GDGTs在黄土古环境重建中的研究进展

Application of Glycerol Dialkyl Glycerol Tetraether Lipids in Paleoenvironment Reconstruction of Loess Deposits:A Review of Recent Progresses

甘油二烷基甘油四醚广泛存在于黄土、泥炭、湖泊、海洋等各类沉积载体中,并有效地记录了地质历史时期的古环境信息。简要概述了甘油二烷基甘油四醚的结构、生物源以及常见的甘油二烷基甘油四醚陆地环境代用指标,重点阐述了甘油二烷基甘油四醚在黄土古环境重建中的研究进展,并提出了展望。主要研究进展包括:①甘油二烷基甘油四醚古环境指标在黄土古气候研究中得到了较广泛的应用,并重建了黄土高原地区过去80万年的古温度变化;②黄土高原地区温度变化主要受当地夏季太阳辐射驱动,并受植被下垫面调控;③黄土高原地区末次冰消期降水的增加明显滞后于温度的升高。甘油二烷基甘油四醚在黄土古环境研究中仍存在重建温度偏高、环境指标与气候因子关系复杂等问题。未来对新指标的开发以及区域性转换函数的建立和应用将有望进一步提高甘油二烷基甘油四醚在黄土古环境重建中的准确性,并为解决不同气候区空间上的水-热配置模式和气候变化机制提供依据。

The Glycerol Dialkyl Glycerol Tetraethers(GDGTs) occur ubiquitously in a wide range of environments, such as loess, peat, lake, soil, and ocean, which vary compositionally in response to environmental changes,and provide a series of biomarker proxies for paleoenvironmental reconstruction. This paper introduced the structures and biological sources of GDGTs,and reviewed the recent progresses of the application of the GDGTs proxies in the paleoenvironmental reconstruction of loess deposits. The main progresses include:① The GDGTs proxies have been widely used in reconstructing the climate changes in loess deposits, and have established the temperature changes of last 800 ka for the Chinese Loess Plateau;②Temperature variations in Chinese Loess Plateau displayed significant correlation with the Northern Hemisphere insolation,which may be also regulated by the surface vegetation conditions;and ③ In the Chinese Loess Plateau,the increase in monsoon precipitation during the last deglaciation significantly lagged behind the rise of temperature. However,problems still exist in the current studies. For instance,the GDGTs-based temperature is likely overestimated,probably reflecting the temperature of warm season,and relationships between GDGT indices and climate factors are still unclear. In the future,the development of new proxies and more accurate regional calibrations based on the separation of 6-methyl GDGTs are expected to provide more reliable paleoenvironmental information,and will provide essential evidence for the evolution of hydrothermal pattern and mechanisms behind climate changes in different regions.