2D tomographic imaging over mineralized zones using self-potential data

Self-potential (SP) anomalies for graphite and other ore bodies have so far been interpreted quantitatively by classical approach only, i.e.. determination of parameters like depth to the top of the body, dip etc. Using the concept of charge occurrence probability (COP) function, two- dimensional tomographic images are presented for three mined-out graphite deposits of Balangir district, Orissa and a sulphide deposit of Kayar, Ajmer district, Rajasthan. These deposits were located earlier on the basis of SP anomalies. Trend of the ore bodies were obtained by mise-a-la-masse method. The anomalies in each of the two areas - Bender and Behermunda - were over single graphite ore body only. The anomaly over the third. area, i.e. in Berni, located three graphite deposits: (i) main ore body, (ii) second ore body of smaller size located 200 m southeast along the strike of the main deposit, and (iii) a small deposit situated 50 in southwest of the main body. Two-dimensional imaging in the tomoplanes clearly define the single ore bodies in Bender and Behermunda as well as all three ore bodies in Berm delineating the ore bodies along strike as well as in depth extent. The sulphide ore body in Kayar is yet to be delineated by large scale drilling but imaging of the ore body agrees well with the available drilling result in the area. The results show that the imaging technique delineates the ore body and, thereby, provides information for better mine planning for the deposits with optimum drilling. The method is recommended for imaging all the ore bodies generating SP anomaly.