Geostatistical Modelling of Lead-Zinc Mineralisation at Rajpura-Dariba (Rajasthan) - A Case Study

Geostatistical modelling of the South lode of Rajpura-Dariba lead-zinc mineralisation has been carried out based on the assay values of 49 borehole cores. From the variograms constructed, the structure of Zinc and Lead mineralisations of this lode can bedescribed by spherical models as: γ(h)=2.01 [Spr(h/a)]; for h≤a=50 m for the variable Pb and γ(h)=13.50 [Spr(h/a)]; for h≤a=50 m for the variable Zn. The variogram for Zn is more stable than for Pb. Based on the above models, kriged estimates, corresponding variances and standard errors were obtained for Zinc and Lead variables in respect of 315 blocks of ore each measuring 15 m × 15 m. From the results, it has been observed that there is close agreement between the observed assay values and the krigedestimates. 68% and 95% confidence limits corresponding to ±10σ and ±1.960σ limits were worked out fora sample set of kriged estimates on the assumption that Pb and Zn variables follow Gaussian distribution. The results are presented.