Titanium-rich phlogopites from the Zangamarajupalle Kimberlitic Rock, Andhra Pradesh, India

Abstract

Electron probe studies on the phlogopites from the Zangamarajupalle kimberlitic rock (14 degrees 76'7'': 78 degrees 88'3'' E) in the Proterozoic Cuddapah basin, Andhra Pradesh, reveal their titanium-rich (6 wt%) nature - a character typical of lamproite micas. The compositions and their systematic variation in the phlogopite micas of the Zangamarajupalle-kimberlitic rock are compared and contrasted with those of other kimberlitic and lamproitic rocks including pipe-2 Wajrakarur, pipe-5 (Muligiripalle) and Maddur (Mahbubnagar) - all of which have an ambiguous identity. The utility of phlogopite compositions in discriminating between kimberlites and lamproites is emphasised and an attempt is made to classify the studied rock types accordingly and the implications are discussed.