MONO-SAMPLE PB-PB DATING OF PYRRHOTITE AND TOURMALINE - PROTEROZOIC VS ARCHEAN INTRACRATONIC GOLD MINERALIZATION IN ZIMBABWE

Gold-sulfide-tourmaline associations are characteristic of large gold resources world-wide. Such parageneses can rarely be dated; hence gene tic models are based on weak age constraints. Stepwise Pb leaching ena bled direct, precise dating of individual samples of hydrothermal pyrr hotite (1.93 +/- 0.05 Ga) and paragenetically older tourmaline (2.02 /- 0.02 Ga) from a shear-zone-hosted gold mineralization within the Ar chean Zimbabwe craton. These ages reveal a multistage Proterozoic hydr othermal event within the craton. The presence of a scheelite-tourmali ne ore dated at 2.65 +/- 0.01 Ga within the same shear zone may point to an Archean precursor. Because of its capability to demonstrate Pb i sotope (dis)equilibrium between associated phases, single-mineral Pb l eaching also traces genetic processes.