Research Projects

Granites and microgranular enclaves may contain megacrysts or phenocrysts of K-feldspar, which are often thought to be early-formed crystals due to their large euhedral size and randomly or preferred orientation. The origin of these megacrysts is debated, with some arguing it is a product of fractional or equilibrium differentiation, mafic-felsic magma mixed, thermal cycling, late-stage textural coarsening processes, or secondary diffusive exchange. K-feldspar megacrysts are ubiquitous in the microgranular enclaves and granites of high-K, calc-alkaline, metaluminous (I-type) to alkali (A-type) post-collisional Cambrian plutons (475-525 Ma) of the Meghalaya Plateau. K-feldspar megacrysts in enclaves and granites resemble identical crystals, suggesting they are mechanically mixed crystals during mafic-felsic magma mixing and/or enclave mingling events. If this hypothesis holds true, K-feldspar megacrysts must exhibit the same structural state, chemical, and isotopic signatures. The host magma composition can be traced from the microchemistry of growth zones of K-feldspar megacrysts, provided they grew close to the crystal-melt equilibrium boundary. The research proposal aims to investigate petrography, mineralogy, microchemical, elemental, and Pb-Sr isotopes of K-feldspar megacrysts from granites and enclaves to infer the origin and evolution of K-feldspar megacrysts and its insight into the petrogenesis of Cambrian plutons and their enclaves of the Meghalaya Plateau. The research results will greatly contribute to our current knowledge on the origin and evolution of granites and enclaves, as well as the crustal evolutionary history of Pan-African orogen.