Abstract: Carbonatite is the only terrestrial rock that is predominantly composed of carbonate minerals of igneous origin, such as calcite and dolomite. It serves as a major host for rare earth element (REE) minerals and holds significant economic value in REE mineralization. Despite numerous proposed theories on the origin of carbonatite complexes, a clear understanding of their formation remains elusive. This study focuses on unraveling the origin and evolution of the Amba Dongar carbonatite complex, which is associated with the Deccan Large Igneous Province. A total of 71 rock samples were collected from Amba Dongar and subjected to analysis for major, trace, and Sr-Nd-Pb isotope ratios. Through geochemical data analysis, isotope binary mixing, and trace element modeling, a plausible petrogenetic model was proposed for the generation of the Amba Dongar carbonatite complex. The petrogenetic model highlights the significant influence of the Deccan-Réunion mantle plume in metasomatism of the sub-continental lithospheric mantle (SCLM) source. It suggests that low-degree partial melting of this SCLM source produced a parental carbonated silicate magma, which underwent liquid immiscibility at lower depths, resulting in the formation of nephelinite and carbonatite at Amba Dongar. Simultaneously, approximately 10% melting of the Deccan mantle plume gave rise to the Deccan Large Igneous Province. In-situ Sr isotope analysis of apatite from carbonatite and silicate rocks further indicates mantle heterogeneity.

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