Nixon, Angus L1, Glorie, Stijn1, Collins, Alan S1, Whelan, Jo A2, Reno, Barry L2, Danišík, Martin3, Wade, Benjamin P4 & Fraser, Geoff5
1Mineral Exploration Cooperative Research Centre, Department of Earth & Environmental Sciences, School of Physical Sciences, The University of Adelaide, SA 5005 Australia, 2Northern Territory Geological Survey, Department Industry Tourism and Trade, Darwin, NT 0801, Australia, 3John de Laeter Centre, Curtin University of Technology, Perth, WA 6845, Australia, 4Adelaide Microscopy, The University of Adelaide, Adelaide, SA 5005, Australia, 5Minerals Energy and Groundwater Division, Geoscience Australia, GPO Box 378, Canberra, ACT2601, Australia
The Precambrian Pine Creek Orogen and Arnhem Province represent two of the oldest basement terrains in northern Australia and are often considered to be devoid of major tectonic or deformational activity since the cessation of regional metamorphism in the Paleoproterozoic. A major caveat in the current hypothesis of long lived structural inactivity is the absence of published low-temperature thermochronological data and thermal history models for this area. This study presents the first apatite U–Pb, fission track and (U–Th–Sm)/He data for igneous samples from both the Pine Creek Orogen and Arnhem Province, complemented with apatite geochemistry data acquired by electron microprobe and laser ablation mass spectrometry methods, and presents detailed multi-kinetic low-temperature thermal history models. Low-temperature thermal history models for the Pine Creek Orogen and Arnhem Province reveal a distinct phase of denudation coeval with the Paleozoic Alice Springs Orogeny in central Australia, suggesting that this orogenic event impacted a larger area of the Australian crust than previously perceived. Low-temperature perturbations observed in northernmost Australia are consistent with widespread mid-Paleozoic denudation is preserved across both the North Australian Craton and South Australian Craton, indicative of a cratonic scale thermal event during north-south shortening via the Alice Springs Orogeny. Additionally, minor localised Mesozoic thermal perturbations proximal to the Pine Creek Shear-Zone record evidence for Mesozoic reactivation contemporaneous with modelled mantle-driven subsidence and the onset of sedimentation in the Money Shoal Basin, while the Arnhem Province samples demonstrate no evidence of Mesozoic thermal perturbations.
Angus Nixon is a PhD student at the University of Adelaide with research focused on unraveling the low-temperature evolution of the North Australia Craton throughout the Phanerozoic , aiming to identify and explain both local and craton scale thermo-tectonic events and their implications for terrain development.