Two New Kimberlites in Bommaganapalli Area, Anantapur District, Andhra Pradesh, Based on Systematic Stream Sediment Sampling and Ground Magnetic Survey

Two Kimberlite pipes in Bommaganapalli area, Kalyandurg, Anantapur District are reported based on stream sediment sampling yielding HIM's viz., garnets ('G 9' lherzolitic, 'G 10' harzburgitic and eclogitic with Na₂O (>0.07 wt%), Cr-diopsides (from garnet peridotites), spinels and ilmenites. Ground magnetic survey indicated magnetic anomaly of about 280 nT in KL-5 and an anomaly of100 n T over KL-6.The anomaly over KL-5 was dipolar. The 'Maturation Index' (MI) of 9.8 and MgO content 8.08 of the calcrete over this area indicate their kimberlitic nature. Analysis indicates that the chrome spinels fall in the diamond stability field. Garnets suggest they are of the nature of "G 10" harzburgitic garnets.