The Elburz chain is located in Northern Iran; it separates the damp and fertile Caspian region from the arid Central Iranian Plateau. The chain consists mainly of Paleozoïc and Mesozoïc rocks folded in a megaanticline, as part of the alpine belt. However, epeirogenic movements took place already during the Paleozoïc.
The studied area shows a complete stratigraphic column from the Cambrian to the Quaternary. There is a definite contrast between the stratigraphic patterns of the northern and southern parts of the chain. Infracambrian and Lower Paleozoïc are more developped in the south and pinch out towards the north. During Silurian and Devonian times an important change took place and thereafter occurred a very thick sequence of trappoid basalts followed by a middle devonian transgression from the north, with locally gypsum at its basis. During the early and probably also part of the Middle Devonian, the Central Iran epicontinental sea withdrew eastward. In the northern part of the studied area, one can follow a complete marine sequence ranging from Middle Devonian to Middle Triassic. Meanwhile the Elburz developped into a continental margin. In the southern part important gaps occur during the Middle and Upper Carboniferous and, after the Lower Permian transgression, during the Upper Permian.
After the Carnian epeirogenic movements very thick molassic deposits (up to 3 000 m) spread over the entire region. The material originated in the South Caspian region. The lower sequence contains boulders of oceanic types sediments, while the upper one consists mainly of quartzeous material dirived from a horst that mobilized precambrian rocks during another epeirogenic movement between Lias and Dogger.
A general sinking of the South Caspian region started during the Malm. In Northern Elburz a complete marine sequence was deposited during the Malm and the Cretaceous. In the southern part gaps in the Lower Cretaceous are found. Two transgressions occur. After some epeirogenic movements Orbitolina Limestone was deposited, followed by chalky senonian limestones. During the Upper part of the Lower Cretaceous basic dykes intruded, in relation with the formation of oceanic rifts which broke into several pieces the cratonic irano-afghan plate.
The Cenozoïc is marked by the Alpine orogenic movements accompagnied in the south by the deposits of flysch-like sediments during the Lower and Middle Eocene. South of the studied area a very thick volcano-sedimentary formation was deposited in the former location of the cretaceous rifts.
During the Miocene and the Pliocene red and yellow molassic sediments were deposited. Their thickness often reached several thousand meters. They are locally folded.
A series of quaternary terrasses, due to isostatic ? reajustment extends along the main valleys and in the pediments of the southern flank of the chain. [...]
