Evaluating the Potential of Rhyolitic Glass as a Lithium Source for Brine Deposits


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Date

2022-01-01

Publication Type

Journal Article

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Abstract

Lithium is an economically important element that is increasingly extracted from brines accumulated in continental basins. While a number of studies have identified silicic magmatic rocks as the ultimate source of dissolved brine lithium, the processes by which Li is mobilized remain poorly constrained. Here we focus on the potential of low-temperature, post-eruptive processes to remove Li from volcanic glass and generate Li-rich fluids. The rhyolitic glasses in this study (from the Yellowstone-Snake River Plain volcanic province in western North America) have interacted with meteoric water emplacement as revealed by textures and a variety of geochemical and isotopic signatures. Indices of glass hydration correlate with Li concentrations, suggesting Li is lost to the water during the water-rock interaction. We estimate the original Li content upon deposition and the magnitude of Li depletion both by direct in situ glass measurements and by applying a partition-coefficient approach to plagioclase Li contents. Across our whole sample set (19 eruptive units spanning ca. 10 m.y.), Li losses average 8.9 ppm, with a maximum loss of 37.5 ppm. This allows estimation of the dense rock equivalent of silicic volcanic lithologies required to potentially source a brine deposit. Our data indicate that surficial processes occurring post-eruption may provide sufficient Li to form economic deposits. We found no relationship between deposit age and Li loss, i.e., hydration does not appear to be an ongoing process. Rather, it occurs primarily while the deposit is cooling shortly after eruption, with δ18O and δD in our case study suggesting a temperature window of 40° to 70°C.

Publication status

published

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Volume

117 (1)

Pages / Article No.

91 - 105

Publisher

Society of Economic Geologists

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Subject

alkali metals; brines; D/H; electron probe data; glasses; hydration of glass; hydrogen; ICP mass spectra; Idaho; igneous rocks; isotope ratios; isotopes; lithium; lithium ores; mass spectra; metal ores; metals; O-18/O-16; oxygen; rhyolites; rhyolitic composition; Snake River plain; spectra; stable isotopes; United States; volcanic glass; volcanic rocks; Yellowstone River

Organisational unit

03958 - Bachmann, Olivier / Bachmann, Olivier check_circle
09656 - Chelle-Michou, Cyril / Chelle-Michou, Cyril check_circle

Notes

Funding

166281 - Understanding eruptive and post-eruptive processes in rhyolites via lithium (Li) isotopes (SNF)

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