Inorganic data from El'gygytgyn Lake sediments: stages 6–11

Geochemical study was performed on sediment of deep drilling core from El'gygytgyn Lake, located in central Chukotka, northeastern Russia (67°30' N; 172°05' E). Major and rare elements were determined by X-ray fluorescence spectroscopy (XRF) on 600 samples covering the timeframe between ca. 450 and 125 ka corresponding to Marine Isotope Stages (MIS) 11 to 6. Inorganic geochemistry data indicates significant variations in the elemental compositions corresponding to the glacials and interglacials periods. Interglacial sediments are characterized by high contents of SiO2, Na2O, CaO, K2O, Sr and are depleted in Al2O3, Fe2O3, TiO2, MgO. Extreme enrichments in SiO2 during MIS 11.3 and 9.3 are caused by an enhanced flux of biogenic silica (BSi). Geochemical structure of stage 11 shows very similar peculiarities to features of stage 11 from records of Lake Baikal/SE Siberia and Antarctic ice cores. High contents of TiO2, Fe2O3, MgO, Al2O3, LOI, Ni, Cr and Zr are typical for sediments of glacial stages, among those MIS 7.4 and 6.6 are the most marked. Peaks in the Fe2O3 content and coinciding low Fe2O3/MnO ratios during glacials indicate reducing condition in the sediments. This is also supported by enrichments in P2O5 and MnO, indicating an increased abundance of authigenic fine grained vivianite. Some elemental ratios indicate an enhanced alteration of glacial sediments accompanied by a loss of mobile elements, like Na, Ca, K and Sr. The higher alteration of sediments can presumably be traced back to changes in the sedimentation regime and diagenetic processes, and thus, reflects environmental changes.