- Dona Paula, Goa, India.
- +91-0832- 2450327
- iiosc2020[at]nio[dot]org
| Abstract Submission No. | ABS-2022-02-0333 |
| Title of Abstract | Regional pteropod preservation records from the Indian Ocean: An overview |
| Authors | Sreevidya E*, M.B.L. Mascarenhas-Pereira2, B. N. Nath , J. Kurian, A. V. Sijinkumar |
| Organisation | Central University of Kerala |
| Address | Central University of Kerala, Tejaswini Hills KASARAGOD, Kerala, India Pincode: 671316 Mobile: 7306901059 E-mail: vidyaenair@gmail.com |
| Country | India |
| Presentation | Poster |
| Abstract | The temporal variations in the shell numbers and post-mortem shell conditions of pteropods within the marine sediments are an excellent proxy for paleoceanographic and paleoclimatic studies. These organisms contribute 10 to 12 % of the total CaCO3 produced in the ocean. Despite their small size, pteropods are astoundingly useful to geologists, paleoclimatologists and paleobiologists because of their sensitivity to ocean acidification and ability to record past oceanic conditions. In order to attain the longer record and to understand the preservation pattern of pteropods, we have analysed several cores collected from different parts of the Indian Ocean, i.e., IODP 359 Site U1467 (water depth of 487m) and U1468 (521m) (collectively date back to ~24 Ma), NGHP-17 (wd of 1325m) (~12.3 Ma) and SK343/GC01 (wd of 1340m) (~50 ka). The pteropod abundance study indicates that though these microorganisms have been known to occur from the Cretaceous, their fossil records only extend to late Quaternary sediments that date back to 1.5 Ma. The pteropods assemblage data combined with the results of carbonate dissolution signals (Limacina Dissolution Index, Fragmentation Ratio and average shell size of Heliconoides inflatus), suggests that the variability in carbonate chemistry, stratification of the water column, seasonality, ventilation and productivity are the main controlling factors for the pteropod preservation in the Indian Ocean. The pteropod preservation record agrees with the preservation records from the Pacific Ocean, where better preservation is seen during glacial periods and cold stadials due to the fall in ACD and biogenic productivity, well-ventilated water column, and highly oxygenated bottom waters. In the last glacial cycle, the highest abundance in pteropods was observed during the deglacial period (18-15 ka) and poor preservation during Holocene. However, it is interesting to report high abundances/preservation of pteropods during the Eemian interglacial, which is analogous to the Holocene. The offsets in the preservation spikes from different physiographic domains of the Indian Ocean is believed to be due to the lag in the oceanic circulation and local climatic variability. The results demonstrate that the ability to calcify and maintain the shells of late Pleistocene pteropods was severely affected by the surface water carbonate chemistry. |