Petrology and regional implications of Early Cretaceous Alkaline Lamprophyres in the Ligure-Maremmano Group (Southern Tuscany, Italy): an outline.

Major geological and petrological features of igneous rocks within the Late Jurassic-Early Cretaceous Ligure-Maremmano Group (Southern Tuscany) are examined and related to an extensional geodynamic environment. Mineral assemblage, texture, characteristics of occurrence and whole-rock chemistry suggest that the rocks belong to the lamprophyre clan and point to an alkaline lamprophyric affinity. These rocks have been interpreted as a product of within-plate magmatism, possibly related to extension during a late stage of the Ligurian ocean development. An age of about 110 Ma (Albian) has been found. This age represents a lower limit for the beginning of the compressional Alpine deformations in this area.