Sedimentology and palaeoecology of a Miocene coralline algal biostrome from the Maltese Islands

Abstract

A large coralline algal biostrome (20 km × 5 km × 16 m thick) is well exposed in western Malta and eastern Gozo. The biostrome is composed of limestones largely constructed by in situ coralline algae or transported algal debris. Some sediments are dominated by rhodoliths and others by crustose coralline frameworks. Six facies are distinguished: Crustose Algal Marl, Crustose Algal Wackestone, Rhodolith Pavement, Algal Branch Packstone, Crustose Pavement and Algal Crust Packstone. Each facies is characterised by different rhodolith morphologies and coralline crusts which are constructed mainly byMesophyllum commune. The coralline morphogenesis is related to the palaeoenvironmental conditions. The biostrome is thought to have developed from a series of relic sand ridges to form a low relief platform of moderate depths containing a mosaic of sedimentary facies. The sequence is affected by growth faulting which divides the biostrome into eight units.