Palaeoenvironmental reconstruction based on non-geniculate coralline red algal assemblages in Miocene limestone of central Crete

Abstract

Neogene coastal sediments of the Mediterranean provide an excellent laboratory for a quantitative study of palaeoenvironmental parameters and their response to climate change. In order to examine change in environmental parameters during deposition of Tortonian limestone of southern central Crete, we use integrated field and biofacies analysis together with a detailed study of foraminfera and non-geniculate red algae. Patterns in the relative abundance of non-geniculate coralline red algae are interpreted by comparison with data from modern non-geniculate coralline red algae and with additional information from the studied sediments. Based on these integrated datasets, four red algal associations are identified: a Lithophyllum-dominated association restricted to the upper photic zone in warm-temperate environments, a Lithothamnion-dominated association found in the lower photic zone in warm-temperate environments, a Spongites-dominated association typical for shallow warm-temperate to tropical environments and an association with dominant Mesophyllum which is characteristic for the lower photic zone in warm-temperate to tropical environments. We introduce coralline red algal indices in order to quantify changes in environmental parameters. We recognise four warm intervals within a succession of the Tortonian limestones in southern central Crete. During the most extensive interval, widespread coral carpets formed under prevalent oligotrophic conditions. Analysis of the stratigraphic architecture shows that warm intervals are related to sea-level highstands and therefore may reflect global climatic processes.