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对位于西风环流下风区日本海中部LV53-23岩芯沉积物的粒度特征进行了研究,重建了日本海末次冰期(~60 ka)以来的西风环流演化历史和空间变化规律.结果显示,岩芯沉积物以粉砂为主且粒度频率分布曲线多呈单峰分布,与现代日本黄沙和前人报道的邻近区域的岩芯粒度特征一致,具有典型的风尘沉积特征.众数粒组-粉砂组分的中值粒径分析表明,粉砂组分中值粒径可以用作岩芯沉积反映西风环流的替代性指标.在亚轨道及千年尺度上,粉砂组分中值粒径在MIS 3期的冰阶-间冰阶千年尺度旋回与西风环流密切相关:冰阶时,粉砂组分中值粒径增大,这与西风急流轴较长时间位于青藏高原南部,西风环流影响范围变大,风速增强,能携带更多近源的蒙古戈壁-中国东北沙地风尘至日本海有关;间冰阶时,粉砂组分中值粒径减小,这是由于西风急流轴位于青藏高原北部,携带更多远源的塔克拉玛干沙漠风尘至日本海.而在轨道尺度上,末次盛冰期时粉砂组分中值粒径的稳定低值与北半球65°N日照辐射量良好对应,表明北半球日照辐射量和中高纬温度梯度差对西风环流远距离输运粉尘起到重要作用,盛冰期时西风急流轴受北半球冰盖扩张影响显著南移导致西风环流范围也随之南移,从而对日本海40°~50°N上空西风影响减弱.
The grain size distribution of core LV53-23 sediments in the central Japan Sea downstream of westerly circulation was studied to reconstruct the history and spatial variation of westerly circulation since the submarine glaciation (~ 60 ka) in Japan. The results show that core Sediments are dominated by silt and the distribution of particle size distribution is mostly monomodal distribution, which is consistent with the core particle characteristics of modern Japan yellow sand and its predecessors, and has typical features of dust deposition. The median particle size analysis of sand components shows that the median particle size of the silt fraction can be used as a proxy for the sedimentation of the core sediments to reflect the westerly circulation. On the sub-orbital and millennial scale, the median diameter of the silt fraction is The MIS-Stage ice-interglacial millennium scale cycles are closely related to the westerly circulation: the median grain size of silt components increases with ice stage, which is located in the southern part of the Tibetan Plateau and the westerly circulation due to the long time of westerly jet stream axis The larger the range, the higher the wind speed, the more likely to carry more near-source Mongolia Gobi - northeasterly sand dust in the southeastern China to the Sea of Japan; the interglacial order, the median particle size of the silt fraction decreases due to the westerly jet stream axis To the north of the Qinghai-Tibet Plateau, carry more Yuanyuan In the orbital scale, the stable low value of median grain size of silt fraction in the last glacial period corresponds well with the solar radiation of 65 ° N in the northern hemisphere, indicating that the radiation in the northern hemisphere and the temperature gradient in mid-high latitudes Poor on long-distance westerly circulation dust transport plays an important role during the ice climax westerly jet stream by the Northern Hemisphere ice sheet expansion significantly southward shift led to the scope of the westerly circulation also will move south, so the Japan Sea 40 ° ~ 50 ° N over Westerly influence weakened.