Relations between Tectonic Zones of the Albanides on the Basis of Results of Geophysical Studies

Abstract

The Ablanides are located between the Dinarides of Yugoslavia and the Hellenides of Greece, which together form the southern branch of the Mediterranean Alpine Belt. Our analysis of the Albanides and their extension into the Adriatic Sea integrates surface geological observations, well data, and results of seismological, reflection-seismic, gravity, magnetic, and geoelectric surveys. Evolution of the Albandies began with the Triassic subsidence of their Hercynian substratum under a tensional regime, culminating in crustal separation and opening of the Hellenic-Dinaride oceanic basin. The internal Albanides (IA) formed part of the oceanic Hellenic-Dinaride Basin, whereas the external Albanides (EA) developed out of the westward adjacent passive margin and continental shelf of the Adriatic plate. This was accompanied by the development of a synorogenic foredeep basin. During the tectonic, tarditectonic, and neotectonic phases, progressive westward shift of the foredeep basin axis to its present location in the Adriatic. The EA evolved out of a shelf and continental margin sedimentary prism and a superimposed foredeep wedge, which together form the Alpine-deformed hydrocarbon-bearing Albanian Sedimentary Basin. Reflection-seismic and gravity surveys done in the EA and the Adriatic Sea define distinct structural belts related to different tectonic zones of the Albanian Sedimentary Basin. The most importantmore » oil and gas accumulations are found in the Jonian zone and in the Periadriatic depression. The carbonate-dominated Late Triassic to Late Cretaceous series of the lonian, Kruja, and Krasta-Cukali zones contains several rich source rock intervals. In the lonian zone, Late Cretaceous, Paleocene, and Eocene carbonates and oligocene-Miocene flysch-type sandstones form the reservoirs of the main oil and gas accumulations. The Tortonian-Pliocene Molasse-type clastics of the Periadriatic depression also contain source rocks and stratigraphically trapped gas accumulations.« less