Different styles of evolution of C02-rich alkaline magmas: the role of melt composition in carbonate-silica te liquid immiscibility

Melt and fluid inclusions were studied in olivine from the olivine melilitite of the Mahlberg complex, Germany. It was shown that the magmas were saturated in C02 at a pressure higher than 5 kbar and 1220°C and showed low Si02 and high CaO and alkal i contents. The magma composition is similar to that of the melilitolites of the Gardiner massif in Greenland (Nielsen et al., 1997), which associate with carbonatite bodies and where evi dence for carbon ati te-si licate liquid immiscibility was detected in melt inclusions. The absence of carbonatite liquids in Mahlberg is probably related to a relatively high Al203 content, which shifted the composition of magma away from the carbonate-silica te liquid immiscibility field.