STATISTICAL MODELING OF EXPLORATION DATA FOR GRADE POTENTIAL OF THE PHOSPHORITE DEPOSIT, KHATAMBA BLOCKS, JHABUA DISTRICT, MADHYA-PRADESH

The Phosphorite deposit (74 degrees 25' to 74 degrees 26'E : 22 degree s 58' to 23 degrees 00'N), Jhabua district, Madhya Pradesh, is one of the productive deposits in India, and has evoked great interest with r egard to its phosphogenesis, stromatolite association and resource pot ential. It is a sedimentary-stromatolite type of deposit within the Pr ecambrian metasediments of the Aravalli Supergroup and represents the southern extension of the well known Jhamarkotra phosphorite deposit o f Rajasthan. The geological set-up shows that the phosphorite occurs i n two separate host rocks of older carbonate and younger chert sedimen ts. Geological Survey of India (Khan et al. 1979), using conventional cross-section method, estimated the weighted average grade of the Khat amba Blocks from the available 21 intersections in 12 trenches as 28.6 0% P2O5. In the present study, statistical modelling of exploration da ta of the Khatamba Blocks, using histogram plots, probability diagrams and skewness and kurtosis parameters for 20 intersections reveals a 3 -parameter log-normal distribution for accumulation (grade-thickness) and thickness values. The graphical estimate of the average grade from the probability diagrams is 29.59% P2O5 and that estimated by compute r is 29.40% P2O5. A computer programme ONEPOP. FOR in interactive FORT RAN77 has been developed for statistical modelling of the exploration data. Using this approach the grade. estimated for phosphorite deposit of the Khatamba Blocks shows a marginal increase in the value of aver age grade of P2O5 content as compared to the estimate made by conventi onal method.