Major and trace element concentrations in sediments of ODP Hole 184-1144A in the South China Sea (Appendix A)

We present here the major and trace element data of the sediments at ODP Site 1144 of the last 230 ka with time resolution about 1.5 kyr to investigate their relations to the climate changes. Estimated from TiO2 and CaO contents, over 70% in weight of the sediments are terrestrial materials, and CaCO3 abundance ranges between 7% and 19%. The variation patterns of some of the major elements, such as Al, Fe, K, Mg and Mn, and some of the trace elements, such as the alkali elements (such as Rb and Cs), the alkali earth elements (such as Ba) and most transition metals (such as Sc, V, Co, Cr, Zn), well match that of the oxygen isotopes of the planktonic foraminifer, after normalized with Ti, with higher values during interglacial periods and lower values during glacial periods. Whilst the Na abundance exhibits inverse variation patterns with lower values during interglacial periods and higher values during glacial periods. However, most refractory elements, such as Y, Zr, Nb, Hf, Ta, REEs, Th and U, do not show such patterns. These agree well with the behaviors of these elements during chemical weathering. Therefore, the changes of chemical weathering intensity in South China, the source area of these sediments may account for such variation patterns. During interglacials, wet and warm climate might occur at South China, which resulted in stronger chemical weathering, and dry climate might occur during glacials, which resulted in weaker chemical weathering. Such paleoclimate interpretation agrees with those from other paleoclimate proxies, such as pollen records, indicating that change of the East Asian monsoon, especially change of the winter monsoon is the key for such paleoclimate variation patterns.

本研究披露了过去230千年以来大洋钻探计划（Ocean Drilling Program, ODP）1144站位沉积物的常量与微量元素数据，其时间分辨率约为1.5千年，旨在探讨该类元素与气候变化之间的关联。基于TiO₂与CaO含量估算，该沉积物中重量占比超过70%的成分为陆源物质，而碳酸钙（CaCO₃）的丰度范围为7%至19%。经钛（Ti）归一化处理后，部分常量元素（如铝Al、铁Fe、钾K、镁Mg及锰Mn）与部分微量元素（如碱金属元素铷Rb、铯Cs，碱土金属元素钡Ba，以及多数过渡金属元素钪Sc、钒V、钴Co、铬Cr、锌Zn）的变化模式，与浮游有孔虫氧同位素的变化模式高度吻合：在间冰期数值偏高，冰期则偏低。而钠（Na）的丰度则呈现相反的变化模式：间冰期数值偏低，冰期偏高。然而，多数难熔元素（如钇Y、锆Zr、铌Nb、铪Hf、钽Ta、稀土元素（Rare Earth Elements, REEs）、钍Th及铀U）则未呈现此类变化模式。该现象与这些元素在化学风化过程中的地球化学行为高度一致。因此，作为该沉积物物源区的华南地区，其化学风化强度的变化或可解释上述元素的变化模式。间冰期时华南地区气候温暖湿润，化学风化作用更强；冰期时则气候干燥，化学风化作用较弱。此古气候解释与其他古气候代用指标（如花粉记录）所得结论一致，表明东亚季风（尤其是冬季风）的变化是驱动上述古气候变化模式的核心因素。