Geomorphic response and 14C chronology of base-level changes induced by Late Quaternary Caspian Sea mobility (middle Kura Valley, Azerbaijan)

Abstract

Recent geomorphological studies in Azerbaijan reveal the importance of climato-eustatic influences on landscape changes in the Caspian Sea Basin during the last 40ka. Radiocarbon-dated fluvial landforms show that the paleohydrosystem of the middle Kura valley and tributaries responded to regressive and transgressive phases of the Caspian Sea. Chrono-sequences and landforms secured by 32 radiocarbon ages show strong correspondence between fluvial sediment accumulation and oscillations of base level in the Caspian Sea.Six phases of valley floor aggradation (e.g. 27,000–13,000; 11,000–3200; 2900–2100; 1600–1000; 400–150cal.yr BP) and seven phases of fluvial incision (>37,000; 37,000–27,000; 13,000–11,000; 3200–2900; 2100–1600; 1000–400; 150–0cal.yr BP) are recorded. Morphodynamics of the fluvial landscape show a strong correspondence with fluctuation in sea levels in the Caspian Sea: the major Upper Pleistocene–Late Glacial Khvalynian (c.a. 26,000 to 12,400cal.yr BP) and various Holocene transgressions as well as the Mangyshlak (c.a. 12,000cal.yr BP) and Derbent (6th–12th century AD) regressions. These data contribute to refining the Caspian relative sea-level curve for the last 30ka using the chronology of changes in the aggradation or incision in the connected fluvial system.