Here we report on the results of a study undertaken in the Flinders Commonwealth Marine Reserve (southeast Australia) designed to test the benefits of two approaches to characterising shelf habitats: (i) MBES mapping of a continuous (~30 km2) area selected on the basis of its potential to include a range of representative seabed habitats , versus; (ii) a novel approach that uses targeted mapping of a greater number of smaller, but spatially balanced, locations using a Generalized Random Tessellation Stratified sample design. We present the first quantitative estimates of habitat type on the shelf of the Flinders reserve, using both survey approaches, based on three MBES analysis techniques. We contrast the quality of information that both survey approaches offer in combination with the three MBES analysis methods. We then consider the implications for future inventory of benthic habitats in shelf environments in the context of monitoring extensive offshore marine reserves.

Reconstruction of the evolution of the Tasmanides in eastern Australia, with special emphasis on the 440 Ma event. Annual Review Meeting Canberra, December 2002 (i. Vos).

Compilation of new and existing data can be used to show systematic variations in initial ore-related Pb isotope ratios and derived parameters for the Lachlan and Delamerian orogens of southeast Australia. In addition to mapping tectonic boundaries and providing genetic context to mineralising processes, these variations map mineralised provinces at the orogenic scale and can provide vectors to ore at the district scale. In New South Wales and Victoria, mapping using a parameter termed the 'Lachlan Lead Index' (LLI), which measures relative mixing between crustal- and mantle-derived Pb using the curves of Carr et al. (1995, Economic Geology 90:14671505), clearly demarcates the boundary between the Eastern and Central Lachlan provinces, and seems to identify boundaries between zones within the Western Lachlan Province of Victoria. The LLI also maps the extent of the isotopically juvenile Macquarie 'Arc' in New South Wales. However, rocks in the Rockley-Gulgong Belt, initially mapped as part of the Macquarie Arc, have a more evolved isotopic character, suggesting that these rocks are not part of the Macquarie Arc. This interpretation supports recent mapping that casts doubt on the attribution of this belt to the Macquarie Arc (Quinn, et al., 2014, Journal of the Geological Society of London 171:723736). The LLI has also identified small exposures of Ordovician volcanic rocks, well removed from the main Macquarie Arc, as possible correlates to this arc, with potential to host porphyry and epithermal deposits. Metallogenically, porphyry Cu-Au deposits in the Macquarie Arc are characterised by juvenile Pb. In contrast, Sn and Mo deposits in the Central Lachlan Province (i.e., the Wagga tin belt) are characterised by highly evolved Pb even though these deposits formed over 30 million years. Moreover, the Pb isotope data suggest that the original interpretation that copper deposits in the Girilambone district are volcanic-associated massive sulfide deposits was correct and that these deposits formed in a back-arc to the Macquarie Arc at ~480 Ma. In the Mount Read Volcanics of western Tasmania, all deposits appear to cluster along the same growth curve. However, when divided according to age (i.e., Cambrian (~500 Ma) versus Devonian (~360 Ma)), spatial patterns are visible in 206Pb/204Pb data. For Cambrian deposits 206Pb/204Pb decreases overall to the southeast, although low values are also present in the far south (i.e., Elliott Bay) and northeast. The most highly mineralised central part of the belt seems to be broadly associated with the zone of highest 206Pb/204Pb. Variations in 206Pb/204Pb for Devonian deposits broadly mimic the patterns seen for the Cambrian deposits. More importantly, a district-scale pattern in 206Pb/204Pb is present in the Zeehan district. Isotopically, the Sn-dominated core of the Zeehan district (e.g. Queen Hill and Severn deposits) is characterised by high 206Pb/204Pb, which decreases outward into the Zn-Pb-Ag-dominated peripheries. Lead isotope distribution patterns can potentially be used as an ore vector in this and other intrusion-centered mineral systems.

Integration of potential field derived architectural maps and mineral deposits in the Tasmanides

Sediments on the continental shelf of eastern Australia increase in carbonate content away from the present shoreline. However, the high values of the outer shelf sands show little latitudinal variation, both tropical and temperate continental shelves being mantled with sediments which are relatively pure carbonates. Thus a high calcimass productivity is not restricted to tropical regions. However, the types of carbonate-secreting organisms do show marked latitudinal variations. North of latitude 24°S the outer continental shelf is dominated by the Great Barrier Reef, and inter-reef and outer shelf sediments contain the remains of hermatypic corals and calcareous green algae, mainly Halimeda, together with varying amounts of foraminifera, Mollusca, Bryozoa, and calcareous red algae. Corals and Halimeda are not present in the sediments south of 24°S, which consists of foraminifera, mollusca, bryozoa and calcareous red algae. The bryozoan content of the sediments increases to the south, and between 38° and 44°S bryozoans become the dominant component of the outer shelf sands. Present-day sea-surface temperature and salinity data have been analysed to predict the distribution of carbonate particle associations. The observed distribution agrees with the predicted one, but the presence of relict carbonate sediments must be taken into account.

Shallow seismic reflection profiles in western Bass Strait and on the west Tasmanian continental shelf have been used to interpret the late Cainozoic geological history of this area. Palaeozoic and Precambrian rocks with little or no sedimentary cover form the structural highs separating the Bass, Torquay, and Otway Basins, and the inner shelf off Tasmania. The Neogene and Quaternary sequences are undeformed and relatively complete in the Bass Basin and off southern Tasmania. Elsewhere, a Late Miocene unconformity separates flat-lying Pliocene-Holocene sediments from gently folded Miocene and older rocks. Subaerial erosion, initiated in the Late Miocene and continued during Pleistocene low sea-level periods, controls sea-floor topography over extensive areas of shelf south of King Island.