中文摘要：

保存在陆地、海洋和冰芯中的风尘沉积物与粉尘源区的干旱化历史、过去大气环流模式及其强度的演化密切相关，因而，直接的海陆风尘记录对比一直是古气候研究中的热点。为了获得对亚洲粉尘源区的干旱化波动和东亚季风演化的全面认识，较高分辨率地提取了北太平洋ODP885站深海沉积物中的风尘组分，进而估算了晚上新世-早更新世时段北太平洋中部的风尘通量变化。结果表明，亚洲内陆粉尘源区的干燥度具有大时间尺度的变化特征，在2．7Ma左右急剧增加，随后在2．7—1．5Ma时段逐渐减小，自1．5Ma开始又逐渐增加。此外，在2．7—0．9Ma时段，粉尘源区经历了多次显著的轨道时间尺度上的干湿波动。通过对北太平洋和黄土高原的风尘记录的直接对比，发现在距今约2．7Ma，东亚地区的古环境发生了显著的变动，表现为亚洲内陆干旱化的加剧和大幅度冬、夏季风环流的盛行。然而，自2．7Ma开始，尤其是1．5Ma以后，由于北太平洋和黄土高原与亚洲粉尘源区的距离不同，两地的风尘通量所揭示的干旱化趋势和变化幅度存有明显差异。北太平洋远离亚洲内陆，其风尘通量变化基本不受粉尘源区范围变化的影响，因而更能反映源区干燥度的变化。相反，黄土高原由于距离粉尘源区较近，风尘通量的变化可能同时受到粉尘源区干燥度和范围的变化以及携带粉尘的风动力强度变化的影响。显然，海洋和陆地古气候记录的直接对比，可为深入认识过去气候变化提供新的思路。

英文摘要：

The eolian dust preserved in terrestrial loess, marine sediments and ice core is highly linked to the changes of the past atmospheric circulation as well as the fluctuations in the aridity in the source region. In order to have a complete view of the evolution of the East Asian monsoons and the aridity in the source region, here we reported a new mass accumulation rate （MAR） record from the central North Pacific （ODP site 885） spanning the Late Pliocene to Early Pleistocene. Our high-resolution MAR record suggests a sudden drying occurred around 2.7Ma in the Asian interior, followed by a gradual decrease in aridity of dust source regions at the interval 2.7 - 1.5Ma, and subsequently a drying trend at the interval 1.5 - 1.0Ma. Meanwhile, our MAR record also exhibits orbital-scale fluctuations, characterized by six predominant 1.90Ma, 1.8-1.6Ma, 1.5-1.4Ma, 1.3-1. drying periods in Asian interior around 2.7 -2.5Ma, 2. 15 - 2Ma and 1.1 - 1.0Ma, respectively. The comparison of paleoclimatic proxy records from the North Pacific and the Chinese Loess Plateau confirms a sharp drying in Asian interior around 2.7Ma and onset of large-amplitude fluctuations of the East Asian monsoon. After 2.7Ma, the MAR record from the North Pacific suggests a trend toward humidity of Asian interior until 1.5Ma followed by a gradual drying in the interval 1.5 - 1.0Ma, whereas the MAR record from the Chinese Loess Plateau indicates a steady drying since 2. 7Ma. Moreover, the amplitude of the superimposed orbital-scale variations is rather uniform in the North Pacific MAR record but increased gradually in the MAR of the Chinese Loess Plateau （CLP）. The discrepancies between the land and ocean are possibly due to the distances between the depositional sites and the dust source regions. Because the Chinese Loess Plateau is proximal to the dust source regions, changes in aridity, the variable area of dust source regions as well as the wind intensity all affect the MAR records at CLP, especially since about 1.5Ma. By contrast, the