Williams et al. (2009) report on new multibeam sonar bathymetry and underwater video data collected from submarine canyons and seamounts on Australia's southeast continental margin to 'investigate the degree to which geomorphic features act as surrogates for benthic megafaunal biodiversity' (p. 214). The authors describe what they view as deficiencies in the design of the Marine Protected Areas (MPAs) in the southeast region of Australia, in which geomorphology information was employed as a surrogate to infer regional-scale patterns of benthic biodiversity. This comment is designed to support and underscore the importance of evaluating MPA designs and the validity of using abiotic surrogates such as geomorphology to infer biodiversity patterns, and seeks to clarify some of the discrepancies in geomorphic terminologies and approaches used between the original study and the Williams et al. (2009) evaluation. It is our opinion that the MPA design criteria used by the Australian Government are incorrectly reported by Williams et al. (2009). In particular, we emphasise the necessity for consistent terminology and approaches when undertaking comparative analyses of geomorphic features. We show that the MPA selection criteria used by the Australian Government addressed the issues of false homogeneity described by Williams et al. (2009), but that final placement of MPAs was based on additional stakeholder considerations. Finally, we argue that although the Williams et al. (2009) study provides valuable information on biological distributions within seamounts and canyons, the hypothesis that geomorphic features (particularly seamounts and submarine canyons) are surrogates for benthic biodiversity is not tested explicitly by their study.

This preliminary report will provide a geochemical and ionic characterisation of groundwater, to determine baseline conditions and, if possible, to distinguish between different aquifers in the Laura basin. The groundwater quality data will be compared against the water quality guidelines for aquatic ecosystem protection, drinking water use, primary industries, use by industry, recreation and aesthetics, and cultural and spiritual values to assess the environmental values of groundwater and the treatment that may be required prior to reuse or discharge.

Hot Rocks in Australia - National Outlook Hill, A.J.1, Goldstein, B.A1 and Budd, A.R.2 goldstein.barry@saugov.sa.gov.au hill.tonyj@saugov.sa.gov.au Petroleum & Geothermal Group, PIRSA Level 6, 101 Grenfell St.Adelaide SA 50001 Anthony.Budd@ga.gov.au Onshore Energy & Minerals Division, Geoscience Australia, GPO Box 378 Canberra ACT 26012 Abstract: Evidence of climate change and knowledge of enormous hot rock resources are factors stimulating growth in geothermal energy research, including exploration, proof-of-concept appraisals, and development of demonstration pilot plant projects in Australia. In the six years since the grant of the first Geothermal Exploration Licence (GEL) in Australia, 16 companies have joined the hunt for renewable and emissions-free geothermal energy resources in 120 licence application areas covering ~ 67,000 km2 in Australia. The associated work programs correspond to an investment of $570 million, and that tally excludes deployment projects assumed in the Energy Supply Association of Australia's scenario for 6.8% (~ 5.5 GWe) of Australia's base-load power coming from geothermal resources by 2030. Australia's geothermal resources fall into two categories: hydrothermal (from relatively hot groundwater) and the hot fractured rock i.e. Enhanced Geothermal Systems (EGS). Large-scale base-load electricity generation in Australia is expected to come predominantly from Enhanced Geothermal systems. Geologic factors that determine the extent of EGS plays can be generalised as: - source rock availability, in the form of radiogenic, high heat-flow basement rocks (mostly granites); - low thermal-conductivity insulating rocks overlying the source rocks, to provide thermal traps; - the presence of permeable fabrics within insulating and basement rocks, that can be enhanced to create heat-exchange reservoirs; and - a practical depth-range, limited by drilling and completion technologies (defining a base) and necessary heat exchange efficiency (defining a top). A national EGS resource assessment and a road-map for the commercialisation of Australia's EGSs are expected to be published in 2008. The poster will provide a synopsis of investment frameworks and geothermal energy projects underway and planned in Australia.

During 2009-2011 Geoscience Australia completed a petroleum prospectivity study of the offshore northern Perth Basin. Basement is deep and generally not resolved in the reflection seismic data. Recent improvements to the magnetic ship-track database and magnetic anomaly grid allowed an assessment of depth to magnetic sources and estimation of sediment thickness, providing new insight into basement depth and trends. 2D models along several seismic transects and analysis using spectral methods indicate that penetration of the lower sediments by high susceptibility bodies is probable. The reflection seismic evidence for these bodies is not clear, though in some cases they may be associated with faults and structural highs. Where the modelled bodies penetrate the sediments, they are mostly below or within Permian strata, except in the west of the strudy area. A moderate positive magnetic anomaly (the Turtle Dove Ridge) is modelled by massive bodies whose tops are 5-15 km below sea floor. The depth to magnetic basement map highlights sub-basins and structural highs within the northern Perth Basin, with up to 12 km of sediment in the Zeewyck sub-basin.

