Distribution and sources of rare earth elements in sediments of the Chukchi and East Siberian Seas

Abstract

Using inductively coupled plasma mass spectrometry (ICP-MS), the distribution of rare-earth elements (REE) at the surface and Holocene sediments of the Chukchi and East Siberian Seas was studied in two cores of up to 8.5 ka in age. The total REE concentration of the surface sediments of the Chukchi Sea varied from 62 mg kg−1 to 169 mg kg−1. The NASC-normalized REE patterns were relatively similar to each other and are characterized by a slight enrichment in the middle lanthanides. The total REE concentrations in surface sediments from the East Siberian Sea ranged from 123 mg kg−1 to 200 mg kg−1. The normalized patterns showed a strong predominance of light REE, in particular, La and Ce. The main concentrators of REE are the sand and silt fractions of the sediment. The East Siberian Sea is characterized by REE association with elements contained in heavy stable clastic minerals (Zr, Nb, Hf, Th, and Ti). REE in this region are derived from the erosion of the mainland coast and the New Siberian Islands ice complex, as well as from river discharge, primarily from the Lena River, the basin of which comprises ancient crystalline shield and magmatic rocks enriched in light REE. The sediments in the eastern and southern Chukchi Sea have low REE contents, indicating that the terrigenous flux supplying the Chukchi Sea is through the Bering Strait.