Exploring Crust–Mantle Relationships in Northeastern Himalayan Ophiolites Through Integrated Geochemical and PGE Systematics

Ophiolites, as fragments of ancient oceanic lithosphere emplaced onto continental margins, offer a valuable record of the magmatic, tectonic, and mantle processes that shaped former oceanic basins. This study investigates crust–mantle interactions within ophiolite complexes of the northeastern Himalaya using a multi-proxy geochemical approach that integrates whole-rock major and trace element chemistry, mineral chemistry, isotopic signatures, and Platinum Group Element (PGE) systematics. PGEs provide a robust means of tracing mantle processes due to their sensitivity to degrees of partial melting, sulphur saturation, and redox conditions. By examining PGEs in mantle-derived peridotites, chromitites, and associated crustal rocks, this research aims to delineate the roles of partial melting, fractional crystallization, and post-magmatic alteration in shaping the composition of ophiolitic sequences. The study further assesses how variations in PGE distribution reflect differences in tectonic setting, from mid-ocean ridge to supra-subduction zone environments. Through comparative analysis of ophiolites formed in diverse geodynamic contexts, this work addresses existing gaps in understanding the processes governing ophiolite genesis and emplacement during subduction, obduction, and continental collision. The results are expected to refine current models of oceanic lithosphere formation, improve constraints on mantle melting regimes, and enhance interpretations of crust–mantle evolution in convergent margin systems. Overall, this research contributes to a more comprehensive understanding of mantle geochemistry, magmatic differentiation, and tectonic reconstruction in the northeastern Himalayan region.