Geology and petrology of the Vulsinian volcanic area (Latium, Italy)

The Vulsinian volcanic area is situated in Latium, west central Italy. This quarternary volcanic complex consists of a series of layered tuffs, lava flows, ignimbrites, and many small cinder and ash cones. A steep central edifice is lacking due to the relatively large amount of pyroclastic deposits. Tectonic movements created a relief with large, shallow depressions: the central Bolsena depression with the Bolsena lake inside and the Latera caldera. The present study is subdivided into three chapters I. The tectonic and volcanologic history of the area, mainly from field studies, paleomagnetic stratigraphy and absolute age determinations. II. The petrographic and chemical characteristics of the Vulsinian rocks. An inventarization of the rock types is given together with chemical trends an conditions of crystallization. A speculative petrogenetic and geodynamic model concludes this chapter. III. A detailed microprobe study of a suite of mafic nodules, which were found in phreato-magmatic deposits in the SE part of the area (Montefiascone). This chapter presents the chemistry of a suite of Al rich clino-pyroxenes, their zoning and paragenesis.