b'John Denhams best of Exploration GeophysicsFeaturemaps produced by the GSV. Geologists and geophysicists nowThe process is now refined to the stage where it is used in all work together as a team to reconcile all the geophysical andof GSVs mapping projects. In crossing the borders between geological observations and produce an accurate, integratedgeology and geophysics we have accelerated field mapping geological maps and associated interpretation. and produced a better understanding of the rocks and their The positive team spirit, mutual respect and teamworkrelationships. The next generation of geological maps in developed during these projects is an important factor in theirVictoria will rely heavily upon the geophysical data to provide success. The geologists now make best use of the geophysicala comprehensive geological interpretation. With renewed responses to better understand the geology. The skills requiredexploration interest in Victoria, these new maps provide a to fully integrate different datasets have developed over severalbasis for the State to be systematically explored using modern years and are reinforced by each new project. The geologistsexploration techniques within extensive exploration programs.need to understand the geophysical responses and the geophysicists need to understand the geology. This requiredReferencesboth formal and informal on-the-job training in magnetic and radiometric interpretation, understanding geological structuresEdwards, J., K. E. Wohlt, K. R. Slater, A. Olshina, and D. F. and field mapping procedures. Hutchinson. 1998. Heathcote and pans of Woodend and Echuca 1: 100 000 map area geological report. Geological Our survey specifications are significantly better than theSurvey of Victoria Report 108.standards used in the past decade. Major advances have beenCayley, R. A., and P. A. McDonald. 1995. Beaufort 1:100 000 map required in the data display and presentation, creating productsgeological report. Geological Survey of Victoria Report 104.of the geophysical data that show greater detail than previouslyIsles, D., R. Valenta, and A. Cooke. 1995. Interpretation and seen or expected. These improved presentation methods ofstructural analysis of aeromagnetic data. Workshop for the data have been a major step in developing our methods ofGeological Survey of Victoria presented by World Geoscience interpretation. Corporation and D Isles and Associates.The new process has raised the overall awareness of theMaher, S., D. H. Moore, A. J. Crawford, R. Twyford, and C. M. limitations inherent in each of the methods. The small-scaleFanning. 1997. Test drilling of the southern Murray Basin: variations observed in outcrop are often not resolved in theVictorian Initiative for Minerals and Petroleum Report 52, geophysical data. The ambiguities in interpretation are, inDepartment of Natural Resources and Environment.part, dependent on the data resolution. Subtle features clearlyNash, C. 1995. Integrated image interpretation for mineral seen in 50 m data may well be unresolved in 400 m data.exploration. Australian Mineral Foundation workshop The geologists will only visit a few thousand sites in any oneSeptember 1995.project and the geophysicist needs to be aware that these areMoore, D. H. 1996. A geological interpretation of the valuable control points. Both geologists and geophysicistsgeophysical data for the Horsham 1:250 000 map sheet area: need to recognise where alternative geological interpretationsVictorian Initiative for Minerals and Petroleum Report 24, could be valid. Department of Agriculture, Energy and Minerals Victoria.Moore, D. H. 1997. A geological interpretation of the The team needs to recognise where the geophysical data willgeophysical data of the Ouyen I :250 000 map sheet area: be useful. In a qualitative sense it may be used to recogniseVictorian Initiative for Minerals and Petroleum Report 39, patterns associated with rock units and variations within them,Department of Natural Resources and Environment Victoria.for example for mapping granites and variations within them,Moore, D. H., and S. Maher. 1998. Lessons from a case study and discontinuities indicative of structure. In a quantitativeof a geophysical interpretation in western Victoria. Expl. sense, it provides 3D information about deep seated featuresGeophys. 29.and enables depth computations to rock units. Slater, K. R. 1997. GSV format for geophysical interpretation Even where semi-regional geophysical data are available, inmaps. Geological Survey of Victoria Technical Record 1997/4.some areas it is unable to assist the mapping. The geologistsTaylor, D. H., M. L. Whitehead, A. Olshina, and J. Leonard. 1996. lament that the Ordovician bedrock units have little or noBallarat 1: 100 000 map geological report. Geological Survey magnetic contrast and rarely have any magnetic markers.of Victoria Report 101.Large layer parallel faults within these units are often missedVandenBerg, A. H. M., R. N. Nott, and R. A. Glen. 1992. Bendoc unless they happen to have dykes along them, have oxidised1:100 000 map geological report. Geological Survey of Victoria a magnetic host rock or have a significant gravity response.Report 90.In these areas, other broad, rapid coverage techniques, suchVandenBerg, A. H. M., C. E. Willman, M. Hendrickx, M. D. Bush, as airborne EM or side-scan radar, may provide answers. and B. C. Sands. 1995. The geology and prospectivity of the 1993 Mount Wellington airborne survey area: Victorian Further developments will take place in the use of geophysicalInitiative for Minerals and Petroleum Report 2 Department of data to streamline the mapping and drafting. We will trialAgriculture, Energy and Minerals.the use of laptop computers in the field with an imageVandenBerg, A. H. M. 1997. Let your geophysics do the walking processing or GIS system linked to GPS to interrogate the data- a mappers perspective. In The 1997 Selwyn Memorial in real time. Having digital geological boundaries availableSymposium Abstracts, Geological Society of Australia and during mapping will improve the iterative interpretationAustralian Society of Exploration Geophysics, Victorian process. Economic geologists now work on the projectDivisions, ed. B.A. Simons, and G.R. Pettifer.teams. Their role, in addition to the more traditional role ofWillocks, A. J., and B. C. Sands. 1995. Recent geophysical and cataloguing mining and exploration history, is to documentmapping progress and implications for exploration. Expl. and understand the mineralisation styles, to integrate themGeophys 26: 307314.into the geological framework, and so to present models forWillocks, A. J. 1997. Regional surveys in Victoria -experiences possible mineral exploration. and lessons. Expl. Geophys. 28: 307312.51 PREVIEW JuNE 2020'