THE MIOCENE PAKHNA FORMATION, SOUTHERN CYPRUS AND ITS RELATIONSHIP TOTHE NEOGENE TECTONIC EVOLUTION OF THE EASTERN MEDITERRANEAN

The Miocene Pakhna Formation is interpreted as relating to onset of th e present northward subduction of the African plate beneath Cyprus and is, thus, critical to understanding of the Neogene evolution of the E astern Mediterranean basin. Following a period of deep-water pelagic c halk deposition in the Late Eocene and Oligocene (Upper Lefkara Fm.), the Pakhna Formation records heterogeneous, mainly carbonate, sediment ation. The Pakhna Formation is bounded by the Limassol Forest Block, a n uplifted ophiolitic terrain to the north, and by the Akrotiri High, a ridge of exotic Mesozoic lithologies to the south. Two sub-basins, M aroni in the E and Khalassa in the W, within the Pakhna Formation were separated by the WNW-ESE-trending Yerasa lineament, located near the S margin of the ophiolite. In most areas, the Pakhna Formation overlie s the Lefkara Formation disconformably. The succession begins with dee p-water pelagic carbonates and shows increased input of shallow-water bioclastic and terrigenous sediment upward. During the Early to mid-Mi ocene, the ophiolitic terrain to the N was uplifted, deformed and erod ed, followed by marine transgression and patch-reef development in the Tortonian (Late Miocene). Ophiotite-derived clastics were mixed with shallow-water bioclastic sediment, reworked in a high-energy coastal s etting and transported downslope within channels into the basin, accum ulating as massive sands, debris flows and calciturbidites. In the Mar oni sub-basin, localised debris aprons prograded into a pelagic carbon ate environment to the SE. Further west, in the Khalassa sub-basin, li ttle uplift occurred along the basin margins and redeposited sediment was mainly bioclastic. Contrasting sediment, including chert, was deri ved from the allochthonous Mamonia Complex, exposed on the Akrotiri Hi gh to the S and its possible offshore extension. Bioclastic sediment, including reef talus, was also derived from an intrabasinal high in th e Khalassa sub-basin. Eventually, normal marine deposition was ended b y the Messinian salinity crisis.