231-11 Lithium Isotope Techniques for Brine-Based Critical Mineral Exploration

Session: Critical Mineral Resources and Recovery in the Americas: Emerging Methods in Exploration and Sustainable Extraction (Posters)

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Lithium batteries for clean energy storage have significantly increased the demand for the element, thereby enhancing the need for geochemical tools to support its source determination. Lithium isotopes (δ⁷Li) offer unique potential to trace fluid–rock interaction processes and assess the origin and evolution of important Li reservoirs such as brines with 3–30 ppm of Li; however, the analytical development of Li isotope protocols in highly saline brines remain limited. At the University of Maryland, we have developed δ⁷Li measurement protocols for high-sodium brine samples, with a focus on achieving high analytical precision and low matrix interference. Our work includes extensive hands-on experience preparing brine samples using AG50W-X8 cation exchange resin for Li purification, focusing on minimizing Na content and reducing critical Na interference. Isotopic analyses are performed using a multi-collector ICP-MS equipped with an Apex desolvating nebulizer, incorporating standard (L-SVEC)-sample bracketing and blank subtraction. We have successfully produced high-quality δ⁷Li data (long-term precision of 0.3‰) for several collaborative studies on modern salar and geothermal brines from North and South America. These studies aim to identify isotopic signatures associated with Li mobilization from volcanic rocks, basin sediments, and hydrothermal fluids, providing insights into the processes that govern economically viable Li accumulation. By characterizing δ⁷Li in these brines, we demonstrate the reliability of our new δ⁷Li analytical technique, as well as how Li isotopes can help distinguish between primary sources and secondary enrichment pathways, ultimately improving resource targeting and sustainable extraction strategies in evaporitic environments.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11003

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