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The published latest Palaeocene to Early–Middle Eocene age limits of the Sabrina microfloras, offshore Aurora Subglacial Basin, East Antarctica, largely depend on 1970s age-range data for fossil pollen and spore species in the continental margin basins of southern Australia. This paper uses updated biostratigraphical data from southern Australia, including the basins closest to the Aurora Basin throughout the Late Cretaceous and Paleogene, to propose that the age of the terrestrial component of the Sabrina microfloras is Campanian to Maastrichtian, not Paleogene. However, the revised age limits do not preclude these microfloras being redeposited more or less intact during the development and expansion of ice-sheets on East Antarctica, i.e. most probably during the late Paleogene based on other evidence from East Antarctica. [ABSTRACT FROM AUTHOR]

Stratigraphic investigations, supported by palynological dating, detrital zircon and monazite dating, and quartz grain micromorphology were undertaken of the Early Cretaceous strata around the southern margin of the Eromanga Basin where they onlap older rocks of the northern Flinders Ranges. The presence of a tillite within the Early Cretaceous Cadna-owie Formation and another in the Trinity Well Sandstone are evidence of two significant glaciations: the oldest, the Livingston Tillite Member, is from the middle Valanginian; the younger, the Sheehan Tillite Member, is from the early Aptian. A significant hiatus encompassing the Barremian interrupts the succession. Extensive dropstones, minor diamictite lenses and beds and a bed containing glendonite crystals, together indicate that cold (limited glacial and/or seasonal freezing) conditions persisted through the Hauterivian and the Aptian, with cold conditions peaking in the late Aptian. [ABSTRACT FROM AUTHOR]

Recently acquired seismic data in the eastern portion of the Amadeus Basin of central Australia have enabled disconformities at the base of both the Sturt and Elatina glaciogenic sequences within the Neoproterozoic succession to be mapped on a semi-regional scale. On a more detailed scale, along the shallowly shelving eastern flank of the basin, seismic data have revealed features that demarcate the transition from a grounded to floating, or possible absent, Sturt ice-sheet. Coincident with this transition is an extensive mound-like accumulation of glacial debris, some 10 to 15km wide, 300 m high and extending at least 150km subparallel to the northeast-southwest-oriented basin margin. This glacial debris entered the basin subglacially through meandering tunnel valleys, one of which can be mapped seismically. [ABSTRACT FROM AUTHOR]

The angular unconformity at the base of the Grant Group forms a distinctive surface evident both at outcrop and in the subsurface on seismic and well logs. Detailed analysis of a 2D seismic dataset, integrated with available well data, suggests a complex suite of processes controlling the formation, deformation and resultant morphology of this surface. They can be subdivided into three categories depending on whether the mechanisms pre-dated, were coeval with, or post-dated deposition of the Grant Group. Pre-Grant faulting during the Devonian–Lower Carboniferous Pillara Extension resulted in development of significant paleotopography that influenced the morphology of the Base Grant Group unconformity. The pre-Grant interval contained thick salt, which was locally removed in the Silurian, with the development of isolated bodies of thickened Worral Formation. Later after deposition of the Grant group, the remainder of the Mallowa salt underwent dissolution/withdrawal, resulting in collapse of the flanks of earlier Worral pods of sediments, forming a ‘sombreros’ structure and folding the Base Grant Group unconformity. The main syn-Grant processes include regional glacial erosion, and extensive development of paleo-tunnel valleys that formed beneath and at the margin of the Permian–Carboniferous ice sheet as it advanced into the Fitzroy Trough. This created significant relief on the Base Grant Group unconformity, with tunnel valleys characterised by steep-sided, often U-shaped valleys up to 525 m deep and 12 km wide. Post Grant deposition, the unconformity surface was subsequently modified during the Triassic–Jurassic Fitzroy Movement, resulting in fault reactivation and development of a series ofen-echelonanticlines associated with a regional wrench system. [ABSTRACT FROM PUBLISHER]

The stratigraphy in Vines 1, a 2017.5 m-deep cored stratigraphic hole drilled by the Geological Survey of Western Australia in 2001 near the Western Australian - South Australian border, has been reinterpreted with implications for the Neoproterozoic to Cambrian geological history of the Officer Basin. A previous interpretation considered the intersected succession as a conformable stratigraphic package, the Vines Formation. An assemblage of palynomorphs, found throughout the hole and previously used to infer an age of no older than earliest Cambrian, is now thought to consist of contaminants. An older assemblage, which is considered to be reworked and inherited from underlying rocks, provides a new maximum age constraint of mid-Neoproterozoic. Based on sedimentological interpretations and comparisons with other drillholes in the western Officer Basin, and the succession in the eastern Officer Basin, the Vines 1 succession is reinterpreted as four discrete sedimentary packages, the Pirrilyungka (new name), Wahlgu, Lungkarta and Vines (redefined) Formations, in ascending order. The Pirrilyungka and Wahlgu Formations include glacigenic sediments and may correlate with similar glacial successions in Supersequences 2 and 3 (mid to late Cryogenian) of the Centralian Superbasin, and the Sturt Tillite and Elatina Formation and their equivalents in the Adelaide Rift Complex of South Australia, respectively. The eolian Lungkarta Formation and fluvial Vines Formation are considered, on regional evidence, to be most likely of Ediacaran to earliest Cambrian age. [ABSTRACT FROM AUTHOR]