中亚地区过去5万年风尘记录的生物气候变化的高分辨率重建

中亚地区 风尘序列 过去5万年 气候环境变化 气候重建。
冯兆东 2007-01 项目
【英文摘要】We propose to reconstruct a detailed bioclimatic history of the last 50,000 years in the westerlies-dominated Central Asia based on a multi-proxy study of several thick eolian sections. The past 50,000 years are targeted because of the needed chronological resolution and the abundance of AMS-datable charcoals in the eolian sections. Here, the westerlies-dominated Central Asia refers to the region including NW Xinjiang of China and the eastern Kazakhstan that has been the conjunction between the East Asian Monsoon and the westerlies-dominated "European" climate systems. A high-resolution reconstruction of bioclimatic changes from eolian sequences in the proposed study area shall provide a more comprehensive context for understanding hemispheric- and global-scale forcing mechanisms and ocean-atmosphere-continent couplings throughout the past 50,000 years. First, we will develop bioclimatic transfer functions of pollen, snails, delta13C of organic matter, and environmental magnetic parameters along three N-S transects. Our study will then focus on reconstruction of bioclimatic changes during the past 50,000 years. Our approach involves a combination of geophysical proxies (magnetic granulometry and grain size), geochemical proxies (delta 13C of organic matter, elements, and iron geochemistry), and geobiological proxies (pollen, charcoals, and snails).
【中文摘要】西风带控制的中亚地区包括准葛尔盆地(中国新疆西北部)和哈萨克斯坦的高地与平原(哈萨克斯坦东部),它是东亚季风系统和控制欧洲的西风气候系统的连接带。西风带控制的中亚地区的风尘记录的生物气候变化的高精度重建将为理解过去50,000年半球和全球尺度规模的气候驱动机制和海洋-大气-陆地耦合提供更全面的背景知识。西风带控制的中亚地区风尘序列记录的过去50,000年的生物气候重建项目计划从新疆西北部和东哈萨克斯坦的黄土/古土壤序列中,获得一相对高精度的(1厘米采样,分辨率40-100年)古气候指标记录。首先,发展一个沿三个南北端面(总计180-240个样品)的孢粉、蜗牛、?13C或有机质和环境磁学参数的转换方程,然后集中于过去50,000的生物气候变化的重建。在14-16个目标研究剖面中,六个剖面以1-2厘米间距取样,剩下的按照土壤地层以5-20厘米间距取样。研究方法包括地球物理指标(磁颗粒和粒度)、地球化学指标(?13C或有机质,元素和铁地球化学)、地球生物指标(孢粉、木炭和蜗牛)。应当指出,对这些地层序列的可行性研究所获得的数据表明在这些地层序列中很有保证获得气候变化的高精度的灵敏的记录。