- Dona Paula, Goa, India.
- +91-0832- 2450327
- iiosc2020[at]nio[dot]org
Abstract Submission No. | ABS-2022-10-0211 |
Title of Abstract | Large salinity gradient and diagenetic changes obscure the limited temperature signal in Globigerinoides ruber d18O in the northern Indian Ocean |
Authors | Rajeev Saraswat*, T. Suokhrie, D.K. Naik, D.P. Singh, S.M. Saalim, M. Salman, G. Singh, S.R. Bhadra, S.R. Kurtarkar |
Organisation | CSIR-National Institute of Oceanography, Goa |
Address | Micropaleontology Laboratory, CSIR-National Institute of Oceanography Dona Paula, Goa, India Pincode: 403004 Mobile: 9421249860 E-mail: rsaraswat@nio.org |
Country | India |
Presentation | Oral |
Abstract | The application of stable oxygen isotopic ratio of surface dwelling Globigerinoides ruber (white variety) (δ18Oruber) to reconstruct past hydrological changes requires precise understanding of the effect of ambient parameters on δ18Oruber. The northern Indian Ocean, with huge freshwater influx, provides a unique setting to understand the effect of both the salinity and temperature on δ18Oruber. Here, we assess the effect of seawater salinity and temperature on δ18Oruber in the northern Indian Ocean. The surface samples (181) for δ18Oruber analysis were collected all along the path of the seasonal coastal currents, covering the entire salinity end member region in the northern Indian Ocean. The data generated was augmented with previous core-top δ18Oruber records published from the northern Indian Ocean. A total of 329 data points (181 from this work and 148 from previous work) were used to understand the factors affecting δ18Oruber in the huge freshwater discharge influenced northern Indian Ocean. The analyzed surface δ18Oruber very well mimics the expected δ18O calcite estimated from the modern seawater parameters (temperature, salinity, and seawater δ18O). We report large diagenetic overprinting of δ18Oruber in the surface sediments with an increase of 0.19⿰ per kilometer increase in water depth. The salinity exerts the major control on δ18Oruber (R2 = 0.73) in the northern Indian Ocean. From the δ18Oruber-salinity relationship, we report 0.24⿰ change per salinity unit in the northern Indian Ocean. The relationship between temperature and (δ18Oruber - δ18Osw) in the northern Indian Ocean [T= -0.80*(δ18Oruber - δ18Osw) + 25.86] is different than reported previously based on the global compilation of plankton tow δ18Oruber data. The revised equations will help in better paleoclimatic reconstruction from the northern Indian Ocean. |