Marine Terraces as Geomorphic Evidence of Different Tectonic Regimes in Southeastern Part of The Caspian Sea in the Late Quaternary

Abstract

The comparison of geomorphologic evidences of Gorgan and Neka Rivers near their estuary point into the Caspian Sea represents different channel down cutting and depositional sequence, so that Neka River shows a deeper down cutting near the estuary point, this research is seeking the reason of the difference. As a result, the marine terraces were used as the geomorphologic indexes to show Neka River down cutting and coastal uplift assessment. Totally there were 8 marine terraces identified by studying geological maps, satellite images and outcrop investigations. 8 bivalve fossil samples were selected for carbon dating of the terraces. Afterwards the exact position and elevation of terraces were measured and their topographic cross sections were drawn up to the coast line. The carbon dating results show that tectonic forces did not act similarly in the eastern and southern parts of the Caspian Sea and the major reason for Neka River down cutting was related to Alborz mountains uplift Based on the results, it can be understood that Alborz Mountains uplifted during some 500 years causing about 1.02 meters’ uplift in southern Caspian in comparison to the eastern part of it.