Executive Summary : | Kimberlites and related magmas are volumetrically small, mantle-derived, volatile-rich (H₂O, CO₂), and mafic to ultramafic (SiO₂ below 52 wt.%) magmas. They are the primary source of diamonds. These magmas (now solidified as rocks) occur in cratons, tectonically more stable parts of the continents. Mineralogically, they are exotic with hybrid mineral assemblages comprising variable proportions of crustal and mantle-derived xenocrysts (e.g., olivine, garnet, Cr-diopside) and phenocrysts directly crystallised from magma (e.g., olivine, phlogopite, spinel) that join the kimberlite factory at different stages of evolution. These minerals reveal novel information on the physicochemical conditions that prevailed by the magma at different stages as well as its source regions and mantle wall rocks. Kimberlites and related rock have been reported from three cratons in India– Eastern Dharwar, Bastar and Bundelkhand, and have been extensively studied for bulk-rock geochemistry and geochronology with minimal mineralogy. In contrast, detailed documentation of morphologies, intragranular and intergranular major and trace elemental variations, and stable isotope systematics in kimberlitic minerals is still scarce, and diffusion profiles in these minerals are yet to be fully addressed. As a result, there is a lack of information on the timescale of magmatic ascent for these magmas. Many key intensive variables controlling mineral-chemical variations and their preservation (including diamond) have remained unconstrained. Apart from that, preliminary analysis has indicated the first occurrence of a few minerals in these rocks, implying the necessity for more focused mineralogical research. This study proposes a detailed morphological and in-situ mineral chemical analysis of distinct phases in kimberlites and related rocks from India. The goals will be; to (1) constrain physicochemical conditions and primitive melt-compositions of the diamond-delivering magmas from India, (2) constrain magmatic timescales, (3) estimate the intensive variables of the magma, (4) reconstruct a detailed lithostratigraphy of the continental lithospheric mantle (CLM), (5) refine diamond prospecting tools by using olivine, (6) search for rare mineral species. In this work, mineral studies will be performed on rock samples from Bastar, Bundelkhand and Eastern Dharwar cratons using EPMA, LA-ICPMS, in-situ SIMS, and Laser Raman microscopy. |