Identification of possible factors that affect Li-mineralizing potential is important to the understanding of the genesis of Li pegmatites. This study provides a comprehensive characterization of the recently discovered Bailongshan Li pegmatite district based on geochronological, petrological, mineralogical, thermal modeling, and Li isotopic data. Columbite-(Fe) U–Pb dating of two pegmatite dikes indicates they were emplaced at 212.3 ± 0.9 and 213.9 ± 0.7 Ma. The spodumene-absent pegmatite dikes yield substantially higher δ⁷Li values (+2.0‰ to +4.9‰) than spodumene-bearing dikes (−1.9‰ to +0.8‰). Modeling of Li isotopic fractionation during fractional crystallization, fluid exsolution, and diffusion after pegmatite emplacement indicates that the lighter Li isotopic compositions of spodumene-bearing pegmatites are attributable to fluid exsolution or diffusion-driven fractionation of short duration, whereas the heavier isotopic compositions of spodumene-absent pegmatites can be attributed to longer-duration, diffusion-driven fractionation. Together with the results of thermal modeling, we suggest that the cooling rate of pegmatite dikes was an important factor controlling the Li isotopic compositions of pegmatites and slower cooling caused heavier Li isotopic compositions. It may have important implications for the ore-forming potential of Li in pegmatites that high cooling rate is beneficial for forming Li pegmatites.

确定影响锂矿化潜力的可能因素对于了解锂伟晶岩的成因非常重要。本研究基于年代学、岩石学、矿物学、热模型和 Li 同位素数据，对最近发现的白龙山 Li 伟晶岩区进行了全面表征。两个伟晶岩脉的铌铁矿-(Fe) U-Pb 测年表明它们位于 212.3 ± 0.9 和 213.9 ± 0.7 Ma。不含锂辉石的伟晶岩脉岩产生显着更高的 δ ⁷Li 值（+2.0‰ 至 +4.9‰）比含锂辉石的堤防（-1.9‰ 至 +0.8‰）。伟晶岩就位后分馏结晶、流体出溶和扩散过程中锂同位素分馏的模拟表明，含锂辉石伟晶岩较轻的锂同位素组成归因于流体出溶或扩散驱动的短期分馏，而锂辉石较重的同位素组成- 缺少伟晶岩可归因于持续时间较长、扩散驱动的分馏。结合热模拟结果，我们认为伟晶岩脉的冷却速度是控制伟晶岩锂同位素组成的重要因素，冷却速度较慢导致锂同位素组成较重。