Precise U-Pb titanite age constraints on the emplacement of the Bushveld Complex, South Africa

The c. 2.06 Ga Bushveld Complex intrudes the Transvaal Supergroup, South Af rica. Calesilicate xenoliths within the mafic phase of the Bushveld Complex (Rustenburg Layered Suite, or RLS) preserve calcsilicate xenoliths with hi gh-temperature (c, 1200 degreesC) mineralogies that were later metasomatize d by hydrous, retrograde (c. 600-700 degreesC) fluids whose timing has been unconstrained. New U-Pb isotope data from newly grown titanite within a co mpletely retrogressed xenolith indicates that retrogression occurred at 205 8.9 +/- 0.8 Ma, This suggests that retrogression was due to hydrothermal ci rculation associated with the cooling RLS, and not slightly later Bushveld- related granites. The new data place a tight constraint on the minimum age of emplacement of the RLS.