Characterizing Eastern Dharwar craton kimberlites in light of petrophysical, geochemical and petrological data

Kimberlites are one of the most unique terrestrial rocks because they, along with rocks such as lamproites and ultramafic lamprophyres, provide direct clues to mantle conditions and are hosts for diamonds in the world. In India, the Eastern Dharwar Craton is host to several kimberlite fields that have been mapped in detail. The present study examines the petrophysical attributes of kimberlites from the Eastern Dharwar Craton (EDC) in India, analyzing magnetic susceptibility and density alongside their petrology and geochemistry on 17 drill core samples from the Wajrakarur Kimberlite Field (WKF) (including Chigicherla Kimberlite Cluster (CC)) and Raichur Kimberlite Field (SK). In this study, the kimberlite samples have a density in the range of 2.6–3.1 g/cm³, grain density (GD) values between 2.5 and 2.9 g/cm³, bulk density (BD) values between 2.4 and 2.76 g/cm³ and porosity <6%. The magnetic susceptibility lies in the range of 12–1550 (×10^–6 C.G.S.). The degree of serpentinization for six kimberlite pipes has been calculated and correlated with the observations of serpentinization both in the field and under the petrological microscope. Examinations combining petrophysical, petrological, and geochemical information indicate a connection between magnetic susceptibility and the ratio of ferromagnetic minerals, whereas density is predominantly affected by iron or titanium oxide minerals, carbonate and olivine. The clear linear correlation between density and magnetic susceptibility underscores the importance of ferromagnetic minerals in shaping the petrophysical properties of kimberlites. Magnetic susceptibility is found to be the most important factor controlling the petrophysical properties of the majority of EDC kimberlites. The present study finds that the magnetic susceptibility of kimberlites found in India belonging to Proterozoic age closely resembles that of kimberlites from Canada and southern Africa of Cretaceous age, while density values indicate global uniformity with Indian kimberlites. The documented petrophysical dataset is expected to aid ongoing exploration efforts for kimberlite occurrences in India, as well as contribute to geophysical mapping endeavors using magnetic and gravity methods.