Accumulation rates of biogenic components of ODP Hole 154-926B

The multi-proxies (BAR, bio-SiO2 MAR, and CaCO3 MAR) of productivity in Ocean Drilling Program (ODP) Leg 154 Site 926 Hole B (3°43'N, 42°54'W) during the late Miocene. Based on the biostratigraphic zones, we convert sediment depths to absolute ages on the Geologic Time Scale 2020 timescale (Gradstein et al., 2020; doi:10.1016/C2020-1-02369-3). We extract barite from marine sediments using the modified sequential leaching method (Eagle et al., 2003; doi:10.1029/2002PA000793; Paytan et al., 1993; doi:10.1038/366445a0) and examine the size and morphology of barite crystals by a scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX). We use the modified method after Mortlock et al. (1989, doi:10.1016/0198-0149(89)90092-7) and Lyle et al. (2019, doi:10.5194/cp-15-1715-2019) to extract biogenic opal from marine sediments. For the carbonate extraction, we digest sediments with 1.5 ml hydrofluoric acid and 0.5 ml concentrated nitric acid in a 50-ml Teflon tube at 180°C for 12 hours. After digestion, we evaporate all the acids on a 150°C electric heating plate. The sample reacts with 1 ml concentrated nitric acid and 1 ml Milli-Q water at 150°C for 12 hours. The supernatants are diluted to 40 g and are further prepared for Inductively Coupled Plasma Optical Emission Spectrometry analysis. We calculate mass accumulation rate (MAR) as a function of linear sedimentation rate (cm/ka) and dry bulk density (g/cm³). Sedimentation rates are obtained from the known reference points from the chronostratigraphic framework. The ODP reports obtain dry bulk density data (Curry et al., 1995; doi:10.2973/odp.proc.ir.154.109.1995). The accumulation rates of biogenic components (i.e., BAR, CaCO3 MAR, and bio-SiO2 MAR) are calculated as the product of MAR and the weight percent of biogenic components (wt%) in sediments. In the meantime, we analyze Baexcess to estimate export productivity (Pnew) following the algorithm equation after Dymond et al., 1992; doi:10.1029/92PA00181.