Inherited Geochemical Characteristics of Palaeo-Domains by Alkaline Complexes and Related Rocks within Southern Granulite Terrain, India-Implications of Crustal Contamination in their Genesis and Emplacement

In a Palaeo-Tectonic-Domain based classification involving an evolutionary model of '"Terrane-Terrane amalgamation through "Palaeo-sutures" for the Southern Granulite Terrain (SGT), India, the alkaline-carbonatite and related rocks fall within three distinct domain groups viz., Group 1 - "Within Micro-terrancs", Group 2 - "Along the Margins of Micro-Terranes with palaeo-sutures" and Group 3 - "Within Palaeo-sutures". These Late Proterozoic to Early Palaeozoic alkaline and related rocks of SGT falling within the above three groups have inherited the geochemical attributes of their respective Archaean Palaeo-Domains and fall in the fields of such domains in many of the tectonic discriminant plots used and studied by various workers in the different sectors of SGT. Such inheritance of Palaeo-Domain characteristics points to the validity of both the terrane amalgamation through Palaeo-Sutures evolutionary model for SGT as well as the Tectanic-Domain-Based classification of the alkaline related rocks of SGT. It also adds further support to the interpretation of crustal contamination in the genesis and emplacement of alkaline and related rocks in SGT, as deduced from other sources such as field relationships, petrographic criteria etc., while evidences from isotopic signatures are inconclusive.