مدل سازي سه بعدي و تخمين ذخيره توده آنومالي شرقي مس- موليبدن كهنگ با استفاده از داده هاي ژئو شيميايي ، ژئو فيزيكي و گمانه هاي حفاري

چكيده انگليسي :

3D Modeling and Reserve Estimation of Mineralized Body of Eastern Cu Mo Anomaly at Kahang Using Geochemical Geophysical and Boreholes Data Hamed Nejadhosseini Fashkhami Date of Submission 16 March 2010 Mining Engineering Department Isfhan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Hooshang Asadi Harooni and Nader Fathianpour Abstract Kahang copper porphyry deposit is located in Uromiye Dokhtar volcanic belt in Isfahan province Kahang alteration system was identified by processing Landsat TM data in 2004 On the basis of hydrothermal alteration intensity type and zonality of altered rocks in addition to surface mineralization leached cap geochemical signatures Cu Mo Au anomaly geophysical anomalies such as magnetic induced polarization and resistivity Kahang is considered as a high potential porphyry deposit After regional and preliminary exploration phases detailed exploration was carried out at Kahang The main objective of this research is 3D reserve estimation and modeling of the East Kahang deposit using available borehole data A geochemical study was carried out on borehole assay data to investigate the subsurface downhole geochemical zonation and present erosion surface In order to determine the zonality of elements sample assay means in 50 68 80 and 100m composites were calculated first and then elements zonality series has been determined In comparison with porphyry copper standard zonality sequences the zonality of 80m composites including Co Be Ba As Mn Pb Zn Sb Cu Ag Mo Bi were found to be present at Kahang The geochemical ratio indices of As Mo and As Mn Cu Mo were found to be indicative of present erosion surface In geophysical studies of the kahang area several IP RS and magnetic profiles were utilized to identify the geophysical signatures associated with porphyry copper mineralizaton In IP RS studies profile number 112 was chosen for further processing and interpretation This profile shows very good correlation between high chargeability and high resistivity in the northern part of the section These signatures could be related to hydrothermal alteration associated with berrecia zones Also 3D inverse modeling of IP RS data shows similar signatures in the central part of deposit Three dimensional inverse modeling of magnetic data suggests that the zone with high susceptibility in the northern part of the studied could be associated with strong magnetic mineralization Since all of the drilled boreholes employed in this project were not assayed by the time this thesis was concluded a neural network method was used to estimate the Cu concentration at all borehole samples The network input layer contains 5 neurons representing spatial coordinate of the samples X Y Z chalcopyrite concentration and magnetic susceptibility Through training and validating this network the optimum number of neurons in the hidden layer was found to be 20 based on Route Mean Square RMS measures After converting primary statistical distribution of data to normal distribution main axis of anisotropy were estimated through computing directional varigrams Through Jacknife kriging optimum block dimension for final reserve estimation using ordinary kriging method was found to be 10 10 10 meter Reserve estimation results at east kahang deposit show a total sum of 3437500 tons ore 13750 tons Cu conatin using a cut off grade of 2500 ppm Cu content In order to simulate the highly variable nature of surface part of deposit down to the depth of 200m a fractal simulation algorithm based on exponetial variogram parameters of 2H and 1 2VH were developed Through applying E type estimation method on 30 realizations the ore reserve was estimated at 3407500 tons 13630 tons Cu content using a cut off grade value of 2500 ppm Cu Finally it was concluded that although the average ore reseve estimates obtained using both ordinary kriging and fractal simulation methods were almost the same but the presence of ore discon

نژاد حسيني فشخامي، حامد

مدل سازي سه بعدي و تخمين ذخيره توده آنومالي شرقي مس- موليبدن كهنگ با استفاده از داده هاي ژئو شيميايي ، ژئو فيزيكي و گمانه هاي حفاري

كانسارپورفيري كهنگ , شبكه عصبي , كريجينگ معمولي , شبيه سازي فركتالي , تخمين E- Type , خودپذيري