This dataset shows paths taken by a vessel holding Sidescan Sonar intruments within the waters of the Cocos (Keeling) Islands used by cargo ships.

Proterozoic mafic-ultramafic intrusions of the Arunta Region record a protracted period of magmatism during the evolution of this geologically complex and tectonically long-lived terrane in central Australia. New U-Pb zircon geochronology data highlight the episodic emplacement of the mafic-ultramafic systems. Five major events of dominantly tholeiitic mafic magmatism have been recognised at not, vert, similar1810 Ma, not, vert, similar1780 Ma, not, vert, similar1690 Ma, and not, vert, similar1635 Ma, and a much younger event of probably early Palaeozoic age. A sixth event at not, vert, similar1135 Ma has alkaline-ultramafic affinities. Chondrite- and mantle-normalised multi-element patterns of rocks with melt-like compositions have refined the correlations of the magmatic systems indicated by the geochronological framework. Continental margin environments (e.g. subduction or back-arc related) are generally indicated for the magmatic events at not, vert, similar1810 Ma, not, vert, similar1780 Ma, and not, vert, similar1635 Ma, whereas the mafic magmatism at not, vert, similar1690 Ma and in the early Palaeozoic is more characteristic of intracontinental settings (e.g. extensional rifts). The intrusions occur in proximity to major province-wide faults. Differential vertical movements along these faults provide the opportunity to examine geological processes at crustal depths ranging from not, vert, similar5 km to 25 km (2 kb to 8 kb). The intrusions form large homogeneous mafic granulite bodies, granulite bodies interfolded with felsic units, contaminated gabbroic sheets, stacked sequences of high-level doleritic sills, small pods and laterally extensive sheets of amphibolite, and rare plug-like ultramafic bodies. Metamorphic overprints range from granulite to sub-amphibolite facies, with a concentration of high-grade mafic granulite bodies in the central Arunta Region attributed to deeper levels of crust uplifted north of the Redbank Thrust. Mafic rocks in the intrusions of high-metamorphic grade are dominantly two-pyroxene mafic granulites with high clinopyroxene to orthopyroxene ratios and variable amounts of minor hornblende, biotite, quartz, and garnet. In contrast, gabbroic rocks in the lower-grade intrusions of the western Arunta Region contain more orthopyroxene, alkali feldspar, quartz, and Fe-Ti oxides. LREE-enrichment trends with decreasing 147Sm/144Nd ratios and initial var epsilonNd values (+1.5 to -4.7) indicate that felsic crustal contamination processes were particularly important during the evolution of the latter intrusions. Incompatible trace-element trends show that the Arunta intrusions fall into two major geochemical groups that for the first time highlight geographical differences in mineral prospectivity. 1. A S-rich group (not, vert, similar1200 to 300 ppm S: Andrew Young Hills intrusion, Mount Hay Granulite, Mount Chapple Metamorphics) from the western and central Arunta regions that has potential for basal Ni-Cu-Co-sulphide associations. 2. A relatively S-poor (<300 ppm S), slightly more primitive group (Attutra Metagabbro, Mordor Complex) from the eastern Arunta Region that has greater potential for stratabound PGE-sulphide associations. Some potential also exists for structurally controlled hydrothermal deposits of Cu-Au ± PGEs ± Ag ± Pb spatially associated with mafic-ultramafic rocks (Riddock Amphibolite). The major challenges for finding massive Ni-Cu-Co sulphides in the lower parts of prospective S-saturated intrusions (e.g. Andrew Young Hills, Mount Hay Granulite) are to determine the pre-deformational geometries of the bodies and to locate favourable mineralised environments, such as embayments in basal contacts and feeder conduits, concealed by thin Cainozoic alluvial deposits.

Sharing the wealth  - Australia 's Mining Monthly, April 2005, by Jess Tyler (contributions by Bob Morrison, John Walshe, Carl Young, Tony Roache, Kas De Luca)

Kendrick et al - Goldschmidt 2005

A presentation given at the Australian X-Ray Analytical Association conference in Fremantle held 14-18 February 2005. Geoscience Australia recently conducted a series of tests on ring mills commonly used for sample preparation of geological materials. Ring mills of five different compositions (tungsten carbide, chrome steel, carbon steel, partially-stabilised zirconia and syalon) were tested to determine qualitative and quantitative contamination imparted to samples ground in them.

This report documents a study into the Late Jurassic to Recent breakup and drift history of southern Australia, Antarctica and New Zealand , and the relationship between these tectonic events and the stratigraphy and drainage history of these areas. The study was conducted between March 1999 and August 2000. Many of the goals have been achieved, but the plate reconstructions still need to be put into a proper geo-referenced kinematic framework. The purpose behind the study was to lay the framework for understanding the palaeogeography, lithofacies, tectonics and geomorphology of these areas in a reconstructed palinspastic setting; something that had not been accomplished before. The methodology has been to first of all compile structural elements maps for the southern Australian and conjugate Antarctic margins. An updated ocean age map was also prepared as a basis for a first-pass reconstruction. Then the stratigraphy was summarised for three representative cross sections in the Great Australian Bight, Otway and Gippsland Basins, and these were displayed as detailed chronostratigraphic sections in order to demonstrate the stratigraphic responses to the breakup history. One of the vital predictive conclusions was to try and understand the structure and stratigraphy under the lower continental margins; the prime tools for this part of the study were deep-penetration seismic lines shot by AGSO under the Law of the Sea and Continental Margins programs. Finally, a set of 18 plate reconstruction maps were compiled for the period from the Oxfordian to the Present Day, with elements of the tectonics and stratigraphy plotted on them. Because of time constraints and the inability to work the appropriate plate kinematic software, the reconstructions presented here were prepared with scissors and tape from the ocean age map and hence must be regarded as indicative cartoons of the plate positions. This situation is obviously not ideal but is considered justified by the need to understand the geological relationships between the various terrains before going to a rigorous kinematic reconstruction. AGSO supported this study as a Collaborative Research Project, providing both data and support with expenses. In addition, this work has been shown at various stages to a large number of people, all of whom helped by making comments and suggestions, and their contributions are gratefully acknowledged. Some of those involved were:- Kevin Hill (La Trobe University) Nick Hoffman (La Trobe University) Mark Smith (Petroleum Consultant) Alan Partridge (La Trobe University) Heike Struckmeyer (AGSO) Jennie Totterdell (AGSO) Howard Stagg (AGSO) Jacques Sayers (AGSO) Russell Korsch (AGSO) Colin Pain (AGSO) Paul O'Sullivan (Syracuse University, NY) Meredith Orr (Monash University) Mike Hall (Monash University) Steve Gallagher (Melbourne University) Guy Holdgate (Melbourne University) Barry Kohn (Melbourne University) Dietmar Muller (U. Sydney) Mike Gurnis (Caltech) Chris Adams (NZIGNS) Tom Bernecker (VDNRE) Andrew Constantine (VDNRE) David Moore (VDNRE) Ross Cayley (Geol. Survey Victoria) Cliff Ollier (ANU) Graham Taylor (University of Canberra)

Product no longer exists, please refer to GeoCat #30413 for the data

Product no longer exists, please refer to GeoCat #30413 for the data

Product no longer exists, please refer to GeoCat #30413 for the data

Product no longer exists, please refer to GeoCat #30413 for the data