Depositional environment of the Laptev Sea (Arctic Siberia) during the Holocene

The holocene depositional setting of the Laptev Sea was studied using three marine sediment cores from water depths between 77 and 46 m. Based on sedi mentary parameters (TOC content, delta(13)C(org) Sedimentation rates) contr olled by radiocarbon age models the palaeoenvironment of a strongly coupled river-shelf system was reconstructed since similar to 11 ka SP. Caused by a transgressing sea after the last glaciation, all cores reveal progressive decreases in sedimentation rates. Using the sedimentary records of a core from the Khatanga-Anabar river channel in the western Laptev Sea, several p hases of change are recognized: (1) an early period lasted until similar to 10 ka BP characterized by an increased deposition of plant debris due to s helf erosion and fluvial runoff; (2) a transitional phase with consistently increasing marine conditions until 6 ka BP, which was marked at its beginn ing near 10 ka BP by the first occurrence of marine bivalves, high TOC cont ent and an increase in delta(13)C(org); (3) a time of extremely slow deposi tion of sediments, commencing at,6 ka BP and interpreted as Holocene sea-le vel highstand, which caused a southward retreat of the depositional centres within the now submerged river channels on the shelf; (4) a final phase wi th the establishment of modern conditions after similar to 2 ka BP.