Abstract

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 significant regional deformation 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. Here we report the first apatite fission track and (U–Th–Sm)/He data for crystalline 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 present multi-kinetic low-temperature thermal history models. The thermal history models for the Pine Creek Orogen and Arnhem Province reveal a distinct phase of denudation coeval with the Paleozoic Alice Springs Orogeny. By integrating with previous studies, we suggest that this event deformed a larger area of the Australian crust than previously perceived. Localized Mesozoic thermal perturbations proximal to the Pine Creek Shear-Zone additionally record evidence for Mesozoic reheating contemporaneous with mantle-induced subsidence and the onset of sedimentation in the Money Shoal Basin, while the Arnhem Province samples demonstrate no evidence of Mesozoic thermal perturbations.

Supplementary Material: EPMA protocol comparison, AFT plots and modelling, additional geochemistry, datasets and instrumentation parameters are available at https://doi.org/10.6084/m9.figshare.c.5206664