Cathodoluminescent (CL) texture and trace element signature of quartz from granite-related uranium deposit in southern China has been investigated to discuss their genetic significance. Results show that the pre-ore quartz (Q1) generally has dark and homogeneous (or slightly mottled) luminescent texture that may result from annealing of original CL textures; the syn-ore quartz (Q2) generally shows bright and oscillatory luminescent texture and the post-ore quartz (Q3) displays bright and homogeneous luminescence texture. LA-ICPMS analyses suggest Al, Li, K, Na and Ca are the most abundant elements in various generations of quartz and mainly occur as solid solution within the crystal lattice, in which Al can be incorporated into quartz by substituting Si in the crystal lattice, with additional cations (e.g., K, Na, Li and Ca) to keep the charge balance. The negative correlation between Ge and Al suggests that Ge may substitute Si independently due to the similar ion radius and charge. Fe and U may be incorporated into quartz in the form of micro-inclusions. The homogeneous CL texture and low concentration of trace elements indicate that the Q3 likely precipitated under stable thermodynamic conditions.

The low Ti concentration and oscillatory euhedral growth zones of CL textures suggest that syn-ore quartz (Q2) may have precipitated from a low-temperature hydrothermal fluid. Thus, it can be inferred that the ore-forming fluid in the No. 302 uranium deposit could be of a low-temperature hydrothermal fluid from which the quartz-pitchblende vein precipitated from, which is also supported by the results from fluid inclusion studies. The significantly large variations of Al and other trace elements concentrations in the syn-ore quartz were likely indicative of the large fluctuations of pH values of ore-forming fluid, probably resulting from the CO2 effervescence or phase separation from ore-forming fluid, which further led to decomposing of uranyl carbonate complexes (UO2(CO3)(2-)), and finally caused the uranium minerals depositing in the favorable structural traps to form the No. 302 uranium deposit. This study highlights that CL textures and trace element chemistry of quartz related to mineralization can be used to fingerprint the physical and chemical history of ore deposit formation.

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