DATE: Thursday 21st March, 2002. 5.30pm for 6pm VENUE: Rugby Club, Rugby Place, Circular Quay SPEAKER: Bob White & Steve Collins TOPIC: "New Developments and Case Histories of 3D IP Surveys" The real 'GlassSee right through? Earth'! About two years ago major revolution occurred in the usefulness of Induced Polarisation (IP) data for mineral exploration. This revolution was due to the implementation of three dimensional inversion techniques. These techniques allow the 3D visualisation of electrical properties of the the earth, and in particular the three dimensional mapping of IP effect which is directly correllatable to sulphide content. In other words it is now possible to see the distribution of sulphides in the earth with real depths and locations as distinct from the now obsolete 'pseudo-sections' previously used for IP display and interpretation. These distributions of minerals can be readily visualised using existing free software. Early use of this powerful software was directed toward reinterpretation of existing data but for the last eighteen months Steve and Bob have been developing field techniques which are inexpensive, use existing hardware and contractors and are optimised for producing data for the inversion software. The result is a field technique which gathers up to 10 times the amount of data gathered through old-fashioned survey procedures for the same survey cost. The talk will concentrate on case histories of relatively well known prospects. The successes, failures, benefits and limitations of these new procedures will be discussed. Examples of 3D visualisation of these data which use existing 'freeware' will be given. Bob and Steve are both independent consultant geophysicists based in Sydney. Between them they have more than 60 years experience in mineral exploration in Eastern Australia and overseas. Bob is currently treasurer of the ASEG. Steve is a committee member of SMEDG.