Stratigraphic resolution of a multiphase intracratonic basin system: the McArthur Basin, northern Australia
Rawlings, DJ, Stratigraphic resolution of a multiphase intracratonic basin system: the McArthur Basin, northern Australia, Australian Journal of Earth Sciences, 46, (5) pp. 703-723. ISSN 0812-0099 (1999) [Refereed Article]
The McArthur Basin is a regionally extensive multiphase Proterozoic basin system in northern Australia. Existing lithostratigraphic elements are amalgamated into five coherent basin phases or 'packages', to provide a basin-wide informal and non-genetic stratigraphic framework on which future genetic models may be based. Packages are basin-scale depositional and magmatogenic rock units, equivalent in magnitude to 2nd-order basin cycles. Each package comprises a set of lithostratigraphic units with similar age, stratigraphic position, lithofacies or lithofacies associations, style and composition of volcanism, basin-fill geometry and depocentre. The Redbank package (ca 1815-1710 Ma) comprises up to ~6 km of shallow-marine to fluvial sandstone, and lesser lutite, conglomerate, dolostone and bimodal volcanic and shallow intrusive rocks. It forms a semi-contiguous sheet throughout most of the McArthur Basin, but thins against the large-scale basin-compartmentalising basement ridges (e.g. Murphy and Urapunga Tectonic Ridges) due to depositional onlap and/or differential erosion. The conformably overlying Goyder package (ca 1710-?1670 Ma) comprises shallow-marine to fluvial sandstone and minor lutite and carbonate. It is areally restricted with a distinct ~6 km-thick depocentre in the central Walker Fault Zone (the proto-Walker Trough) and is flanked by attenuated successions onlapping the adjacent shelves suggesting deposition in a synsedimentary 'rift'. The conformably or disconformably overlying Glyde package (?1670-1600 Ma) comprises ~5 km of stromatolitic-evaporitic dolostone, siliciclastics and minor tuffaceous rocks, deposited in shallow- to moderately deep-water and locally emergent environments. It is restricted to the Walker, Batten and Urapunga Fault Zones, subsequent to deposition in the fault-bounded Walker and Batten Troughs. The unconformably to disconformably overlying Favenc package (ca 1600-?1570 Ma) is a regionally extensive, ~50-1600 m-thick, stromatolitic and evaporitic dolostone-sandstone succession with minor basaltic volcanics deposited in shallow-water, marginal-marine, peritidal-shelf and/or continental sabkha settings. It was deposited as a series of broad interconnected sag basins that transgressed the pre-existing tectonic framework of troughs and shelves. The Wilton package (?1500-?1400 Ma) is a widely distributed cyclic sequence of siliciclastics deposited in a shallow-marine, nearshore to shelf environment. It unconformably overlies all older basin packages, transgressing the pre-existing tectonic elements of the McArthur Basin. Distribution and depocentres have evolved significantly from the underlying packages, the Wilton package thickening to ~5 km in the Beetaloo Sub-basin.