In situ elemental and Sr-Nd isotopic compositions of hydrothermal apatite from the Shazhou U deposit in the Xiangshan complex: Implications for the origins of ore-forming fluids of volcanic related U deposits in South China

•In situ Sr-Nd isotopes of apatite are effective in tracing origins of ore forming fluids in the Shazhou U deposit.•The reducing U-poor fluid was derived from mantle-derived magma which formed the mafic dikes in wall rocks.•The oxidizing U-rich fluid originated from percolation of meteoric water in the adjacent red-bed basins.•The Late Cretaceous mafic magmatism and red-bed basins are two key factors controlling U mineralization in South China.