Trace and Rare Earth Elements Geochemistry of Alkaline Rocks of Sarnu-Dandali, Harmer, Rajasthan

The alkaline rocks belonging to ijolite series and carbonatites constitute the Sarnu-Dandali igneous complex (68.5 Ma) associated with Precambrian acid volcanics. Trace elements including REE of ten selected Late Cretaceous rock-types viz. melteigite, melanephelinite, phonolite, carbonatite, basalt and Precambrian rhyolites of SDIC have been examined and discussed. The data of alkaline rocks suggest their derivation from an alkaline (ijolitic) magma formed by the partial melting of mantle source. Ba-Sr-REE enriched carbonatites possibly represent an immiscible split from nephelinite. The basalt (Hawaiite) represents a subalkaline magmatic pulse unrelated to alkaline suite. The associated Precambrian rhyolites have formed by a combination of magmatic processes such as partial melting, fractional crystallization and/or magma-mixing.