New magnetic and gravity images of Victoria, Australia

Abstract

A new compilation of magnetic and gravity data for Victoria has enabled the production of images of these data bases. The magnetic image of Victoria has been produced by combining regional and detailed airborne surveys. All the 1:250 000 standard map sheets in Victoria (21 in total) have been flown by the Bureau of Mineral Resources (BMR) and the Geological Survey of Victoria (GSV), and the data have been gridded using a 150 m ´ 150 m cell size and merged together by linear adjustment to adjacent data sets. Detailed company and government airborne surveys, and marine surveys have been superimposed onto the regional data to produce a composite image of the total magnetic intensity of Victoria. The GSV has edited existing onshore gravity data, added new data, and converted the data base to the IGSN71 (Isogal 84) datum. A summary is given of the five methods used to convert the gravity data from the Potsdam datum (Isogal 65) to IGSN71 datum (Isogal 84). The resultant gravity data base has been gridded using a 300 m ´ 300 m cell size and imaged. The images of the magnetic and gravity data sets highlight a number of major geological features not previously apparent. The improved ability and increased computing power of modern imageprocessing software to handle and merge images of large, multiple data sets has substantially enhanced the contribution that regional geophysical surveys have made to the geological knowledge of Victoria.