东北印度洋沉积岩芯热释光与古气候变化

Thermoluminescence and Paleoclimate Changement Using Sedimentary Cores in Northeast Indian Ocean

孟加拉深海扇中扇的MD77181和下扇的MD81345岩芯沉积物天然热释光变化与古气候变化有明显的对应关系,岩芯记录的时间跨度约300 ka BP。将两支岩芯的热释光测量结果与δ18O、CaCO3含量和磁化率结果对比后发现,热释光强度与磁化率变化存在显著的一致性。它们与间冰期和冰期气候变化的对应关系表现为:间冰期,风化作用减弱,输入海洋的陆源性矿物减少,对碳酸盐的稀释作用低于冰期,热释光和磁化率同时降低。此时,热释光强度随碳酸盐含量的增加而增大,说明沉积物热释光主要来自于碳酸盐矿物的贡献,表现为海进沉积环境特征。在冰期,陆地风化作用加强,输入海洋的陆源性矿物增加,对碳酸盐的稀释作用增强,热释光强度随陆源物的增多而增强,热释光和磁化率同时增大。说明沉积物热释光主要来自陆源矿物,表现为海退沉积环境特征。

Natural thermoluminescence （NTL） has been carried out on sediment cores MD77181 and MD81345 from the Bengal fan of the Indian Ocean. The cores span the past 300 ka. The variation of TL and palaeomagnetic with core depth, i. e. with time, shows features which can reasonably be associated with climatic change. The nature of the obtained variation are discussed in relation to palaeoclimatic fluctuations impact on minerals of the sediment deposition of theglacial and other solar-terrestrial agents. The intensity of TL is closely correlated to the content of calcite in interglacial climatic cycles and results of TL and palaeomagnetic turn down at the same time. In glacial climatic cycles, due to dilution by the sediments, the content of calcite cut down, the intensity of TL is closely correlated to the sediments and results of TL and palaeomagnetic go up at the same time.