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

The Australian Geological Survey Organisation (AGSO) through the partnership in the Australian Geodynamics Cooperative Research Centre (AGCRC) and Kalgoorlie Consolidated Gold Mines (KCGM) completed a joint research project to image the crustal structure of the Kalgoorlie region to develop a knowledge of the shallow and deep structures, tectonics, and fluid migration pathways. The Australian National Seismic Imaging Resource (ANSIR) was contracted to acquire the seismic data. The project's objectives were to obtain a better understanding of - sub-surface geology at a regional and mine scale - provide more information on regional crustal thickness and major features - stratigraphic and structural architecture of the mineral system - timing and locations of fluid migration pathways The seismic survey obtained 25 km of 10 fold CMP (common midpoint) regional reflection seismic data along two traverses and 8 km of 10 fold CMP high-resolution reflection seismic data along another two traverses. The data are of good quality and similar to both the 1991 and 1999 Eastern Goldfields reflection seismic data to the north and south of the survey area. The major outcome of imaging the four localities included mapping the Golden Mile and Bolder-Lefroy Faults, and the Boorara Shear at depth. This new information indicates the Golden Mile Mine was fed by a suite of relatively minor faults dangling off the major crustal-scale Boorara Shear. The dangling element relates to percolation theory. The detachment surface was imaged on all seismic traverses. Thrust duplexes were interpreted above the detachment surface.

This report describes gravity meter ties conducted to establish new gravity control stations in Tasmania

The Australian Geological Survey Organisation (AGSO) flew an airborne geophysical survey of 49 397 line km covering the Julia Creek 1:250 000 map Sheet area in the northwestern Queensland. The survey formed part of the National Geoscience Mapping Accord and was flown along east-west flight lines, 400 metres apart at an altitude of 80 metres above ground level. The survey was flown from 24 April to 6 June 1999. The total magnetic intensity, gamma-ray spectrometric and digital elevation model data collected during the survey, have been processed and are available for purchase. These data are sold as digital point located data, grids and hardcopy maps by the Australian Geological Survey Organisation. Colour and greyscale pixel image maps are also available.

A digital elevation model (DEM) is a digital representation of the height of the terrain usually interpolated onto a regularly spaced grid. Traditionally, DEMs have been estimated from ground surveys, digitised topographic maps, satellite (SPOT) images and aerial photography. Since the advent of the Global Positioning System (GPS) for aircraft navigation, DEMs can be derived from positional and aircraft radar altimeter data recorded on airborne geophysical surveys. A DEM is useful in any situation where knowledge of the height, slope and aspect of the ground is important. DEMs are widely used in the following landscape studies - botanical, geochemical, environmental, forest, soil, geological, climatological, geophysical, glaciological and natural hazard (eg landslide). Florinsky (1988) gives a comprehensive list of applications for DEMs. These include: - stream flow modelling - landscape analysis - land use and soil mapping - geological/geophysical mapping - road design and other engineering projects Although DEMs have been derived from airborne geophysical survey data for several years, there is little information available on the precision and accuracy of these models. The purpose of this paper is to review the procedure for generating an airborne geophysical survey DEM and to investigate the sources and amplitudes of errors in these models.

Legacy product - no abstract available

A WET Labs SAFire multi-spectral and absorption meter was used to identify dissolved poly-aromatic hydrocarbons and anomalous biological activity in near surface waters. Over 6000 km of data were collected southwest of Noumea. No obvious hydrocarbon anomalies were detected but blue-green algal blooms (Trichodesmium ?), identified also by satellite and biological analysis (Dupouy et al, 2000), were commonly encountered in the survey area. An extremely high absorption anomaly centred at 162.7 deg E and 22.7 deg S, with a strong algal fluorescence signature at 440 nm excitation, is also likely to be from the same source.

This report describes gravity surveys conducted in Western Australia during 1991 and 1993, to establish new Absolute and Australian Fundamental gravity control stations in new areas and where existing fundamental gravity stations had been lost.

The geophysical data collected includes a total of 1827 km of multi-channel seismic data and 562 km of Chirper sonar data. A total of 11 gravity cores, 28 piston cores, 18 surface grabs and 11 short trigger cores were collected on the voyage. Water profile (CTD) measurements and water samples were collected at nine stations and seabed bottom photographs were made at 11 stations. The expedition discovered and mapped a shelf sediment drift deposit covering about 400 km2 lying in an >800m deep section of the George Vth basin west of the Mertz Glacier. It is a true "drift" deposit, since these sediments exhibit a depositional architecture indicative of contour-parallel sediment transport. A significant observation is that the drift thins to the north into an acoustically-transparent veneer; this observation implies that the drift is sourced from the outer continental shelf, with sediment being transported landwards, across the shelf and into an 850m deep inner shelf basin.

ACRES acquired Landsat 7 satellite images showing bushfires in northern New South Wales in early October 2000. Fire fighters brought more than 80 bushfires under control, after more than 150,000ha of bushland were burnt. The image on the left was acquired on 2 June 2000. The second image shows the extent of the fires in the region from South West Rocks in the south to Grafton and the Clarence River in the North.