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.

This report summarises the outcomes of the NPI-AB's second meeting in July 2015.

This report is a contribution to the 2016 State of the Environment Report prepared by the Commonwealth Department of the Environment. It presents a summary desciption of benthic habitats and communities within submarine canyons, including statistics on the number and regional disrtibution of canyons. An assessment of the current state and trend of canyon ecosystems is also provided.

The ecosystems of northern Australia have very high global rankings in terms of the estimated dollar values of the ecosystem services they provide. Estuaries, which are abundant along the northern Australia coast, are some of the most productive ecosystems on earth, and provide vital nursery habitat for economically important species of fish and crustaceans. Most of the world's population lives in close proximity to estuaries therefore they also tend to be amongst the most degraded marine ecosystems on the planet. However, due to the small population sizes, most of Northern Australia's estuaries are unique in the respect that they are in near-pristine condition. One of the key triggers in estuarine productivity is the fresh water inflow received during the wet season and the flow recession periods afterward. To date there have been no studies of the environmental flow requirements for estuaries in the Northern Territory. As northern Australia develops there will be greater reliance on these important ecosystems for food production and recreation, while at the same time there will be competing demands for freshwater. The designation of environmental flows to river-estuary systems should be based on estuary requirements. If adequate estuarine environmental flows are maintained then it is likely that flows in upper river reaches will also be sufficient for riverine species. Studies of the roles of environmental flows on productivity in estuaries in catchments slated for development will be key in providing the foundation for economically and ecologically sustainable development of these important ecosystems. These studies will also provide additional information on how other uses of estuaries may be developed. For example wetland systems may be used for aquaculture or as watering points. Good information on estuarine processes will not only provide previously unexplored opportunities but help to ensure that our estuaries remain in excellent condition.

Several belts of poorly-exposed igneous rocks occur in the Grampians-Stavely Zone of western Victoria, close to the interpreted Cambrian east Gondwana continental margin. Previous geochemical studies on the outcropping igneous rocks around Mount Stavely, Mount Dryden and in the Black Range have recognised characteristics similar to those found in modern magmatic arcs. These rocks are collectively considered to form part of a single Middle to Late Cambrian arc system, referred to as the Stavely Arc. While outcropping examples of the Stavely Arc magmas are well studied, the character of other (likely) arc-related rocks imaged by magnetic data beneath recent, thin cover has remained enigmatic. New geochemical data from a recent stratigraphic drilling program, together with analysis of rocks from government and industry drill holes has allowed for a more complete understanding of the Stavely Arc package. A range of rock associations have been recognised, including low-Ti boninite-like rocks, back-arc-related tholeiitic rocks, adakitic porphyry intrusives, serpentinites, and highly-depleted mafic to intermediate volcanics and intrusives. The majority of arc-related rocks comprise low- to high-K calc-alkaline basalt, andesite, dacite, and geochemically-related quartz diorite, which display similar N-MORB-normalised trace element patterns, LREE-enriched REE patterns and moderately evolved to weakly juvenile Nd isotopic compositions (Nd 500 Ma = -3.95 to +0.46). High-Al basalts intersected during stratigraphic drilling also show weakly-developed calc-alkaline compositions. However, these are distinguished from the other calc-alkaline rocks by higher Al2O3, N-MORB-like trace element patterns, relatively flat REE patterns and much more juvenile Nd isotopic compositions (Nd 500 Ma = +4.73 to +6.33). High-Al basalts are spatially associated with boninites intersected by mineral exploration drilling. The earliest geochronological evidence for Stavely Arc magmatism is provided by an isotopically juvenile felsic intrusive with an interpreted arc-related origin dated at ~510 Ma. This age is synchronous with tholeiitic dolerite from the western Grampians-Stavely Zone interpreted to have been emplaced in a back-arc extensional setting. Available ages for volcanic rocks of the Stavely Arc are only known from the Mount Stavely Belt, and show that arc magmatism reached maturity around ~505-500 Ma. Overall geochemical systematics suggest that the majority of calc-alkaline rocks of the Stavely Arc have affinities with modern island arcs with (limited) continental crust involvement. It is unlikely that the thickness of any pre-existing Precambrian crust was great, given the Nd isotopic compositions and lack of inherited Mesoproterozoic or older zircons. In comparison, the more juvenile isotopic characteristics, weakly-developed subduction-related features, and spatial association with boninites of the high-Al basalts are more consistent with a more primitive arc setting, and may represent an (early?) phase of Stavely Arc magmatism in which there was insignificant crustal involvement. Similar geochemical characteristics, ages, and inferred tectonic setting are consistent with the Stavely Arc forming part of a larger Middle to Late Cambrian arc system that also includes the Mount Wright Arc in New South Wales and the Jamison Volcanic Group (Selwyn Block) in central Victoria.

