Formation of the Mahuaping Be–W–F deposit in South China: Evidence from beryl chemistry, wolframite and monazite U–Pb dating

Abstract

The Mahuaping deposit, hosted within metasedimentary rocks, is a large-scale Be–W–F deposit in the Sanjiang region, distinguished by a unique mineral assemblage that includes beryl, scheelite, wolframite euclasite, fluorite, calcite, and quartz, among others. However, its genetic model remains a subject of debate, particularly regarding whether mineralization was sourced from granite-derived fluids or metamorphic hydrothermal systems. The precise formation age of the Mahuaping deposit can be reliably determined through in-situ U–Pb dating of wolframite and monazite using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Wolframite U–Pb dating yield an age of 30.6 ± 0.5 Ma (2σ, MSWD = 0.74), closely aligning with the monazite U–Pb age of 29.4 ± 0.3 Ma (2σ, MSWD = 0.63). These results indicate that the Mahuaping deposit formed during the Late Paleogene. Given its temporal similarity to porphyry-related Cu–Au–Mo deposits associated with intracontinental transpression in the Sanjiang region, as well as multi-stage mineral textures and the variability in FeO (0.09–1.68 wt%) and Na₂O (0.59–2.05 wt%) contents in beryl, we propose that the Mahuaping Be–W–F deposit was formed by magmatic-hydrothermal fluids. Under this magmatic-hydrothermal model, we suggest that the Sanjiang region holds significant potential for additional economic Be–W–F mineralization. Furthermore, this study highlights that, in addition to the well-documented Cu–Au–Mo mineralization event, the Late Paleogene also witnessed a notable Be–W–F mineralization episode, thereby expanding the metallogenic framework of the Sanjiang region and providing critical insights for future exploration.