Orogens and detritus: unravelling the Mesoproterozoic tectonic geography of northern Australia through coupled detrital thermo- and geo-chronometers

Abstract

This study presents detrital muscovite ⁴⁰Ar/³⁹Ar data from the Mesoproterozoic Roper Group and overlying informally named successions, in the Beetaloo Sub-basin, northern Australia. Detrital muscovite chronology reveals tectono-thermal processes within source regions and provides new constraints on the basin provenance, revising previous interpretations based on detrital zircon data. Detrital thermo- and geochronology, together demonstrate three main periods when the basin paleogeography was altered that correspond to the evolving tectonic history of the North Australia Craton (NAC) through the Mesoproterozoic. The first is characterised by an increased sediment contribution from source regions that lay along the eastern margin of Proterozoic Australia. These source regions are interpreted to have formed the uplifted rift-shoulders between Proterozoic Australia and Laurentia at ca 1.45 Ga. After that, sediments derived from eastern Proterozoic Australia sources become less voluminous up-section. The youngest analysed formation from the Roper Group, the Kyalla Formation, was predominately from sources to the south of the basin, representing another modification of basin geography. This is interpreted to result from the closure/subduction of the Mirning Ocean as the West Australian Craton (WAC) approached and collided with the NAC, resulting in an uplift of the southern margin of the NAC, at ca 1.35–1.31 Ga. The uppermost Mesoproterozoic to lower Neoproterozoic sandstone successions that overlie the Roper Group were derived from the Musgrave Province. Coupled detrital zircon and muscovite data imply a rapid cooling at ca 1.20–1.15 Ga that is interpreted to reflect syn-orogenic exhumation during the Musgrave Orogeny. Furthermore, data from the Beetaloo Sub-basin suggest that the changed basin tectonic settings reshaped basin geography and result in distinctive detrital zircon and muscovite geochronology records. In this study, we used the detrital U–Pb zircon and muscovite ⁴⁰Ar/³⁹Ar age data from the Beetaloo Sub-basin and a range of other basins deposited in different tectonic environments, including the convergent, collisional and extensional settings, to reconstruct the basin tectonic geography and illustrate various tectonic controls on basin formation in different tectonic backgrounds.

KEY POINTS

1. Detrital muscovite ⁴⁰Ar/³⁹Ar data provide thermochronological constraints on basin provenance, complementing previous interpretations based on detrital zircon data.

2. Spatial and temporal variation of provenance reconstructs the basin tectonic geography, reflecting the Mesoproterozoic tectonic history of the North Australia Craton.

3. Coupled thermo- and geochronology constrain tectonic settings of basin deposition.

Keywords:

• detrital muscovite ⁴⁰Ar/³⁹Ar thermochronology
• Beetaloo Sub-basin
• Mesoproterozoic North Australia Craton
• provenance analysis
• tectonic geography
• basin tectonic setting

Acknowledgements

T. J. Munson and A. J. M Jarrett and thanked for their suggestions. The authors gratefully acknowledge the contribution of the MinEx CRC and this manuscript forms MinEx Record 2023/12. We also thank Peter Haines and Vincent Crombez whose comments greatly improved this paper.

Additional information

Funding

This research was funded by Australian Research Council Linkage Projects [LP160101353 and LP200301457], with the Northern Territory Geological Survey, SANTOS Ltd., Origin Energy, Empire Energy, Teck Resources and BHP as valued partners.