Spatial distribution of sponge species richness and its relationship with environmental variables are important for the informed monitoring of ecosystem health and marine environmental management and conservation within the Oceanic Shoals Commonwealth Marine Reserve, in the Timor Sea region, northern Australia. However, the spatially continuous data of sponge species richness is not readily available, and the relationship is largely unknown. In this study, we modelled sponge species richness data of 77 samples using random forest (RF) and generalised linear model (glm) and their hybrid methods with geostatistical techniques (i.e. ordinary kriging (OK) and inverse distance weighting (IDW)) based on seabed biophysical variables. These methods are RF, RFOK, RFIDW, glm, glmok and glmidw that is a new hybrid method. We also examined effects of model averaging using four averaged methods (RFOKRFIDW, RFRFOKRFIDW, glmokglmidw and glmglmokglmidw) and the effects of various predictor sets on the accuracy of predictive models. Four feature selection methods, 1) averaged variable importance (AVI), 2) Boruta, 3) knowledge informed AVI (KIAVI) and 4) recursive feature selection (rfe), were used for RF; and four variable selection methods: 1) stepAIC, 2) dropterm, 3) anova and 4) RF, were employed to select glm predictive models. Predictive models were validated based on 10-fold cross validation. Finally the spatial distribution of sponge richness was predicted using the most accurate model and examined. The main findings are 1) the initial input predictors affect the status of important and unimportant variables; 2) AVI is not always reliable and KIAVI is recommended for selecting RF predictive model, 3) using Boruta can improve the accuracy in comparison with the full model, but it may lead to sub-optimal models; and features selected using rfe are not optimal and can be even misleading; 4) the accuracy of glm predictive model did not align with AIC, deviance explained (%) and deviance explained adjusted (%), suggesting that conventional model selection approaches for glm is unable to identify reliable predictive models; 5) joint application of RF and AIC is a useful model selection approach for developing glm predictive models; 6) the goodness of fit should not be used to assess glm predictive models; 7) the hybrid methods have significantly improved the predictive accuracy for both RF and glm; and the hybrid methods of RF and geostatistical methods are considerably more accurate and able to effectively model count data; and 8) the relationships of sponge species richness with the predictors are non-linear, and high sponge species richness is usually associated with hard seabed features. This study further confirms that: 1) the initial input predictors affect the model selection for RF; 2) the inclusion of highly correlated predictors could improve predictive accuracy, providing important guideline for pre-selecting predictors for RF; and 3) the effects of model averaging are method dependent or even data dependent. This study also provides important information for future monitoring design, particularly on the areas where the management and conservation of sponge gardens should be focused.

Short abstract for 35th International Geological Congress, Capetown, South Africa, August/September 2016

The Coompana Province is one of the most poorly understood pieces of crystalline basement geology in the Australian continent. It lies entirely concealed beneath a variable thickness of Neoproterozoic to Cenozoic sedimentary rocks, and is situated between the Gawler Craton to the east, the Musgrave Province to the north, and the Madura and Albany-Fraser Provinces to the west. A recently-acquired reflection seismic transect (13GA-EG1) provides an east-west cross-section through the southern part of the Coompana Province, and yields new insights into the thickness, seismic character and gross structural geometry within the Coompana Province. To assist geological interpretation of the 13GA-EG1 seismic line, new SHRIMP U-Pb zircon ages have been acquired from samples from the limited drill-holes that intersect the Coompana Province. New results from several granitic and gneissic rocks from the Coompana Province yield magmatic and/or high-grade metamorphic ages in the interval 1100 1200 Ma. Magmatic or high-grade metamorphic ages in this interval have not been identified in the Gawler Craton, in which the last major magmatic and metamorphic event took place at ~1590 1570 Ma. The Gawler Craton was largely unaffected by ~1100 1200 Ma events, as evidenced by the preservation of pre-1400 Ma 40Ar/39Ar cooling ages. In contrast, magmatic and metamorphic ages of 1100 1200 Ma are characteristic of the Musgrave Province (Pitjantjatjara Supersuite) and Madura Province (Moodini Supersuite). The new results from the Coompana Province have also yielded magmatic or inherited zircon ages at ~1500 Ma and ~1640 Ma. Once again, these ages are not characteristic of the Gawler Craton and no pre-1700 Ma inherited zircon has been identified in Coompana Province magmatic rocks, as might be expected if the province was underlain by older, Gawler Craton-like crust. The emerging picture from this study and recent work from the Madura Province and the Forrest Zone of the western Coompana Province is that the Coompana Province has a geological history that is quite distinct from, and generally younger than, the Gawler Craton to its east, but that is very similar to the Musgrave and Madura Provinces to the north and west. The contact between the Coompana Province and the Gawler Craton is interpreted in the 13GA-EG1 seismic line as a prominent west-dipping crustal-scale structure, termed the Jindarnga Shear Zone. The nature and timing of this boundary remain relatively poorly constrained, but the seismic and geochronological evidence suggests that it represents the western edge of the Gawler Craton, marking the western limit of an older, more isotopically evolved and multiply re-worked craton to the east, from a younger, more isotopically primitive crust that separates the South Australian Craton from the West Australian Craton.

Abstract for SEISMIX 2016 Conference

Abstract for oral presentation at the ASEG-PESA-AIG 2016 25th Geophysical Conference and Exhibition August 21-24, 2016