Testing long‐term patterns of basin sedimentation by detrital zircon geochronology, Centralian Superbasin, Australia

Abstract

Detrital zircon geochronology of Neoproterozoic to Devonian sedimentary rocks from the Georgina and Amadeus basins has been used to track changes in provenance that reflect the development and inversion of the former Australian Superbasin. Through much of the Neoproterozoic, sediments appear to have been predominantly derived from local sources in the Arunta and Musgrave inliers. Close similarities between the detrital age signatures of late Neoproterozoic sedimentary rocks in the two basins suggests that they were contiguous at this time. A dominant population of 1.2–1.0 Ga zircon in Early Cambrian sediments of the Amadeus Basin reflects the uplift of the Musgrave Inlier during the Petermann Orogeny between 560 and 520 Ma, which shed a large volume of detritus northwards into the Amadeus Basin. Early Cambrian sedimentary rocks in the Georgina Basin have a much smaller proportion of 1.2–1.0 Ga detritus, possibly due to the formation of sub‐basins along the northern margin of the Amadeus Basin which might have acted as a barrier to sediment transfer. An influx of 0.6–0.5 Ga zircon towards the end of the Cambrian coincides with the transgression of the Larapintine Sea across central Australia, possibly as a result of intracratonic rifting. Detrital zircon age spectra of sedimentary rocks deposited within this epicontinental sea are very similar to those of coeval sedimentary rocks from the Pacific Gondwana margin, implying that sediment was transported into central Australia from the eastern continental margin. The remarkably consistent ‘Pacific Gondwana’ signature of Cambro‐Ordovician sediments in central and eastern Australia reflects a distal source, possibly from east Antarctica or the East African Orogen. The peak of the marine incursion into central Australia in the early to mid Ordovician coincides with granulite‐facies metamorphism at mid‐crustal depths between the Amadeus and Georgina basins (the Larapinta Event). The presence of the epicontinental sea, the relative lack of a local basement zircon component in Cambro‐Ordovician sedimentary rocks and their maturity suggest that metamorphism was not accompanied by mountain building, consistent with an extensional or transtensional setting for this tectonism. Sediments deposited at ∼435–405 and ∼365 Ma during the Alice Springs Orogeny have detrital age signatures similar to those of Cambro‐Ordovician sedimentary rocks, reflecting uplift and reworking of the older succession into narrow foreland basins adjacent to the orogen.

Thermochronology and stratigraphy of the Thomson Orogen, north-eastern Australia

“…In addition to the east Australian correlations described above, there are also likely correlations between the Thomson Orogen and strata of the Neoproterozoic to Paleozoic Centralian Superbasin (Walter et al, 1992;Maidment et al, 2007). Specifically, the Mount McLaren beds correlate with the shallow marine, Early Ordovician Pacoota Sandstone of the Amadeus Basin in central Australia on the basis of similarities in detrital zircon ages, with the main histogram peak at ~500 Ma (Maidment et al, 2007;Oorloff, 2014).…”

“…The late Neoproterozoic saw the deposition of the Centralian Superbasin from a large epicontinental sea that covered much of what is now central Australia (Walter et al, 1996;Maidment et al, 2007). The second super-sequence of the Centralian Superbasin is associated with the rifting of the supercontinent Rodinia (Li and Powell, 2001).…”

“…East-west contraction during the Delamerian Orogeny occurred at ~514 -490 Ma (Foden et al, 2006), with the effects felt as far north as the Anakie Inlier of the Thomson Orogen (Withnall et al, 1996). In the late Cambrian to Ordovician the shallow Larapintine Sea covered much of central Australia (Maidment et al, 2007), and quartz turbidites were deposited in the Lachlan Orogen and southern…”

“…Specifically, the Mount McLaren beds correlate with the shallow marine, Early Ordovician Pacoota Sandstone of the Amadeus Basin in central Australia on the basis of similarities in detrital zircon ages, with the main histogram peak at ~500 Ma (Maidment et al, 2007;Oorloff, 2014). The widespread Cambrian-Ordovician sandstones of eastern and central Australia are depositional remnants of the Larapintine Sea, an early Paleozoic shallow, epi-continental sea that covered much of central and eastern Australia (Li and Powell, 2001;Haines and Wingate, 2007;Maidment et al, 2007;Figure 2.6).…”

“…Specifically, the Mount McLaren beds correlate with the shallow marine, Early Ordovician Pacoota Sandstone of the Amadeus Basin in central Australia on the basis of similarities in detrital zircon ages, with the main histogram peak at ~500 Ma (Maidment et al, 2007;Oorloff, 2014). The widespread Cambrian-Ordovician sandstones of eastern and central Australia are depositional remnants of the Larapintine Sea, an early Paleozoic shallow, epi-continental sea that covered much of central and eastern Australia (Li and Powell, 2001;Haines and Wingate, 2007;Maidment et al, 2007;Figure 2.6). The early Paleozoic deposits of the Larapintine Sea are linked by detrital zircons that have both Pacific-Gondwanan (~700 to 500 Ma) and Grenville-Gondwanan (~1300 to 1000 Ma) age populations, attributes that are useful for tracing sediment provenance (Fergusson et al, 2001;Squire et al, 2006;Maidment et al, 2007;Fergusson et al, 2007c).…”