Geochronological analysis of the McArthur and Tawallah groups, McArthur Basin: age constraints, provenance and implication for basin evolution

Abstract

The informally termed greater McArthur Basin records nearly a billion years of Earth’s history in the Northern Territory. The basin contains sedimentary successions that include evidence of their provenance, age constraints and implications for how the basin evolved through time. Although several previous studies have looked at the age and deposition of the upper Glyde Package, very little is known for the lower Glyde and upper Redbank Packages. By using LA-ICP-MS detrital zircon U–Pb and rare earth element (REE) analyses, the maximum depositional age and age of major detrital input will be constrained. These ages will determine the provenance source and constrain the evolution of the basin. Using the youngest, near-concordant, zircon grains from sandstones, the maximum depositional age of the target formation is established. The following maximum depositional age constraints have been obtained from this study: Mallapunyah Formation (1740 ± 28 Ma), Masterton Sandstone (1709 ± 28 Ma), Wollogorang Formation (1746 ± 29 Ma), Wuraliwuntya Member (1745 ± 38 Ma), and Wununmantyala Sandstone (1712 ± 39 Ma). REE data suggest that the samples grew in a garnet- and plagioclase-bearing melt. Provenance shows that the main source of sediments is the Aileron Province. Magmatic and orogenic events in the Aileron Province are coeval with the Stafford (ca. 1810 to 1800 Ma), Yambah (ca. 1790 to 1770 Ma) and Strangways (ca. 1740 to 1690 Ma) Events. This is believed to be the product of a long-lived subduction zone in the southern margin of the North Australian Craton.