00 PM
RCC, Lower Level Hall

Effect of Depth on Metamorphic Decarbonation in the Sierra Nevada Batholith: Isotopic Analysis of Carbon and Oxygen

Paper number: 10-0
Program: Technical Sessions
Time: 9:00 AM – 9:00 AM

Authors

Abstract

CO2 degassing in metamorphic environments is shown to be a significant input flux in the global carbon cycle, having critical environmental implications and perturbing Earth’s climate (Stewart et al, 2019). The Sierra Nevada batholith is a compelling area to study as the existing calcareous rocks underwent contact metamorphism in its expansive region (Kerrick, 1970). While we know that metamorphism releases CO2, it remains unconstrained if and how the amount of CO2 released depends on the depth of metamorphism. In the southern part of the Sierra Nevada batholith, different depths of igneous emplacement (from >8 kbar to 3 kbar according to Nadin and Saleeby, 2008) are exposed at the surface. This makes the Sierra Nevada batholith an ideal place to study the effects of depth on CO2 release. 

 

We aim to test the hypothesis that as rocks undergo metamorphism at greater depths, the amount of CO2 degassed is smaller, as more of the CO2 is trapped. Through analysis by mass spectrometry at the National High Magnetic Field Laboratory and geochemical techniques, we will report the d13C and d18O isotope values across a range of samples from different depths (3 kbar to >8 kbar). We will then compare the isotope values between samples and literature values, interpreting that samples with higher positive isotope values degassed less CO2 and/or experienced less interaction with magmatic fluid. We hypothesize that the samples that underwent metamorphism at deeper depths (>8 kbar) will record higher positive isotope values than those that underwent metamorphism at shallower depths (3-5 kbar).

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411808

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