The genesis of the Shaping carbonate-hosted uranium deposit, South China: Constraints from in situ calcite U-Pb dating and Sr isotopes

The South China host various types of uranium deposits, including granite-hosted, volcanic-hosted, and sedimentary rock-hosted (carbonaceous-siliceous-pelitic rocks) uranium deposits. However, the genesis of carbonate-hosted uranium deposits, an important subtype of the sedimentary rock-hosted uranium deposit, remains insufficiently investigated. Here, we conducted in situ U-Pb dating, Sr isotopes analysis, trace elements and fluid inclusion on the Shaping uranium deposit hosted in the Ordovician dolostone in Guizhou Province. The calcite U-Pb age of 80.5–83.0 Ma indicates Late Cretaceous mineralization, classifying the deposit as epigenetic. The ore-stage calcite exhibits 87 Sr/ 86 Sr ratios ranging from 0.70851 to 0.70888, comparable to unaltered host rocks (0.70910–0.70948). The coupled relationship between high U contents in unaltered host rocks and Sr isotopic signatures indicates that uranium mineralization originated from fluid extraction of U from the carbonate rocks. Ore-stage calcite exhibiting low Fe concentrations (288–348 ppm) and strong negative Eu anomaly, which suggests an oxidizing fluid environment. Simultaneously, low-salinity fluid inclusions (