Contrib Mineral Petrol (1995) 122: 275–288 C Springer-Verlag 1995 F. Stoppa  A. Cundari A new Italian carbonatite occurrence at Cupaello (Rieti) and its genetic significance Received: 17 January 1995  Accepted: 14 June 1995 Abstract Field, mineralogical and petrological data are presented on a newly found carbonatite occurrence asso- ciated with “kamafugite” lava at Cupaello, central Italy. This carbonatite occurrence is part of the Late Pleis- tocene Umbria-Latium ultra-alkaline district (ULUD) which extends southwards within the Apennines to Mount Vulture, delineating an important magmatic province along the most peripheral belt of the Tyrrheni- an extensional tectonic system. This province is distinct, but probably related genetically with the more abundant and common leucite-bearing assemblages of the Roman Comagmatic Region and represents the first reported oc- currence of carbonatite assemblages in the Mediter- ranean Basin. The Cupaello suite indicates that primary or near-primary mantle silicate melts of “kamafugitic” composition are transitional with Ca-carbonatite liquid and provides direct evidence of immiscibility of carbon- atite from “kamafugite” magma. It is inferred that a pri- mary mantle origin of Ca-carbonatites is conditional upon a potential silicate magma that may be coupled with the carbonatite, but may not have reached the surface. The data indicate a strong genetic link between ULUD Ca-carbonatites and some African analogues, support- ing the view that their genesis depends on similar source and associated tectonic conditions. Introduction The genetic significance of extrusive carbonatites has been recently highlighted by Gittins and Jago (1991) and Bailey (1993). These carbonatites are believed to repre- sent magmatic carbonate liquids which escaped CO 2 ex- solution plus decarbonatation processes and remained above the solidus until they reached the volcanic P-T regime. Crucial to the survival of primary calcite-bear- ing liquid at or near atmospheric pressure is a rapid as- cent to the surface (Bailey 1990). This would also ac- count for the associated mantle xenolithsxenocrysts which, according to Bailey (1993), reflect a direct erup- tion of the carbonatitic liquid from its mantle source. Notable, Dawson et al. (1970) described carbonatite tuffs associated with ultramafic assemblages from northern Tanzania and concluded that they may repre- sent primitive magma erupted directly from the mantle. Late Plestocene carbonatitic rocks, associated in time and space with “kamafugitic” lavas (group II of Foley et al. 1987; Cundary and Ferguson 1991), melilitolites (“uncompahgrite”; Stoppa 1988, 1995) and phonolitic pyroclastics of the Umbria-Latium ultra-alkaline dis- trict, ULUD (Stoppa and Lavecchia 1992) provide a firm genetic link between “kamafugites” and carbonatites in Italy. The ULUD-type carbonatitic rocks occur within the Apennine Range along the most peripheral belt of Tyrrhenian extensional tectonics in Recent times (Lavec- chia and Stoppa 1990). This belt, extending southwards through the Abruzzi region (Bosi and Locardi 1991) to Mount Vulture (Principe and Stoppa 1994), is character- ised by lower heat flow, thicker lithosphere and stronger seismic activity, relative to the Roman Region (Lavec- chia et al. 1994). The ULUD rock types represent prima- ry or near-primary mantle liquids which may be germane to the petrogenesis of more common leucite-bearing lavas of the adjacent, coeval Roman region, RRL (i.e. Roman region lavas; group III of Foley et al. 1987). Car- bonate is a common accessory in mafic RRL and associ- ated ejecta and, where investigated, may be of primary igneous origin (Fornaseri and Turi 1969). Quaternary kamafugites and carbonatite assemblages occurring in the Fort Portal volcanic field (Barker and Nixon 1989; Barker 1989) and group III leucite-bearing lavas (Foley et al. 1987) in Bufumbira, Ungandan Rift, F. Stoppa ( ✉ ) Dipartimento di Scienze della Terra, Universita ` di Perugia, I-06100 Perugia, Italy A. Cundari Dipartimento di Geofisica e Vulcanologia, Universita ` Federico II, I-80138 [PEA] Napoli, Italy Editorial responsibility: I. Parsons