AN ASSESSMENT, BASED ON U-PB ZIRCON DATA, OF RB-SR DATING IN THE ARUNTA-INLIER, CENTRAL AUSTRALIA

The chronology of the Arunta Inlier was originally based mostly on Rb- Sr dating. Although some of the ages derived from that technique are n ow shown to be erroneous, those which were constrained by structural o bservations and which relied only on whole-rock (and not mineral) anal yses have proven to be remarkably realistic. Ion-microprobe data show that even conventional multigrain U-Pb zircon analysis is not a partic ularly appropriate dating technique in a region of this complexity. Th ree new U-Pb zircon ages and others previously derived from the same i sotopic system date three of the main tectonic events that were impose d on the Arunta Inlier. The widespread Strangways Orogeny of the North ern and Central provinces occurred at 1760-1750 Ma. The Argilke Event is not older than 1680 Ma, demonstrating that the Southern Province is the youngest in the inlier. The dominantly thermal Ormiston Event is dated at similar to 1140 Ma.