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New research suggests that a newly characterized type of lithium deposit, found in volcanic lake sediments from McDermitt Caldera at Thacker Pass in northern Nevada, could place the site among the largest known lithium reserves in the world. Thomas Benson and colleagues report that sediments bearing the clay mineral illite may contain more than double the concentration of lithium compared with smectite-bearing clay, which is more abundant at the site. To meet growing demand for lithium-ion batteries as the energy and transportation sectors decarbonize, mining companies and researchers are rushing to identify additional lithium resources.
Thacker Pass is a lithium mining project in northern Nevada, known for the resistance developers faced from Indigenous and environmental groups before ultimately being approved to proceed earlier in 2023. The mine is situated at the southern portion of McDermitt Caldera, where claystone lake sediments of volcanic origin, bearing clay minerals such as smectite and illite, have been enriched with lithium. Research suggests that lithium enrichment occurred during and after the caldera’s formation around 16.4 to 16.1 million years ago. However, the details of this process and the properties of different sedimentary layers at the site are still under investigation. Here, Benson et al. examined smectite and illite claystone lake sediments from three drill core samples recovered from the southern portion of McDermitt Caldera using a sensitive high-resolution ion microprobe (SHRIMP-RG). Illite-bearing sediments, most prominent around faults, appeared as though they had been transformed from smectite to illite during resurgence after the caldera’s initial collapse. Lithium concentrations in these sediments were more than double those found in smectite sediments elsewhere in the caldera and at other lithium sites globally. “Caldera systems with similar high-temperature, hydrothermally altered [lake] sediments associated with intracaldera magmatic resurgence are therefore likely to serve as the best exploration targets to help meet increasing [lithium] demand,” the authors conclude
Expert Reaction
These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.
Dr. Matthew Coble, Research Scientist at GNS Science, comments:
"Our paper highlights the unique combination of geological and volcanological conditions necessary to concentrate lithium and form extremely high-grade deposits. The lithium resources at Thacker Pass are unique because the magmas were relatively enriched in lithium, the McDermitt Caldera was the first voluminous explosive eruption to occur in the area that was closely associated with contemporaneous flood basalt volcanism.
"The lithium was remobilized from erupted magma and concentrated within clays deposited in the caldera lake sediments. Subsequent re-heating and hydrothermal circulation from renewed magma intrusion further concentrated the lithium forming extremely high grades deposits. This process has not previously identified in other volcano-sedimentary lithium resources.
"While many calderas world-wide, including New Zealand, have similar caldera lake sediments and can contain lithium at various concentrations, they do not contain the same unique sequence of events that appear to be a prerequisite for forming the extremely high-grade lithium deposits found at Thacker Pass in Nevada, USA."
