MIS3—MIS1时期闽东沿海地区高分辨率沉积与孢粉地层对古环境变化的响应特征

Response characteristics of high-resolution sedimentation and palynostratigraphy to paleoenvironmental changes in the coastal area of eastern Fujian during the MIS3—MIS1 period

  • 摘要: 为探究气候与环境剧烈转变背景下沉积物及古植被的响应特征,在前期已有研究的基础上,本研究提供了更为详细的MIS3时期至MIS1早中期的沉积与孢粉地层数据,重建了古植被与沉积演化序列,讨论了古植被、沉积特征对气候、环境演化过程的关系。结果显示该区段岩性以砂质粉砂、粉砂质砂为主,每个钻孔均存在4个孢粉带,指示了不同的气候环境阶段。在MIS3早期与MIS1早—中期过渡阶段,出现了海相沟鞭藻孢囊及有孔虫内衬。通过地层沉积特征、孢粉特征与全球海平面、石笋δ18O曲线对比分析,发现宁德沿海岩芯在MIS3至MIS1时期沉积环境存在明显的波动,导致不同区域存在沉积间断。孢粉特征指示的MIS3中期区域气候冷期可能受H4事件影响,H3事件在沉积特征上有所响应,表明宁德地区环境受全球气候环境变化影响,在万年尺度上受控于北半球夏季太阳辐射驱动的冰期-间冰期旋回,千年尺度也受到亚洲季风及Heinrich事件影响。

     

    Abstract: To explore the response characteristics of sediments and ancient vegetation under the background of drastic climate and environmental changes, based on previous research, we provided more detailed sedimentary and pollen stratigraphic data from the MIS3 period to the early and middle stages of MIS1, reconstructed the sequence of ancient vegetation and sedimentary evolution, and discussed the relationship between ancient vegetation and sedimentary characteristics and climate and environmental evolution processes. Results show that the lithology of this section is mainly sandy silt and silty sand, and there are four sporopollen zones in each borehole, indicating different climate and environmental stages. In the transitional stage between early MIS3 and early-mid MIS1, marine dinoflagellate cysts and foraminiferal linings appeared. Comparative analyses in stratigraphy sedimentology, palynology, and global sea level and stalagmite δ18O curves showed significant fluctuations in the depositional environment of the Ningde coastal cores during the period from MIS3 to MIS1, which resulted in depositional discontinuities in different regions. The mid-MIS3 cooling indicated by sporo-pollen characteristics might be influenced by the H4 event, while H3 event responded to sedimentary characteristics, indicating that the environment in Ningde region was affected by the global climate and environmental changes, which was controlled by the glacial interglacial cycle driven by summer solar radiation in the northern hemisphere on a ten-thousand-year scale, and by the Asian monsoon and the Heinrich events on a thousand-year scale.

     

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