Large freshwater-influx-induced salinity gradient and diagenetic changes in the northern Indian Ocean dominate the stable oxygen isotopic variation in <i>Globigerinoides ruber</i>
<p>The application of stable oxygen isotopic ratio of surface-dwelling planktic foraminifera <i>Globigerinoides ruber</i> (white variety; <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"...
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Copernicus Publications
2023-01-01
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| Series: | Earth System Science Data |
| Online Access: | https://essd.copernicus.org/articles/15/171/2023/essd-15-171-2023.pdf |
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| author | R. Saraswat T. Suokhrie D. K. Naik D. P. Singh S. M. Saalim M. Salman M. Salman G. Kumar G. Kumar S. R. Bhadra M. Mohtadi S. R. Kurtarkar A. S. Maurya |
| author_facet | R. Saraswat T. Suokhrie D. K. Naik D. P. Singh S. M. Saalim M. Salman M. Salman G. Kumar G. Kumar S. R. Bhadra M. Mohtadi S. R. Kurtarkar A. S. Maurya |
| author_sort | R. Saraswat |
| collection | DOAJ |
| description | <p>The application of stable oxygen isotopic ratio of surface-dwelling planktic foraminifera <i>Globigerinoides ruber</i> (white variety; <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span>) to reconstruct past hydrological changes requires a precise understanding of the effect of ambient parameters on <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span>. 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 <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span>. 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 <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span> in the northern Indian Ocean. The analysed surface <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span> mimics the expected <span class="inline-formula"><i>δ</i><sup>18</sup></span>O calcite estimated from the modern seawater parameters (temperature, salinity, and seawater <span class="inline-formula"><i>δ</i><sup>18</sup></span>O) very well. We report a large diagenetic overprinting of <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span> 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 <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span> (<span class="inline-formula"><i>R</i><sup>2</sup>=0.63</span>) in the northern Indian Ocean, with an increase of 0.29 ‰ per unit increase in salinity. The
relationship between temperature- and salinity-corrected <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span> (<span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub>−<i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>sw</sub></span>) in the northern Indian Ocean [<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M23" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi>T</mi><mo>=</mo><mo>-</mo><mn mathvariant="normal">0.59</mn><mo>⋅</mo><mo>(</mo><mrow class="chem"><msup><mi mathvariant="italic">δ</mi><mn mathvariant="normal">18</mn></msup><msub><mi mathvariant="normal">O</mi><mi mathvariant="normal">ruber</mi></msub></mrow><mo>-</mo><mrow class="chem"><msup><mi mathvariant="italic">δ</mi><mn mathvariant="normal">18</mn></msup><msub><mi mathvariant="normal">O</mi><mi mathvariant="normal">sw</mi></msub></mrow><mo>)</mo><mo>+</mo><mn mathvariant="normal">26.40</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="193pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="e21ea60806b189cab07d4e3e5f56813b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="essd-15-171-2023-ie00001.svg" width="193pt" height="16pt" src="essd-15-171-2023-ie00001.png"/></svg:svg></span></span>] is different than reported previously, based on the global compilation of plankton tow <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span> 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 (<a href="https://doi.org/10.1594/PANGAEA.945401">https://doi.org/10.1594/PANGAEA.945401</a>; Saraswat et al., 2022).</p> |
| first_indexed | 2024-04-10T23:59:31Z |
| format | Article |
| id | doaj.art-fa1cd4d817be4d0e83a530ace01aeaba |
| institution | Directory Open Access Journal |
| issn | 1866-3508 1866-3516 |
| language | English |
| last_indexed | 2024-04-10T23:59:31Z |
| publishDate | 2023-01-01 |
| publisher | Copernicus Publications |
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| series | Earth System Science Data |
| spelling | doaj.art-fa1cd4d817be4d0e83a530ace01aeaba2023-01-10T07:58:13ZengCopernicus PublicationsEarth System Science Data1866-35081866-35162023-01-011517118710.5194/essd-15-171-2023Large freshwater-influx-induced salinity gradient and diagenetic changes in the northern Indian Ocean dominate the stable oxygen isotopic variation in <i>Globigerinoides ruber</i>R. Saraswat0T. Suokhrie1D. K. Naik2D. P. Singh3S. M. Saalim4M. Salman5M. Salman6G. Kumar7G. Kumar8S. R. Bhadra9M. Mohtadi10S. R. Kurtarkar11A. S. Maurya12Micropaleontology Laboratory, Geological Oceanography Division, National Institute of Oceanography, Goa, IndiaMicropaleontology Laboratory, Geological Oceanography Division, National Institute of Oceanography, Goa, IndiaDepartment of Geology, Banaras Hindu University, Varanasi, Uttar Pradesh, IndiaDepartment of Earth Sciences, Indian Institute of Technology–Roorkee (IIT–Roorkee), Roorkee, Uttarakhand, IndiaAntarctic Science Division, National Center for Polar and Ocean Research, Goa, IndiaMicropaleontology Laboratory, Geological