The importance of the Triassic-Jurassic unconformity to the hydrocarbon potential of Bulgaria

Bulgaria occupies 110 000 km2 of territory on the Balkan Peninsula, which includes numerous, varied tectonic units. The Balkanide Alpine belt, which is part of the Alpine-Himalayan orogenic chain, divides the territory into two parts - north and south, each with its own geological features (Figs land 2). In southern Bulgaria igneous and metamorphic rocks are widespread .. Four different orogenic units dominate (Fig. 2)-the so-called Srednogorie, Kraistide, Rhodope massifs and the Sakar-Strandja zone. Several quite smalI, shallow and discrete Palaeogene-Neogene basins are developed in these zones, but none has hydrocarbon potential.