| 70万年来西太平洋暖池北缘上层水体结构演化 | |
贾奇1
| |
| 学位类型 | 硕士 |
| 导师 | 李铁刚 |
| 2015-05-23 | |
| 学位授予单位 | 中国科学院大学 |
| 学位授予地点 | 北京 |
| 学位专业 | 海洋地质 |
| 关键词 | 西太平洋暖池 南极中层水 温跃层 生产力 厄尔尼诺-南方涛动 |
| 摘要 | 本论文以西太平洋暖池北部边缘的MD06-3047B孔为研究材料，该柱状样由中法合作执行的Marco Polo 2 IMAGES XIV 航次取得，该孔位于吕宋岛东部的西菲律宾海本哈姆高原，位于17°00.44’ N, 124°47.93’ E，柱长8.9 m，水深2510 m。本次研究利用该柱状样来研究西太平洋暖池北部边缘过去70万年来的古海洋学变化。 通过将底栖种C. wuellerstorfi的δ18O与大洋底栖有孔虫标准曲线LR04曲线进行对比，并以约出现在距今12万年的粉红色G.ruber 末现面为参照点建立MD06-3047B孔的年龄模式。结果显示MD06-3047B孔共包括17个氧同位素期次，约70万年。 除了G. ruber的δ18O记录在MIS14-13期冰期间冰期变化特征相对不明显，底栖种C. wuellerstorfi、次表层种P. obliquiloculata与表层种G. ruber 的δ18O记录整体上具有明显的冰期间冰期变化特征。底栖有孔虫C. wuellerstorfi 的碳同位素也具有较为明显的冰期间冰期变化特征，冰期时偏轻，间冰期时偏重；G. ruber 的碳同位素变化特征为冰期时逐渐变重，间冰期时逐渐变轻， P. obliquiloculata的碳同位素表现为冰期时逐渐变轻，间冰期时逐渐变重。在冰期终止期Ⅰ、Ⅱ 、Ⅳ 和Ⅴ期， P. obliquiloculata的δ13C表现出明显的负偏，而在MIS13期和MIS3期左右，P. obliquiloculata的δ13C表现出明显的正偏。 MD06-3047B孔次表层种P. obliquiloculata与表层种G. ruber δ18O的差值反映的温跃层变化具有冰期逐渐变浅，间冰期逐渐变深的特点。表层种G. ruber与次表层种P. obliquiloculata的碳同位素记录，以及底栖种C. wuellerstorfi 和表层种P. obliquiloculata的碳同位差值反演的研究区古生产力变化特征为冰期时升高，间冰期时降低。结合MD06-3047B孔的差值结果与西太平洋暖池核心区ODP805站位和赤道东太平洋ODP847站位的差值对比结果，得出热带太平洋在过去70万年来存在类ENSO式的变化特征，冰期时为偏类厄尔尼诺状态，间冰期时为偏类拉尼娜状态，冰消期时为典型的类厄尔尼诺状态。 在冰期终止期Ⅰ、Ⅱ 、Ⅳ 和Ⅴ期，次表层种P. obliquiloculata的碳同位素记录存在极小值事件，说明在这几个冰期终止期来自南极的低δ13C海水到达了西太平洋暖池北部边缘地区。 浮游有孔虫Mg/Ca反演的表层水和次表层水的温度，整体趋势上存在冰期间冰期的变化，冰期间冰期温度的变化范围最大达到6℃。 |
| 其他摘要 | Core MD06-3047B (17º 00.44’ N, 124º 47.93’ E, length 8.90 m, water depth 2510 m) was retrieved during Marco Polo2 IMAGES XIV Cruise, east off Luzon Island in the Western Philippine Sea, from the Benham Rise, was used to investigate paleoceanographic variations at the north margin of the Western Pacific Warm Pool (WPWP) over the past 700,000 years. The age model of Core MD06-3047B was established by comparing benthic foraminifera C. wuellerstorfi δ18O curve with the LR04 stack combining the last appearance datum of C. wuellerstorfi (pink) which indicates a numerical age of 120 ka. Core MD06-3047B contains 17 MIS and about 700 000 years. The results of the stable oxygen isotope records of C. wuellerstorfi , G. ruber and P. obliquiloculata show obvious changes over glacial-interglacial cycle except of the stable oxygen isotope records of G. ruber during MIS 14-13. The stable carbon isotope records of C. wuellerstorfi also show glacial-interglacial changes, small in glacial periods and large in interglacial periods. The results of the stable carbon isotope records of G. ruber become progressively lager in glacial periods and become progressively smaller in interglacial periods, and the P. obliquiloculata have opposite characteristics. And the stable carbon isotope records of P. obliquiloculata occur intense negative excursions during termination Ⅰ, Ⅱ, Ⅳand Ⅴ and obvious positive excursion during MIS13 and MIS3. The δ18O difference between the subsurface dwelling P. obliquiloculata and the surface dwelling G. ruber in the Core MD06-3047B suggests shallower thermocline during most glacial episodes and deeper thermocline during interglacial intervals. The results of the stable carbon isotope records of G. ruber and P. obliquiloculata, the δ18O difference between the benthic foraminifera C. wuellerstorfi and the subsurface dwelling P. obliquiloculata shows that the productivity are higher in glacial periods and lower in interglacial periods. By comparing the δ18O differences of Core MD06-3047B in the north margin of WPWP, Site ODP805 in the center of WPWP and Site ODP847 in the eastern tropical Pacific, we infer that equatorial Pacific was in ENSO-like variation mode since 70,000 ka, just like El Niño condition in glacial periods, and La Niña condition in interglacial periods. The intense negative δ13C excursions at thermocline during termination Ⅰ, Ⅱ, Ⅳand Ⅴ indicates that the low δ13C waters from Southern Ocean had arrived at the north margin of the WPWP. The Mg/Ca temperature of surface and subsurface water shows changes over glacial-interglacial cycles. Glacial-interglacial amplitudes of the surface temperature are 6℃. |
| 学科领域 | 海洋地质与环境 |
| 语种 | 中文 |
| 文献类型 | 学位论文 |
| 条目标识符 | http://ir.qdio.ac.cn/handle/337002/22790 |
| 专题 | 海洋地质与环境重点实验室 |
| 作者单位 | 1.中国科学院海洋研究所 2.中国科学院大学 |
| 第一作者单位 | 中国科学院海洋研究所 |
| 推荐引用方式 GB/T 7714 | 贾奇. 70万年来西太平洋暖池北缘上层水体结构演化[D]. 北京. 中国科学院大学,2015. |
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