Summary of results. Joint NTGS-GA geochronology project : Rum Jungle, basement to southern Georgina Basin and eastern Arunta Region 2001-2003

This record presents new SHRIMP U-Pb zircon geochronology results from the Rum Jungle area of the Pine Creek Orogen, the northeastern margin of the Arunta Region and basement underlying the southern Georgina Basin. The samples were collected as part of geoscientific studies of these regions by the Northern Territory Geological Survey in 2001–2002, and the data were obtained and interpreted through the NTGS-Geoscience Australia (GA) geochronology project in the period 2001–2003. Six samples of intrusive rocks from the Rum Jungle Complex all give SHRIMP U-Pb zircon ages in the range 2545 ± 4 Ma to 2521 ± 4 Ma, suggesting that the entire complex comprises Neoarchaean rocks. Some of these rocks show evidence for new zircon growth and/or recrystallisation during a poorly defined event, probably in the early Palaeoproterozoic. A sample of Beestons Formation, the basal unit of the Pine Creek Orogen immediately overlying the Rum Jungle Complex, has a predominantly Neoarchaean provenance and a maximum deposition age of 2506 ± 14 Ma. A sample of Acacia Gap Quartzite Member of the Wildman Siltstone (Mount Partridge Group) also has a Neoarchaean provenance and a maximum deposition age of 2512 ± 13 Ma. Three samples were dated from crystalline basement intersected in drillcore beneath the southern Georgina Basin in TOBERMOREY1. A sample of granitic rock from drillhole NTGS99/1 has an age of 1846 ± 6 Ma. Granites intersected at the base of drillholes Hacking-1 and Owen-2 have ages of 1749 ± 7 Ma and 1763 ± 5 Ma, respectively. These are consistent with the ages of three granite samples from outcrop in TOBERMOREY, which have ages ranging from 1766 ± 7 Ma to 1753 ± 7 Ma. In one of these samples, two zircons have early Mesozoic ages, reflecting an event of unknown significance. Bibliographic Reference: Cross A, Claoué-Long JC, Scrimgeour IR, Ahmad M and Kruse PD, 2005. Summary of results. Joint NTGS-GA geochronology project: Rum Jungle, basement to southern Georgina Basin and eastern Arunta Region 2001-2003. Northern Territory Geological Survey, Record 2005-006.