Miocene Reef Distributions and their Associations in the Central Mediterranean Region: An Overview
Martyn Pedley, 1996. "Miocene Reef Distributions and their Associations in the Central Mediterranean Region: An Overview", Models for Carbonate Stratigraphy from Miocene Reef Complexes of Mediterranean Regions, Evan K. Franseen, Mateu Esteban, William C. Ward, Jean-Marie Rouchy
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A review of the distribution of Miocene coral bioherms and biostromes is presented for Italy, Malta, Libya and Tunisia. These can be grouped into three natural settings related respectively to stable forelands, Alpine fold belts and graben zones. Morphological development within each zone is controlled by such factors as water depth, exposure to water currents, tectonism and siliciclastic sedimentation rates. The more diverse reefs developed in clear seas within stable foreland settings. Three principal reef development episodes are recognised. The earliest reefs (Aquitanian) are modest developments and represent a continuation of Oligocene coral reef growth with a high species diversity. Middle Miocene reefs are dominated by non-coral faunas and coralline algal biostromes; many are related to ramp situations. Corals return in Late Tortonian time though with much lower diversities than their Aquitanian predecessors. Many low diversity coral reefs typically contain up to five species but are always dominated by Porites and Tarbellastraea together with abundant coralline algae. Quite distinct from these are the reefs containing only Porites and Tarbellastraea and even more peculiar, the monogeneric (Porites) reefs. The latter are particularly typical of the Early Messinian. The slender coral rods are never as long and thin as those from strata of similar age in Spain; however, they are similarly associated with stromatolites and abundant Halimeda plates, particularly in the highest beds. It is suggested that locally introduced toxin and nutrient imbalances may contribute significantly to such aberrant reef growth. The driving force for these fluctuations appears to be a combination of tectonic basin deformation and small-scale, intra-Mediterranean eustatic oscillations marking the onset of the principal desiccation event.