Geology and geochronology of the newly discovered LCT-type pegmatite belt in the Altyn Tagh Orogenic Belt, NW China

• A world-class LCT pegmatite belt is discovered in Altyn Tagh Orogenic Belt (ATOB). • Six stages of Li mineralization are identified in the pegmatite belt from the ATOB. • Li mineralization was closely related to the tectonic evolution of the Tethys Recently, a world-class Li‒Cs‒Ta (LCT) pegmatite belt with significant rare metal resource potential was discovered in the Altyn Tagh Orogenic Belt (ATOB), NW China. However, the spatial and temporal distribution characteristics and the related tectonic regimes of the pegmatite belt have not been well constrained. In this study, we address these issues using columbite − tantalite group minerals (CGMs) and cassiterite U–Pb dating, as well as in situ mica Rb–Sr geochronology. Our new results reveal that two metallogenic epochs (Epochs I and II) associated with Li mineralization can be identified. Epoch I contains six mineralization stages in the sequence of Li‒Ta mineralization (Stage 1–1: 486.0–454.0 Ma) → Li‒Ta‒Sn mineralization (Stage 1–2: 445.5–435.0 Ma) → aplite (Li-bearing) mineralization (Stage 1–3: 435.0–412.0 Ma) → superimposed mica-rich greisen mineralization (Stage 1–4: 384.1–351.4 Ma). Epoch II occurred mainly in the Shaliangxi–Kumusayi ore field, which experienced an LCT-type pegmatite stage (Stage 2–1: 233.6–228.6 Ma), followed by a Li-rich hydrothermal stage (Stage 2–2: 189.9 Ma). Regionally, three distinct zonal mineralization patterns can be identified. Zone-I was derived from the OH – - and F-poor and highly evolved S-type granitic magmatism, which underwent prolonged uplift and erosion. Zone-II consists of two subgroups. The P-, F-, and B-rich subgroup was subjected to the constitutional zone refining (CZR) and the self-metasomatism, whereas the lepidolite-poor subgroup was caused by the consumption of F during the early Sn-Li mineralization process. Similar to Zone-I, Zone-III was associated with the magmatic fractionation followed by the self-metasomatism process. Late hydrothermal alteration, which was Li-poor, could be linked to a deep Li‒F felsic melt‒fluid system, whereas Li-poor hydrothermal alteration must be derived from a less evolved magma source. Combined with previously published data, our study revealed that Li mineralization in the ATOB was closely associated with the tectonic activity of the Tethy tectonic domain. Three main tectonic–metallogenic coupling events, characterized by the Precambrian supercontinents’ breakup-related Fe, Cu, Pb, and Zn mineralization, Proto − Tethys-related rare metal mineralization and Paleo − Tethys-related Li mineralization, collectively formed the economic ATOB.