Research Projects

Alkaline igneous rocks constitute a small fraction of the Earth’s continental crust, yet they are important due to their economic potential for hosting rare and critical metal deposits. Alkaline rocks, including feldspathoid-bearing syenites, kimberlites, lamproites, lamprophyres, and associated carbonatites, also provide valuable insights into the composition of the deep lithosphere and geological and geodynamic processes. These rocks are enigmatic to petrologists because of their exotic mineralogy and complicated origin. There is as yet no consensus on our understanding of their formation, petrogenetic evolution and emplacement mechanisms. Since some of these rocks contain crustal and mantle xenoliths, they offer direct access to rare sections of the Earth’s interior that are otherwise inaccessible. Consequently, research on such rocks and their entrained xenoliths enhances our understanding of the fundamental processes and components of the solid Earth while also driving the exploration for rare and critical metals that are essential for modern technologies. Besides, continental alkaline magmatism releases a significant proportion of carbon in the Earth’s atmosphere impacting global climate. This project proposal focuses on two geologically distinct alkaline complexes: (i) the alkaline complex emplaced along the Nongchram Fault Zone in Shillong plateau, northeast India and (ii) the Kunavaram complex located along the tectonic contact of the Eastern Dharwar Caton and the Eastern Ghat Mobile Belt. The main objective of the proposal is to decipher the genesis of these complexes, understand the genetic linkages between different alkaline rocks of the complexes, decipher fundamental geological processes that played a crucial role in their evolution, and evaluate their overall potential for rare and critical metals. One of the novel aspects of the proposal is the approach to address the above-listed problem – utilizing in situ mineral chemical study (major as well as trace and isotopic) to unravel the origin and petrogenetic history of the alkaline rocks, in addition to the conventional petrological and geochemical study. In situ mineral chemical studies offer more critical resolution to understand the petrological processes because each phase is characterized in detail, including their changing composition from core to rim as the crystallization proceeds. Several accessory phases, such as apatite, allanite, perovskite, titanite and rutile, contribute to low modal abundance in alkaline rocks but are ubiquitous. These phases, which usually crystallize from early magmatic to late magmatic stages, offer better insights into the petrogenetic evolution and therefore, in situ mineral compositions of the accessory phases will be the most important tool in achieving the goals of the study