关中东部全新世黄土—古土壤序列粒度组分变化特征及古气候意义  

Characteristics of Holocene Loess-Palaeosol Particle Size Composition and Paleoclimatic Significance in East Guanzhong,Shaanxi Province

作　　者：王兆夺 黄春长 周亚利 庞奖励 查小春 Wang Zhaoduo;Huang Chunchang;Zhou Yali;Pang Jiangli;Zha Xiaochun(Department of Geography Shannxi Normal University National Demonstration Center for Experimental Geography Education, Xi＇ an 710119 ,China)

机构地区：[1]陕西师范大学地理科学与旅游学院地理学国家级实验教学示范中心,陕西西安710119

出　　处：《地球科学进展》2018年第3期293-304,共12页Advances in Earth Science

基　　金：国家自然科学基金项目"黄河上游官亭盆地全新世群发性重大自然灾害发生年代与成因机制研究"(编号:41771110);中央高校基本科研业务费专项"全新世黄土古土壤序列高分辨率沉积旋回划分"(编号:GK201704013)资助~~

摘　　要：通过在陕西关中东部的一条全新世黄土古土壤剖面(尧禾村剖面)进行高分辨率采样,对150个样品的粒度数据做了端元分析,并进一步对各端元组分含量在深度变化的时间尺度上做了小波变换。粒度端元分析结果认为,可以把代表3种不同沉积动力以及改造动力的组分端元分离出来。并结合磁化率、地球化学指标的对比分析,初步认为,尧禾村剖面端元1可能代表了沉积物沉积后在东亚夏季风作用下的风化及成壤改造作用;端元2可能代表了东亚冬季风作用下典型的风成黄土组分特征;端元3可能代表了区域东北风或北风搬运的近源沉积物。小波分析认为,各端元所代表的动力强弱大致在1.5,3.0和4.5 ka的尺度上具有较为明显的准周期性。通过对沉积物进行粒度端元划分,在识别沉积物沉积动力环境和物源特征上具有良好的效果,各端元组合特征能够很敏感地反映出沉积动力组合特征,对全新世各动力变化特征能够很好地反映,同时在更长时间尺度上重建古季风气候具有参考意义,应用小波分析对划分相应时间尺度上的周期性和推断未来可能的变化趋势提供了可能。This paper made an end-member analysis of particle size data collected from 150 samples based on the continuous Holocene Loess-Paleosol profile （Yaohecun profile） in east Guanzhong, Shaanxi Province. Wavelet analysis was also performed for the EMs along the time scale of depth.The result shows that three end members can be separated from different sediment particle sizes. Based on comparative analysis of magnetic susceptibility and ge- ochemical index, it was considered that the End-member 1 might indicate the weathering and pedogenic remoulding after sediment deposition under the east Asian summer monsoon. The End-member 2 might indicate dynamic effect of dust storm accumulation under the influence of northwest monsoon, representing typical component characteristics of aeolian loess.The End-member 3 indicated the stronger transporting force for coarse components, which should belong to the northeasterly winds for the coarse-grained near-source sediments from the Yellow River flood plain. Results of wavelet analysis show that each EM has different periodic characteristics at 1.5 ka, 3.0 ka and 4.5 ka scales.The End-element analysis method has a good effect in indicating the sedimentary environment and provenance characteristics of sediments. The combination characteristics of each End-member can reflect the characteristics of sedimentary dynamics combination and can well reflect the Holocene dynamic change course. At the same time, it hasreference significance to reconstruct the paleoclimate on the longer time scale.The wavelet analysis method pro- vides significant results in terms of inversion cycles and trends of dynamics change of sedimentary particle size with- in each EM.

关 键 词：全新世 黄土-古土壤 粒度 端元分析 古气候 

分 类 号：P642.131[天文地球—工程地质学] F129.9[天文地球—地质矿产勘探]