Widespread reductions in the thickness and extent of Antarctic ice shelves are triggering retreat, acceleration and increased discharge of marine-terminating glaciers. However, while the impacts of recent ice-shelf changes are now well documented, their role in modulating past ice sheet dynamics – especially at a resolution required to identify drivers of change and test ice sheet models - remains poorly constrained. This reflects two persistent issues: (i) the effective discrimination between sediments and landforms deposited in a sub-ice-shelf setting from other glacimarine environments, and (ii) challenges associated with dating these records. Here we summarise recent progress in deciphering the ‘geological imprint’ of Antarctic ice shelves, including important advances in dating methods and the proxies required to reconstruct the drivers of change. Despite this improved ‘toolbox’ for establishing ice shelf presence and absence, we recognise several challenges that need to be overcome if we are to fully exploit the palaeo record. <b>Citation:</b> Smith, J.A., Graham, A.G.C., Post, A.L. et al. The marine geological imprint of Antarctic ice shelves. <i>Nat Commun</i> <b>10</b>, 5635 (2019). https://doi.org/10.1038/s41467-019-13496-5

Browse Basin Biozonation and Stratigraphy, 2008, revised February 2008

This teaching aid includes instructions and layout calculations for creating a Geological TimeWalk of your own. A set of information plaques marking each geological time interval is also available to download and use with the TimeWalk.

Canning Basin Biozonation and Stratigraphy updated in February 2008

The Lower Darling Valley (LDV) contains Cenozoic shallow marine, fluvial, lacustrine and aeolian sediments capped by a number of Quaternary fluvial units associated with the Darling River and its anabranches, which were poorly dated prior to this study. Recent investigations in the LDV area have used an Airborne Electromagnetic (AEM) survey, a new high-resolution LiDAR survey, sonic drilling, shallow hand-augering, examination of tractor-dug pits, sediment sample analyses, landform mapping, and river bottom profiling in combination with OSL and radiocarbon dating to provide new insights into the nature and chronology of Quaternary fluvial landscape evolution. The Quaternary sequence in the LDV consists of scroll-plain tracts of different ages incised into higher, older and more featureless floodplain sediments. Samples for OSL and radiocarbon dating were taken in tractor-excavated pits, from sonic cores and from hand-auger holes from a number of scroll-plain and older floodplain sediments. The youngest, now inactive, scroll-plain phase associated with the modern Darling River, was active in the period 5-2 ka. A previous anabranch scroll-plain phase has Last Glacial Maximum dates around 20 ka. Less distinct scroll-plain tracts, older than the anabranch system, have ages around 30ka. A poorly preserved scroll-plain phase with very indistinct scroll and channel traces is associated with the Darling River tract and has ages around 45-50 ka. Older dates of 85 ka and >150 ka have been obtained beneath the higher floodplain from lateral-migration sediments that lack visible scroll-plain traces. This chronologic sequence suggests regular recurrence of approximately 5 ka lateral-migration episodes separated by approximately 10 ka periods of quiescence. There is a lack of coincidence with the glacial-interglacial climate cycles. This suggests that the onset and termination of lateral-migration phases is probably a combination of changes in discharge and sediment regimes r

The Gawler Craton, South Australia, preserves extensive sedimentary sequences and associated magmatic rocks that span the interval covering the Archaean-Palaeoproterozoic transition, with bimodal calc-alkaline volcanism and associated sedimentation occurring over the interval ~2560-2480 Ma. The pervasive high geothermal gradient metamorphism in the earliest Palaeoproterozoic, ~2470-2420 Ma (Fanning et al., 2007; Jagodzinski et al., 2009) within the Gawler Craton suggests the Gawler Craton is potentially more likely a correlative of the Dhawaar Craton, Sask Craton and other similar terranes, in terms of timing of magmatic and orogenic events (Payne et al., 2009). We report new zircon U-Pb ion probe data collected from Neoarchaean to Earliest Palaeoproterozoic metasedimentary and meta-igneous rocks of the Gawler Craton, South Australia, an important time interval for the development of the Gawler Craton itself that has been investigated by relatively few geochronological studies. The new data show that the interval ~2560-2480 Ma was characterised by deposition and associated magmatism. This was terminated by contractional deformation and high geothermal gradient metamorphism over the interval ~2470-2410 Ma.

This black and white education resource is a 58 page booklet which contains information on geological time, fossilisation, characteristics of major groups of vertebrate and invertebrates, micropaleontology (e.g.. spores and pollen), trace fossils and the uses of fossils. It includes student activities. Suitable for secondary Years 7-10

This black and white resource is an 18 page booklet including geological time, rock clocks, the age of famous Australian places, Australia on the move, Australian volcanoes, Ice Ages, Ancient Australian life, how fossils form and some common Australian fossils. Includes student activities suitable for primary Years K-6.

This record contains zircon U-Pb geochronological data obtained between July 2001 and May 2003 on diamond drillcore from the Olympic Domain, Gawler Craton, South Australia. The data were collected as part of the Gawler Craton Project; a collaboration between Geoscience Australia (GA) and the Division of Mineral and Energy, Primary Industry and Resources, South Australia (PIRSA). The project aims to provide an improved geological and metallogenic framework for the Gawler Craton, with initial emphasis on the Olympic Domain. The term Olympic Domain (formerly 'Olympic Subdomain'; Daly et al. 1998) refers to the eastern extension of the Gawler Craton, concealed beneath Mesoproterozoic, Neoproterozoic and Cambrian sedimentary rocks of the Stuart Shelf. It also encompasses outcrop and subcrop of the Gawler Craton further south in the Moonta-Wallaroo region of the Yorke Peninsula. The sedimentary cover sequence of the Stuart Shelf is between about 300 and 1000 m thick, and the only knowledge of the underlying crystalline basement comprising the Olympic Domain is derived from exploratory drillholes. The long distances between drillholes impede inter-hole correlations. Thus U-Pb isotope dating of rocks intersected by (diamond) drillcore plays a key role in regional stratigraphic studies, establishing an absolute basis for temporal correlations across the Olympic Domain. This record describes the samples analysed and the analytical results obtained, and provides a brief discussion of their geochronological interpretation. The broader geological implications of the data will be published elsewhere.

The Ranger deposit is one of Australia's largest known uranium resources, with current open pit mining of the No. 3 orebody and a total resource of 109,600 tonnes of U3O8 grading 0.08% at this orebody (ERA, January 2011). This unconformity-related deposit is hosted by Paleoproterozoic metasedimentary rocks of the Cahill Formation which is unconformably overlain by sandstones of the Kombolgie Formation. A maximum depositional age of ~1818 Ma is inferred for the sandstones, based on the presence of the Nabarlek Granite of this age in the basement beneath the Kombolgie Formation. Most mineralisation occurs within a largely stratabound shear and breccia zone and is associated with intense proximal chlorite and distal white mica alteration. The Kombolgie Formation is weakly deformed, faulted and weakly chloritised above the mineralisation.