Roccamonfina

Ure A, Berrow M (1982) The elemental constituents of soils. In Bowen HJM (ed) Environmental chemistry. Royal Society of Chemistry, London, pp 94-203 Vacca A, Adamo P, Pigna M, Violante P (2002) Genesis of tephra-derived soils from the Roccamonfina volcano, Central-Southern Italy. Soil Sci Soc Am J 67 198-207... 

Antonone, R., F. de Simone, P. Mor-rica, and E. Ram undo. Traditional phytotherapy in the Roccamonfina volcanic group, Campania, southern Italy. J Ethnopharmacol 1988 22(3) 295-306. 

Giannetti, B. and Ellam, R., 1994. The primitive lavas of Roccamonfina volcano, Roman region, Italy new constraints on melting processes and source mineralogy. Contrib. Mineral. Petrol., 116 21-31. 

Ernici -Roccamonfina (0.7 to 0.1 Ma) Ernici Pofi, Ceccano, Patrica, etc. (0.7-0.1) Roccamonfina (0.58-0.1) - Monogenetic pyroclastic and lava centres (Emici), and a stratovolcano (Roccamonfina) formed of mafic to felsic ultrapotassic and potassic rocks. 

Fig. 1.8. Magmatic provinces in Italy, as identified from major, trace element and isotopic characteristics of mafic rocks. The Ancona-Anzio, Ortona-Roccamonfina, 41° Parallel, Tindari-Letojanni-Malta and the Sangineto tectonic lines are also indicated. Inset distribution of volcanism with orogenic (i.e. high LILE/HFSE ratios) and anorogenic (i.e. low LILE/HFSE ratios) compositions. Arrows indicates migration of orogenic magmatism from Oligocene to present. See text for explanation.

This province is characterised by the close association of KS and HKS rocks, showing diverse geochemical and isotopic signatures. Some low-potassium mafic rocks falling in the calc-alkaline compositional field have been also found. Potassic rocks display ratios of some incompatible trace elements such as Ba/La, and radiogenic isotope signatures that are close to those of the Neapolitan volcanoes (Vesuvio, Campi Flegrei, Ischia). On the contrary, ultrapotassic rocks resemble the Colle Albani and other Roman volcanoes. Therefore, the Ernici-Roccamonfina zone is characterised by the coexistence of Roman-type and Campanian-type rocks. 

Information on age, volcanology and petrology for Emici and Roccamonfina is summarised in Table 5.1. Major, trace elements and isotopic data for representative rocks are reported in Table 5.2. 

The volcanoes of Emici and Roccamonfina occur on the Tyrrhenian side of the central Apennines, a sector of the Apennine orogen delimited by the Ancona-Anzio line in the north and by the Ortona-Roccamonfina line in the south (Locardi 1988). The pre-volcanic basement consists of various rock types belonging to distinct paleogeographic-structural units formed... 

Fig. 5.1. Location map of Emici (full triangles) and Roccamonfina volcanoes.

Table 5.1. Age, petrology and volcanology of Emici and Roccamonfina volca-...

Roccamonfina 0.58 to 0.1 Potassic rocks generally younger than ultrapotassic rocks - Stravolcano with a main central caldera and eccentric cones, formed of alternating lava flows and pyroclastic products with a mafic to felsic subalkaline to alkaline potassic (KS) and ultrapotassic (HKS) composition. 

The Emici-Roccamonfina zone has a crustal thickness of about 30 km. The uppermost mantle is characterised by a thin layer of material with relatively low S-wave velocity (Vs = 3.95 km/sec), which passes into a thick lid that has higher S-wave velocities (Vs = 4.40-4.65 km/sec). This upper mantle structure is unique in the circum-Tyrrhenian area (Panza et al. 2004 Chap. 10). 

Fig. 5.3. A) TAS diagram for the Emici and Roccamonfina volcanic rocks. The dashed line is the divide between alkaline and subalkaline fields of Irvine and Baragar (1971). B) K20 vs. Si02 classification diagram (modified after Peccerillo and Taylor 1976). C) K20/Na20 vs. AQ for the mafic rocks (MgO > 4 wt%). For definition of AQ see Chap. 1.

Fig. 5.4. Variation diagrams of selected major and trace elements and 87Sr/86Sr vs. MgO for Emici and Roccamonfina volcanoes.

Fig. 5.6. Sr, Nd and Pb isotope variations for the Emici and Roccamonfina volcan-ics. The fields of mafic rocks from the Campania and Roman provinces are also shown. Symbols as in Fig. 5.4.

Roccamonfina is an asymmetric truncated composite cone, with a base diameter of about 20 km and a 6 km wide, NW-SE-elongated summit caldera that is breached on the east side (Fig. 5.7). The caldera floor, sited at about 600 m above sea level, hosts several lava flows and domes which reach a maximum altitude of about 1000 m. The volcano is composed of alternating lava flows, domes and pyroclastic deposits which were emitted both from central and parasitic vents between about 0.6 and 0.1 Ma. As shown in Fig. 5.3, rock compositions range from mafic to felsic, and from subal-kaline to alkaline potassic and ultrapotassic (Appleton 1972 Giannetti and Ellam 1994). The volcanic activity took place in a zone of NW-SE trending extensional faults cut by younger N-S faulting (Chiesa et al. 1995 Fig. 5.1). 

Fig. 5.7. Schematic geological map of the Roccamonfina volcano. Simplified after Giannetti and Luhr (1983).

The lowest exposed products of the cone have an age of about 550 ka. However, tephra recovered from the nearby areas have shown a somewhat older age of about 580 ka, which most probably represents the beginning of the volcanic activity at Roccamonfina. The youngest lava from the main cone has an age of about 370 ka. The BLT and WTT sequences result from various eruptions that occurred from about 380 to 230 ka. The activity inside the caldera and along the cone flanks developed between about 300 and 100 ka (Chiesa et al. 1995 Giannetti and De Casa 2000 and references therein). 

The Emici and Roccamonfina magmas exhibit peculiar compositional characteristics in terms of their very variable geochemical and isotopic signatures for potassic to ultrapotassic mafic rocks. These are not encountered in other potassic volcanoes of central Italy (i.e. Roman and Campanian provinces, with the possible exception of Vico volcano), where coexisting KS and HKS rocks have different potassium and incompatible trace element abundances but exhibit similar incompatible element ratios and radiogenic isotope signatures (Peccerillo 1999, 2002). 

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