Clay mineral records for the last two glaciations at the East Siberian continental margin

• Main Authors: Ye, Liming, Zhang, Weiyan, Wang, Rong, Yu, Xiaoguo, Jin, Lu
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2023
• Subjects: Arctic Ocean; clay mineral; East Siberian ice sheet; ice event; Chukchi; Ice Sheet
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.955002; https://doi.org/10.1594/PANGAEA.955002

Four gravity sediment cores used for clay mineral analysis were recovered from the East Siberian continental margin. Core M04 (172.199W,75.982N ), with a length of 560 cm, was recovered from the Chukchi Basin during the fifth Chinese National Arctic Research Expedition (CHINARE) in 2012; core C22 (154.581W, 77.164N ), with a length of 200 cm, from the Northwind Ridge during the sixth CHINARE in 2014; and cores E23 (179.715E, 77.060N ) and P13 (159.865W, 77.991N ), with lengths of 354 cm and 246 cm from the southern Mendeleev Ridge and Chukchi Plateau, respectively, during the seventh CHINARE in 2017. The fine-grained fractions (<63 μm) of each sample were retained for clay mineral analysis. Decalcification and organic material removal were performed at room temperature with 1 M HCl and 30% H2O2, respectively. Clay fractions (<2 μm) were determined using Stokes’ law (Liu et al., 2010 and references therein). Each sample was oriented by wet smearing onto two glass slides before being air-dried. One of the slides was used for qualitative identification of clay minerals, whereas the other was solvated with ethylene glycol in an under-pressurized desiccator for at least 36 h at 35 ℃. Clay minerals were then measured by a PANalytical diffractometer, scanning from 3°–35° 2θ with a step of 0.0167° 2θ, at the KLSG. Semi-quantitative estimates of peak areas for the main clay minerals were carried out on the ethylene-glycol solvated curve using MDI Jade 6.0 software, and the percentage of clay minerals was calculated using Biscaye’s (1965) weighting factors. The 17Å and 10Å peaks were used for quantification of smectite and illite, respectively. Kaolinite (3.58Å) and chlorite (3.54Å) peaks were identified to calculate their proportional percentage from the 7Å kaolinite + chlorite peak (Biscaye, 1965). Analytical precision was checked using 15 replicates with a standard deviation of <3%.