This dataset comprises comprehensive analytical results for basaltic glass, diabase, and gabbro samples collected from the Onnuri Oceanic Core Complex (Central Indian Ridge). The data includes: Major and chlorine element compositions for amphibole in gabbro and diabase (EPMA) and major element compositions for clinopyroxene and plagioclase in hornfelsic diabase (EPMA); Whole-rock trace element (LA-ICP-MS) and oxygen isotope (IRMS) compositions for diabase; Major and chlorine element compositions for basaltic glass (EPMA); Fluid inclusion parameters (salinity and homogenization temperatures) for hornfelsic diabase (Linkam THMS 600 heating-freezing stage); Analytical results of reference materials used for quality control.