2016
Type of resources
Keywords
Publication year
Service types
Scale
Topics
-
This service has been created specifically for display in the National Map and the chosen symbology may not suit other mapping applications. The Australian Topographic web map service is seamless national dataset coverage for the whole of Australia. These data are best suited to graphical applications. These data may vary greatly in quality depending on the method of capture and digitising specifications in place at the time of capture. The web map service portrays detailed graphic representation of features that appear on the Earth's surface. These features include the administration boundaries from the Geoscience Australia 250K Topographic Data, including state forest and reserves.
-
New geophysical data, including gravity, airborne electromagnetic (AEM) and broadband magnetotelluric (BBMT) were collected along a series of traverses in the southern Thomson Oregon region of north-western New South Wales and southwestern Queensland in 2014 as part of the Southern Thomson Project. Comparing and integrating this data over the same spatial extents aimed to provide a better understanding of the crustal architecture of this region, and help estimate cover thicknesses above basement rocks. When comparing all available datasets, AEM cannot be reliably used when cover thickness is > ~150m because of limitations in Depth of Investigation (DOI), and BBMT tends to overestimate cover thickness where it is less than 50m. Audio-MT (AMT) likely provides the best resolution for estimating cover thicknesses of 0-1000m on this regional scale. Forward modelling of the gravity data along selected traverses tested the interpreted crustal architecture and cover thicknesses inferred from available seismic images and the new AEM and MT conductivity models. The variable cover thicknesses interpreted from this combined approach produce a closer match with the observed gravity response when compared to a uniform, average cover thickness. The most accurate crustal-scale forward model was a thickened crust north of the Olepoloko Fault (the proposed southern boundary of the southern Thomson), split into simplified lower, middle and upper layers with basement lithologies immediately beneath cover based on the most recent basement interpretation map. Resistive bodies shown in the MT models were included in the gravity modelling, producing a good match between the observed and calculated gravity responses. These results demonstrate the utility in using a combination of different geophysical techniques to understand crustal architecture and estimations of basement depths in regions of Australia with little surface outcrop and thick cover sequences.
-
This Record contains new zircon U-Pb geochronological data, obtained via Sensitive High-Resolution Ion Micro Probe (SHRIMP), from two samples of metamorphosed felsic igneous rocks of the Proterozoic Pinjarra Orogen (Western Australia), intersected in diamond drillcore at the base of deep petroleum exploration wells penetrating the Paleozoic sedimentary successions of the Perth Basin. In the southern Perth Basin, petroleum exploration well Sue 1 was terminated at depth 3074.2 m, in crystalline basement rocks of the southern Pinjarra Orogen. Abundant zircon from a biotite-bearing felsic orthogneiss at depth 3073.2-3073.7 m yielded a complex array of U-Pb isotopic data, indicative of significant post-crystallisation disturbance of the isotopic system. A Discordia regression fitted to the array yielded an upper intercept date of 1076 ± 35 Ma (all quoted uncertainties are 95% confidence intervals unless specified otherwise) interpreted to represent magmatic crystallisation of the igneous precursor to the orthogneiss, and a lower intercept date of 680 ± 110 Ma which is our best estimate of the age of the tectonothermal event responsible for post-crystallisation disturbance of the U-Pb system. Crust of known Mesoproterozoic age is rare in the southern Pinjarra Orogen: pre-1000 Ma igneous crystallisation ages in the Leeuwin Complex were previously known only from two c. 1090 Ma garnet-bearing orthogneisses at Redgate Beach (Nelson, 1999), 30 km west of Sue 1. All other dated outcrops have revealed Neoproterozoic (780-680 Ma) granitic protoliths reworked by Early Cambrian (540-520 Ma) magmatism, deformation and metamorphism (Nelson, 1996, 2002; Collins, 2003). In the northern Perth Basin, petroleum exploration well Beagle Ridge 10A was terminated at depth 1482 