Application of Ground Magnetic Surveys over Heavy Mineral Sand Strands to Increase Confi dence in the Interpreted Continuity of the Modelled Resources

摘要

The suitability of magnetic surveys fl own at low altitudes to identify buried heavy mineral (HM) strandsrnhas long been accepted. This is despite the low intensity magnetic response often obtained from suchrnstrands. The fundamentals of the magnetic survey method dictate that the closer the instrument isrnto the source the stronger the response. As such the optimal elevation for the magnetometer is at orrnnear the surface.rnIluka sought to use a ground based magnetometer to aid in the exploration target generation processrnand allow accurate targeting of exploration drill holes. Following the initial trial Iluka recognisedrnthe potential additional application of data obtained by a ground based magnetometer over knownrnstrand deposits.rnThe detail of the ground magnetic images can confi rm the assumed strand continuity betweenrncross-sections of close spaced drilling and can aid in the defi nition of the geometry of differentrngenerations of mineralisation. The ability to confi dently determine that the deposit has not beenrntruncated by post emplacement erosion of the mineralised deposit may enable reductions in drillingrnrequirements as well as assisting mine planning activities. Iluka intends to investigate advancedrnmodelling of the magnetic data to determine the level of strand geometry and HM content resolutionrnthat can be achieved from the ground magnetic survey data and its potential application in the miningrngrade control process.rnIt is anticipated that the surveying of Iluka’s known resource deposits will provide the ability torncorrelate the magnetic response from new exploration targets with those from known deposits for arngiven depth, HM grade and mineralogy suite.