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 now shown to be erroneous, those which were constrained by structural observations and which relied only on whole-rock (and not mineral) analyses have proven to be remarkably realistic. Ion-microprobe data show that even conventional multigrain U-Pb zircon analysis is not a particularly appropriate dating technique in a region of this complexity. Three new U-Pb zircon ages and others previously derived from the same isotopic system date three of the main tectonic events that were imposed on the Arunta Inlier. The widespread Strangways Orogeny of the Northern 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.