Biogenic silica at IODP Site U1475 during the early Pliocene

This dataset provides the early Pliocene biogenic silica (BSi) concentrations from IODP Site U1475, drilled on the southwestern flank of the Agulhas Plateau in the southwestern Indian Ocean during IODP Expedition 361: South African Climate (30 January to 31 March 2016). BSi weight percent (wt. %) was measured for 74 samples using a modified Mortlock and Froelich (1989) method. Each sample, approximately 55 mg, was freeze-dried and processed to remove organic matter and carbonates with 30% hydrogen peroxide and 1-M hydrochloric acid. Following this preparation, the samples were treated with 10% sodium carbonate and heated at 80°C for 5 hours to break down the opal content. BSi concentration was then quantified using a molybdate-blue spectrophotometer, calibrated with standards ranging from 0 to 50 ppm.