末次盛冰期以来南海沉积孢粉的南北变化及季风信息

Asian monsoon is the most active and important member of the global monsoon. Currently, researches on the Asian monsoon climate focus more on temperate and subtropical vegetation while tropical vegetation is still lagging behind. In this study, we are adopted by pollen analysis of six marine sedimentary cores distributed continuously in north-south direction，which are collected from the continental shelf（including the Sunda Shelf and the Beibu Gulf shelf）and continental slope west coast of the southern South China Sea, based on more accurate and unified AMS14C dating. Combined with East Asia Surface pollen database, the change of pollen terrestrial sources will be discussed. The vegetation biome classification in the past will be reconstructed based on the percentage of airborne and herb pollen assemblage, thus people will know where the boundary of savanna and tropical rain forest had moved on the pollen terrestrial sources (Sunda Shelf and the Beibu Gulf shelf) since the Last Glacial Maximum. Some specific types of pollen will be used as winter and summer monsoon proxy indicator respectively. The information of climate events on the scale of thousands year will be achieved based on pollen percentage. Change of climate humid and transformative distance will be discussed from the nature fire based on the charcoal information. From above works, the continuous, high-resolution sequences of changes in East Asian winter, summer monsoon will be established since the end of late Pleistocene epoch. The monsoon frequency, period and intensity that had been reflected from the sequences of the summer and winter Asian monsoon will be compared. Based on this study, the dynamic mechanism of the tropical Asian monsoon will be explored and validated from the perspective of marine sediments. It will help to improve and perfect the theory of global monsoon system.

亚洲季风是全球季风最活跃和最重要的成员。目前针对亚洲季风气候的研究相对忽略了热带植被类群。本研究拟通过南海西部的陆架和陆坡6个南北连续分布的沉积岩芯的孢粉分析，基于较精确而统一的AMS14C测年，结合陆地表土孢粉数据库，获得陆源地信息；以木本和草本花粉组合重建末次盛冰期以来陆源地的植被类型，尤其是判断巽他古陆和北部湾陆架热带雨林、季雨林和热带稀树草原的界线变迁；以孢粉特有类型分别作为冬夏季风的代用指标；通过孢粉百分比的计算获得千年尺度气候事件发生的信息；通过炭屑指示的陆源地天然火信息推测气候的干湿和传播距离变化；通过上述工作构建末次盛冰期以来亚洲冬、夏季风在南海较为连续、详细的历史演化序列；并对比亚洲冬、夏季风爆发频率、周期和幅度，从海洋沉积的角度探讨和验证亚洲季风末次盛冰期以来的变化规律和动力机制。该研究将弥补亚洲季风对热带植被的历史变迁研究的不足, 有助于完善对亚洲季风系统的认识。

亚洲季风是全球季风最活跃和最重要的成员。目前针对亚洲季风气候的研究相对忽略了热带植被类群。本研究通过南海西部陆架和陆坡沉积岩芯南北断面的孢粉分析， 以孢粉特有种属作为冬夏季风的代用指标，获得末次盛冰期以来冬夏季风演化的序列，通过孢粉陆源区的变化获得季风和洋流的变化信息，通过草本和木本花粉的百分比变化获得陆源区干湿交替的信息，建立南海周围、特别是巽他陆架和北部湾陆架森林植被向开阔植被（草本）方向进行渐进变化的过程，并尝试从海洋沉积角度探索和验证它们的驱动机制。本研究的孢粉组合表明LGM期间巽他陆架东北部一直分布有广阔的热带低地和低山雨林，草原植被没有明显扩张，指示当时的湿度没有变得稍干旱。该研究尝试利用更为密集、更靠近陆源地的样点，采用更为准确的季风研究替代指标分析南海西部的沉积断面, 探讨热带植被内部的演化，将为讨论全球的古季风提供宝贵的基础资料。