摘要
晚第四纪的气候变化控制了南极地区的冰架进退。冰架崩塌形成的冰山在其破碎、漂流、融化过程中把冰筏碎屑(IRD)搬运到海洋中。同时,大量的冰川融水促进了海洋垂直剖面结构和动力的改变,从而影响冰筏碎屑的沉积过程。此前对于揭示极地海域冰筏碎屑与底流活动变化之间关系的研究尚不充分。因此,本文分析了南极威德尔海西北部柱状沉积物的沉积记录,在对比沉积物粒度数据特征、分析沉积物端元模型的基础上,发现4次明显的沉积物粒度变化事件和底流增强事件同时发生。这种同步性说明冰架系统与海洋环境之间存在内在的调节机制。两次较强的冲刷事件证明岩心形成过程中存在着两次沉积间断,同时也合理地解释了古地磁数据和AMS^(14)C数据存在的显著年龄差异。此外,鉴于D4-9岩心样品蛋白石、有机碳等指标均指示了极低的输出生产力情况,且与冰期的生产力水平相当,推断该岩心主要形成于末次冰期期间。综上分析,D4-9岩心所记录的事件反映出南极地区千年尺度的气温变化诱发了冰架的后退,导致了明显的冰筏碎屑事件和底流增强事件,解释了威德尔海区冰架-海洋过程的内在耦合关系。
During the late Quaternary,climate changes drove the advance and retreat of ice shelves in and around the Antarctic.Icebergs carried iceberg rafted debris(IRD)by calving,floating,and melting into the ocean.The large amount of melt water altered the structure of ocean water profiles and activities,which also affected the deposition of IRD.The association between IRD events and bottom current activities is not yet fully understood.Here,we present a sediment record retrieved from the northwestern Weddell Sea.Obvious peaks of four-IRD events were observed parallel with four bottom water enhancement events,based on a precise comparison of grain size data and End Member Model Analysis.These synchronous events revealed a coupling mechanism between the ocean and glacial systems.Two strong washing events supported the existence of two discontinuities of sedimentation,which explained the age difference between the paleomagnetism reverse and the AMS^(14)C data.As the very low export productivity was similar to that at a glacial level,we deduced that most of this core was deposited in the last glacial period.The millennial temperature increases in the Antarctic triggered ice shelf retreats and led to obvious IRD events and bottom current activities.
作者
颜彬
谢敬谦
武力
黄博
Yan Bin;Xie Jingqian;Wu Li;Huang Bo(South China Sea Marine Survey Center,MNR,Guangzhou 510300,China;Laboratory for Coastal Ocean Variation and Disaster Prediction,College of Ocean and Meteorology,Guangdong Ocean University,Zhanjiang,524000,China;Key Laboratory of Marine Environmental Survey Technology and Application,Ministry of Natural Resources,Guangzhou 510300,China;Marine Science Research Institute of Shandong Province(National Oceanographic Center,Qingdao),Qingdao 266000,China;State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China)
出处
《极地研究》
CAS
CSCD
北大核心
2023年第4期542-555,共14页
Chinese Journal of Polar Research
基金
国家自然科学基金面上基金(42276077)
海洋地质国家重点实验室开放基金(MGK202207)
国家海洋局南海分局海洋科学技术局长基金重点项目(180107)资助。
关键词
粒度
冰筏碎屑
生产力
沉积物
威德尔海
grain size
ice rafted debris
productivity
sediment
Weddell Sea
