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

Melt inclusions in olivine and pyroxene phenocrysts in kersantite and campt onite 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 degrees to 1245 degrees C for the melt inclusions in olivine in camptonite and 1220-1245 degrees C for olivine in kersantite. The temperatu re for melt inclusions in pyroxene ranged from 1000 degrees to 1150 degrees C in camptonite and 850-1100 degrees C for pyroxene in kersantite. The bub ble inside these melt inclusions is mainly CO2. The T(h)degrees C of CO2 in to liquid phase occurred between 26 degrees and 31 degrees C in olivine and 25-30 degrees C: in pyroxene from kersantite and camptonite. The maximum d ensity 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 pre ssure of entrapment of melt inclusion in olvine is 4.6 kbar where as that i n pyroxene is 3.7 kbar. The lamprophyres in the Chhaktalao area are conside red to be derived from low depth and low pressure region, possibly within s pinel Iherzolite zone. (C) 2000 Elsevier Science Ltd. All rights reserved.