It is noteworthy that Amba Dongar carbonatite complex as both intrusive and extrusive phase carbonatjtes The stratified tuff with componenrs of both carbonatite and nephelinite have been recently traced in western part of Amba Dongar complex.In this preliminary report wc present tracc and rare earth elements data and C and 0 isotopes of rhese tuffs. The C and 0 isotopes of the least altered tuff falls within the mantle box while the remaing samples plot in the narrow field of 16-20% in oxygen.These values arc explained using slmplc model of water-rock interaction.