玛曲谷地3 ka以来气候变化对黄河一级阶地土壤发育过程的影响  

Soil development process depending on climate change in the first terrace of the Yellow River in Maqu valley since 3 ka

作　　者：庞奖励 黄春长 周亚利 查小春 王忻宇 赵晓康 周家和 李瑜琴 张玉柱[2] PANG Jiangli;HUANG Chunchang;ZHOU Yali;ZHA Xiaochun;WANG Xinyu;ZHAO Xiaokang;ZHOU Jiahe;LI Yuqin;ZHANG Yuzhu(School of Geography and Tourism,Shaanxi Normal University,Xi’an,Shaanxi 710119,China;College of Urban and Environmental Sciences,Northwest University,Xi’an,Shaanxi 710127,China)

机构地区：[1]陕西师范大学地理科学与旅游学院,陕西西安710119 [2]西北大学城市与环境学院,陕西西安710127

出　　处：《地质学报》2024年第7期2269-2280,共12页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号42271046,41971116,42277449,42071112)资助的成果。

摘　　要：青藏高原东部若尔盖盆地不同地貌位置发育了较好的黄土-古土壤序列,但目前关于这些风积物的时间序列、空间分异及其对地表过程的指示意义尚不十分清楚。本文根据野外考察所获资料和实验室数据,针对这些问题进行分析论述,成果可为准确理解若尔盖古湖泊消亡后,该地区风沙活动的盛衰变化、风化成土强度变化和气候变化规律及其他们之间的关系提供直接证据。选择黄河一级阶地玛曲老桥西(LQX)剖面为探究对象,对其剖面构型、磁化率、地球化学、微形态等进行研究,用光释光(OSL)方法进行测年断代。研究认为:在若尔盖盆地普遍发育多周期土壤,但不同地貌位置发育的黄土-古土壤序列的时间序列和构型并不相同。LQX剖面具有MS0-MS1-L-MS2-L构型,为近3.0 ka以来连续发育所成,风沙活动强度变化是影响土壤连续发育的主要原因;矿物组合、CIA、Rb/Sr比值、磁化率等数据指示该剖面整体处于低级风化强度阶段,土壤层风化成土强度有所增加,但增强的幅度有限;5~4 ka形成的黄河一级阶地为风成堆积和保存提供了有利条件,3.0 ka前后区域气候转向较干旱,风沙活动较强形成了黄土L。1.5 ka前后,气候向较湿润方向转化,降水增加,地面的水热条件有利于草甸类植物生长,形成土壤层MS2。0.6 ka前后,出现短暂的气候较干旱时段,土壤发育中断,风尘堆积加剧形成约30 cm厚的黄土。0.3/0.4 ka始,气候干旱降低,风沙活动减弱,土壤又重新发育,形成MS1+MS0。In the Zoige basin,located in the Eastern Tibet Plateau,several loess-paleosol sequences have formed in different geomorphological locations.However,the spatio-temporal variation of these eolian deposits and their geographical significance to surface processes remain unclear.This paper aims to address these issues by analyzing material obtained from detailed field investigations and experimental data.The results provide direct evidence for accurately understanding the relationship between paleoclimate evolution,sandstorm activity fluctuations,and changes in weathering intensity since the disappearance of ancient Zoige Lake.Extensive and detailed field surveys were conducted in the Zoige basin in the eastern Tibetan Plateau.The Laoqiaoxi(LQX)site,situated on the first river terrace of the Yellow River in the Maqu reach,was selected as the research focus and systematically sampled.Through a comprehensive study of various proxies,such as soil profile structure,magnetic susceptibility,geochemistry,micromorphology,and optically stimulated luminescence(OSL)dating,the following conclusions were obtained:①Multi-period soils are commonly found in the Zoige basin,with different loess-paleosol sequences developing in various landform locations.The LQX profile has been continuously developing since 3.0 ka,with a stratigraphic sequence from top to bottom(MS0-MS1-L-MS2-L).The variation in aeolian activity intensity primarily influences the continuous soil development.②Mineral assemblage data,CIA,Rb/Sr ratio,and magnetic susceptibility indicate that the LQX profile exhibits a stage of low weathering intensity.The weathering intensity slightly increases from the loess layer to the soil layer.③The relationship between paleoclimate evolution and soil development in the Maqu valley can be summarized as follows:Around 3.0 ka,the regional climate became dry,and the loess(L)layer formed due to intense aeolian sand activities.Approximately 1.5 ka ago,the climate gradually became warmer,with increased precipitation providing favor

关 键 词：若尔盖盆地 黄河一级阶地 多周期土壤 微形态 气候变化 

分 类 号：S151[农业科学—土壤学]