Thermoluminescence And Paleoclimatic Change Of Sedimentary Cores In The Northeast Indian Ocean

The Northeastern Indian Ocean lies to the south of Himalayas. It is the main sedimentary areas of the denudation due to the uplift of Qinghai-Tibet Plateau and Himalayas.The Bay of Bengal and its adjacent water hosted a great deal of terrigenous sediments have denuded from the Tibetan plateau and transported by the GangeBrahampoutra fluvial system. The oceanic sediment in Northeastern Indian not only distributes widely but also is of high deposit rate. In addition, these sediments also contain reliable high-resolution paleoenvironmental information both with long-timescale and short-timescale. Therefore, this area is an ideal one for the research on the paleoceanography and paleoclimate.For the last decade Thermoluminescence (TL) has been used for a viable tool for age determination of a variety of rock types and sediments. The TL in oceanic sediments has been used for the first time to study paleoclimatic change successfully. Based on the elaborate research on the stable Oxygen isotope stratigraphy, carbonate stratigraphy, biostratigraphy, magnetic susceptibility, grain size and clay mineral of cores marked MD81349, MD77190, MD77181 and BAR9427 in the Northeastern Indian Ocean, this thesis focus on the application of the TL properties in the above cores to infer the paleoclimatic change, and discuss the response of TL of sedimentary records with climatic cycles during the last 300,000 years. The results improve our understanding of the utility of TL as an indicator of sedimentary environment and provide insight into what types of ocean sediments are amenable for study.The comparison of the 18O with the TL cycles indicates that the TL dose display the expected coupling relation with interglacial and glacial climate cycles. It is noteworthy that TL dose shows an increase associated with the interglacial cycles (Oxygen Isotopic Stage 1,3,5,7) and a decrease associated with the glacial cycles (Oxygen Isotopic Stage 2,4,6,8). The carbonate content is high during the interglacial interval and low during the glacial interval. However the TL dose of pure foraminiferan (Calcite) dose not have direct correlation with the carbonate, which leads to a result that the TL changes in the samples might be induced by the difference of crystallization. Temperature and pressure play key roles for the TL properties of a crystal, even the temperature difference between glacial and interglacial is very small. The TL capacity of crystal of calcite is closely related to the type and quantity of lattice defects existed in the crystal resulting from the physical-chemical conditions which existed at the time of crystallization. The TL study of samples in the Northeastern Indian Ocean show that there is one peak on the TL glow curve between 375 and 395 while terrestrial calcite show peaks between 177 and 456 .This study also reveal that no direct correlation between the TL does and U, Ra, Th, K activity, exist.The trace element analyses show negative correlation between Fe, Cu, Cr, Co, Ni, Eu ,clay and TL. and positive correlation between Cs and TL, but the research on concrete mechanism is needed.