Current Science

Open Access Open Access  Restricted Access Subscription Access

Pliocene Indonesian Throughflow Change and Planktic Foraminiferal Diversity in the Eastern Subtropical Indian Ocean


Affiliations
1 Department of Earth and Planetary Sciences, University of Allahabad, Allahabad 211 002, India
2 Department of Earth Sciences, Indian Institute of Technology, Mumbai 400 076, India
 

The opening and closing of seaways due to plate tectonic movement strongly influenced the past oceanic circulation patterns which have their influence on the past climate and faunal record. The considerable restructuring of one such seaway, Indonesian seaway, took place during Pliocene (4–3 Ma). This would have changed the source of Indonesian Throughflow (ITF)from warm and saline south Pacific waters to thenorth Pacific cool and relatively fresh waters. In the present study, three indices of diversity (Shannon-Wiener Index; H(S), equitability; E' and alpha index;α) at ODP sites 762B and 763A in the eastern subtropicalIndian Ocean are calculated to better understand the role of ITF on Pliocene surface hydrography and planktic foraminiferal diversity. A major interval of early Pliocene demonstrates more diverse fauna and low abundance of fertile taxa along with increased planktic Mg/Ca ratios. Strong influence of warm ITF waters due to broad and open seaway until the end of early Pliocene, increased the sea surface temperature(SST) and depth of thermocline in the Leeuwin current area of eastern subtropical Indian Ocean. This would have been responsible for more vertical niche partitioning of surface water and thus, higher planktic foraminiferal diversity. The significant decline in faunal diversity between critical interval of ~3.5 and 3 Ma (beginning of Late Pliocene) is suggested to be the response of fall in SST and increase in surface water productivity possibly due to relatively less influence of ITF waters in the eastern Indian Ocean as a consequence of significant constriction of Indonesian Seaway.

Keywords

Diversity, Indian Ocean, Indonesian Throughflow, Pliocene, Planktic Foraminifera.
User
Notifications
Font Size

  • Kennett, J. P., Keller, G. and Srinivasan, M. S., Miocene planktonic foraminiferal biogeography and paleoceanography development of the Indo-Pacific region. In The Miocene Ocean (ed. Kennett, J. P.), Mem. Geol. Soc. Am., 1985, vol. 163, pp. 197–236.

  • Ravelo, A. C., Andreasen, D. H., Lyle, M., Lyle, A. O. and Wara, M. W., Regional climate shifts caused by gradual global cooling in the Pliocene epoch. Nature, 2004, 429, 263–267; doi:10.1038/nature02567.

  • Mudelsee, M. and Raymo, M. E., Slow dynamics of the northern hemisphere glaciations. Paleoceanography, 2005, 20, PA4022; doi:10.1029/2005PA001153.

  • Cane, M. and Molnar, P., Closing of the Indonesian seaway as a precursor to east African aridification around 3–4 million years ago. Nature, 2001, 411, 157–162; doi:10.1038/35075500.

  • Karas, C., Nürnberg, D., Tiedemann, R. and Garbe‐Schonberg, D., Pliocene Indonesian Throughflow and Leeuwin current dynamics: implications for Indian Ocean polar heat flux. Palaeoceanography, 2011, 26, PA2217; doi:10.1029/2010PA001949.

  • Feng, M., Meyers, G., Pearce, A. and Wijffels, S., Annual and interannual variations of the Leeuwin Current at 32۰S. J. Geophys. Res., 2003, 108(C11), 3355; doi:10.1029/2002JC001763.

  • Smith, R. L., Huyer, A., Godfrey, J. S. and Church J. A., The Leeuwin current off western Australia 1986–87. J. Phys. Oceanogr., 1991, 21, 323–345; doi:10.1175/1520-0485(1991)021<0323:TLCOWA>2.0.CO;2.

  • Morrow, R., Fang, F., Fieux, M. and Molcard, R., Anatomy of three warmcore Leeuwin current eddies. Deep Sea Res., Part II, 2003, 50, 2229–2243; doi:10.1016/S0967-0645(03)00054-7.

  • Rai A. K. and Singh, V. B., Late Neogene deep-sea benthic foraminifera at ODP site 762B, eastern Indian Ocean: diversity trends and paleoceanography. Palaeogeogr. Palaeoclimatol. Palaeoecol., 2001, 173(1–2), 1–8; http://dx.doi.org/10.1016/S0031-0182(01) 00299-1.

  • Buzas, M. A. and Gibson, T. G., Species diversity: benthic foraminifera in the western North Atlantic. Science, 1969, 163, 72–75.

  • Fisher, R. A., Corbet, A. S. and Williams, C. B., The relationship between the number of species and number of individuals in a random samples of an animal population. J. Anim. Ecol., 1943, 12, 42–58.

  • Murray, J. W., Ecology and Palaeoecology of Benthic Foraminifera, Longman Group, 1991, p. 397.

  • Williams, C. B., Patterns in the Balance of Nature, Academia, New York, 1964, p. 324.

  • Be, A. W. H. and Tolderlund, D. S., Distribution and ecology of living planktonic foraminifera in surface waters of the Atlantic and Indian Oceans. In The Micropaleontology of Oceans (eds Funnell, B. M. and Riedel, W. R.), Cambridge University Press, Cambridge, UK, 1971, pp. 105–149.

  • Vergnaud Grazzini, C., Vénec-Peyré, M. T., Caulet, J. P. and Lerasle, N., Fertility tracers and monsoon forcing at an equatorial site of the Somali basin (Northwest Indian ocean). Mar. Micropaleontol., 1995, 26, 137–152; doi:10.1016/0377-8398(95)00070-4.

