Composition and flux of Holocene sediments on the eastern Laptev Sea shelf, Arctic Siberia

A 467-cm-long core from the inner shelf of the eastern Laptev Sea provides a depositional history since 9400 cal yr. B.P. The history involves tempora l changes in the fluvial runoff as well as postglacial sea-level rise and s outhward retreat of the coastline. Although the core contains marine fossil s back to 8900 cal yr B.P., abundant pf ant debris in a sandy facies low in the core shows that a river influenced the study site until similar to 810 0 cal yr B.P. As sea level rose and the distance to the coast increased, th is riverine influence diminished gradually and the sediment type changed, b y 7400 cal yr B.P., from sandy silt to clayey silt, Although total sediment input decreased in a step-like fashion from 7600 to 4000 cal yr B.P., this interval had the highest average sedimentation rates and the greatest flux es in most sedimentary components, While this maximum probably resulted fro m middle Holocene climate warming, the low input of sand to the site after 7400 cal yr B.P. probably resulted from further southward retreat of the co astline and river mouth. Since about 4000 cat yr B.P., total sediment flux has remained rather constant in this part of the Laptev Sea shelf due to a gradual stabilization of the depositional regime after completion of the Ho locene sea-level rise. (C) 2001 University of Washington.