Summary of Abstract Submission

Abstract Submission No. IO50-06-0004PresentationOral

CLIMATIC INFLUENCE ON THE TERRESTRIAL AND MARINE ORGANIC CARBON FLUXES IN THE MARINE REALM: A STUDY FROM THE MAHANADI BASIN OFFSHORE

Aninda Mazumdar*1, R. Da Silva1, R. K. Joshi2, M.A. Carvalho3, A. Shaji,4, P.Mahalakshmi5, B.G. Naik1

1 national institute of oceanography, India
2 Geological Survey of India, Kolkata-700 091, India, India
3 Directorate of Mines and Geology, Panaji, Goa-403001, India
4 Centre for Marine Living Resources & Ecology-682030, Indiaa-403002, India
5 Flat No. CS-1, Block-C, Astral Garden, Panaji, Go, India

ABSTRACT :

We report here high resolution vertical profiles of total inorganic carbon (TIC wt%), and 13CTOC values from a core MD161-19 acquired off Mahanadi basin, Bay of Bengal onboard R/V Marion Dufrense (May 2007). Based on the AMS 14C dates and 18O (G.ruber) values, the maximum depositional age of the core is estimated at ~300 ky covering 8 marine isotope stages. The age depth model for sediment core is obtained from the correlation of δ18O profile with the SPECMAP data. The TIC content ranges from ~0.2 wt% to ~5 wt%. Several well defined TIC peaks are recognized in the profile. The 13CTOC values range from -16.3 to -22.3 VPDB. The TOC content ranges from 0.19 to 2.9 wt%. The TOC/TN ratios range from 6.1 to 29.9. The 13CTOC values show significant vertical variations which may be linked to the nature of terrestrial organic flux (i.e., C3 vs C4) and marine organic matter (MOM) production. The 13CTOC values show remarkable correlation with temporal pCO2 change. Additional effects like rainfall/ aridity and temperature etc., possibly superimposed on the broad13CTOC variation at MIS scale. High rainfall/ freshwater flux during interglacials resulted in less marine productivity and relatively high C3 flux, whereas during glacial periods, low pCO2 and freshwater flux supported C4 vegetation and prompted enhanced marine productivity due to upwelling. The net 13C values are combined result of complex mixture of at least three different organic end members (C3-C4-MOM).