m, in crystalline basement rocks of the northern Pinjarra Orogen. A leucocratic orthogneiss sampled within the interval 1464.0-1467.0 m yielded only sparse zircon, but four of the seven grains analysed yielded a weighted mean 207Pb/206Pb date of 1092 ± 27 Ma, interpreted to represent magmatic crystallisation of the igneous precursor to the orthogneiss. Our data show no evidence for Neoproterozoic U-Pb resetting of the c. 1090 Ma zircons: where present, post-crystallisation isotopic disturbance is predominantly geologically recent. The two newly dated samples are located at opposite ends of the Perth Basin (about 470 km apart), and although the two magmatic crystallisation ages are imprecise, the date of 1092 ± 27 Ma from the Beagle Ridge 10A leucocratic orthogneiss is indistinguishable from the date of 1076 ± 35 Ma from the Sue 1 felsic orthogneiss. Furthermore, both rocks contain inherited zircon of Mesoproterozoic age (1620-1180 Ma in Sue 1; 1290-1210 Ma in Beagle Ridge 10A), indicating the presence of pre-1100 Ma crustal components in their parent magmas. This is consistent with a suite of Paleoproterozoic Sm-Nd model ages determined by Fletcher et al. (1985) on buried Pinjarra Orogen orthogneisses, which span 2.01 ± 0.06 Ga to 1.78 ± 0.04 Ga in the north (near BMR Beagle Ridge 10A), and including a model age of 1.80 ± 0.04 Ga from a sample of granitic gneiss obtained from Sue 1. Fletcher et al. (1985) argued that the consistency of 2.1-1.8 Ga Nd model ages obtained from crystalline basement in drillcore beneath the southern and northern Perth Basin, and from outcrop in the Northampton Complex and Mullingarra Complex of the northern Pinjarra Orogen, indicated a similar or shared crustal evolution. Our new U-Pb zircon data support this model, expanding the known extent of 1100-1050 Ma felsic magmatism in both the southern and northern Pinjarra Orogen, and indicating that Neoproterozoic tectonothermal overprinting appears to be restricted to the Leeuwin Complex, with no corresponding event discernible in the northern Pinjarra Orogen.
-
In January 2011 extreme flooding occurred in the South-east corner of Queensland resulting in over 17000 homes inundated in the cities of Brisbane and Ipswich. In the weeks following the floods, Geoscience Australia conducted a field survey to assess the scale of the damage on individual homes. The engineering survey was then supplemented with GA's first social survey. This report presents the results of the survey investigating the impacts of the 2011 floods on flooded households in the Brisbane and Ipswich City Councils, combined with the results of a follow up survey conducted following the 2013 floods in the same area. The report chapters cover: warnings and risk perception; preparation, evacuation and returning home; damage and repair; financial implications; and medical impacts, mental health and social support.
-
The Cooper Basin is an upper Carboniferous-Middle Triassic intracratonic basin in northeastern South Australia and southwestern Queensland. The basin is Australia's premier onshore hydrocarbon producing province and also hosts a range of unconventional gas play types within the Permian Gidgealpa Group, including basin-centred gas and tight gas accumulations, deep dry coal gas associated with the Patchawarra and Toolachee formations, the Murteree and Roseneath shale gas plays and deep coal seam gas in the Weena Trough (e.g. Goldstein et al., 2012). The principal source rocks for these plays are the Permian coals and coaly shales of the Gidgealpa Group (Boreham & Hill, 1998; Deighton et al., 2003; Carr et al., 2016). Mapping the petroleum generation potential of these source rocks, together with describing the resulting fluid composition, is critical for understanding the hydrocarbon prospectivity of the basin. This study applies petroleum systems analysis to investigate the maturity and generation potential of the Cooper Basin source rocks and is underpinned by a public domain, pseudo-3D petroleum systems model (Hall & Palu, 2016). Over ninety 1D thermal and burial history models were integrated with the 3D geological model and source rock property characteristics to create a regional pseudo-3D petroleum systems model for the basin, to assess generated, expelled and retained volumes of hydrocarbons. The pseudo-3D model was calibrated using present day corrected temperatures and maturity indicators (Ro, Tmax). In addition, lithologies were assigned for key wells and formations and were calibrated