潘梦迪, 邬黛黛, 吴能友, 刘丽华. 南海北部神狐海域晚末次冰期以来有孔虫特征及其对古海洋环境的指示[J]. 海洋地质与第四纪地质, 2017, 37(2): 127-138. DOI: 10.16562/j.cnki.0256-1492.2017.02.013
引用本文: 潘梦迪, 邬黛黛, 吴能友, 刘丽华. 南海北部神狐海域晚末次冰期以来有孔虫特征及其对古海洋环境的指示[J]. 海洋地质与第四纪地质, 2017, 37(2): 127-138. DOI: 10.16562/j.cnki.0256-1492.2017.02.013
PAN Mengdi, WU Daidai, WU Nengyou, LIU Lihua. CHARACTERISTICS OF FORAMINIFERAL ASSEMBLAGES SINCE LAST GLACIAL FROM SHENHU AREA OF NORTHERN SOUTH CHINA SEA AND IMPLICATIONS FOR PALEOCEANOGRAPHIC[J]. Marine Geology & Quaternary Geology, 2017, 37(2): 127-138. DOI: 10.16562/j.cnki.0256-1492.2017.02.013
Citation: PAN Mengdi, WU Daidai, WU Nengyou, LIU Lihua. CHARACTERISTICS OF FORAMINIFERAL ASSEMBLAGES SINCE LAST GLACIAL FROM SHENHU AREA OF NORTHERN SOUTH CHINA SEA AND IMPLICATIONS FOR PALEOCEANOGRAPHIC[J]. Marine Geology & Quaternary Geology, 2017, 37(2): 127-138. DOI: 10.16562/j.cnki.0256-1492.2017.02.013

南海北部神狐海域晚末次冰期以来有孔虫特征及其对古海洋环境的指示

CHARACTERISTICS OF FORAMINIFERAL ASSEMBLAGES SINCE LAST GLACIAL FROM SHENHU AREA OF NORTHERN SOUTH CHINA SEA AND IMPLICATIONS FOR PALEOCEANOGRAPHIC

  • 摘要: 南海北部陆坡有大量高分辨率沉积记录,对研究全球变化响应及驱动机制有着举足轻重的作用。本研究选取南海北部神狐海域2007年水合物钻探区Site 6A站位柱状沉积物,开展有孔虫群落、稳定同位素及AMS14C分析研究,试图了解该区域晚末次冰期以来古海洋和古气候演化历史。结果显示,Site 6A站位柱状沉积物中底栖有孔虫连续分布,优势属种突出,丰度、分异度波动明显。沉积物底界为MIS3期约50 kaBP,全新世沉积速率最高,为13.37 cm/ka,在MIS2期可能存在由水合物分解导致的地层缺失。有孔虫氧碳同位素特征恢复了冰期/间冰期气候旋回变化及冰盖体积变化,也指示该海域沉积环境氧化还原状况基本不变。通过对具有特殊生态意义的底栖有孔虫UvigerinaCibicidoidesBulimina的相对丰度分析,结合似瓷质壳体百分含量及浮游有孔虫碳同位素,得出在末次冰期40 kaBP东亚夏季风增强带来大量降雨,陆径流量增大导致古生产力增加。12~17 ka的古生产力高值可能与增强的冬季风携带大量陆源碎屑沉积有关,并使得北大西洋低温、低氧、高营养盐的水团对该站位影响更大。

     

    Abstract: The northern slope of South China Sea (SCS), as the area rich in high-resolution depositional records, is critical to the study of regional response and driving mechanism of global change in the South China Sea. For a better understanding of the evolution of the paleoclimate and paleoenvironment since the late last glacial period in SCS, foraminiferal records at Site 6A from the Shenhu hydrate drilling area 2007 on the northern slope are selected as the target to study the foraminifera assemblages with the support of stable isotopes and AMS14C dating data. Information on sedimentary events since MIS3 of the last 50 000 years has been recorded in the core, and the highest Holocene sedimentation rate is as high as 13.37 cm/ka. In MIS2, there may be lack of deposition due to decomposition of gas hydrate. Benthic foraminifera are present throughout the core. It is easy to distinguish dominant species. The abundance as well as the diversity of the assemblage fluctuates significantly with time. Two stages of high surface productivity in about 40 kaBP and 12~17 kaBP respectively are identified through the analysis of some species with specific ecological significance, such as Uvigerina, Bulimina, Cibicidoidesat, combined with the proportion of porcellaneous shells and variations in planktonic foraminiferal carbon isotopes. The strengthening of summer monsoon in 40 ka was supposed to have brought in a large amount of rainfall, and thus increased the land surface runoff and paleo-productivity. The increase in terrigenous input contributed to the high paleo-productivity 12~17 ka. Furthermore, the North Pacific Deep Water with low temperature, low oxygen content and high nutrient content, may render stronger influence on the core as the winter monsoon enhanced.

     

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