16 Ma以来南海北部海域古水温变化规律与机制

长期以来古海洋表层古水温研究的热点主要集中在第四纪,很少涉及到2.5 Ma之前。利用ODP 184航次1147和1148站位的获得的相关资料,并主要采用长链烯酮U37k)和底栖有孔虫氧同位素(δ18O)两种方法,计算海水氧同位素组成,然后,利用浮游有孔虫氧同位素法计算16 Ma以来的海水温度变化,探讨南海北部16 Ma以来的古海水温度变化机制。结果表明,南海北部水温总体趋势与全球气候发展相对应,在北半球冰盖形成时期,海水表层温度与代表高纬冰盖体积大小的底栖有孔虫δ18O几乎同步变化,反映出南海热带海区古气候变化的特殊性,为进一步研究低纬热带海区在全球古气候变化中的作用提供了新证据。

VARIATION OF ANCIENT WATER TEMPERATURE AND ITS MECHANISM IN THE NORTHERN SOUTH CHINA SEA SINCE 16 MA

The research of surface water temperature of paleo-oceans is usually focused on Quaternary, rarely earlier than 2.5Ma. Based on the data obtained from sites 1147 and 1148 of ODP 184 Cruise, using long-chain alkenones and oxygen isotopes of benthic foraminifera as proxies, we calculated the marine oxygen isotope composition and the seawater temperature changes since 16Ma in this paper. The planktonic foraminifera oxygen isotope method was adopted to explore the mechanism of ancient seawater temperature change. The results show that the trends of water temperature change in the northern South China Sea kept step with the global climate changes. During the formation of the northern hemispheric ice sheets, the sea surface temperatures are changed synchronously with the benthic foraminiferal δ18O, which indicate the size of the high-latitude ice sheet. It shows the special nature of ancient climate changes in such a tropical sea as the South China Sea and provides new evidence for the further study of the ancient global climate change in the low-latitude tropical sea.