FIELD GEOLOGY, PETROGRAPHY, AND ORTHO-PYROXENE CLUSTERS OF THE DHULE-PAROLA DIKE, TAPI VALLEY, CENTRAL DECCAN BASALT PROVINCE

The > 40 km-long, E-W-trending Dhule-Parola multiple dike masks the so uthern limit of the Tapi rift, It is made up mainly of an aphyric and a plagioclase (pl)-phyric dike, with large loose boulders of dioritic gabbros, Unlike a previous report, we have found no clearcut basement xenoliths in it, In the pl-phyric dike; the groundmass plagioclases ar e more calcic (An(89-92)) than the phenocrysts (An(82-85)). This unusu al phenomenon indicates contamination or magma mixing, An interesting observation is the presence of orthopyroxene clusters in the pl-phyric dike, Each of these clusters comprises hundreds of microscopic, indiv idual orthopyroxene crystals, Except from Shir-pur, in the same genera l area as that of the present study, the development of such puzzling clusters is not yet reported from basalts of the entire Deccan provinc e.