The total weight percent of sedimentary carbon (% C) and nitrogen (% N), as well as inorganic carbon (% Cinorg) and organic carbon (% Corg) were measured using a macro elemental analyzer LECO CNS2000 at CACTI (Universidade de Vigo, Spain). For the estimation of %Cinorg an aliquot of the homogenized and ground samples was heated at 450ºC for 3 hours to remove organic carbon. The % Corg content was calculated as the difference between % C and % Cinorg. The concentration opal was determined using the method of Mortlock and Froelich (1989). The Siopal/Corg(Si/C) were calculated after transformation of the biogenic silica (opal) and % Corg into molar ratios. The age model is calculated as indicated in doi:10.1594/PANGAEA.971417.