The North Australian Element (NAE) is one of the most richly endowed cratonic blocks in the world, containing major Zn-Pb, U, Cu-Au, diamond and Au deposits as well as smaller deposits with a range of other commodities. This richness results from a complex tectonic history extending from the Archean through to the Paleozoic. The NAE largely assembled before ~1840 Ma through accretion of the Kimberley and Pine Creek provinces from the northwest, the Numil-Kowanyama Province from the east and Aileron Province from the south onto a proto-NAE comprising the Tanami-Tennant and Isa provinces. The last major growth of the NAE occurred during accretion of the Warumpi Province from the south at ~1640 Ma. This overlapped development of the North Australian Basin System along the eastern flank between ~1800 Ma and 1540 Ma. Since then the NAE has been affected by 1540-1500 Ma A-type magmatism, Meso- to Neoproterzoic alkaline magmatic events, and the development of the intracratonic Neoproterozoic-Paleozoic Centralian superbasin, which was terminated by Paleozoic inversion associated with accretion in the Tasman Element to the east. The oldest significant mineral deposits - VHMS, orthomagmatic Ni-Cu-PGE and REE deposits - relate to convergence and docking of the Kimberley and Pine Creek provinces at 1865-1830 Ma. The ~1850-1845 Ma Tennant Creek IOCG event may relate to convergence of the Aileron Province. Small VHMS (1810-1765 Ma) deposits and, possibly, the Tanami and Pine Creek lode gold provinces (1810-1795 Ma) relate to north-dipping subduction along the southern margin of the NAE. Syn- to post-collisional magmatism associated with the Strangways event, which terminated subduction, produced widespread but relatively minor W-Mo and Sn deposits at 1740-1720 Ma. Development of the North Australian Basin System was accompanied by U (1740-1610 Ma) and Zn-Pb (1690-1575 Ma) events, many of which correspond in time to bends in the apparent polar wander path. The last Mesoproterozoic mineralising events in the NAE occurred at 1540-1500 Ma, involving IOCG, sediment-hosted Cu, and apatite-REE-U-Th vein deposits. Between ~1500 Ma and initiation of the Centralian Basin System at ~850 Ma, mineralisation was associated with alkaline magmatism, including one of the world's the world's largest diamondiferous diatreme at ~1180 Ma. The most recent period of mineralisation accompanied inversion of the Centralian superbasin and included ~360 Ma MVT and ~320 Ma lode gold deposits.

The Tonga subduction zone is among the most seismically active regions and has the highest plate convergence rate in the world. However, thrust events confidently located on the plate boundary have not exceeded Mw 8.0. The possibility of a low probability maximum magnitude event of Mw 8.6 to 9.1 has been raised, but a paucity of geodetic observations and their distance from the Tonga trench have precluded direct assessment of megathrust slip deficit accumulation. We analyze two major thrust fault earthquakes that occurred in central Tonga in 2006 and 2009. The 3 May 2006 Mw 8.0 event has a focal mechanism consistent with interplate thrusting, was located west of the trench, and caused a moderate regional tsunami. However, long-period seismic wave inversions and finite-fault modeling by joint inversion of teleseismic body waves and local GPS static offsets indicate a slip distribution centered ~65 km deep, about 30 km deeper than the plate boundary revealed by locations of aftershocks, demonstrating that this was an intraslab event. The aftershock locations were obtained using data from 7 temporary seismic stations deployed shortly after the mainshock, and most lie on the plate boundary, not on either nodal plane of the deeper mainshock. The fault plane is ambiguous and investigation of compound rupture involving co-seismic slip along the megathrust does not provide a better fit, although activation of megathrust faulting is responsible for the aftershocks. The 19 March 2009 Mw 7.6 compressional faulting event occurred below the trench; finite-fault and W-phase inversions indicate an intraslab, ~50-km deep centroid, with ambiguous fault plane. There continues to be a paucity of large megathrust earthquakes in Tonga.

