geomorphology
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This record summarises the physical environments of the seabed for the Ceduna and Eyre Sub-basins.
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The term 'surrogacy' is used in habitat mapping with reference to the biophysical variables that can be mapped with a quantifiable correspondence to the occurrence of benthic species and communities. Surrogacy research can be defined as an empirical method of determining which easily measured characteristics best describe the species assemblage in a particular space and at a particular time. These characteristics act as predictors (with some known probability and uncertainty) for the occurrence of species assemblages in unexplored areas. Abiotic variables are, in general, more easily and less expensively obtained than biological observations, which is a key driver for surrogacy research. However, the suite of abiotic factors that exert control over the occurrence of species (its niche) is also a scientifically interesting aspect of ecology that provides important insights into a species evolution and biogeography. This chapter provides a review of surrogates used by case study authors and of the methods used to quantify relationships between variables.
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The Antarctic continental slope spans the depths from the shelf break (usually between 500-1000 m) to ~3000 m, is very steep, overlain by 'warm' Circumpolar Deep Water and life there is poorly studied. This study investigates whether life on Antarctica's continental slope is essentially an extension of the shelf or the deep-sea fauna, a transition zone between these or clearly distinct in its own right. Using data from several cruises to the Weddell and Scotia sea, including the ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) I-III and BIOPEARL (BIOdiversity, Phylogeny, Evolution and Adaptive Radiation of Life in Antarctica) 1 and EASIZ II cruises as well as current data bases (SOMBASE, SCAR-MarBIN), we selected four different taxa (i.e. cheilostome bryozoans, isopod and ostracod crustaceans, and echinoid echinoderms) and two areas, the Weddell and the Scotia Sea, to examine faunal composition, richness and affinities. The answer has important ramifications to the link between physical oceanography and ecology, and the potential of the slope to act as a refuge and resupply zone to the shelf during glaciations (and therefore support or not glaciological reconstructions of ice sheets covering continental shelves).
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The central aim of the Comparative Geomorphology of Estuaries Project of the Coastal CRC was to improve our understanding of Australia's near-pristine estuaries. As the title implies, the project had a geomorphic focus in that a major output was mapping of geomorphic habitats of a representative selection of nearpristine estuaries from around Australia.
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Keppel Bay is a macrotidal environment that represents the interface of the large catchment of the Fitzroy River with the southern GBR continental shelf. In this study, we assessed the distribution of sediments and their depositional characteristics using a combination of sediment sampling, and acoustic (sonar) seabed mapping tools. Using statistical techniques, we classified the seabed sediments of Keppel Bay into five distinct classes, based on sediment grainsize, chemical composition, and modelled seabed hear stress (the influence of waves and tidal currents).
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Dense coral-sponge communities on the upper continental slope off George V Land have been identified as a Vulnerable Marine Ecosystem in the Antarctic. The challenge is now to understand their likely distribution. The CEAMARC survey found these communities at sites on the upper slope in depths of 570 - 950m. Based on these results we propose some working hypotheses defining the physical settings suitable for such assemblages. Icebergs scour to 500m in this region and the lack of such disturbance is probably a factor allowing growth of rich benthic ecosystems. In addition, the richest communities are found in the heads of canyons. We suggest two possible oceanographic mechanisms linking abundant filter feeder communities and canyon heads. The canyons in which they occur receive descending plumes of Antarctic Bottom Water formed on the George V shelf and these water masses could entrain abundant food for the benthos. Maps of water properties measured during the Collaborative East Antarctic Marine Census (CEAMARC) survey provide some support for this idea. Another possibility is that the canyons harbouring rich benthos are those that cut the shelf break. Such canyons are known sites of high productivity in other areas because of a number of oceanographic factors, including strong current flow and increased mixing, and the abrupt, complex topography. These hypotheses provide a framework for the identification of areas where there is a higher likelihood of encountering these Vulnerable Marine Ecosystems.
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In May 2013, Geoscience Australia (GA) and the Australian Institute of Marine Science (AIMS) undertook a collaborative seabed mapping survey (GA0340/ SOL5754) on the Leveque Shelf, a distinct geological province within the Browse Basin, offshore Western Australia. The purpose of the survey was to acquire geophysical and biophysical data on seabed environments over a previously identified potential CO2 injection site to better understand the overlying seabed habitats and to assess potential for fluid migration to the seabed. Mapping and sampling was undertaken across six areas using multibeam and single beam echosounders, sub-bottom profilers, sidescan sonar, underwater towed-video, gas sensors, water column profiler, grab samplers, and vibrocorer. Over 1070 km2 of seabed and water column was mapped using the multibeam and single beam echosounder, in water depths ranging between 40 and 120 m. The sub-surface was investigated using the multichannel and the parametric sub-bottom profilers along lines totalling 730 km and 1547 km in length respectively. Specific seabed features were investigated over 44 line km using the sidescan sonar and physically and sampled at 58 stations. Integration of this newly acquired data with existing seismic data will provide new insights into the geology of the Leveque Shelf. This work will contribute to the Australian Government's National CO2 Infrastructure Plan (NCIP) by providing key seabed environmental and geological data to better inform the assessment of the CO2 storage potential in this area of the Browse Basin. This catalogue entry refers to an interpreted geomorphic map, mapped at 1:10 000 scale. Geomorphic mapping was completed using a combination of semi-automated feature extraction and hand digitisation from bathymetry and backscatter grids collected during the survey along with their derivatives and reference to broader scale geomorphic maps (Heap and Harris, 2008).
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Interactive Maps is a discovery and exploration view of Geoscience Australia's geospatial services. The following scientific and decision support themes have curated content comprised of maps and functions. Each map has queries and functions with linked access to OGC (Open Geospatial Consortium) web services and metadata. This system replaces MapConnect and AMSIS applications.
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As part of Australian Government's National Low Emission Coal Initiative (NLECI) and National CO2 Infrastructure Plan (NCIP), Geoscience Australia (GA) has been assessing offshore sedimentary basins for their CO2 storage potential. These studies, scheduled for completion by 30 June 2015, aim to identify potential sites for the geological storage of CO2 and provide pre-competitive information for the development of CO2 transport and storage infrastructure near major emission sources. The basins targeted for these studies are the Bonaparte Basin (Petrel Sub-basin), Browse Basin, Perth Basin (Vlaming Sub-basin) and Gippsland Basin. GA completed a series of marine surveys over the Petrel and Vlaming sub-basins and the Browse Basin during 2012-2013, that acquired 2D reflection seismic, multibeam bathymetry/backscatter and sub-bottom profiling data, and seabed samples and video footages. The datasets have been analysed to inform the assessment of potential CO2 storage capacity and containment for each study area. Integrated interpretation of the seabed, shallow subsurface and deep basin data has assisted the identification of potential fluid migration features that may indicate seal breach and the presence of migration pathways. Data on seabed environments and ecological habitats will provide a baseline for an assessment of the potential impacts of CO2 injection and storage, and associated infrastructure development.
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This investigation was undertaken primarily to assess the importance of a discovery of gold in the tributaries of the Porgera River west of Mt. Hagen, Mandated Territory of New Guinea. Two patrols were carried out. The first patrol was from Wabag to Mongureba. The purpose of the patrol was to inspect the main gold find in the vicinity of Mongureba. The occurrence of alluvial gold was also reported from the River Timen area, and consequently a patrol from Wabag to Mt. Hagen Police Post by way of the River Timen was undertaken. This report gives an account of the geological reconnaissance and its findings. The physiography, geology, geomorphology, and economic geology of the area are described. Accompanying maps and photographs are included.