Surface-water evolution of the eastern East China Sea during the last 36,000 years
Surface-water evolution of the eastern East China Sea during the last 36,000 years
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DOI：
10.1016/s0025-3227(98)00183-2
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发表时间：
1999-03
期刊：
影响因子：
2.9
通讯作者：
Xuedong Xu;M. Oda
中科院分区：
文献类型：
--
作者：
Xuedong Xu;M. Oda
为重建东海东部陆坡的表层水历史，对两个高分辨率岩心中的浮游有孔虫进行了研究。对15个层位的AMS 14 C测年显示，KH 82 -4-14和RN 80-PC 3两个岩心分别包含了过去3.6万和1.7万cal.年的连续记录。在取芯样品中共鉴定出31种浮游有孔虫，它们是现今北太平洋西部和东中国海中常见的有孔虫。三个动物群阶段（III、II和I）以特征性的南极有孔虫组合为特征，表明自36，000年B. P.以来东南极洲地表水的三个主要古环境阶段：(1)36，000 ~ 19，500年B. P.受沿岸海水影响的阶段; (2)19，500 ~ 10，500 yr B. P.也受沿岸水和极低盐度影响的阶段;（3）1.05 -8.5万年前，与黑潮有关的现代公海水控制阶段，具有较高的温度和盐度。bulloides表明，南极有孔虫动物群的三个阶段分别对应于末次冰期、冰消期和冰后期。冰消期以高比例的G. quinqueloba，与冰期和冰后期的大不相同，与中国大陆的大量河流排泄有关。氧同位素的负漂移。在同一时期的bulloides是高度相关的`G。quinqueloba anomaly '，也表明地表水盐度下降。此外，KH 82 -4-14柱样在1.9 - 1.5万年B. P.期间的沉积速率远高于冰期和冰后期的沉积速率，这表明陆源物质的供应大大增加，这与冰消早期河流和沉积物排放量的增加有关。东中国海沿岸水影响阶段在10.5-8.5万年B. P.逐渐结束，因为温暖的黑潮及其分支在东中国海流动，直到今天。东海东部冰后期表层水环流格局的形成与黑潮的流态密切相关。
Planktic foraminifera have been studied in two high-resolution cores raised from the continental slope of the eastern East China Sea (ECS) to reconstruct the surface-water history. AMS14C dating on fifteen horizons revealed that the two cores KH82-4-14 and RN80-PC3 contain continuous records of the last 36 and 17 thousand cal. years, respectively. Thirty-one planktic foraminiferal species which are commonly found in the present western North Pacific and the ECS are recognized in down-core samples. Three faunal phases (III, II and I) distinguished by characteristic planktic foraminiferal assemblages suggest three major paleoenvironmental stages of the surface water of the eastern ECS since 36,000 yr B.P.: (1) a stage influenced by coastal water from 36,000 to 19,500 yr B.P.; (2) a stage also influenced by coastal water and extremely low salinity from 19,500 to 10,500 yr B.P.; and (3) a stage controlled by the modern open-sea water related to the Kuroshio with both higher temperature and higher salinity since 10.5–8.5 thousand years B.P. Oxygen isotope records of the planktic foraminiferal species G. bulloides show that the three planktic foraminiferal faunal phases correspond to the last glacial, deglacial and postglacial stages, respectively. The planktic foraminiferal assemblage during the deglacial stage which is represented by high percentages of G. quinqueloba, is quite different from those during the glacial and postglacial stages, linked to a large amount of river discharge from the Chinese continent. A negative oxygen isotope excursion in G. bulloides during the same period is highly correlated to the `G. quinqueloba anomaly', also indicating a decrease in surface-water salinity. Furthermore, the sedimentation rate of core KH82-4-14 during 19–15 thousand years B.P. is much higher than the rates during the glacial and postglacial stages, suggesting a great increase in the supply of terrigenous material, related to an increased river and sediment discharge during the early deglaciation. The coastal-water-influenced stage of the eastern ECS terminated gradually at 10.5–8.5 thousand years B.P. since the warm Kuroshio Current and its branches flowed in the eastern ECS as today. The formation of the postglacial surface-water circulation pattern in the eastern ECS was closely related to the flow patterns of the Kuroshio current.