Diatom assemblages and biogenic silica from IODP Site 383-U1539

From the complete downcore record of IODP Site 383-U1539, sampling was conducted at 1 m resolution. Quantitative diatom slides were prepared following the settling method of Warnock and Scherer (2015, doi:10.1016/j.csr.2015.04.012) using 15-25 μg of dry bulk sediment treated with 2 ml of 10 % hydrogen peroxide and two drops of saturated sodium hexametaphosphate. Sample solution was added to 2 L Elix water in B-KER2 chambers with prepared coverslips secured on a table above the height of the drainage valve. After settling and draining, coverslips were adhered to glass slides using Norland Optical Adhesive #61 (refractive index = 1.56). Slides were observed with a Leitz Dialux 20 light microscope, using a 100X oil immersion objective and 10X eyepieces for 1000X total magnification. A minimum of 400 valves were counted for each slide. Absolute diatom abundance and relative abundances of species are reported here.