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    渤海西缘YRD-1101孔晚更新世以来沉积物粒度特征及其环境变迁

    Grain size distribution of sediment of core YRD-1101 in the western margin of the modern Bohai Sea since the latest Pleistocene and its environmental change

    • 摘要: 对现代黄河三角洲地区YRD-1101孔上部岩心开展粒度分析,并结合AMS14C和光释光(OSL)年代学测试结果、沉积特征、微体古生物鉴定及周边钻孔对比,建立了MIS5期以来的地层框架,揭示出该地区主要经历了3个阶段的沉积环境演化过程:(1)晚更新世—早全新世河流与海相交替沉积,其中MIS5c阶段海侵水动力环境中等,MIS3期海侵水动力环境较弱,MIS2期河流沉积水动力较强;(2)全新世滨、浅海沉积环境,动力环境整体较强,相对比较稳定;(3)1855年至今形成的黄河三角洲沉积,水动力强度较弱到中等。海平面变化和构造沉降是影响研究区晚更新世以来沉积演化的主要因素,此外,黄河带来的大量泥沙对海侵强度也有显著影响。

       

      Abstract: Three stages of sedimentary environment evolution since MIS 5 were recognized based on the data of grain size analysis, AMS14C dating, OSL dating, sedimentary characteristics, benthic foraminifera and ostracoda identification in the upper part of core YRD-1101 drilled in the modern Yellow River Delta, and comparison with surrounding boreholes. Three stages of sedimentary evolution are identified. (1)Interactive deposition of rivers and marine facies were formed during the Late Pleistocene-Early Holocene. Among them, the transgressive sediments in the MIS5c phase were formed in a medium hydrodynamic conditions, the transgressive sediments in the MIS3 phase were formed in a weak hydrodynamic environment, and the river sediments in the MIS2 phase were formed in a strong hydrodynamic environment. (2) The nearshore and shallow sea deposits during the Holocene formed in a strong and stable environment. (3) Modern Yellow River Delta sediments deposited since 1855 A.D. were formed in weak to medium sedimentary dynamic environments. Sea-level changes and neotectonic subsidence have been the major factors controlling the sedimentary evolution on the western margin of the modern Bohai Sea since MIS 5. In addition, the sediments were transported to the study area from Yellow River, which had a significant influence on transgression intensity.

       

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