Cassiterite U-Pb dating of the Yelonggou pegmatite-type lithium deposit in western Sichuan and its metallogenic age constraints

1. Objective Pegmatite hosts important resource of rare metals, e.g., lithium (Li) and beryllium (Be). In recent years, increasingly more studies were dedicated to characterize and unravel the formation of pegmatite-type deposits, for which accurate dating of pegmatite formation and mineralization is essential. The Songpan-Ganzi orogenic belt is a major rare metal metallogenic belt in China, hosting many important pegmatite-type Li deposits, including the Lijiagou, Dangba, Jiajika, Yelonggou, Cuola, and Declalongba. Radiometric age data (mica Ar-Ar and zircon/cassiterite U-Pb) from these Li deposits are sparse, ranging from 210 to 152 Ma. However, obtaining reliable zircon U-Pb dates can be a challenge due to the strong decidualization in pegmatites. As a result, the formation and mineralization ages of these rare metal pegmatites remain controversial, which hampers the development of pegmatite-type metallogenic model for the Songpan-Ganzi orogenic belt.