Melt inclusions in olivine and pyroxene phenocrysts from lamprophyres of Chhaktalao Area, Madhya Pradesh, India

Abstract

Melt inclusions in olivine and pyroxene phenocrysts in kersantite and camptonite at Chhaktalao in Madhya Pradesh, India are mainly of the evolved type forming daughter minerals of olivine, pyroxene, plagioclase, spinel, mica, titanomagnetite and sulphides. Heating studies exhibit a temperature range from 1215° to 1245°C for the melt inclusions in olivine in camptonite and 1220–1245°C for olivine in kersantite. The temperature for melt inclusions in pyroxene ranged from 1000° to 1150°C in camptonite and 850–1100°C for pyroxene in kersantite. The bubble inside these melt inclusions is mainly CO 2. The T h°C of CO 2 into liquid phase occurred between 26° and 31°C in olivine and 25–30°C in pyroxene from kersantite and camptonite. The maximum density estimated is 0.72 g/cm 3 and the minimum is 0.45 g/cm 3. The depth of entrapment of the melt inclusion is estimated between 10–15 km. The pressure of entrapment of melt inclusion in olvine is 4.6 kbar where as that in pyroxene is 3.7 kbar. The lamprophyres in the Chhaktalao area are considered to be derived from low depth and low pressure region, possibly within spinel lherzolite zone.