Chapter 24 - The Ionian Fold-and-Thrust Belt in Central and Southern Albania: A Petroleum Province With Triassic Evaporites

Abstract

The Ionian fold-and-thrust belt (FTB) is formed by a piggyback sequence of W-directed thrusts that were emplaced over the Apulian Platform during the late Oligocene to the latest Miocene. From bottom to top, the Cika, Kurveleshi, and Berati belts constitute the three main thrust sheets of the Ionian FTB. All of them contain a rather similar thick sequence (~2–3km) of basinal, pelagic carbonates of latest Triassic to Eocene age. The Late Triassic evaporite sequence (in Keuper facies) acts as a regional decoupling level for thrusting during the Alpine contraction. The structure of three major structures of Triassic evaporites has been studied in detail in central and southern Albania. They document different styles of salt tectonics in the precursor Ionian basin and different initial conditions for the structural style during the subsequent Alpine contraction. The Dumre diapir is interpreted as a thick salt plug, which has been squeezed and displaced toward the west, promoting a marked change in the geometry of the overlying thrust that passes from a frontal to a lateral hanging-wall ramp. In southern Albania, a variation of the Triassic salt structures was reconstructed toward the W and SW, possibly representing a downslope evolution from salt pillows (Delvina and Picari-Kardhiq) to massive salt walls (Butrinti-Xarra).