Oceanography Division, National Institute of Oceanography, Goa, IndiaSchool of Earth, Ocean and Atmospheric Sciences, Goa University, Goa, IndiaMicropaleontology Laboratory, Geological Oceanography Division, National Institute of Oceanography, Goa, IndiaSchool of Earth, Ocean and Atmospheric Sciences, Goa University, Goa, IndiaMicropaleontology Laboratory, Geological Oceanography Division, National Institute of Oceanography, Goa, IndiaCenter for Marine Environmental Sciences (MARUM), University of Bremen, Bremen, GermanyMicropaleontology Laboratory, Geological Oceanography Division, National Institute of Oceanography, Goa, IndiaDepartment of Earth Sciences, Indian Institute of Technology–Roorkee (IIT–Roorkee), Roorkee, Uttarakhand, India<p>The application of stable oxygen isotopic ratio of surface-dwelling planktic foraminifera <i>Globigerinoides ruber</i> (white variety; <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span>) to reconstruct past hydrological changes requires a precise understanding of the effect of ambient parameters on <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span>. 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 <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span>. 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 <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span> in the northern Indian Ocean. The analysed surface <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span> mimics the expected <span class="inline-formula"><i>δ</i><sup>18</sup></span>O calcite estimated from the modern seawater parameters (temperature, salinity, and seawater <span class="inline-formula"><i>δ</i><sup>18</sup></span>O) very well. We report a large diagenetic overprinting of <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span> 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 <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span> (<span class="inline-formula"><i>R</i><sup>2</sup>=0.63</span>) in the northern Indian Ocean, with an increase of 0.29 ‰ per unit increase in salinity. The relationship between temperature- and salinity-corrected <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span> (<span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub>−<i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>sw</sub></span>) in the northern Indian Ocean [<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M23" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi>T</mi><mo>=</mo><mo>-</mo><mn mathvariant="normal">0.59</mn><mo>⋅</mo><mo>(</mo><mrow class="chem"><msup><mi mathvariant="italic">δ</mi><mn mathvariant="normal">18</mn></msup><msub><mi mathvariant="normal">O</mi><mi mathvariant="normal">ruber</mi></msub></mrow><mo>-</mo><mrow class="chem"><msup><mi mathvariant="italic">δ</mi><mn mathvariant="normal">18</mn></msup><msub><mi mathvariant="normal">O</mi><mi mathvariant="normal">sw</mi></msub></mrow><mo>)</mo><mo>+</mo><mn mathvariant="normal">26.40</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="193pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="e21ea60806b189cab07d4e3e5f56813b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="essd-15-171-2023-ie00001.svg" width="193pt" height="16pt" src="essd-15-171-2023-ie00001.png"/></svg:svg></span></span>] is different than reported previously, based on the global compilation of plankton tow <span class="inline-formula"><i>δ</i><sup>18</sup></span>O<span class="inline-formula"><sub>ruber</sub></span> 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 (<a href="https://doi.org/10.1594/PANGAEA.945401">https://doi.org/10.1594/PANGAEA.945401</a>; Saraswat et al., 2022).</p>https://essd.copernicus.org/articles/15/171/2023/essd-15-171-2023.pdf |
| spellingShingle | R. Saraswat T. Suokhrie D. K. Naik D. P. Singh S. M. Saalim M. Salman M. Salman G. Kumar G. Kumar S. R. Bhadra M. Mohtadi S. R. Kurtarkar A. S. Maurya Large freshwater-influx-induced salinity gradient and diagenetic changes in the northern Indian Ocean dominate the stable oxygen isotopic variation in <i>Globigerinoides ruber</i> Earth System Science Data |
| title | Large freshwater-influx-induced salinity gradient and diagenetic changes in the northern Indian Ocean dominate the stable oxygen isotopic variation in <i>Globigerinoides ruber</i> |
| title_full | Large freshwater-influx-induced salinity gradient and diagenetic changes in the northern Indian Ocean dominate the stable oxygen isotopic variation in <i>Globigerinoides ruber</i> |
| title_fullStr | Large freshwater-influx-induced salinity gradient and diagenetic changes in the northern Indian Ocean dominate the stable oxygen isotopic variation in <i>Globigerinoides ruber</i> |
| title_full_unstemmed | Large freshwater-influx-induced salinity gradient and diagenetic changes in the northern Indian Ocean dominate the stable oxygen isotopic variation in <i>Globigerinoides ruber</i> |
| title_short | Large freshwater-influx-induced salinity gradient and diagenetic changes in the northern Indian Ocean dominate the stable oxygen isotopic variation in <i>Globigerinoides ruber</i> |
| title_sort | large freshwater influx induced salinity gradient and diagenetic changes in the northern indian ocean dominate the stable oxygen isotopic variation in i globigerinoides ruber i |
| url | https://essd.copernicus.org/articles/15/171/2023/essd-15-171-2023.pdf |
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