Located along the northeastern flank of the Greater Caucasus and
alongside the Central Caspian Sea, the Dagestan fold-thrust belt is
characterized by a combination of deep-seated, south-dipping thrust
faults, high-level detachment surfaces, and ‘‘tectonic wedging’’,
with thrust transferal occurring within the highly incompetent shales
and mudstones of the Oligocene-Miocene Maikop Formation. North of
the Dagestan fold-thrust belt, the Terek-Caspian foredeep is a southward-deepening,
asymmetric structural depression that began developing as a foreland
basin during the middle to late Miocene as a result of compressional
deformation, uplift and thrust-loading along the Greater Caucasus.
Both the Dagestan fold-thrust belt and the Terek-Caspian foredeep
have known commercial hydrocarbon accumulations, though hydrocarbon
charge and migration pathways differ between the two structural zones.
Within the Dagestan fold-belt, hanging wall anticline structural traps
are charged with hydrocarbons sourced from the Oligocene-Miocene Maikop
Formation, with migration occurring along pathways facilitated by
thrust faults and fracture systems. In contrast, hydrocarbon accumulations
located within the Terek-Caspian Foredeep are charged from Triassic-Jurassic
source rocks located within the Permo-Triassic graben-system of the
East Manych Trough; up-section migration into high-level reservoirs
is facilitated by the presence of fault and fracture systems which
have developed as a result of Tertiary reactivation of Mesozoic extensional
faults. Understanding the structural evolution and petroleum systems
of the Dagestan fold-belt and the Terek-Caspian Foredeep will be critical
to understanding the hydrocarbon potential of the Central Caspian
Sea, and may assist in exploration efforts within other actively deforming
thrust belts of the world.