A dataset of the Plio-Pleistocene at IODP Site U1489: Benthic foraminifera stable carbon and oxygen isotopes, coarse fraction, and selected benthic foraminifera abundances

Site U1489 was drilled during the International Ocean Discovery Program (IODP) Expedition 363 and is located on the western slope of the southern Eauripik Rise (2.12°N, 141.03°E, 3421 m water depth). We collected 183 samples from the upper ∼84 m of Site U1489 with an average sampling interval of ~50 cm, and performed the analyses of sediment washing and sieving, benthic foraminifera stable carbon and oxygen isotopes, and the relative abundance of selected benthic foraminifera. The data of these analyses are discussed in “Possible linkage between the long-eccentricity marine carbon cycle and the deep-Pacific circulation: Western equatorial Pacific benthic foraminifera evidences of the last 4Ma” [1], which provide a series of Plio-Pleistocene records of the western equatorial Pacific serving for regional and global comparisons of changes in the deep Pacific water mass properties and circulation.


Data description
The dataset contains two datasheets, one named "benthic isotopes" and the other "benthic species". The first one contains the data on stable carbon and oxygen isotopic compositions of the benthic foraminifera. The second demonstrates the data on sediment weight, coarse fraction and the counts of the selected benthic foraminifera species/genus. More detailed information are given below. Datasheet 1. Benthic isotopes: Column A-E: basic information about the sample, including: Expedition (A), Site (B), Hole (C), Core (D), and Section (E).
Column FeI: information about the sample depth, column F and G give the sample depth range in the Section, and column H and I give the sample depth at Site U1489 in the depth scale of CSF (H) and CCSF (I).
Column J-AM: the data on d 13 C, d 18 O and size for selected benthic foraminifera species. In the columns of "size (mm) & note", the numbers denote the size of the measured specimens (unit: millimetre), and the note gives additional information: "frag." means some fragmental specimens were included, "C.m þ C.r" means a combination of C. mundulus and C. robertsonianus, "C.l þ C.r" means a combination of C. lobatulus and C. robertsonianus. Table   Subject Oceanography Specific subject area Paleoceanography, Marine Micropaleontology Type of data Raw data Table  How data were acquired The data were acquired firstly by a standard marine micropaleontologic process of sediment washing and sieving, then observing and specimen picking under a microscope, and finally some of the specimens were measured for stable carbon and oxygen isotopes by a mass-spectrometer Finnigan MAT253 with the aid of a Kiel-IV carbonate device. Data format Raw data Parameters for data collection Time: Pliocene to Pleistocene, about 4 million years ago (Ma) to present. Place: Western Equatorial Pacific. Indexes: benthic foraminifera proxies for investigating deep-water properties and circulation Description of data collection

Specifications
The raw data were collected from sediment sieving and washing, benthic foraminifera taxa identification and counting, and stable isotopic analyses on carbon and oxygen. All these processing and analyses were performed at State Key

Datasheet 2. Benthic species: Column A-E: basic information about the sample, including: Expedition (A), Site (B), Hole (C), Core (D), and Section (E).
Column FeI: information about the sample depth, column F and G give the sample depth range in the Section, and column H and I give the sample depth at Site U1489 in the depth scale of CSF (H) and CCSF (I).
Column J-L: data on dry bulk weight, dry coarse fraction weight (particles larger than 0.063 mm) and the coarse fraction (%), units for the weights are in gram.

Experimental design
We selected benthic foraminifera taxa of different geochemical characteristics and environmental preference to investigate paleoceanographic changes including Cibicidoides, Uvigerina and Favocassidulina favus. Cibicidoides and Uvigerina are widely used in paleoceanographic reconstructions particularly for the stable oxygen and carbon isotopes, and they have major differences in oxygen tolerance range and depth preference in sediment [2e4]. Favocassidulina favus is selected as it characterizes the southern-sourced deep Pacific waters over the Ontong-Java Plateau and in the South China Sea [5e7], and the past variations in its relative abundance were emblematic of changes in the contribution of Circum-polar Deep Waters [7e10].

Materials
The upper~84 m sediment succession from four holes drilled on Site U1489 by the IODP Expedition 363 [11] was sampled every~50 cm for foraminifera sieving and washing. The samples, which are 2cm-thick half-round, are taken from the working half of the IODP cores. The sediment cores are reposited in the IODP Gulf Coast Repository, Texas A&M University, College Station, USA. The acquired foraminifera samples and remnant sediment samples of this work are stocked at State Key Laboratory of Marine Geology, Tongji University, Shanghai, China.

Methods
1. Sediment Treatments. The sediment samples were dried in an oven at 55 C for over 24 hours, and then weighed for dry bulk weight. The dried samples were sieved and washed in a 63-mm sieve, and the coarser particles (>0.063 mm) were collected and dried in an oven at 55 C for over 24 hours, and weighted afterwards. The percent ratio between the coarser particle weight and dry bulk weight is used as the proxy of coarse fraction content (CF%). 2. Clean and intact benthic foraminifera shells of selected taxa were picked and counted under a microscope from the >0.150 mm size fraction. 3. About 2e5 specimens of Cibicidoides (0.5e0.7 mm size, mainly C. mundulus) and Uvigerina (0.7e0.9 mm size, mainly U. peregrina) were picked for stable carbon and oxygen isotope measurements. The specimens were gently cracked and the fragment materials (about 0.10 mg) were cleaned with deionized water and methanol (99.7%) in an ultrasonic bath, and then dried at 60 C.