Helium is a commodity of strategic importance to high-technology fields, with applications in defence, medicine, manufacturing and energy. A secure supply of helium enables the continuing operation of MRI scanners, the manufacture of fibre optic cables, and the continuation of the aerospace industry to name just a few applications. A supply of helium into the future may enable the emergence of new technologies in energy production, transport, or information technology. The 2013 Geoscience Australia report into critical commodities (Skirrow et al., 2013) included helium as one of the commodities of strategic importance to Australia. Following on from this report, Geoscience Australia is working towards producing a resource assessment and data package based on its Australia-wide helium data holdings, incorporating gas data from more than 1400 gas and petroleum wells across Australia both offshore and onshore, and from conventional and unconventional reservoirs. Initial assessment of helium resources indicates that Australia has world-class helium resources which could provide helium for the domestic and export market for at least the next 40 years. With appropriate management, supply could be guaranteed for much longer. Helium gas can be economically extracted from many natural gas reservoirs, and Australia's supply is strongly tied to the liquefied natural gas (LNG) industry. With LNG production projected to grow from 24 million tonnes to 80 million tonnes per year by 2018 (BREE, 2013), the helium industry in Australia could also grow strongly. The large volumes of LNG production coupled with sufficient helium content in the natural gas mean that at least 700 MMCF (million cubic feet) of helium per year (almost 20 times estimated Australian consumption) could realistically be recovered from Australian reservoirs. Any helium that is not recovered from natural gas during extraction is lost to the atmosphere, meaning that helium resources are continually depleted regardless of whether the helium is recovered. Basins in and around the Northern Territory are some of the most prospective for helium in Australia. The Bonaparte Basin off the northwest coast of the Northern Territory has rich reserves of natural gas and may host significant helium resources that can be economically extracted in coordination with LNG production. Australia's only helium extraction plant, based in Darwin, already processes gas derived from this basin and is evidence supporting the commercial viability of helium extraction from offshore reservoirs. The Amadeus Basin in the south of the Northern Territory, although much lower in total natural gas reserves, has indications of significant helium abundance with some wells recording helium abundances to the percent level. With no associated LNG production planned for this basin, the commercial viability of helium extraction is much more dependent on high concentrations of helium. The uniquely-high concentration of helium in some wells in the Amadeus Basin suggests that helium extraction independent of natural gas extraction may be feasible a feat that has yet to be achieved anywhere else in the world. References BREE (Bureau of Resources and Energy Economics), 2014. Eastern Australian domestic market study. BREE, Canberra. Skirrow, R.G., Huston, D.L., Mernagh, T.P., Thorne, J.P., Dulfer, H., Senior, A.B., 2013. Critical commodities for a high-tech world: Australia's potential to supply global demand. Geoscience Australia, Canberra. GA 13-7166

The National Computational Infrastructure (NCI) at the Australian National University (ANU) has organised a priority set of 30+ large volume national earth and environmental data assets on a High Performance Data (HPD) node within a High Performance Computing (HPC) facility, as a special node under the Australian Government's National Collaborative Research Infrastructure Strategy (NCRIS) Research Data Storage Infrastructure (RDSI) project. The Australian National Geophysical Collection was identified as a nationally significant collection and approved as one of the RDSI funded collections. It includes the most comprehensive publicly available collections of Australian airborne magnetic, gamma-ray, seismic, electromagnetic, magnetotelluric and gravity data sets. The total size allocated for this geophysical data collection is currently 300Terabytes. Organising this major geophysical data collection within a high performance computing environment creates a new capacity for accessing and processing data at both high resolution, and at full-continent spatial extent. Further by co-locating and harmonising the geophysical data assets with other significant national digital data collections (e.g., earth observation, geodesy, digital elevation, bathymetry) new opportunities have arisen for Data-Intensive interdisciplinary science at a scale and resolution not hitherto possible. To support this integrated HPC/HPD infrastructure our data management practices include co-development of Data Management Plans (DMP) with the data collection custodians; the development of standards compliant catalogues on data collections/data sets; and minting and maintaining persistent identifiers. The data are accessible either via direct access or via international standards compliant data services including geospatial standard (ISO 19115) catalogues, metadata harvesting protocols (OAI-PMH) and OGC protocols. A Virtual Geophysics Laboratory has also been established that links the geophysical data assets with online software and tools using cloud based scientific workflows.

Preface to Special Issue of Mineralium Deposita on critical commodities

Compositional data, commonly used in geochemistry (proportions, percentages, mg/kg), have specific properties that are not compatible with the Euclidean geometry requirement of most standard statistical methods. In order to represent compositional data in the usual Euclidean geometry, they need to be expressed in orthonormal coordinates prior to statistical processing. As it is not possible to construct Cartesian coordinates for compositions that assign a coordinate for each of the parts separately, a choice of interpretable orthonormal coordinates is of particular interest. Although recent experience shows clear advantages of such coordinates where the first coordinate aggregates information from logratios for a particular compositional part of interest, their usefulness is limited if there are distortions like rounding errors or other data "problems" in the involved parts. The purpose of this contribution is to introduce a "weighted" version of these coordinates, where the remaining parts (with respect to the part of interest) in the first coordinate are weighted in a way that is relevant to the aims of the statistical analysis. In a geochemical context, quality assessment analysis and elements of the variation matrix of compositions are proposed to derive possible relevant weights. Theoretical considerations are accompanied by examples using data from the National Geochemical Survey of Australia.