Zoning Characteristics of Pegmatite and Multi-stage Tectono-Magmatic Superimposed Mineralization Mechanism of Huanglongling Lithium Deposit in Altyn Region, Xinjiang

The Huanglongling lithium deposit is a newly discovered superlarge pegmatite-type lithium deposit in the Altyn area of Xinjiang in recent years, Owing to its tremendous resource potential, this area has rapidly emerged as a focal point for research on rare-metal metallogenesis within the region.The pegmatite dykes in the Huanglongling deposit exhibit distinct regional zonation and internal textural zoning. Centered on muscovite granite, the regional zoning consists successively of microcline pegmatite (Zone I), quartz-muscovite-albite pegmatite (Zone II), quartz-spodumene pegmatite (Zone III), and spodumene-lepidolite-lithium tourmaline pegmatite (Zone IV) outward.In addition, individual pegmatite dykes show variable internal textural zonation, ranging from fully mineralized spodumene-bearing pegmatite dykes without zoning to those developed with six internal textural zones. Based on U-Pb dating of monazite and columbite-tantalite from the zoned pegmatites, four episodes of magmatism and mineralization have been identified in the Huanglongling pegmatites: ① the main mineralization stage (442–436 Ma), ② a magmatic stage (422–419 Ma), ③ another magmatic stage (413.3–411.0 Ma), ④ the secondary mineralization stage (401.8–396.9 Ma). It is inferred that the multi-stage magmatism and mineralization of the Huanglongling deposit are coupled with regional tectonic-magmatic evolution.The regional zoning pattern and rare metal evolutionary characteristics indicate that the Huanglongling pegmatites belong to typical LCT-type pegmatites. The complex internal textural zonation of pegmatite dykes reveals that the mineralization process was overprinted by multi-phase tectono-magmatic activities, and formed via the combined effects of multiple metallogenic processes including magmatic fractional crystallization and fluid exsolution.