Magnetic anomaly grid of the Australian Region

Brief description

These data represent the January 2002 edition of the Magnetic Anomaly Grid of the Australian Region. This version is the first integrated onshore/offshore magnetic anomaly grid for the complete Australian margin extending across 8S - 52S, 106E - 172E. The grid cell size is 0.01 degree (approx. 1 km). Earlier releases were restricted to portions of NW and SW Australia. - Magnetic anomaly unit is nanoTesla (nT). Appropriate IGRFs have been removed. Horizontal datum is GDA94 (which is equivalent to WGS84). - The marine data were levelled independently of the onshore data in three sectors (see below). The NNW and SSW sectors were released as grids previously. The eastern sector was levelled in 2000 in collaboration with Intrepid Geophysics (Melbourne, Australia). The three levelled sectors, together with the unlevelled sectors were combined with the onshore grid to give the present grid. Altogether, 3,022,656 data points are in the database from which the marine grid was created. - Unlevelled sectors: (-8 -25 160 172), (-39 -52 156 172), (-46 -52 106 140) - Levelled sectors: (-37 -52 140 156), (-25 -39 143 172), (-8 -25 143 160), (-24 -46 106 140), (-8 -24 106 143) - There are several places at the join between onshore and offshore grids where the two grids do not match. The problem exists because the onshore grid was developed earlier, and there was poor control on the grid merging process at the margins. Future work will attempt to address this issue and improve the continuity between the onshore and offshore grids.

Lineage

Maintenance and Update Frequency: asNeeded

Statement: The magnetic anomaly grid is a combination of the Magnetic Anomaly Map of Australia (3rd edition, derived from aeromagnetic data) and levelled ship-track data. The onshore grid has been released separately and is available digitally in a higher resolution format with a cell size of 15 seconds of arc (approx. 400 m)(see GEOMET record 4381), and also in 1:5,000,000 and 1:25,000,000 scale hardcopy form as enhanced images. Geoscience Australia gratefully acknowledges the contribution of aeromagnetic data and assistance by the following organisations:Northern Territory Geological Survey; Department of Primary Industries and Resources South Australia; Department of Infrastructure, Energy and Resources Tasmania; New South Wales Department of Mineral Resources; Department of Natural Resources and Environment Victoria; Geological Survey of Queensland; Geological Survey of Western Australia The offshore portion of the grid is derived from data in Geoscience Australia database GA-Mardat which has over 900 surveys acquired since 1963 by GA and foreign institutions.GA gratefully acknowledges the contribution of marine data and assistance by the following organisations: Bundesanstalt fur Geowissenschaften und Rohstoffe; Dept. Science, Industry and Resources (NZ); Geoscience Australia; Institut Francais de Recherche pour l'Exploitation de la Mer; Institut Francais pour la Recherche et la Technologie Polaires; Lamont Doherty Geophysical Observatory; Mobil Corporation; Division of National Mapping (Australia); National Geophysical Data Centre (USA); National Oceanic and Atmospheric Administration; Institut de Recherche pour le Developpement; Scripps Institution of Oceanography, U California; School of Ocean and Earth Science and Technology; South Pacific Applied Geoscience Commission; Texas A and M University; Institute of Oceanographic Sciences, UK; United States Geological Survey; US Navy; Woods Hole Oceanographic Institute