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Free keywords:
xenotime U-Pb dating
heavy rare earths
crust metal endowment
south China
Gondwana assembly
Abstract:
The South China Block hosts a variety of U and HREE mineralisation styles. The
Yushui Cu deposit is located at a sedimentary unconformity and is enriched in
HREEs and U. U-Pb ages of uraninite and xenotime indicate that the HREE miner-
alisation is epigenetic and formed at ca. 223 ± 1 Ma. Ore petrography, elemental map-
ping, and Nd isotope data suggest that HREEs and U were leached from the footwall
sandstone and transported to the Cu deposit via oxidised basinal brines. U-Pb ages of
detrital xenotime and zircon from the sandstone show that this sedimentary sequence
was mainly derived from Silurian S-type granites, which were emplaced during
Gondwana amalgamation. Rapid erosion formed clastic sedimentary rocks that con-
tain accessory HREE-U minerals which could be remobilised by younger mineralising
events. S-type granite magmatism during the final assembly of Gondwana established the crustal metal reservoir which was
repeatedly tapped over geological history, including the modern formation of regolith hosted HREE deposits in South
China. Given the global distribution of analogous S-type granites in other terranes globally, our study has exploration implica-
tions outside of China. This will be enlightening for finding new HREE deposits, which is vital to support the transition to a low
carbon footprint energy.
