Allochthonous blocks misidentified as the basement: Implication for petroleum exploration in the SW Thrace Basin (Turkey)

Abstract

The sedimentary sequence of the SW Thrace Basin (NW Turkey) comprises of three major sedimentary packages: a) Cretaceous (Meastrichtien)-Early Eocene package formed as pelagic carbonate, turbidite. shelf and nearshore-fluvial deposits, b) Middle Eocene-Early Oligocene package formed as shallow marine, slope apron and turbidite sediments, c) Middle Miocene-Early Pliocene package formed as alluvial fan-fluvial and nearshore deposits. This basin is structurally complex and its southern margin is represented by a fold-thrust zone. The Westward Propagation of the North Anatolian Fault (WPNAF) intersects the Thrace Basin along its southwestern flank. In the SW Thrace Basin, there are ophiolite and limestone blocks in the sedimentary succession, which previously were interpreted as suture of the Intra-Pontide Ocean, Cretaceous aged Yenikoy Melange or Olistostromal Unit in the Eocene sediments. In this study these rocks have been defined as allochthonous blocks facies of the Gazikoy Formation aged Middle-Late Eocene.