Gold deposits of the Bardoc tectonic zone; a distinct style of orogenic gold in the Archaean Eastern Goldfields Province, Yilgarn Craton, Western Australia. Australian Journal of Earth Sciences, 54, 783-800.

Re-examination of the Ordovician geology between Mandurama and Bigga in the Lachlan Orogen of central western New South Wales has produced new interpretations of the stratigraphy and structural geology. The Abercrombie beds have been previously inferred to comprise an Ordovician turbidite package with interbedded black shale bands. Although hampered by a paucity of fossil ages, new data suggest that the Ordovician geology of this region instead represents an imbricate stack of Lower Ordovician turbidites (Adaminaby Group) and Upper Ordovician black shales (Warbisco Shale). Structural data from the north of this region suggest that duplication occurred in a D1 event (with formation of broadly east-west to west-northwest-trending thrust slices or fold limbs) and was accompanied by formation of cleavage and isoclinal folds. Thrusting of the Adaminaby Group and Warbisco Shale over or under the Lower Ordovician Coombing Formation (southern part of the Molong volcanic belt) also occurred at this time. East-vergent imbrication and thrusting and formation of a regional near-meridional steeply west-dipping cleavage occurred in the D2 event, when D1 thrusts or folds were folded around overturned (east-vergent) D2 folds. These new data also suggest that there is a north-to-south gradient in the intensity of the D2 deformation, with D2 effects decreasing from south to north approaching the Lachlan Transverse Zone. Such a gradient mirrors similar but more subtle local changes from the north. Together, they imply that the Lachlan Transverse Zone was a major zone of weakness during north-south shortening that resulted in the formation of D1 structures but was relatively rigid in local areas during the regional D2 deformation that resulted from east-west shortening when it formed a major tear/accommodation zone. This D2 rigidity may be caused by strength imparted by the earlier emplacement of large (variably mineralised) intrusive/volcanic complexes along the transverse zone.

Geodata TOPO250K Series 3 Topographic Data - Horizontal Control Points (A line which represents an imaginary line on the ground joining points of equal elevation in relation to the Australian Height Datum - AHD66). Series 3 contains a medium scale vector representation of the topography of Australia. The data include the following ten themes and 92 feature classes: Cartography: Annotations, CartographicLines, CartographicPoints, GraticuleAnnotations, Graticules, GridAnnotations and Grids Elevation: Contours, BenchMarks, HorizontalControlPoints and SpotElevations Framework: ProhibitedAreas, Reserves, FrameworkBoundaries, Islands, LargeAreaFeatures, Locations, Mainlands, Seas, GeodataIndexes and MapIndexes Habitation: BuildingAreas, BuildingPoints, BuiltUpAreas, CemeteryAreas, CemeteryPoints, Homesteads, PlaceNames, PopulatedPlaces and RecreationAreas Hydrography: CanalLines, Locks, RapidLines, Spillways, WatercourseLines, WaterfallPoints, Bores, CanalAreas, Flats, Lakes, PondageAreas, RapidAreas, Reservoirs, Springs, WatercourseAreas, Waterholes, WaterPoints, MarineHazardAreas, MarineHazardPoints and ForeshoreFlats Infrastructure: AerialCableways, DamWalls, Fences, MarineInfrastructureLines, MarineInfrastructurePoints, VerticalObstructions, WaterTanks, Yards, Conveyors, MineAreas, MinePoints, PetroleumWells and StorageTanks Terrain: Caves, Craters, DeformationAreas, Discontinuities, Pinnacles, SandRidges and Sands Transport: AircraftFacilityPoints, RailwayBridgePoints, RailwayCrossingLines, Railways, RailwayStopPoints, RailwayTunnelLines, RailwayTunnelPoints, BarrierPoints, FerryRouteLines, FootTracks, RoadCrossingLines, RoadCrossingPoints, Roads, RoadTunnelLines and RoadTunnelPoints Utility: Pipelines and Powerlines Vegetation: ClearedLines, CultivatedAreas, NativeVegetationAreas and Windbreaks

