b'Education matters The lack of soil profile and presence ofGeorge D Manton, Monash University: acidic waters have led to the failure ofWhat is the southern extension of the rehabilitation programs after mine closure.Mount Isa Fault Zone?Implications for This study aims to define and characterisesediment hosted massive sulphide Pb-Zn-the thickness and internal structure ofAg exploration strategiesabandoned mine waste at the legacy Endurance mine site using four near-surface geophysical techniques: Direct-current (DC) resistivity, electromagnetics (EM), ground penetrating radar (GPR) and near-surface seismic.DC resistivity was successful in detectingTernary RGB radiometric image of the Borborema the contrasting apparent resistivitiesProvince, NE Brazilbetween dry and saturated mine waste, within 510 m of the surface. In addition,The Borborema Province, NE Brazil, DC resistivity was able to differentiate ais characterised by a continent-scale kaolinitic clay layer, weathered graniteanastomosing shear zone network and fresh granite to depths of ~2030 m.activated during the Brasiliano Orogeny, Those layers are verified by drilling fromduring which province-wide intrusion on-going hydrogeological study. Due toof predominantly granitic plutons the un-differentiable resistivity valuesoccurred. Previous studies have used the between saturated mine wastes andapparent close spatial and geometric weathered granite, the method doesrelationship between plutons and not show the boundary between bothshear zones in the region to argue for compositional layers. An EM38 wasa causative relationship between the used to map the change in of apparenttwo, however other studies suggest conductivity across the Endurance site.these relationships do not exist. ThisA RTP image of magnetic data of NW Queensland with the outcrop extent of the Mount Isa terrane EM was useful for defining areas ofstudy aims to compare the spatialsuperimposedAMD, and the spatial distribution of claydistribution and geometry of pre-, materials and dry mine waste withinsyn- and post- kinematic plutons, asRegional aeromagnetic and gravity 1 m depth. However, much of thesewell as undated plutons, to determinedatasets indicate that the Mount Isa data were unreliable, due to culturalwhether plutons are geometrically,Inlier extends ~300 km south under noise and instrument failure. GPR signalsspatially or temporally related to shearsedimentary cover. Although the buried were used to delineate the location ofzones in the Borborema Province.extent of the terrane is very likely the water table and to depths of ~15 m.Using detailed maps produced throughto be well endowed, there has been GPR has been proven to be a quick andinterpretation of aeromagnetic andrelatively little mineral exploration due reliable way to detect the boundaryradiometric data, sub-domains with theto challenges associated with exploring between the quartz-rich mine wastegreatest cumulative shear zone lengthunder cover. There is a strong spatial and kaolinitic clay layers. Refractionwere found to contain the highestlink between giant sediment hosted seismic analysis indicates the presencepercentage area of plutons, indicatingmassive sulphide Pb-Zn-Ag mineral of weathered granite overlying graniticthat plutons and shear zones have asystems and the Mount Isa Fault Zone basement and is useful for inferringclose spatial relationship. Furthermore,(e.g. Mount Isa deposit). Within the basement depth. the vast majority of plutons with highexposed extent of the Mount Isa Inlier, By integrating interpretation ofaspect ratios were found to intersectthe Mount Isa Fault bifurcates into the geophysical data and modelsor occur within 200m of a shear zone.the Rufus Fault and Wonomo Fault. produced in this study, a three- A linear relationship between plutonBoth splays can be mapped using dimensional model of depth to theellipticity and distance to shear zonesregional aeromagnetic date into the base of mine waste, the water tablewas also established, indicating a strongsouthern, buried extent of the Mount and granitic basement is created.geometric relationship where the mostIsa terrane. Determining the southern This three-dimensional model waselliptical or circular plutons tend to beextension of the Mount Isa Fault may used to estimate the mass of minefurther from the shear zones. Finally,reduce exploration cost and mitigate waste at the legacy Endurance mine70% of syn-kinematic plutons and 38%exploration risk, creating a more site ~4 Mt and provide constraintsof pre-kinematic plutons were foundefficient exploration strategy. This for concurrent hydrogeological andto occur within 200m of a shear zone,study focused on formulating a new sediment geochemistry honoursuggesting that shear zones may controlstructural and lithological aeromagnetic projects. Collectively, the results ofthe emplacement of syn-kinematicand gravity interpretation of the these projects will inform rehabilitationplutons, or they nucleate on existingsouthern, Western Fold Belt and Sybella strategies at the legacy Endurancesyn-kinematic plutons. It also indicatesDomain within the Mount Isa Inlier. mine site. that shear zones preferentially nucleateThe interpretation reveals a complex away from pre-kinematic plutons.fault evolution and was used to inform Shannon Brown, Monash University:This temporal relationship thereforerelationships observed between Causative relationship between sheardemonstrates a causative relationshipregional scale faults within the study zones and plutons: Examples from thebetween shear zones and plutons in thearea. Discrete geophysical domains Borborema Province, NE Brazil Borborema Province. were identified and were linked to DECEMBER 2020 PREVIEW 36'