黄土高原古气候变化定量重建的新进展  

New progress in quantitative reconstruction of paleoclimate changes in the Chinese Loess Plateau

作　　者：孙有斌[1] 卢红选[1] 章泽科 SUN Youbin;LU Hongxuan;ZHANG Zeke(State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,Chinese Academy of Sciences,Xi'an,Shaanxi 710061,China)

机构地区：[1]中国科学院地球环境研究所,黄土与第四纪地质国家重点实验室,陕西西安710061

出　　处：《地质学报》2024年第3期1006-1023,共18页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号42230514);中国科学院战略先导专项(编号XDB40000000)联合资助的成果。

摘　　要：中国黄土-红黏土沉积是可与深海沉积媲美的陆相沉积载体,记录了晚新生代东亚大陆气候环境变化历史。基于中国黄土的多种理化指标,重建了黄土高原地区构造-千年尺度东亚季风变化历史,为探讨区域与全球气候的联系提供了关键证据。近年来,黄土高原古气候变化研究逐步从定性描述拓展到定量重建,本文旨在回顾基于中国黄土定量重建古温度和古降雨变化取得的重要进展。首先,梳理了古气候要素定量重建的指标和方法,古温度重建指标包括植硅体、碳酸盐耦合同位素、微生物脂类代用指标等;古降水变化敏感指标包括磁化率、白云石/方解石含量、生物微钙体Sr/Ca比值、有机碳同位素以及^(10)Be等。然后,汇总了典型黄土剖面定量重建的古气候变化序列,分别从构造、轨道及千年时间尺度上探讨了古温度和古降雨的变化特征。结果表明,基于生标重建的不同时间跨度的土壤古温度变化序列,在冰期—间冰期尺度上的波动特征基本一致,但在冰盛期—冰消期时段出现了增温超前现象,说明陆地植被对土壤温度变化有重要调制作用。然而,不同指标重建的降水变化幅度差异较大,主导周期也存在差异,说明定量重建降水变化仍有较大挑战。最后,简要总结了黄土高原古气候定量重建存在的问题,明确了区分温度和降水季节性变化的重要性,指出加强地质记录与模拟结果的对比同化,将有助深化对多尺度季风变化动力学的理解。Chinese loess,as a unique terrestrial archive comparable to deep-sea sediments,has been investigated intensively to infer late Cenozoic continental climate changes in East Asia.Multiple physiochemical proxies of Chinese loess have been used to reconstruct East Asian monsoon variations at tectonic to millennial timescales.These reconstructions provide key evidence for assessing the relationship between regional and global climate changes.In recent years,paleoclimate research on Chinese loess has gradually changed from qualitative descriptions to quantitative reconstructions.The objective of this paper is to review the new progress made in the quantitative reconstruction of paleo-temperature and paleo-precipitation changes on the Chinese Loess Plateau(CLP).Firstly,we present new proxies and methods that are relevant to the quantitative reconstruction of paleoclimate variables.The paleotemperature proxies include phytolith,carbonate coupling isotopes,and brGDGTs,while the proxies sensitive to paleo-precipitation comprise magnetic susceptibility,dolomite/calcite content,Sr/Ca ratio of microcodium,carbon isotopes of organic and inorganic carbon,and ~(10)Be flux.Secondly,we summarize representative time series of quantitative reconstructions from several typical loess profiles,addressing spatio-temporal changes in paleo-temperature and paleo-rainfall at orbital and millennial timescales.Biomarker-based paleotemperature changes reveal similar glacial-interglacial fluctuations in soil temperature on the CLP.However,during the transition from the glacial maximum to deglaciation on the Chinese Loess Plateau,the increase in soil temperature diverged from marine records,indicating that land vegetation cover likely played an important role in regulating the change in soil temperature.By contrast,paleo-precipitation changes reconstructed through different proxies show large-amplitude glacial-interglacial fluctuations ranging from 100 to 900 mm/a,suggesting that robustly reconstructing precipitation changes still poses a signif

关 键 词：黄土高原 黄土-古土壤序列 古温度 古降水 东亚季风 

分 类 号：P532[天文地球—古生物学与地层学]