Cathodoluminescent textures and trace element signatures of hydrothermal quartz from the granite-related No. 302 uranium deposit, South China: A reconnaissance study for their genetic significances

摘要

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.