using measured velocity, density and thermal conductivity data. The base thermal boundary condition was set as transient heat-flow /fixed temperature at base lithosphere and the top thermal boundary condition was defined by modelled surface temperature changes through time. Crustal thickness and radiogenic heat production properties were from published studies (e.g. Beardsmore, 2004; Meixner et al., 2012; Hall et al., 2015b). Parameters for source rock distribution, amount and quality were added from analysis of log data and source rock geochemical data (Hall et al., 2016) and new Permian source rock kinetics (Mahlstedt et al., 2015). The modelling outputs quantify both the spatial distribution and total maximum hydrocarbon yield for ten source rock intervals in the basin. A map of total hydrocarbon generation of all Gidgealpa Group source rocks demonstrates the broad extent of the Permian source kitchen across the basin, the distribution of which is consistent with the location of major conventional fields across the basin. Results highlight the variability in burial, thermal and hydrocarbon generation histories for each source rock across the basin. Although source rock maturity varies between depocentres, large areas of the Nappamerri, Patchawarra and Windorah troughs are gas mature. Key variables influencing the thermal history include: higher radiogenic heat production associated with the Big Lake Suite granodiorites, Late Cretaceous uplift and erosion of the Winton Formation and the thermal blanketing effect of the thick Permian coals. Monte Carlo simulations were used to quantify the uncertainty associated with hydrocarbon yield and to highlight the sensitivity of results to each input parameter. The combined theoretical volume of hydrocarbons generated from all Permian source rocks is mapped, highlighting the broad extent of the source kitchen. The total modelled volume of hydrocarbons generated from the Cooper Basin Permian source rocks is estimated to be ~1,750 BBOe (P50 scenario), however the difference between the P90 (~730 BBOe) and P10 (~4,100 BBOe) scenarios quantifies the large range of uncertainties inherent in the modelling. The large disparity between the calculated amounts of hydrocarbons expelled and the amounts so far found in reservoirs highlights (a) the large amounts of hydrocarbons which have been lost by leakage and water washing (b) the potential for large volumes to remain within and near the source rocks. The latter are a potential target for production using unconventional technologies.
-
Geoscience Australia conducted an absolute gravity survey during April and May 2015 in order to maintain and update the Australian Fundamental Gravity Network (AFGN). During the 2015 AFGN field campaign 35 absolute gravity readings were taken with an A10 gravity meter out of which 29 were new additions to the network. Six of the readings were taken over older AFGN stations in order to update and validate existing values. The re-measures found the previous gravity values agreed with the new A10 measurements within their stated uncertainties. Two ties were made with the CG5 gravity meter from a newly established station in order to resolve discrepancies with existing gravity values. 30 pre-existing stations were checked for their condition during this survey and 5 stations were found to be destroyed. GPS readings were taken at existing stations and their locations updated in the database as many of the old stations had poorly defined locations.
-
This gravity anomaly image has been generated from the Bouguer Gravity Anomaly Grid of Australia 2016. The Bouguer grid has been image enhanced and displayed as a hue-saturation-intensity (HSI) image with sun shading from the northeast. The product has been derived from observations stored in the Australian National Gravity Database (ANGD) as at February 2016 together with the 2013 New South Wales Riverina gravity survey. Out of the almost 1.8 million records in the ANGD approximately 1.4 million stations were used to generate this image. The image shows spherical cap Bouguer anomalies over onshore continental Australia. The data used in this image has been acquired by the Commonwealth, State and Territory Governments, the mining and exploration industry, universities and research organisations from the 1940's to the present day. The spherical cap Bouguer anomalies in this image are the combination of Bullard A and B corrections to the Free Air anomaly values using a density of 2670 kg/m^3.
