Coastal progradation and very early diagenesis of ultramafic sands as a result of rubble discharge from asbestos excavations (northern Corsica, western Mediterranean)

Abstract

The western coast of Cape Corse in northern Corsica is a remarkable area by virtue of its geological, biological and landscape diversity. Asbestos extraction between 1948 and 1965 however at Canari Mine, has modified the natural rocky escarpments, cutting the mountain into steps and has altered the coastal and marine zones from Punta di Canella to Farinole. Albo harbour was filled with rubble discharging directly to the sea, and the coast prograded 400 m after 4 years between 1954 and 1958. Artificial shores of up to 300 m in width appeared at the bottom of existing steep cliffs over a distance of more than 5 km between 1948 and 1973. The Posidonia seagrass was buried by the introduction of debris. Since June 1965, the mine is closed and coastal modification results from material movement from north to south. As an exception, Campana beach appeared in the northern part of the discharge area in 1973. The sediment on Nonza beach already displays cemented slabs that attest to very early diagenesis. This particular environment of ultramafic sands and pebbles appear to have produced alkaline conditions and probably enhances carbonate precipitation.