Reconstruction of the Paleoenvironmental Condition Using Geochemical Proxies in the Lower Baitarani Basin,Coastal Odisha,India

The subsurface sediment archives provide clues to the past climate of the Earth. To reconstruct the paleoclimate of Lower Baitarani Basin, a 1000 cm deep sediment core (JP) was collected from the flood plain located in Jhumpuri village of Jajpur, Odisha. A total number of eleven distinct layers were identified based on variations in the sediment colour and textural at varying depths. From each layer, a representative sample was collected and carried to the laboratory for further assessment. Each of these sub-samples was examined for particle size analysis, availability of total organic carbon (TOC), and elemental concentration. The physical and geochemical proxies as paleoproductivity, terrestrial flux, weathering, level of salinity, colour, and texture variations were utilised to examine the paleoclimate of the area. The colour variations of the subsurface sequences suggest that the deposition has occurred under both freshwater and stagnated/marshy conditions. The texture variations—clay, silty clay, and loamy fine sand—also indicate deviations in sediment supply and rate of sediment aggradation during climatic shift between warm-humid and cold-arid episodes.

With the help of geochemical proxies to illustrate the terrestrial flux: Fe₂O₃, Al₂O₃, TiO₂, MgO, CaO, Cu, Co, Ba, and Zn; paleoproductivity: TOC,CaO/Al₂O₃, Zn/Al₂O₃,Sr/Al₂O₃, Cu/Al₂O₃, and Ba/Al₂O₃; weathering: Fe₂O₃/Al₂O₃, TiO₂/Al₂O₃, and MgO/Al₂O₃; and the salinity index, a relatively cold-dry climate is inferred during the sedimentation of basal layers. Subsequently, a shift to the relatively warm-humid phase is suggested which again was followed by a cold-dry, and warm-humid phases. In the recent deposits, the proxies have not shown any considerable variation indicating prolongation of the existing warm-humid phase. However, some indications of a climatic shift to colder climate is also marked in the surface layer (JPL1).