-
Winds, waves and tides associated with storms are capable of causing severe damage to property and infrastructure on the coast. Natural disasters of this type are often attributed to misfortune, however this view falsely implies an inability to reduce exposure to the risks of these hazards through well informed mitigation efforts (e.g. sand bypassing, beach nourishment, coastal structures and planned retreat). Locations that are prone to severe erosion first require an accurate assessment of risk before deciding the most cost effective mitigation option. This research aims to produce probabilistic assessments of the coastal erosion and resultant inundation risks associated with natural hazards, particularly for coincident or clustered storm events, thereby helping to strengthen the resilience of coastal communities. Coastal erosion and resultant inundation risk is assessed in this research by simulations of realistic storm condition forcing (waves and tides) through a morphodynamic model to calculate return periods for maximum extent of shoreline retreat. This direct approach of characterizing erosion response return periods is superior to the naïve assumption that the most energetic storm forcing cause the worst erosion events. This methodology is demonstrated for beaches in metropolitan Adelaide and at Old Bar, NSW. These sites were selected to develop the methodology for a span of geographic conditions in terms of storm climate and deep water wave exposure, working towards developing this method into a transportable framework that is applicable to other coastal areas. Desktop and field assessments of each site were conducted to document geomorphic and sediment characteristics to inform the shoreline modelling. Having established the historical framework at each location, multivariate statistical analysis of wave (buoy or hindcast models) and tides for peak storm events allows for the synthesis of realistic future conditions. Ongoing work is aimed at analysis of the complex sequencing of cycling between accretion and erosion in terms of cross-shore and alongshore sediment transport. Additionally, the potential for storm clustering to cause enhanced coastal erosion and impact on coastal infrastructure will be assessed.
-
Terrain illumination correction is an important step in the normalisation of remotely sensed data for the inversion of land surface parameters, and for applications that aim to detect land surface change through time series analysis. An appropriate resolution of the Digital Elevation Model (DEM) data with sufficient quality is critical for effective correction of remotely sensed data over mountainous areas. Conversely, using terrain illumination correction and scale-based analysis, such as filter bank analysis, the quality of DEM data can be evaluated relative to the scale of the target data. In this study, TanDEM-X Intermediate DEM (IDEM) data at 12 m and 30 m resolutions, and the 1-arc second Shuttle Radar Topography Mission (SRTM) data (~ 30 m resolution) were used to evaluate their absolute and relative effectiveness in terrain illumination correction for Landsat satellite optical data. The island of Tasmania in Australia has significant local terrain detail as well as high regional relief. This, together with its high latitude and wide variation in terrain illumination throughout the year, makes it an ideal study site to test correction methods and assess different resolution candidate DEM data. A set of images from both Landsat 7 and 8 multispectral bands (MS) and panchromatic (Pan) band were collected. These images were put through standard atmospheric and BRDF processing as well as terrain illumination correction using different sources of DEM. Comparisons were made by undertaking terrain correction with the various input DEMs and using visual and difference image methods to evaluate them. Quantitative Filter Bank analysis is also used to evaluate performance as a function of spatial scale. In total, five DEMs were used for the study, which include three at Landsat MS scale (derived from 12m and 30m IDEM and 1 sec SRTM data) and two at Landsat Pan scale (derived from 12m IDEM and 1 sec SRTM data). Results from the terrain illumination correction and filter bank analysis show that (provided the analysis is confined to areas without some specific data issues), although all data sets can carry out the task well, the IDEM 12 m resolution based datasets can resolve finer details of terrain shading than the SRTM based DEM. This indicates that IDEM can deliver better results in areas with detail-rich terrain monitored with Landsat data. However, since the data available for this study is a sample from an intermediate product, spikes and other noise artefacts not expected in operational data were prevalent. Noise artefacts occurred especially over areas covered by water. Operational use of the IDEM will require the removal of such noise artefacts, but from the present study we can say if that were fully achieved, the 12m resolution data could form the basis for better terrain correction of Landsat data. The filter bank analysis also found that both Landsat panchromatic data and IDEM 12 m data seem to be over-sampled; studies using even finer DEM data would be required to examine this further. It should be possible to correct for noise issues, as similar processing was carried out with SRTM data at an early stage to good effect. More detailed evaluation of the relative merits of the TanDEM-X based DEM compared with the SRTM based DEM data for terrain illumination correction may be possible when the WorldDEM product based on TanDEM-X data becomes routinely available with the water areas noise issues resolved.
-
This Record contains new zircon and monazite U-Pb geochronological data obtained via Sensitive High-Resolution Ion Micro Probe (SHRIMP) from nine samples of volcanic, volcaniclastic and plutonic igneous rocks of the central Lachlan Orogen and the New England Orogen, New South Wales. These data were obtained during the reporting period July 2014-June 2015, under the auspices of the collaborative Geochronology Project between the Geological Survey of New South Wales (GSNSW) and Geoscience Australia (GA), which is part of the National Collaboration Framework (NCF).