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  • Henson P.A., Gibson G.M., Debenham S., Kalinowski A., Barlow M. & McIntyre A. 2004. 3D structural model for the northern Leichhardt River Fault Trough and adjacent Lawn Hill Platform, Mt Isa. In: Barnicoat A.C. & Korsch R.J. eds. Predictive Mineral Discovery Cooperative Research Centre: Extended Abstracts from the June 2004 Conference. Geoscience Australia, Record 2004/9, 91-94.

  • Multibeam sonar swath-mapping has revealed small submarine volcanic cones on the northeastern Lord Howe Rise (LHR), a submerged ribbon continent. Two such cones, aligned NNW and 120 km apart, were dredged at 23-24Degrees S. Water depth is about 1150 m nearby: the southern cone rises to 750 m and the northern to 900 m. Volcanic rocks dredged from the cones are predominantly highly altered hyaloclastites with minor basalt. The clasts are mostly intensely altered vesicular brownish glass with lesser basalt, in zeolitic, clayey, micritic or ferruginous cement. Lavas and hyaloclastites contain altered phenocrysts of olivine and plagioclase, and fresh clinopyroxene. The latter have compositions between acmite and Ti-augite, and match well clinopyroxene phenocrysts in undersaturated intraplate basanitic mafic lavas. Interbedded micrites in the volcaniclastics represent calcareous ooze that was deposited with (or later than) the volcanic pile. Foraminifera indicate that the oldest micrite is late Early Miocene (~16 Ma), and that the original ooze was deposited in cool water. Late Miocene to Pliocene micrites, presumed to be later infillings, all contain warm water forms. This evidence strongly suggests that both cones formed in pelagic depths in the Early Miocene. Ferromanganese crusts from the two cones are up to 7 cm thick and similar physically, but different chemically. The average growth rate is 3 mm/m.y.. Copper, nickel and cobalt content are relatively high in the north, but copper does not exceed 0.08 wt %, nickel 0.65% and cobalt 0.25%. The Mn:Fe ratio is high in the south (average 13.7) suggesting strong hydrothermal influence. Such small volcanic cones related to intraplate hotspot-type magmatism may occur in extensive fields like those off southern Tasmania. On Lord Howe Rise, the known small volcanic cones coincide with broad gravity highs in areas of shallow continental basement. The highs probably represent Neogene plume-related magmatism. The thick continental crust may dissipate and spread the magma widely, whereas plumes may penetrate thin oceanic crust more readily and build larger edifices. The correspondence of the ages derived from micropalaeontology and from extrapolating from nearby dated hotspot traces support such a genesis. Accordingly, gravity highs in the right setting may help predict fields of small volcanic seamounts.

  • This dataset contains points, lines and polygon data of topographical, cultural and infrastructual features. A sample of the Arc View legend that accompanies the above view can be seen here. This dataset covers all of Home Island and most of West Island however the detail is lost outside of the built up areas. The other islands and North Keeling Atoll are not included in this dataset.

  • Recent field observations have identified the widespread occurrence of fluid seepage through the eastern Mediterranean Sea floor in association with mud volcanism or along deep faults. Gas hydrates and methane seeps are frequently found in cold seep areas and were anticipated targets of the MEDINAUT/MEDINETH initiatives. The study presented herein has utilized a multi-disciplinary approach incorporating observations and sampling of visually selected sites by the manned submersible Nautile and by ship-based sediment coring and geophysical surveys. The study focuses on the biogeochemical and ecological processes and conditions related to methane seepage, especially the anaerobic oxidation of methane (AOM), associated with ascending fluids on Kazan mud volcano in the eastern Mediterranean. Sampling of adjacent box cores for studies on the microbiology, biomarkers, pore water and solid phase geochemistry allowed us to integrate different biogeochemical data within a spatially highly heterogeneous system. Geophysical results clearly indicate the spatial heterogeneity of mud volcano environments. Results from pore water geochemistry and modeling efforts indicate that the rate of AOM is 6 mol m-2 year-1, which is lower than at active seep sites associated with conditions of focused flow, but greater than diffusion-dominated sites. Furthermore, under the non-focused flow conditions at Kazan mud volcano advective flow velocities are of the order of a few centimeters per year and gas hydrate formation is predicted to occur at a sediment depth of about 2 m and below. The methane flux through these sediments supports a large and diverse community of micro- and macrobiota, as demonstrated by carbon isotopic measurements on bulk organic matter, authigenic carbonates, specific biomarker compounds, and macrofaunal tissues...

  • Gibson G. M., Henson P., Barlow M. & Murphy B. 2004. Basin architecture and fault geometries in the Mount Isa Western Succession: implications for mineral exploration. North Queensland Exploration and Mining 2004; extended abstracts. Australian Institute of Geoscientists Bulletin 40, p.121-22.

  • Basin architecture and fault geometries in the Mount Isa Western Succession: implications for mineral exploration. North Queensland Exploration and Mining 2004; extended abstracts. Australian Institute of Geoscientists Bulletin 40, p.121-22.

  • This dataset shows the approximate flight paths (lines) and centres of the aerial photography in relation to the Cocos Islands. This data is used to establish and map the approximate coverage and location of orthophotos over the island. Two shape files were created, one to describe the flight lines the other to describe the photo centers.

  • We describe the use of a temporary seismometer deployment to monitor local earthquakes in the Flinders Ranges, South Australia. 16 seismograph stations were deployed over a 200 x 100 km area, which is one of the most seismically active regions in Australia. The instrumentation consisted of short-period and broadband Guralp seismometers combined with Reftek and Kelunji data loggers, which sample data continuously at 100-200 sps. Analysis of data from the period Sept.-Dec., 2003, resulted in the determination of hypocentres for over 175 earthquakes, most of which could not be located using PIRSA's permanent network. 54 of these earthquakes had depths resolved at 10 km or greater, and the proportion of deep events appears to increase from the southern to the northern part of the Flinders Ranges. The largest earthquake, ML-4, occurred near Hawker on 22 November, 2003, and has a depth of 17±2 km, and a well-resolved normal focal mechanism.

  • Generic modelling approach to understanding the Kanowna Belle Au system

  • This dataset contains point, line and polygon data of the marine environment surrounding the Cocos (Keeling) Islands. It includes coastlines, bathymetric contours, coral outcrops and other features. Coverage extends to the whole of Cocos Keeling Isalnds. The themes have been grouped so as to increase the ease of use of the data. The individual themes have been grouped into the following shapefiles: Infralin.shp - Infrastructure lines Boundlin.shp - Boundary lines Marinelin.shp - Marine lines Surveylin.shp - Survey lines Islandlin.shp - Island outlines Marineply.shp - Marine polygon Islandply.shp - Island polygon Boundply.shp - Boundary polygon These shapefiles retain all spatial and non spatial data as supplied to GA. To view the sample of the marine environment with the legend click here. In December 2003 GA projected the data to UTM (WGS84) zone 47 using Arcview.