Late Miocene to Early Pliocene Paleoceanographic evolution of the Central South Pacific: A deep-sea benthic foraminiferal perspective

Description

Data on the major benthic foraminiferal percentage abundance from Site U1541 were generated for this study covering Late Miocene to Early Pliocene epoch. Data regarding dominant benthic foraminiferal abundance (%, present in >7% in 7 or more sample), oxic species assemblage (%), suboxic species assemblage (%), sedimentation rate (cm kyr-1), Dry Bulk Density (g cm-3), Orbulina universa (>125µm), Ostracoda (>125µm), ice-rafted debris (IRD) & detrital (>125µm), and benthic foraminifera (>125µm) per gram of dry sediment, and benthic foraminiferal accumulation rate (BFAR, g cm-2 kyr-1), organic flux (Jsf, gC cm-2 kyr-1), paleoproductivity (PP, gC cm-2 kyr-1), total organic carbon (%), CaCO3 (%), coarse fraction (%, >63µm), and Coarse Fraction Accumulation Rate (CFAR, g cm-2 kyr-1) are presented.

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Samples were dried, and ~20 g of the dry sediment samples were soaked in water for 8-12 hours with 4-5 drops of H₂O₂ and wet sieved over a 63 μm sieve using a gentle shower of water following Das et al. (2018). The > 63 μm sieve samples were dried in a vacuum oven at 45°C before being transferred into glass vials with proper labeling. Adequate measures were taken to avoid any contamination. All the sieves were washed in an ultrasonicator for 15 minutes before use, and methylene blue was applied to the sieve net to identify potentially contaminating specimens if any. The washed samples were dry-sieved over a 125 μm sieve, and ~300 benthic foraminifera specimens were picked and counted from a suitable aliquot using a stereo zoom microscope. An Otto splitter was used to get the suitable aliquot. Counted Ice rafted debris (IRD), planktic foraminifera Orbulina spp., and Ostracoda carapace in >125 μm size fractions, and all abundance data are reported as per gram dry sediment. For total carbon (TC) and total organic carbon (TOC) analysis, we followed the method described in Das et al. (2021). Sediment samples weighing 60–65 mg were crushed and homogenized. Homogenized 30–35 mg of the dry sample was packed in tin foil for TC analysis using a TOC analyzer (Elementar Vario TOC Select) at the School of Earth, Ocean, and Climate Sciences, IIT Bhubaneswar. The remaining 30–35 mg of the homogenized sample was weighed in a silver boat, and a few drops of concentrated HCl were added to remove inorganic carbon. The acidified samples were dried in an oven at 105°C for 5–6 hours. The inorganic carbon-free dry sample was wrapped in tin foil along with the silver boat and analyzed TOC.

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