Summary of results. NTGS geochronology project: Detrital zircon LA-ICP-MS U-Pb results from the Warburton and Pedirka basins

Abstract

This Record presents laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) U-Pb isotope data and accompanying trace element data for detrital zircons from two sandstone samples of the Warburton Basin and one sandstone sample of the overlying Pedirka Basin. This study aims to constrain maximum depositional age, and the results will be included in a developing detrital zircon dataset for the Warburton and Pedirka basins in the southeast Northern Territory.

Detrital zircons from the samples described in this Record have U-Pb ages ranging from ca 3.4 Ga to ca 360 Ma. In all three samples, the major peak in detrital zircon age spectra occurs from ca 1.3 to 1 Ga, with a lesser peak from ca 700 to 500 Ma. These major age peaks are similar to those of many previously reported samples of Phanerozoic sandstone from the Amadeus Basin.

The youngest concordant zircon from undivided Warburton Basin sandstone in well SHEL27109-1 is ca 430 Ma, a result that, in conjunction with stratigraphic relationships, constrains the age of the uppermost Warburton Basin intersected by SHEL27109-1 to between Silurian and Carboniferous. A sample of early Permian sandstone of the Crown Point Formation from well McDills-1 contains no concordant zircons younger than Lower Mississippian, a result that is in strong contrast to Permian sandstones of eastern Australia, which are dominated by Permian zircons. This disparity is likely related to distance from the Permian arc system of eastern Australia.