8 Innovative Climate Solutions and Relevant Science for Resilient Communities (Posters)

Monday, 19 May 2025
8:00 AM - 5:30 PM
Ballroom A&B

QUANTIFYING MINERAL REACTION RATES OF LOW-TEMPERATURE SERPENTINIZATION USING SILICON ISOTOPE DOPING TECHNIQUE

Paper number: 8-4
Program: Theme Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

Olivine minerals are unstable in the presence of water and CO2 and undergo serpentinization and carbonations at low temperatures. Constraining the reaction rates of this process can give us a better understanding of the viability of using ultramafic mantle peridotites for mineral-based carbon sequestration and storage at large scale. Although many studies have measured serpentinization rates under higher temperature-pressure conditions, previous attempts to quantify the slow kinetics of this reaction near-equilibrium (below ~150°C) were unsuccessful due to the high uncertainty involved in measuring such small chemical changes using traditional analytical techniques. Here we use a novel 29Si doping method to create serpentinization reactions at low temperatures (<100°C) and analyze changes over time to the experimental fluid using ICP-MS.

We present results from two sets of experiments to monitor the fluid-mineral interaction between olivine grains and fluid doped with ~400 ppb 29Si. One set ran for approximately three months at ~25°C and atmospheric pressure, using olivine grains <53 μm. The other set ran for approximately three months at 85°C and atmospheric pressure, using olivine grains >150 μm and <250 μm. Time series for both sets for 28Si and 29Si show reaction between mineral and fluids over this time scale. Preliminary analysis by ICP-MS using 28Si and 29Si standard solutions indicate that small concentrations down to ~1 ppb are measurable for both isotopes. These time-series results should enable us to calculate the reaction rates of very slow serpentinization.

Geological Society of America Abstracts with Programs. Vol. 57, No. 5

doi: 10.1130/abs/2025RM-410120

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