Biosiliceous sediments sampled from a submarine valley system on the continental shelf of East Antarctica contain intervals of ripple cross-lamination interspersed with massively bedded units. Based on radiocarbon dates from one core collected on the Mac.Robertson Shelf, the most intensely cross-laminated sediments were deposited between 6 000 and 3 500 years before the present, with isolated cross-laminae deposited at other times in the Holocene.

The product comprises digital outcrop geology and interpreted basement geology layers in ArcInfo, MapInfo and ArcView formats. The data were compiled from geological mapping of the Bogan Gate 100K sheet from 1995 to 1999 by the NSW Geological Survey and AGSO under the NGMA. The data layers are a subset of the Forbes 250K sheet GIS data package.

ACRES Update, Issue 22, December 2000 ACRES Archive a National Resource First MODIS poster of Australia

ACRES Update, Issue 21, July 2000 Terra Oberving the Earth New Product Catalogue Remote Sensing and emergency management

Mineral deposits can be described in terms of their mineral systems, i.e., fluid source, migration pathway, and trap. Source regions are difficult to recognize in seismic images. Many orebodies lie on or adjacent to major fault systems, suggesting that the faults acted as fluid migration pathways through the crust. Large faults often have broad internal zones of deformation fabric, which is anisotropic. This, coupled with the metasomatic effects of fluids moving along faults while they are active, can make the faults seismically reflective. For example, major gold deposits in the Archaean Eastern Goldfields province of Western Australia lie in the hanging-wall block of regional-scale faults that differ from other nearby faults by being highly reflective and penetrating to greater depths in the lower crust. Coupled thermal, mechanical, and fluid-flow modeling supports the theory that these faults were fluid migration pathways from the lower to the upper crust. Strong reflections are also recorded from two deeply penetrating faults in the Proterozoic Mt. Isa province in northeastern Australia. Both are closely related spatially to copper and copper-gold deposits. One, the Adelheid fault, is also adjacent to the large Mt. Isa silver-lead-zinc deposit. In contrast, other deeply penetrating faults that are not intrinsically reflective but are mapped in the seismic section on the basis of truncating reflections have no known mineralization. Regional seismic profiles can therefore be applied in the precompetitive area selection stage of exploration. Applying seismic techniques at the orebody scale can be difficult. Orebodies often have complex shapes and reflecting surfaces that are small compared to the diameter of the Fresnel zone for practical seismic frequencies. However, if the structures and alteration haloes around the orebodies themselves, seismic techniques may be more successful. Strong bedding-parallel reflections were observed from the region of alteration around the Mt. Isa silver-lead-zinc orebodies using high-resolution profiling. In addition, a profile in Tasmania imaged an internally nonreflective bulge within the Que Hellyer volcanics, suggesting a good location to explore for a volcanic hosted massive sulfide deposit. These case studies provide a pointer to how seismic techniques could be applied during mineral exploration, especially at depths greater than those being explored with other techniques.

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

This data package comprises the following data sets covering the state of Victoria: GIS MapInfo and MapInfo Export format files containing geographically referenced information. MapInfo Export files can be imported into ArcView software. Vicmine Microsoft Access and ASCII text format files containing detailed mineral resource information. Geochemistry ASCII text format files containing geochemical sample data. The data is only available in this data package in text format because of disk space limitations. It is available in other formats through GSV.

Colour ternary (K-U-TH R-G-B) gamma-ray spectrometry pixel image digital BIL file covering the Andamooka, Copley, Parachilna, Orroroo and part of the Port Augusta 1:250,000 map Sheet areas.

This data package comprises data sets which cover the Hamilton 1:250 000 map sheet (HAMILTON). This area has recently been covered by airborne geophysical surveys by the Geological Survey of Victoria and these data sets intend to compliment this data.

Legacy product - no abstract available