Sedimentology of two fan-delta systems in the Pliocene-Pleistocene of the Mesaoria Basin, Cyprus

Abstract

Two fan-delta systems have been recognised in the Pliocene-Pleistocene deposits of the Mesaoria Basin, an asymmetrical half-graben located on the northern side of the Troodos ophiolite, Cyprus. The older fan-delta system, the Pliocene Nicosia Formation, was deposited when the Mesaoria Basin was actively subsiding. It comprises a number of small, isolated fan deltas which built across a narrow ( < 5 km), steep, fault-controlled, largely submerged basin margin. The preserved marine facies of this fan-delta system are confined to channels cut into the basin margin, and are dominated by marine conglomeratic, mass-flow deposits. In contrast, the much thinner ( < 20 m), younger (Late Pliocene-Pleistocene) fan-delta system of the Kakkaristra Formation was deposited when basin subsidence had virtually ceased and the Mesaoria seaway had filled to become a shallow, sandy platform. This renewed fan-delta sedimentation was initiated by uplift of the Troodos ophiolitic massif. In response to uplift, alluvial systems built northwards and coalesced at the coastline, giving rise to a large shelf fan delta that prograded into the basin. Conglomeratic sediments were largely trapped in subaerial and coastal areas, and were deposited by both mass-flow and traction-current processes. In addition, some gravel was redistributed along the shoreline by wave action. Coastal fan-delta deposition was terminated by renewed uplift of the Troodos Massif, initiating deposition of the Pleistocene fanglomerate unit.