Stable oxygen isotopes in planktonic foraminifera from surface sediments in the California Current system

Sánchez, Alberto; Sánchez-Vargas, Lilia; Balart, Eduardo F.; Domínguez-Samalea, Yaima

doi:10.1016/j.marmicro.2022.102127

Cited by 2 publications

(1 citation statement)

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“…The δ 18 O of surface-dwelling planktic foraminifera Globigerinoides ruber (δ 18 O ruber ) is often used to reconstruct past surface seawater conditions (Pearson, 2012;Saraswat et al, 2012Saraswat et al, , 2013Mahesh and Banakar, 2014). Therefore, continuous efforts are made to understand the factors affecting δ 18 O ruber (Vergnaud-Grazzini, 1976;Mulitza et al, 1997Mulitza et al, , 1998Mulitza et al, , 2003Waelbroeck et al, 2005;Mohtadi et al, 2011;Horikawa et al, 2015;Hollstein et al, 2017;Sánchez et al, 2022). The depth habitat of G. ruber in the tropical Atlantic Ocean has been inferred from its stable oxygen isotopic ratio (Farmer et al, 2007).…”

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confidence: 99%

Large freshwater-influx-induced salinity gradient and diagenetic changes in the northern Indian Ocean dominate the stable oxygen isotopic variation in Globigerinoides ruber

Saraswat

Suokhrie

Naik

et al. 2023

Earth Syst. Sci. Data

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Abstract. The application of stable oxygen isotopic ratio of surface-dwelling planktic foraminifera Globigerinoides ruber (white variety; δ18Oruber) to reconstruct past hydrological changes requires a precise understanding of the effect of ambient parameters on δ18Oruber. The northern Indian Ocean, with its huge freshwater influx and being a part of the Indo-Pacific Warm Pool, provides a unique setting to understand the effect of both the freshwater-influx-induced salinity and temperature on δ18Oruber. Here, we use a total of 400 surface samples (252 from this work and 148 from previous studies), covering the entire salinity end-member region, to assess the effect of freshwater-influx-induced seawater salinity and temperature on δ18Oruber in the northern Indian Ocean. The analysed surface δ18Oruber mimics the expected δ18O calcite estimated from the modern seawater parameters (temperature, salinity, and seawater δ18O) very well. We report a large diagenetic overprinting of δ18Oruber in the surface sediments, with an increase of 0.18 ‰ per kilometre increase in water depth. The freshwater-influx-induced salinity exerts the major control on δ18Oruber (R2=0.63) in the northern Indian Ocean, with an increase of 0.29 ‰ per unit increase in salinity. The relationship between temperature- and salinity-corrected δ18Oruber (δ18Oruber−δ18Osw) in the northern Indian Ocean [T=-0.59⋅(δ18Oruber-δ18Osw)+26.40] is different than reported previously, based on the global compilation of plankton tow δ18Oruber data. The revised equations will help create a better palaeoclimatic reconstruction from the northern Indian Ocean by using the stable oxygen isotopic ratio. The entire data set (newly generated and previously published) used in this work is available both as a Supplement to this article and at PANGAEA (https://doi.org/10.1594/PANGAEA.945401; Saraswat et al., 2022).

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