The Elba Island: an intriguing geological puzzle in the Northern Tyrrhenian Sea

The Elba Island is located in the Northern Tyrrhenian Sea at midway between Tuscany (Northern Apennines Chain) and Corsica (Alpine Corsica structural pile). The complex Elba I. stack of nappes, which is considered the innermost outcrop of the Northern Apennines Chain, is also well known for its Fe-ore bodies and the relationships between the emplacement of the Mio-Pliocene magmatic bodies and tectonics. The CARG geological survey of Elba I. performed at a scale of 1: 10.000 and 1: 5.000, partially published by Babbini et al. (2001) and Bortolotti et al. (2001a) allowed a revision of the stratigraphic and structural setting of the central and eastern Elba I. This new scheme results more complex compared to Trevisan's classical one, which was based only on five tectonic "Complexes" (Trevisan, 1950; Barberi et al., 1969). Nine tectonic units were defined, and they all pertain to the Tuscan and Ligurian (including the Ligurian-Piedmontese units) paleogeographic domains. Before their final emplacement the Elba's tectonic pile, some of these units were intruded by two acidic plutons (Mt. Capanne and La Serra-Porto Azzurro monzogranites), and by dikes of variable composition during the 8.5 to 5.4 Ma time interval.