Bocciolaro

At the Bocciolaro geosite, it is possible to observe the mixing of magmas within the Basic Complex.

Before complete crystallisation, large magma intrusions cool to the point where they consist mainly of crystals rather than molten material. This state is known as ‘crystal mush’ – a mixture of crystals, almost like a hot granita. As the crystals compact, this mush thickens and the remaining molten material is forced upwards.

In this outcrop, which was situated at a depth of around 20 km, fine-grained gabbro pillows can be observed embedded within the diorite, as at Aniceti; here, however, the gabbro pillows are flattened and elongated. This is the result of the compaction of the crystal slurry at greater depths during the growth of the Basic Complex, which continued to be fed from the upper parts (for example, at Aniceti).