Melilitite

Melilitite is a rare, silica-undersaturated volcanic rock, a member of the melilite group, composed primarily of melilite, olivine, pyroxene, and often nepheline or leucite. It's characterized by a relatively high concentration of calcium, magnesium, and iron, typically formed from highly alkaline magmas at relatively low temperatures and high water pressure, often associated with other unusual rock types like carbonatites. Its formation is linked to mantle upwelling, particularly in continental rift zones and oceanic islands, contributing to understanding Earth's deep interior and magmatic processes.

Melilitite meaning with examples

• The geologists found the unusual mineral assemblage characteristic of melilitite in the newly discovered volcanic field. It's composed of brown melilite, rounded olivine, and augite. The team immediately hypothesized this rock type to give indications to mantle source. This discovery can change the understanding of the area's geological history and the formation of its magma.
• Analysis of the melilitite samples revealed a high concentration of rare earth elements. This finding suggests the magma originated from a deep-seated, enriched mantle source. Studying these rocks help us to understand the chemical composition of the Earth's mantle. These can also give clues on the processes happening at that location.
• The presence of melilitite on the island chain suggested a complex history of mantle plumes and crustal melting. The rock's distinctive texture, with large crystals of melilite set in a fine-grained groundmass, was carefully examined. Understanding the eruption dynamics and magma compositions has been valuable to understanding the history of the island.
• During a seismic survey, the researchers correlated changes in seismic velocity to areas where melilitite outcrops were known. This allowed them to infer the presence of similar rock bodies deeper in the crust. The researchers concluded that the correlation between the rock type and its position in the deep has allowed scientists to study the deep composition of the rock's sources.