| 赣北风沙-粉尘堆积体系元素地球化学变化特征及其对黄土物源示踪意义 |
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| 引用本文： | 曹向明,钟威,张智,贾玉连,薛滨,万智巍,李晓峰,凌超豪.赣北风沙-粉尘堆积体系元素地球化学变化特征及其对黄土物源示踪意义[J].第四纪研究,2020(1):203-213. |
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| 作者姓名： | 曹向明 钟威 张智 贾玉连 薛滨 万智巍 李晓峰 凌超豪 |
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| 作者单位： | 江西师范大学地理与环境学院;枣庄学院旅游与资源环境学院;中国科学院南京地理与湖泊研究所;中国科学院大学 |
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| 基金项目： | 江西省重大生态安全问题监控协同创新中心项目(批准号:JXS-EW-00);国家自然科学基金项目(批准号:41262007);鄱阳湖湿地与流域研究教育部重点实验室(江西师范大学)开放基金项目(批准号:PK2018004);江西省教育厅科学技术研究项目(批准号:8884)共同资助。 |
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| 摘 要： | 粉尘的搬运与堆积过程,理论上是不同粒径的岩屑与矿屑颗粒被风力分选并依次沉降的过程,而元素在不同粒级的岩屑与矿屑的富集程度有所差异;因此,对岩屑与矿屑颗粒分选,在一定程度上是对地球化学元素的分选。因此,基于元素地球化学对黄土粉尘示踪研究中,单一节点或(和)剖面均不具有对粉尘源区的严格代表性,通过比较单一节点或剖面的元素地球化学而进行物源示踪的方法往往存在较大的不确定性。本文通过对中亚热带赣北鄱阳湖地区芙蓉-周溪一带的风沙-粉尘堆积体系常量和微量元素的多维度统计分析,发现地球化学元素及其元素对均存在系统性的分选与分异特点。稳定元素(如Al、Ti、Zr、Nb、Lu、Hf、Ta)及其元素对随距物源区的远近呈现线性、指数或对数等的单向变化特点,其变化幅度在沉积体系中可达31%~42%;在二维和三维散点图中其元素对的投影轨迹,是一个有方向的线状或者带状区域。这表明,风沙-粉尘堆积体系内元素地球化学从上风向到下风向是单调变化的,传统上基于元素地球化学的黄土粉尘物源示踪,通过判断投影区域的远近而进行示踪分析,在理论上有一定缺陷。初步建议,未来的元素地球化学示踪应避免单一剖面元素示踪的方法,而应根据粉尘堆积体系的分布情况系统采样,通过揭示粉尘堆积体系元素地球化学的系统特征来开展基于地球化学元素的黄土粉尘物源示踪研究。
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| 关 键 词： | 赣北鄱阳湖地区 风沙-粉尘堆积体系 元素的分选与分异 黄土粉尘示踪 |
THE SYSTEMATIC VARIATION OF GEOCHEMISTRY IN FURONG-ZHOUXI AEOLIAN SAND-DUST DEPOSITAL CELL IN MIDDLE AND LOWER REACHES OF YANGTZE RIVER AND ITS IMPLICATIONS FOR PROVENANCE OF LOESS |
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| Cao Xiangming,Zhong Wei,Zhang Zhi,Jia Yulian,Xue Bin,Wan Zhiwei,Li Xiaofeng,Ling Chaohao.THE SYSTEMATIC VARIATION OF GEOCHEMISTRY IN FURONG-ZHOUXI AEOLIAN SAND-DUST DEPOSITAL CELL IN MIDDLE AND LOWER REACHES OF YANGTZE RIVER AND ITS IMPLICATIONS FOR PROVENANCE OF LOESS[J].Quaternary Sciences,2020(1):203-213. |
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| Authors: | Cao Xiangming Zhong Wei Zhang Zhi Jia Yulian Xue Bin Wan Zhiwei Li Xiaofeng Ling Chaohao |
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| Institution: | (Key Laboratory of Poyang Lake Wetland and Watershed Research,Ministry of Education,School of Geography and Environment,Jiangxi Normal University,Nanchang 330022,Jiangxi;College of Tourism,Environmental Resource,Zaozhuang University,Zaozhuang 277160,Shandong;State Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Science,Nanjing 210008,Jiangsu;University of Chinese Academy of Sciences,Beijing 100049) |
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| Abstract: | Enrichment states of elements in various size particles are different.Therefore,theoretically,the process of entrainment transportation and accumulation of aeolian particles in which lithic and ore fragments of different particles are sorted by wind and settled successively at various landforms is the sorting and separating process of geochemical elements to some extent.Therefore,the element geochemistry research of loess provenance tracing by comparing element geochemistry of few loess sections which does not have a strict representation of loess source remains much uncertainty.Furong-Zhouxi aeolian sand-dust deposital cell formed during the last glacial period(90~10 ka B.P.)in the Poyang Lake area in the central subtropical region of East Asia presents a thining loess stratigraphy of distance south of the Yangtze River from 4~16 m thick in Furong Town upwind to 1.0~2.5 m thick in Zhouxi Town downward.Nine sections were sampled along Furong-Zhouxi transection,41 loess samples were obtained to measure geochemistry elements by XRF(major elements)and ICP-MS(minor elements)methods.Based on multi-dimensional statistical analysis of the major and minor elements of this deposital cell,it is found that the geochemical elements and their pairs have systematic sorting and differentiation characteristics.Undoubtedly,at pedogenic process weathering and leaching of mobile elements including Mg,Ca,Na,P,Be,Co,Sr,Tl,Pb and Bi,and unstable elements K,Sc,V,Ga,Rb,Ba,Th and light rare earth elements(La-Tb)significantly impacted their geochemistry composition and distribution at this cell,whereas stable elements including Al,Fe,Ti,Mn,Li,Y,Zr,Nb,Hf,Ta,U and heavy rare earth elements(Dy-Lu)probably mainly indicated the systematic sorting and differentiating characteristics of lithic and ore fragments particles at this cell.Stable elements,such as Al,Ti,Zr,Nb,Lu,Hf,Ta and their pairs show linear,exponential,logarithmic function of distance south of the potential source area-the Yangtze River channel with relative variation of 31%~42%in this cell;and the projected track of loess samples in two-dimensional or three-dimensional scatter diagrams is a directional line or belt.This kind of monotonous changing of the element geochemistry in this aeolian deposital cell suggests that the traditional method of provenance tracing based on element geochemistry exhibit certain theoretical defects by judging the distance of plotting areas.This paper preliminarily advises that the method of single section as element tracer would necessarily be avoided in future work,and systematic sampling should be carried out according to the geographical distribution of aeolian accumulational cell,then by revealing the systematic characteristics of element geochemistry of aeolian accumulational cell to implement provenance tracing on geochemical elements. |
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| Keywords: | Poyang Lake area in northern Jiangxi the aeolian sand-dust cell element sorting and and differentiating loess provenance tracing |
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