Petrology of the Carbonatites and Associated Alkaline Rocks of Siriwasan, Cahota Udaipur

The upper portions of the Bagh sandstones of Siriwasan have been penetrated and soaked by a sill-like intrusive of carbonatite which has also penetrated the overlying Deccan Trap basalts at a few places. The carbonatite is intimately associated with tinguaite which shows the same form and occurs as discrete dykes as well. The carbonatite mainly forms the matrix of the brecciated sandstone but in places, where it collected as pools, large pockets of sovite are found. Pools of sovite are also found within tinguaite which shows brecciation at places. Thirty-four samples have been analysed for Sr, Rb, Zr, Nb, Zn, Mn, P, Ce, La, Y and Th. Thirteen of these have also been analysed for U. Analytical data show a consanguinity of the carbonatites and the tinguaites. Immiscible liquid fractions of a carbonatite-alkalic magma are considered to have produced the different rock types.