This record presents new SHRIMP U-Pb zircon geochronology results from the southern Arunta Region that were obtained through the NTGS-GA geochronology project in the period 2000–2003. The samples were collected as part of the geological mapping of MOUNT LIEBIG1 and MOUNT RENNIE by the Northern Territory Geological Survey in 2000–2002.
Sixteen samples were analysed from the newly defined Warumpi Province, located along the southwestern margin of the Arunta Region. The Warumpi Province in the Northern Territory has been divided into three domains – the amphibolite facies Haasts Bluff Domain in the south, the granulite to upper amphibolite facies Yaya Domain in the north, and the greenschist facies Kintore Domain in the far west. In the Haasts Bluff Domain, the Talipata Granite has an age of 1683 ± 2 Ma, and felsic volcanic rocks of the Peculiar Complex were extruded at 1680 ± 4 Ma. A second period of magmatism in the Haasts Bluff Domain is represented by the Udor Granite, with an age of 1663 ± 4 Ma, and a sample of Glen Helen Metamorphics, which has an age of 1661 ± 8 Ma. Five samples of metasedimentary rocks from the Iwupataka Metamorphic Complex in the Haasts Bluff Domain have maximum deposition ages in the range 1670–1630 Ma. An exception is the Putardi Quartzite, which has a maximum deposition age of 1752 ± 11 Ma, with a different provenance to that of the Iwupataka Metamorphic Complex. In the Kintore Domain, the undeformed Tinki Granite has an age of 1691 ± 4 Ma, which is the oldest recorded age for an igneous rock in the Warumpi Province.
In the Yaya Domain, igneous zircons in four samples of granite and charnockite give ages that range from 1642 ± 3 Ma to 1631 ± 4 Ma. A sample of quartzite from the Yaya Metamorphic Complex has a maximum deposition age of 1760 ± 8 Ma, with a different provenance from the Putardi Quartzite. This is also different to three other samples from the Yaya Metamorphic Complex that were sampled by Kinny (2002) and have maximum deposition ages of 1660 Ma. The Yaya Metamorphic Complex has metamorphic zircon rims with an age of 1636 ± 6 Ma, and metamorphic rims in two charnockites with an age of 1637 ± 2 Ma and 1631 ± 4 Ma grew within error of the time of igneous crystallisation. These ages are interpreted to reflect the Liebig Orogeny. A number of samples from both the Yaya and Haasts Bluff Domains show evidence for resetting or new zircon growth during the Chewings Orogeny, which was previously considered to have occurred at 1610–1600 Ma (Collins et al 1995). The most well constrained of these ages are for zircon rims in two samples of the Warumpi Granite, which have ages of 1591 ± 4 Ma and 1585 ± 8 Ma.
Three samples have been analysed from the Aileron Province in northern MOUNT RENNIE. A granite from the Andrew Young Igneous Complex has an age of 1640 ± 6 Ma, whereas adjacent granulite facies metasedimentary rocks of the Nyirripi beds have a maximum deposition age of 1790 ± 12 Ma and metamorphic rims with an age of 1644 ± 9 Ma. Lower amphibolite facies turbiditic metasedimentary rocks of the Lander Rock beds from the Dufaur Hills have a maximum deposition age of 1858 ± 5 Ma.
Bibliographic Reference: A Cross, JC Claoué-Long, IR Scrimgeour, DF Close and CJ Edgoose, 2005. Summary of results. Joint NTGS-GA geochronology project: southern Arunta Region. Northern Territory Geological Survey, Record 2004-003.
