Cupaello Quarry, Cupaello Basso Locality, Rieti, Rieti Province, Latium, Italy

A quarry in a kalsilite melilitite lava flow. The Cupaello carbonatite occurrence is associated with kamafugitic lava, and forms part of the Umbria-Latium ultra-alkaline belt.

The Cupaello occurrence comprises a small eruptive vent, located on the eastern marginal fault of the Rieti graben, from which a kalsilite melilitite (coppaelite) lava flow emanated. Nearby, a sequence of carbonatitic pyroclastic rocks is preserved. Ash tephra deposits preserved around the vent are several meters thick and comprise angular lapilli and abundant chert lithics which are overlain by spatter scoria. The 750 m long melilitite flow occupies a river valley and quarrying operations have exposed the underlying carbonatitic pyroclastic rocks. The pyroclastic sequence comprises, from bottom to top, a massive ashfall tephra succeeded by a massive carbonatitic lapilli-ash tuff, at the base and top of which are thin, coarser ash-lapilli surge layers. These are covered by a pyroclastic breccia composed of bombs of melilitite supported by a micritic carbonate matrix. Slump structures occurring in the breccia and injections of tephra into the overlying melilitite flow suggest that the breccia was unconsolidated at the time of its emplacement. 39Ar-40Ar dating of a kalsilite concentrate from the melilitite lava and a 99% pure phlogopite concentrate from the underlying pyroclastics yielded a maximum age of 639 ka.

Ref.:
- Stoppa, F., and Woolley, A.R. (1997): The Italian carbonatites: field occurrence, petrology and regional significance. Mineralogy and Petrology 59, 43-67.