Geologic observations suggest two stages of hydrothermal activity at a number of presently subeconomic iron oxide copper-gold systems in the Olympic Dam district, eastern Gawler craton. They contain high-, and moderate- to low-temperature Fe oxide-rich hydrothermal alteration. The mineral assemblages include magnetite-calc-silicate-alkali feldspar ± Fe-Cu sulfides and hematite-sericite-chlorite-carbonate ± Fe-Cu sulfides ± U, REE minerals. In all documented prospects, the minerals of the hematitic assemblages replace the minerals of the magnetite-rich assemblages. The bulk of the subeconomic Cu-Au mineralization is associated with the hematitic alteration assemblages. Microanalysis by proton ion probe (PIXE) of hypersaline fluid inclusions in magnetite-rich assemblages, however, demonstrates that significant amounts of copper (>500 ppm) were transported by the early-stage high-temperature (>400C) fluids responsible for the magnetite-rich alteration. These brine inclusions contain multiple solid phases (liquid + vapor + multiple solids) including chalcopyrite in some cases. In comparison, inclusions of the hematitic stage are relatively simple liquid + vapor types, with homogenization temperatures of 200C to 300C and containing 1 to 8 wt percent NaCl equiv. The Br/Cl ratios of the magnetite-forming fluids measured by PIXE lie beyond the range of typical magmatic and/or mantle values, allowing for the possibility that the fluids originated as brines from a sedimentary basin or the crystalline basement. Sulfur isotope compositions of chalcopyrite and pyrite demonstrate that sulfur in both alteration assemblages was derived either from cooling magmas and/or crystalline igneous rocks carried by relatively oxidized fluids ({sum}SO42- {approx} {sum} H2S, {delta}34Ssulfides from +5 to +2{per thousand}) or from crustal sedimentary rocks ({delta}34Ssulfides from +5 to +10{per thousand}). Oxygen and hydrogen isotope compositions of waters calculated for minerals of the magnetite-rich assemblage have {delta}18O values of +7.7 to +12.8 per mil and {delta}D values of +15 to +21 per mil. The only available {delta}18O and {delta}Dfluid values for the hematitic assemblage are +4.7 and +9 per mil, respectively. The isotopic compositions of both fluids, coupled with the available literature data, can be explained in terms of fluid reequilibration with felsic Gawler Range Volcanics or other felsic igneous rocks in the region and with metasedimentary rocks of the Wallaroo Group at low water-to-rock ratios prior to their arrival at the mineralization sites. The lack of significant copper mineralization associated with magnetite-forming fluids that carried copper suggests that there was no effective mechanism of saturation of copper minerals or the quantity of these fluids was not sufficient to produce appreciable copper mineralization. Association of the copper-gold mineralization with the hematitic alteration in the subeconomic prospects can be explained by a two-stage model in which preexisting hydrothermal magnetite with minor associated copper-gold mineralization was flushed by late-stage oxidized brines that had extensively reacted with sedimentary or metamorphic rocks. The reduction of these brines, driven by conversion of magnetite to hematite, resulted in precipitation of copper and gold. The oxidized brines may have contributed additional copper and gold to the system in addition to upgrading preexisting subeconomic Cu-Au mineralization. When compared to published models for the Olympic Dam deposit, the new data for fluids in subeconomic Fe-oxide Cu-Au prospects of the Olympic Dam district indicate the diversity of origins of iron oxide-copper-gold systems, even within the same geologic region.

This map is produced fro the Australian Fisheries Management Authority to assist in their enforcement of Australia's Maritime Bounadries. It has an explanation of the maritime boundaries and their coordinates in the Arafura Sea and Torres Strait. Originally produced using the Indonesian language. This version is an English translation. It is not for sale or public release by Geoscience Australia. Public release is thru DEH and AFMA.

Proterozoic Gold Mineralising events on Australian Proterozoic Georgions base, 1:5 000 000 October 2007 Version (PDF and JPG)

Detailed analysis and modeling of regional gravity and magnetic data from the Stuart Shelf around the Olympic Dam iron oxide copper-gold (IOCG) deposit, constrained by geologic observations obtained from deep drill cores, show that the eastern Gawler craton basement at 1.61 to 1.59 Ga consisted of an Archean core with two sequences of successively younger supracrustal rocks stepping out eastward from it. These were overprinted by the tectonothermal Hiltaba event. Forward models of potential-field data show no convincing evidence for the presence of widespread mafic rocks or extensional basin systems developed immediately prior to, or during, IOCG mineralization. The high intrusive level and sill-like geometry of Hiltaba Suite plutons emplaced immediately prior to IOCG mineralization is difficult to explain in terms of a genetic association with a dominantly extensional tectonic setting. Instead, the tectonic setting inferred from the basement architecture during mineralization is one of low-strain shortening, consistent with regional field observations. A case can be made for intrusion of the Hiltaba Suite in localized accommodation zones in an overall orogenic setting. This style of low-strain shortening (<10%) is consistent with maximum rates and volumes of fluid flow in the upper crust, and access of these fluids to a variety of basement rock types to buffer metal-scavenging fluids. This fluid-driving mechanism does not necessitate a role for regional mafic magmatism and volcanism in the formation of IOCG deposits. Modeling of regional gravity and magnetic data is generally applicable to exploration for IOCG systems, and other mineral systems, in covered terranes that have distinctive geophysical signatures resulting from fluid-wall-rock redox geochemical reactions.

This map developed for ACMA from previous map Geocat 64114 (June 2006). Including Defence Practice Area data supplied by ACMA in relation to Protection Zones off Sydney. These maps are for ACMA internal use and not for sale or GA distribution.

This map shows the area of the Great Australian Bight Trawl Gulper Shark Closure - Southern Dogfish. It was produced for the Australian Fisheries Management Authority.

This maps shows the area of the East Coast Deepwater Trawl Sector 700m Depth Closure. Produced for the Australian Fisheries Management Authority.