氧同位素第6期北印度洋的一次重大古海洋学事件  

A Significant Paleoceanographic Event Taking Place in Northeastern Indian Ocean during Oxygen Isotope Stage 6

作　　者：方念乔[1] 丁旋[1] 胡超涌[1] 宋成兵[1] 张振芳[2] 

机构地区：[1]中国地质大学海洋地学研究中心,北京100083 [2]中国地质调查局发展研究中心,北京100037

出　　处：《地球科学（中国地质大学学报）》2004年第2期127-134,共8页Earth Science-Journal of China University of Geosciences

基　　金：国家重点基础研究发展规划项目 (G19980 40 80 0 ) ;国家自然科学基金自由申请项目 (No .40 2 72 0 74)

摘　　要：北印度洋赤道海岭的远洋沉积记录在氧同位素第 6期的早期 ,即 16 7～ 16 0ka期间 ,揭示出一次重大的古海洋学事件 .在多项代用指标中 ,浮游有孔虫组合和通量的变化对该事件的反映最为强烈 ,因此将其命名为“第 6期海洋生态环境严重恶化事件” .该事件以广适性种Globigerinitaglutinata的高度发育、凉水种Neogloboquadrinapachyderma和Globigerinabulloides的异常增多、其他有孔虫常见种的普遍减少及有孔虫总量的大幅度降低为特征 .结合其他代用指标和邻区资料 ,认为导致事件发生的主控因素在于超强的南亚冬季风及其所引发的表层水温降低和贫瘠的深层水团上涌 .一般情况下 ,南亚冬季风对研究区环境的影响力远较夏季风弱 ,它的阶段性超常强化似乎总与青藏高原的强烈隆升有关 .可推测 ,发生在第 6期的生境恶化事件很可能是最近一次高原大规模构造抬升的产物 .The pelagic sedimentary records conserved on the equatorial Ninetyeast Ridge have mirrored a significant event dating from the early oxygen isotope stage 6 (167-160 ka). We call it the ”great event of worsened ecologic environment” because the strongest indications of the event among all proxies are from an exceptional change of assemblage and flux of planktonic foraminifera. The event is characterized by a high development of the eurytropic species Globigerinita glutinata, an unusual promotion of the cool-water species Neogloboquadrina pachyderma and Globigerina bulloides, an evident reduction of the major common species and a large downfall of the foraminifera sedimentary quantity. Referring to the other indications and the materials from the neighboring areas, we believe that the essential factor resulting in the event is (”ultraintense”) south Asian winter monsoon that leads to the lower temperature of superficial water and upwelling of infertile deeper water. In general, the winter monsoon is much weaker than summer monsoon for affecting the environment of the study area in the system of the south Asian monsoon. Its periodic extraordinary intensification seems to relate constantly with the violent uplift of the Tibetan plateau. We guess that the ”great event of worsened ecologic environment” revealed in this paper is very probably the result of the last extensive tectonic elevation of the plateau.

关 键 词：氧同位素第6期 古海洋学事件 生态环境恶化 南亚冬季风 青藏高原隆升 

分 类 号：P736[天文地球—海洋地质]