Major, Trace and Rare Earth Element Geochemistry of Suspended Particulate Material of East Siberian Rivers Draining to the Arctic Ocean

Abstract

The study presents data on the major, trace, and rare earth element (REE) composition of suspended particulate material (SPM) of the majors rivers draining to the Laptev Sea (the Lena, Yana, and Khatanga), as well as their major tributaries. The chemical data can be used to distinguish between material supplied by individual rivers and to fingerprint the sediment transport to the Laptev Sea and further to the Arctic Ocean. Due to the size of the drainage basin, the average chemical composition of Lena SPM is very similar to average shale, representing the weathering product of the upper continental crust. Small variations in the chemical composition along the course of the river can be related to material input through major tributaries. The SPM of these tributaries draining more restricted basins of specific lithologies exhibits significant differences from the Lena which is seen in the trace element composition and the REE pattern. The Yana SPM is characterized by the strongest variations in chemical composition, which are related to the heterogeneity of the Yana basin. In particular, the Yana SPM shows higher Zr concentrations and an enrichment in As and Cs. The latter is attributed to granitic intrusions forming the source of Au and Sn ore deposits in the Yana catchment. As a result of the dominance of basaltic rocks of the Siberian Trap in the Khatanga basin, the chemical composition of Khatanga SPM differs significantly from both the Lena and the Yana. The Khatanga SPM is strongly enriched with elements that are associated with basalts, i.e. Ca, Co, Cu, Fe, Mg, Ni, Ti, and V. The shale-normalized REE pattern shows a depletion in light REE and a positive Eu anomaly, which corresponds with the Siberian Trap. However, due to weathering, a heavy REE depletion relative to light REE is superimposed on this pattern. Factor analysis of the chemical data set identifies the major processes controlling the SPM composition and clearly differentiates the SPM of the three studied rivers.