Periadriatic Foredeep (onshore Albania) Is Developed as Dextral Pull-Apart Basin

Abstract

The Periadriatic Foredeep onshore Albania is the only Foredeep basin located in the frontal part of the Albanides orogeny bordering eastward the Adriatic Foreland. The recent neotectonic investigations and previously published ones prove the formation of Periadriatic Foredeep as a dextral pull-apart basin in the Middle Miocene (Serravallian), subsequently to the main folding and thrusting of the Ionian Zone, through the strike-slip faulting mechanism. The two elements that commonly lead to the formation of the Periadriatic Foredeep Pull-apart Basin are the cross-basin strike-slip faults of Drini Bay-Lezha and Vlora-Bishqemi, and the oblique normal faults of Durresi-Frakulla and Preza-Rova-Bishqemi. The infill consists of the Serravallian to Pliocene molasses succession up to 6 km in thickness. The Periadriatic Foredeep Basin is located between the South Adriatic and Tirana Marginal Basins. The development of the Periadriatic Foredeep finally led to the different evolution of both the Periadriatic and Tirana depressions with different structures and mineral resources. The Periadriatic Depression structure is built by an NNW trending narrow anticline and wide syncline lines. From southwest to the northeast, these lines are distinguished: Frakulla-Durresi anticlinal line, Myzeqe syncline, Lushnja-Golem Kavaja anticlinal line, Erzeni i poshtem syncline, and Preza monocline. The Myzeqe and Erzeni i poshtem depocenters are separated by the intrabasinal Mliku-Shkoza high. The Divjaka gas field and Patosi, Marinza, and Kuçova oil fields are well known in the Periadriatic Depression. The Tirana Depression is developed from the Tirana marginal basin eastward bordering the Periadriatic Foredeep. It is characterized by the prevailing continental and shallow-marine Miocene sediments (with coal-bearing fields in Tortonian and Messinian deposits) that formed a wide northeast verging asymmetrical syncline due to the Preza-Rova-Bishqemi backthrust. The Tirana Depression overlies the Kruja Zone substratum to the north of Tirana, and partly, the Ionian Zone substratum to the south of Tirana along its western limb to the east of the Rova anticline backthrust. Deformation of orogenic crust at the Albanides-Adria collision zone during Tertiary occurred and occurs into both levels: i) a basal fold-and-thrust system in the Ionian Zone, that accommodated an increasing amount of SW directed shortening, and ii) a structurally higher system of thrust faulting affecting the overlying structure of the Periadriatic Depression, that underwent a strong structural rearrangement.