近50 kaBP以来西菲律宾海盆沉积物风尘组分对东亚季风演化的响应

Response of terrigenous eolian dust sediment composition to the East Asian monsoon evolution in the West Philippine Basin since 50 kaBP

  • 摘要: 西菲律宾海盆因其特殊的地理位置和环境条件成为研究东亚季风演化的理想区域,但目前对海盆中部沉积物沉积记录演化及其对古气候指示的研究较少。基于对海盆中部两根柱状沉积物(MC09、MC13)的AMS14C年代学、沉积物粒度和常量元素的分析,建立了高分辨率的沉积学和地球化学沉积记录,提取了反映亚洲风尘输入的替代性指标,进而揭示了近50 kaBP以来西菲律宾海盆沉积物风尘组分对东亚季风演化的响应。结果表明,利用沉积物粒度和元素地球化学综合指标能有效指示东亚季风及源区气候变化,MC09、MC13柱状样沉积物相关指标的变化表明:47~26 kaBP,全球气候处于弱暖期,东亚冬季风强度相对较弱;26~19 kaBP,东亚冬季风显著增强,陆源风尘输入增加;19~12 kaBP,气温逐渐升高,东亚冬季风强度减弱,沉积记录受到新仙女木事件等的影响出现波动;12 kaBP以来,全球气候相对稳定,东亚冬季风强度小幅减弱。本研究可为深入理解古环境和古气候变化对边缘海沉积作用的影响提供参考。

     

    Abstract: The West Philippine Basin is an ideal area to study the evolution of the East Asian monsoon due to its special geographical location and environmental conditions. However, there are few studies on the source of sediment and its sedimentary evolution in the middle of the basin. Based on the analysis of AMS14C chronology, grain size and major elements of two columnar sediments (MC09 and MC13) in the middle of the basin, high-resolution records of sedimentology and geochemical deposition were established, the proxy index reflecting the input of Asian eolian dust was extracted, and then the response of sediment composition of the West Philippine Basin to the evolution of East Asian monsoon since nearly 50 kaBP was revealed. Results show that the comprehensive indexes of sediment grain size and element geochemistry could effectively indicate the changes of the East Asian monsoon and the climate in its source region. The variations of sensitive grain size fractions and terrigenous component fractions of major elements in the MC09 and MC13 columnar sediments indicate that the global climate was in a weak warm period and the East Asian winter monsoon was relatively weak from 47 to 26 kaBP. During 26 to 19 kaBP, the East Asian winter monsoon was obviously strong, and the terrigenous component of sediment increased significantly. From 19 to 12 kaBP, the temperature gradually increased and the intensity of the East Asian monsoon decreased, and the sedimentary record fluctuated under the influence of the Younger Dryas event. Since 12 kaBP, the global climate was relatively stable, and the intensity of winter winds in East Asia had weakened slightly. This study provided a reference for understanding the influence of the paleo-environment and paleo-climate changes on the sedimentation in the marginal sea.

     

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