末次冰消期以来秦岭高山湖泊沉积高分辨率温度与降水重建

Due to lack of high-resolution paleoclimate records in the Qinling Mountain region, the boundary between the north and the south in east China, is still poorly understood its climate change and forcing mechanism during Last Deglaciation. In this proposal, we plan to use sediments from 2 alpine lakes in Qinling Mountain to reconstruct high-quality records. The chronology will be determined with AMS 14C dating and varve counting technique. Based on reliable chronology model and modern process research, we use GDGTs, Compound-specific Hydrogen isotope and pollen assemble as temperature and moisture/precipitation proxy, together with other multi-proxies(Grain-Size, LOI), reconstruct the region Temperature and precipitation. The aims of this study are to better understand the temporal and spatial pattern of Last Deglaciation climate changes between monsoon region, by comparing with other high-resolution climatic records obtained in the monsoon region, and try to systematically understand the climate mechanisms of Last Deglaciation.

秦岭地区是我国东部重要的南北气候分界带，该区域一直缺乏末次冰消期以来高分辨率气候变化记录，因而对该区域气候变化的机制缺乏深入了解。项目拟以我国季风区南北气候分界带秦岭高山湖泊大爷海、玉皇池沉积物为载体，在建立代用指标和气候要素的定量-半定量关系后，结合可靠年龄-深度模式，通过GDGTs、单体氢同位素、孢粉组合和其他代用指标（XRF岩芯扫描、粒度、烧失量等），定量或半定量重建末次冰消期以来秦岭地区温度和降水变化，进而了解该区域气候变化模式。在此基础上，对比其他季风区气候记录，结合气候模拟资料结果，探讨季风区南北气候变化规律与机制，认识该区域气候环境变化对全球环境变化的响应与影响。

本项目针对当前国际气候变化研究的热点问题-全新世温度重建展开，尝试在关键区域定量重建温度、湿度等气候要素。针对当前中国季风区南北全新世气候的差异和矛盾，项目选择我国南北气候分界线秦岭上的高山湖泊沉积物为载体，通过孢粉与有机地球化学指标（GDGTs、单体氢同位素等）以及XRF、粒度等常规指标重建秦岭区域末次冰消期以来的温度和湿度变化，进而了解该区域气候环境变化模式。通过全有机质与孢粉浓缩物的AMS 14C定年，结合210Pb/137Cs定年，在充分考虑碳库效应后，建立可靠的末次冰消期以来湖泊沉积年代序列。然后在通过现代过程建立的代用指标-气候要素关系的基础上，采用湖泊沉积物GDGTs定量重建温度；采用湖泊沉积物长链和短链单体氢同位素分别重建大气降水和湖泊水体氢同位素变化，进而恢复该区域的湿度或降水量；结合中国表土孢粉数据库，在确定孢粉组合主要控制因子的基础上定量重建温度或降水量变化序列。最后基于可靠的区域气候记录揭示末次冰消期以来季风区南北气候模态和气候驱动机制，为区域的气候变化趋势预测提供基础资料和科学依据。总结如下:1）高山湖泊大爷海与玉皇池的沉积岩芯年代序列建立；2）现代过程研究；3）重建秦岭地区高分辨率气候环境变化模式；4）区域温度、湿度对比与驱动机制探讨。