Lithium concentration and isotopic data from hydrothermal experiments on basaltic glass and gabbro with synthetic seawater (150–300 °C)

This dataset provides lithium (Li) concentrations and isotopic compositions (δ⁷Li) in both solid and fluid phases from 23 controlled hydrothermal experiments conducted at 150–300 °C and water-to-rock ratios of 10 and 100. The experiments involved fresh basaltic glass from the East Pacific Rise (EPR) and gabbro from the Southwest Indian Ridge (SWIR), reacted with synthetic seawater. The dataset includes time-series results for basaltic glass at 250 °C and 300 °C over durations of 3–30 days, as well as final-state measurements at multiple temperatures. It also contains BET surface area data, SEM and XRD mineralogical characterization results, and major and trace elemental compositions of starting materials and reacted solids. This dataset supports the GCA manuscript “L. Li et al., 2025, Li partitioning and isotope fractionation in basaltic glass, gabbroic rocks and synthetic seawater: new experimental constraints on Li behavior in oceanic crust” and underpins interpretations regarding temperature-dependent Li uptake, mineral-fluid partitioning, and isotopic fractionation during seafloor alteration.