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  • This report describes the ornamental stones used in the ground floor foyer of the Geoscience Australia building. There are three ornamental stones used. The flooring tiles are basalt. The 'fault' line through this is a polished norite and the blade walls are covered by a Persian red Travertine. Investigations have established that the basalt and norite are from Australian quarries and the travertine is from an unknown source overseas possibly Italy.

  • 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.

  • Recent centuries provide no precedent for the 2004 Indian Ocean tsunami, either on the coasts it devastated or within its source area. The tsunami claimed nearly all of its victims on shores that had gone 200 years or more without a tsunami disaster. The associated earthquake of magnitude 9.2 defied a Sumatra-Andaman catalogue that contains no nineteenth-century or twentieth-century earthquake larger than magnitude 7.9. The tsunami and the earthquake together resulted from a fault rupture 1,500 km long that expended centuries -worth of plate convergence. Here, using sedimentary evidence for tsunamis, we identify probable precedents for the 2004 tsunami at a grassy beach-ridge plain 125 km north of Phuket. The 2004 tsunami, running 2 km across this plain, coated the ridges and intervening swales with a sheet of sand commonly 5-20 cm thick. The peaty soils of two marshy swales preserve the remains of several earlier sand sheets less than 2,800 years old. If responsible for the youngest of these pre-2004 sand sheets, the most recent full-size predecessor to the 2004 tsunami occurred about 550-700 years ago.

  • 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

  • Optically stimulated luminescence (OSL) dating of sand sheets provides a chronology of the largest tsunamis in western Thailand over the late Holocene. Four sand sheets deposited by pre-2004 tsunamis were dated by luminescence to 380 ± 50, 990 ± 130, 1410 ± 190 and 2100 ± 260 years ago (at 1-sigma precision). These compare with previous radiocarbon ages of detrital bark high in buried soils (Jankaew et al., 2008), which suggest that the most recent large-scale predecessor to the 2004 tsunami occurred soon after 550-700 cal BP, and that at least three such tsunamis occurred over the past 3000 years. Concordant OSL ages from successive beach ridges (1600 ± 210 to 2560 ± 350 years ago) and tidal flat deposits (2890 ± 390 years ago) provides a set of limiting maximum ages for sand sheet deposition which, when combined with the sand sheet ages, provide a robust average for tsunami recurrence. The ages imply that between 350 to 700 years separates successive tsunamis on the Andaman coast of Thailand with an average tsunami recurrence interval of 550 years. These results show OSL can provide independent estimates of tsunami recurrence for hazard analysis, particularly in areas where suitable material for radiocarbon dating is unavailable.

  • This set of four charts provide an update of the million year numbers assigned to Australian palynological zone boundaries to the latest Geologic Time Scale 2004, authored by Gradstein et al. (2004), over the geological time interval Jurassic to Recent. These charts have been drafted to help display the relationships of the palynological zones to the new timescale and to assist in scaling the zones and subzones, so that most million year ages assigned to the zone boundaries are mostly numbers with not more than one decimal place.

  • As part of Geoscience Australia's 2002-2004 work program, the Petroleum and Marine Division initiated a collaborative study of the Otway Basin (Figure 1) with Primary Industries and Resources SA (PIRSA) and the Department of Primary Industries (DPI), Victoria. The aim of the project was to enhance the petroleum prospectivity of the basin through an improved understanding of depositional systems, integrated petroleum systems analysis and enhanced access to basic datasets critical to the exploration industry. Major project work components included seismic- and well-interpretation to construct a new regional chronostratigraphic framework for the basin (Figure 2), geochemistry and geohistory modelling to document regional petroleum systems elements (Boreham et al ., 2004), and biostratigraphy to refine age-control, biozonations and correlations within the basin (Krassay et al ., 2004). Biostratigraphic work for the Otway Basin Project involved a major program of new sampling, processing and palynological analysis combined with a thorough review of existing biostratigraphic reports and data. Collection, processing and preparation of new samples were conducted in-house by Geoscience Australia staff. New palynological analyses were carried out by Morgan Palaeo Associates on a commercial contract basis. This Record (CD-ROM) contains consultants palynological reports (Microsoft Word) and digital data files as originally submitted (wmf and dex formats) and as updated and standardised (csv format) for over 200 new samples collected from 14 selected Otway Basin wells (Table 1). This Record also contains revised palynological data files (csv format) for 18 Otway Basin wells (Table 2). Revision and updating of palynological data from existing reports and new consultants reports involved initial quality-assurance and quality-control of the data followed by updating of synonyms and systematics to comply with a standardised taxonomy. Revised data files contained in this Record adhere to a standardised taxonomy in current use at Geoscience Australia. Revised data files are presented in a csv format (Excel spreadsheets).

  • This report presents new geochronological results for five uranium deposits in Australia, detailing the timing of uranium mineralisation in relation to regional geological events. The purpose of the study is to better constrain ore genetic and exploration models for these uranium mineral systems, and ultimately to improve understanding of the uranium resource potential of the Australian continent. The work was carried out under the auspices of the Onshore Energy Security Program. Each of the five uranium deposits represents a different style of mineralisation within three broad families of uranium mineral systems: magmatic-related, basin-related, and metamorphic-related. The results contribute to the current paucity of age data for uranium deposits in Australia, and for most of the deposits the new dates are the first reported direct ages for mineralisation or associated alteration.