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

• Published in: Climate of the Past
• Main Authors: P. S. Minyuk, V. Y. Borkhodoev, V. Wennrich
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2014
• Subjects: Environmental pollution; TD172-193.5; Environmental protection; TD169-171.8; Environmental sciences; GE1-350; Antarctic; Antarc*; Chukotka; Siberia
• Online Access: https://doi.org/10.5194/cp-10-467-2014; https://doaj.org/article/1fc4e5966feb4e48acb3f60b91664ec0

Geochemical analyses were performed on sediments recovered by deep drilling at Lake El'gygytgyn in central Chukotka, northeastern Russia (67°30' N; 172°05' E). Major and rare element concentrations were determined using X-ray fluorescence spectroscopy (XRF) on the < 250 μm fraction from 617 samples dated to ca. 440 and 125 ka, which approximates marine isotope stages (MIS) 11 to 6. The inorganic geochemistry indicates significant variations in elemental composition between glaciations and interglaciations. Interglacial sediments are characterized by high contents of SiO 2 , Na 2 O, CaO, K 2 O, and Sr and are depleted in Al 2 O 3 , Fe 2 O 3 , TiO 2 , and MgO. An extreme SiO 2 enrichment during MIS 11.3 and 9.3 was caused by an enhanced flux of biogenic silica (BSi). The geochemical structure of MIS 11 shows similar characteristics as seen in MIS 11 records from Lake Baikal (southeastern Siberia) and Antarctic ice cores, thereby arguing for the influence of global forcings on these records. High sediment content of TiO 2 , Fe 2 O 3 , MgO, Al 2 O 3 , LOI, Ni, Cr, and Zr typifies glacial stages, with the most marked increases during MIS 7.4 and 6.6. Reducing conditions during glacial times are indicated by peaks in the Fe 2 O 3 content and coinciding low Fe 2 O 3 /MnO ratios. This conclusion also is supported by P 2 O 5 and MnO enrichment, indicating an increased abundance of authigenic, fine-grained vivianite. Elemental ratios (CIA, CIW, PIA, and Rb/Sr) indicate that glacial sediments are depleted in mobile elements, like Na, Ca, K and Sr. This depletion was caused by changes in the sedimentation regime and thus reflects environmental changes.