Crustal architectural controls on critical metal ore systems in South China based on Hf isotopic mapping

Abstract

Abstract There is increasing demand for critical metals (e.g., W-Sn, Li-Be-Nb-Ta, and rare earth elements [REEs]) to sustain the transition to green energy, yet it is unclear what controls the formation of such critical metal ore systems. Here, we focus on South China, which is well endowed with critical metals, and imaged its crustal architecture by zircon Hf isotopic mapping using 1096 zircon Hf isotope data sets for 1457 samples of Mesozoic granitoids and silicic volcanic rocks. We demonstrate that the crust is isotopically heterogeneous, characterized by spatial juxtaposition of ancient, reworked, and juvenile crustal domains. The granite-related W-Sn-Nb-Ta and REE deposits occur mainly in reworked crustal domains, where multiple stages of reworking and Mesozoic melting events likely resulted in the release of these metals into crust-derived magmas. Compared with W-Sn deposits, REE deposits occur mostly in strongly reworked crustal blocks with a juvenile input. The porphyry Cu-Au deposits are spatially confined to Cu-fertilized juvenile crustal domains, whereas U and Ag-Pb-Zn deposits occur predominantly in old crustal domains and at their margins. This study demonstrates the importance of isotopic mapping as a tool for characterizing crustal architecture and processes that lead to the formation of metal ore systems.