La sédimentation sur la plateforme de Tripolitza au Crétacé inférieur-Cénomanien en Crète centrale (Grèce)

Abstract

The Tripolitza zone of the Hellenic orogen is closely related to the south Tethys passive margin. It represents the internal part of the Gavrovo-Tripolitza platform which crops out in the central-south Peloponnese, Crete and the south-east Aegean islands. From bottom to top, the Tripolitza sequence is composed of Triassic clastic sediments (Tyros beds), Triassic to upper Eocene platform carbonates and a clastic flysch series. In the present paper the sedimentation and stratigraphy of the Lower Cretaceous to Cenomanian carbonate succession of the Tripolitza zone in central Crete, are investigated. The basal beds consist of 100 m of laminated to brecciated dolomites with some intercalations of micritic limestones which are interpreted as peritidal deposits. They are of Early Cretaceous, probable Barremian age. They are overlain by 150 m of carbonates, which represent a shelf-lagoonal facies with sea-level fluctuations from upper subtidal to upper intertidal conditions. Influence of the open sea is observed towards the top of this series, dated as early Aptian on the basis of a fairly rich microfauna. The Aptian continues with 130 m of stromatolitic dolomites and dolomite breccia of intertidal to supratidal environments and 45 m of limestones reflecting a subtidal environment. A shallow water, subtidal limestone facies 15 m thick containing gastropods and rudists probably constitute the base of the Albian formation. It is followed by a regressive series 240 m thick. This is composed of laminated limestones and dolomites, gradually becoming stromatolic dolomites with dolomite breccia intercalations. This regressive carbonate sedimentation took place during the Aptian p.p.(?)-Albian-early Cenomanian. Sedimentation during the middle-late Cenomanian had a transgressive character. The succession is characterized by the presence of rudist-reef facies as well as of low-energy subtidal-lagoonal facies. The latter are expressed by limestones with intercalations of dolomites. Locally, the microfauna and microflora are rich and of high diversity.