MELTING BEHAVIOUR OF RAJMAHAL BASALTS OF EASTERN INDIA AT ONE-ATMOSPHERE CONDITION

摘要

One-atmospherie-melting studies of Rajmahal Basalts of eastern India throw some new liglil on the appearance of several Iiquidus phases. Experimental studies indicate that the crystallisation began at 1190 deg with initial nucleation of piagioclase. This was later joined by clinopyroxene (and/or orthopyroxene) and opaque minerals at subsequently lower temperatures. It was found that the entire crystallisation regime corresponding to one-atmospheric condition was rather restricted and ranged from 1190 deg to 1050 deg C. The narrow temperature interval indicates rapid cooling of the eruptive magma corresponding to huge effusion of the lava flows onto the Earth's surface.