  • Singh, A. D., Jung, S. J. A., Darling, K., Ganeshram, R., Ivanochko, T. and Kroon, D., Productivity collapses in the Arabian Sea during glacial cold phases. Palaeoceanography, 2011, 26, PA3210; doi:10.1029/2009PA001923.

  • Rai, A. K. and Singh, V. B., Response of eastern Indian Ocean (ODP Site 762B) benthic foraminiferal assemblages to the closure of the Indonesian seaway. Oceanologia, 2012, 54(3), 449–472.

  • Sinha, D. K., and Singh, A. K., Late Neogene planktic foraminiferal biochronology of the ODP Site 763A, Exmouth Plateau, southeast Indian Ocean. J. Foraminiferal Res., 2008, 38, 251–270; doi:10.2113/gsjfr.38.3.251.

  • Ottens, J. J., Planktonic foraminiferal diversity as indicator of ocean environments. Mar. Micropaleontol., 1992, 19, 13–28.

  • Stehli, F., Paleontological technique for defining ancient ocean currents. Science, 1965, 148, 943–946.

  • Balsam, W. and Flessa, K., Patterns of planktonic foraminiferal abundance in surface sediments of the western North Atlantic. Mar. Micropaleontol., 1978, 3, 279–294.

  • Rutherford, S., D’Hondt, S. and Prell, W., Environmental controls on the geographic distribution of zooplankton diversity. Nature, 1999, 400, 749–753.

  • Schmidt, D. N., Renaud, S., Bollmann, J., Schiebel, R. and Thierstein, H. R., Size distribution of Holocene planktic foraminifer assemblages: biogeography, ecology and adaptation. Mar. Micropaleontol., 2004, 50, 319–338.

  • Loubere, P., Population diversity of planktonic foraminifers and stable isotope record across the Eocene/Oligocene boundary: hole 549A. Proc. DSDP, 1985, 80, 557–566; doi:10.2973/dsdp.proc.80.115.1985.

  • Srinivasan, M. S. and Sinha, D. K., Early Pliocene closing of the Indonesian Seaway: evidence from northeast Indian Ocean and southwest Pacific deep sea cores. J. Southeast Asian Earth Sci., 1998, 16, 29–44.

  • Gourlan, A. T., Meynadier, L. and Allegre, C. J., Tectonically driven changes in the Indian Ocean circulation over the last 25 Ma: neodymium isotope evidence. Earth Planet. Sci. Lett., 2008, 26(1–2), 353–364; http://dx.doi.org/10.1016/j.epsl.2007.11.054.

  • Fedorov, A. and Philander, G., Is El Nino changing? Science, 2000, 288(5473), 997–1002; http://dx.doi.org/10.1126/science.288.5473.1997.

  • Sinha, D. K. and Singh, A. K., Surface circulation in the eastern Indian Ocean during last 5 million years: Planktic foraminiferal evidences. Indian J. Mar. Sci., 2007, 35(3), 342–350.

  • Gaina, C. and Müller, D., Cenozoic tectonic and depth/age evolution of the Indonesian gateway and associated back-arc basins. Earth Sci. Rev., 2007, 83, 177–203; doi:10.1016/j.earscirev.2007.04.004.

  • Karas, C., Nürnberg, D., Gupta, A. K., Tiedemann, R., Mohan, K. and Bickert, T., Mid-Pliocene climate change amplified by a switch in Indonesian subsurface throughflow. Nat. Geosci., 2009, 2, 434–438; doi:10.1038/ngeo520.


Abstract Views: 364

PDF Views: 129




  • Pliocene Indonesian Throughflow Change and Planktic Foraminiferal Diversity in the Eastern Subtropical Indian Ocean

Abstract Views: 364  |  PDF Views: 129

Authors

Ajai Kumar Rai
Department of Earth and Planetary Sciences, University of Allahabad, Allahabad 211 002, India
Vishwesh K. Pathak
Department of Earth and Planetary Sciences, University of Allahabad, Allahabad 211 002, India
Lakshmi K. Sharma
Department of Earth Sciences, Indian Institute of Technology, Mumbai 400 076, India
Ajhar Hussain
Department of Earth and Planetary Sciences, University of Allahabad, Allahabad 211 002, India

Abstract


The opening and closing of seaways due to plate tectonic movement strongly influenced the past oceanic circulation patterns which have their influence on the past climate and faunal record. The considerable restructuring of one such seaway, Indonesian seaway, took place during Pliocene (4–3 Ma). This would have changed the source of Indonesian Throughflow (ITF)from warm and saline south Pacific waters to thenorth Pacific cool and relatively fresh waters. In the present study, three indices of diversity (Shannon-Wiener Index; H(S), equitability; E' and alpha index;α) at ODP sites 762B and 763A in the eastern subtropicalIndian Ocean are calculated to better understand the role of ITF on Pliocene surface hydrography and planktic foraminiferal diversity. A major interval of early Pliocene demonstrates more diverse fauna and low abundance of fertile taxa along with increased planktic Mg/Ca ratios. Strong influence of warm ITF waters due to broad and open seaway until the end of early Pliocene, increased the sea surface temperature(SST) and depth of thermocline in the Leeuwin current area of eastern subtropical Indian Ocean. This would have been responsible for more vertical niche partitioning of surface water and thus, higher planktic foraminiferal diversity. The significant decline in faunal diversity between critical interval of ~3.5 and 3 Ma (beginning of Late Pliocene) is suggested to be the response of fall in SST and increase in surface water productivity possibly due to relatively less influence of ITF waters in the eastern Indian Ocean as a consequence of significant constriction of Indonesian Seaway.

Keywords


Diversity, Indian Ocean, Indonesian Throughflow, Pliocene, Planktic Foraminifera.

References





DOI: https://doi.org/10.18520/cs%2Fv113%2Fi05%2F955-959