【作者】 付淑清；

【导师】 朱照宇； 欧阳婷萍；

【作者基本信息】 中国科学院研究生院（广州地球化学研究所） ， 地球化学， 2007， 博士

【摘要】 对南海南部86GC沉积柱状样进行了较高分辨率的微体古生物分析、浮游有孔虫稳定碳氧同位素分析、元素地球化学分析、矿物学分析、粒度分析和AMS¹⁴C测年等，并获取了许多可信的数据。在对这些古环境、古气候指标综合分析的基础上，得出了一些有意义的认识。86GC沉积柱状样涵盖了过去约31 ka B．P．以来南海南部的沉积历史。在这段地质历史时期内，29 ka B．P．之前为MIS3期（未见底），18.5～29 ka B．P．为末次盛冰期（LGM）；11.5～18.5 ka B．P．为末次冰消期；11.5 ka B．P．以来为全新世。由于冰期-间冰期气候变化引起的海．陆变迁、通道启闭和上升流活动等，造成南海南部海区的沉积环境发生改变。其中在末次冰期期间，海洋生态环境较差；同时由于水域封闭，水体流通状况较差，海底的沉积环境基本上为还原状态。冰后期海洋生态环境趋好，生物产率提高；并且由于水体交换作用的加强，海区深层水的含氧量也增加。自MIS3晚期以来，南海的南部海区以及为其提供陆源碎屑沉积的南海南部的陆-岛地区，古气候和古环境都发生了明显变化。其中，MIS3的气候、环境条件较为适宜。LGM的气候条件最差，尤以在大约26～28 ka B．P．之间最差，而在传统所认为的LGM（18～24 ka B．P．）期间并非气候条件最差时期。不过，即使是末次冰期的极盛期，当时当地的气温仍然较高，热带气候可能在当地依然盛行，气候状况的变差只是相对于当地的间冰期阶段而已。末次冰消期和全新世期间的气候似乎非常不稳定，推测可能与厄尔尼诺影响有关系。再者，在86GC柱状样中记录的一些气候突变事件，可能与北半球高纬地区发现的8k事件、YD事件及H事件（H1～H3）分别有关。综合分析认为，南海南部热带区域晚第四纪的气候变化可能主要受低纬过程的控制，但同时也有高纬区的影响。更多还原

【Abstract】 This paper presents the records of planktonic foraminifera （PF） census, stable carbon and oxygen isotopes of PF G.ruber （white）, element geochemical analysis, mineralogical analysis, grain size and AMS¹⁴C dating from the deep-sea sediments of core 86GC in the southern South China Sea （SCS）. The 1.68m long profile covers the last ca. 31,400 years including the late part of Marine Oxygen Isotope Stage 3 （MIS 3, before 29 ka B.P.）, the Last Glacial Maximum （LGM, ca. 18.5-29 ka B.P.）, the Termination I （ca.11.5-18.5 ka B.P.） and the Holocene （since 11.5 ka B.P）.The paleoenvironment changes, the close or open of the straits and the occurrence of upwelling induced by the glacial-interglacial climate changes, together led to changes in the sedimentary environment. During the last glaciation, the ecologic environment of the southern SCS was bad. At the same, owing to the closed water condition, the depositional environment at the sea bottom was dominated by reduction condition. When it came to the postglacial period, ecologic environment of the southern SCS got better and the water mass changes were enhanced. As a result, the oxygen content in the deep water also increased.Since the late MIS3, the paleoclimate in the southern SCS and its detrital sediments source areas had suffered obvious changes. During the MIS3, the paleoclimate was generally favorable. The worst climatic condition occurred during the LGM, especially during its early part （ca.26 - 28 ka B.P.） which we defined as the maximum of the LGM in our studied area. While between 18 and 24 ka B.P, that is, the period of LGM defined by the early studies, the climate in our studied area was not as bad as that during the early LGM. Nevertheless, the tropical climate had probably still prevailed in the adjacent land and islands of the southern SCS even during the LGM, although there had been temperature fall more or less.The climate during the last glacial and the Holocene was changeable in all probability, which, we suppose, was potentially associated with frequent occurrence of ENSO. Furthermore, five distinct climate events are identified in our studied area, which may correlate with the well-known climate events in high latitude including the Heinrich events （H3-H1）, the Younger Dryas （YD） and the 8 200 event.Based on the tradeoff analysis, we deduce that the climate changes during the late quaternary in the tropic zones of the southern SCS were mainly controlled by the low -latitude processes, but born the imprints of the high-latitude processes at the same time.更多还原