Colli Albani

Roman Province (Latium) (0.8 to 0.02 Ma) Vulsini (0.6-0.15), Vico (0.4-0.1), Sabatini (0.8-0.04), Colli Albani (0.6-0.02) - Large volcanic complexes formed of potassic (trachybasalt to trachyte) and ultrapotassic (leucite tephrite, to phonolite) pyroclastics and minor lavas. 

Ultrapotassic rocks from Tuscany have a lamproitic composition (see Appendix for nomenclature of potassic rocks). Older lamproites (14 Ma) occur at Sisco, Corsica. Kamafugitic rocks make up a few monogenetic centres in the internal zones of northern-central Apennines (Umbria, Latium, Abruzzi), and have been found at Vulsini and as ejected blocks in pyroclastic deposits at Colli Albani (Federico et al. 1994). Roman-type potassic and ultrapotassic rocks (KS and HKS) form the bulk of magma-... 

Latium Province) defined here only includes Vulsini, Vico, Sabatini and Colli Albani volcanoes. Potassic rocks (KS) basically consist of trachyba-salts, latites and trachytes ultrapotassic rocks (HKS) are represented by... 

Colli Albani (Alban Hills) 0.6 to 0.02 possible historical activity - Stratovolcano with central nested calderas and several post-caldera explosion craters and maars, consisting of HKS (leucitite, leucite tephrite and phonotephrite) pyroclastic fall, flow and hydromagmatic products, and minor lavas. 

Fig. 4.15. Total alkali vs. silica diagrams for Sabatini and Colli Albani.

The Colli Albani volcano has long attracted the attention of scientists, who reported important field observations and clarified several first-order vol-canological, petrological and morphological features of the volcano (e.g. Sabatini 1900). However, the extensive study by Fomaseri et al. (1963)... 

Volcanological and geochronological studies (Fomaseri et al. 1963 De Rita et al. 1995 Kamer et al. 2001 Marra et al. 2003) have resulted in the recognition of three main phases of activity at Colli Albani ... 

Fig. 4.18. Schematic geological map of Colli Albani volcano. Simplified after De Rita et al. (1995) and Trigila et al. (1995).

There is considerable debate on the present condition of the Colli Albani volcano. As mentioned earlier, shallow seismicity has been repeatedly registered. Moreover, historical documents from Roman authors (e.g. Titus Livius, Pliny the Elder, etc.) report on phenomena, such as rain of stones, sudden explosions and fires, which can be ascribed to volcanic eruptions. Moreover, findings of pre-Roman pottery and other human artefacts beneath pyroclastic products are considered as an evidence of a volcanic activity which is much younger than the latest dated rock (see Voltaggio and Barbieri 1995 and references therein). Therefore, based on archaeological and historical records and on seismicity, the volcano is now considered in a quiescent state (Montone et al. 1995 Voltaggio and Barbieri 1995 and references therein). 

The Colli Albani rocks have a silica underaturated ultrapotassic composition, and range from tephrite to foidite (leucitite) and tephriphonolite (Fig. 

Variation diagrams of major and trace elements vs. MgO at Colli Albani (Fig. 4.19) show a positive correlation for CaO, TiC>2, FeOtotai and ferro-magnesian trace elements (Cr, Ni, Co, etc.), negative correlations for Na20, K2O, AI2O3 and incompatible elements (Th, La, Ta, etc.), and a bell shaped trend for P2O5. Incompatible elements show smooth inter-element positive trends (Fig. 4.19g). The pre-caldera lavas seem to define different trends on some major and trace element variation diagrams, especially on plots of incompatible element vs. incompatible element ratios (Fig. 4.19h). REE and incompatible element patterns have shapes that are similar to those for other ultrapotassic rocks from the Roman Province (Fig. 4.20). 

Fig. 4.19. Variation diagrams for the Colli Albani volcanic rocks.

Bemhardsdottir AE, Thorvaldsdottir S, Sigbjomsson R, Musacchio G, Nave R, Falsaperla S, D Adda S, Sansivero F, Zonno G, Sousa ML, Carvalho A, Raposo S, Ferreira MA, Nunes JC, Jimenez Ml (2012) Disaster prevention strategies based on an education information system. 15WCEE, Lisbona. htq> //hdl.handle.net/2122/8148 Carapezza ML, Barberi F, Tarchini L, Ranaldi M, Ricci T (2010) Volcanic hazards of the Colli Albani. In Funiciello R, Giordano G (eds) The Colli Albani volcano. Special Publications of lAVCEI 3. Geological Society, London, pp 279-297... 

---