矿源地球化学元素在黄土覆盖层中纵向长程研究

The study of the migration of geochemical elements in different medium has been brought to the attention of the scientific community. The resulted deep penetrating geochemical method has played a unique role in deep prospecting. The identification and extraction method and technology for the weak and slow anomaly in the surface of overburden area based on the multifractal theory have made a large number of landmark achievements. The thick loess cover is chosen to be our particular study object. The spatial content sequences in the order of embedded depth of ore-sourced geochemical elements both in ungraded and graded samples taken from the long vertical core of the loess cover above a known deposit are considered to be the results of coupling and superposition of multi-scale migration mechanisms. The coupling and superposition process is cascade, the result of which is multifractal. Spatial statistical modeling methods will be used to study the correlation of the geochemical elements in the (element×depth ×grade) three dimensions. The power-law test and multifractal spectrum test will be used to test which sequences have fractal and multifractal distribution characteristics. It is designed to use all those known multifractal spectrum decomposition method to decompose the content sequences of elements or element combinations, to inverse the characteristics of those mechanism driving the long-term migration of the ore-sourced geochemical elements in the loess medium and the coupling mechanisms among the multi-scale mechanisms. Our aim of this study is to provide theoretical support for explaining the formation and recognition of the surface geochemical anomalies in the loess covered area and, also provide references to the study of geochemical element migration mechanisms in other types of coverings.

地球化学元素在不同介质中的迁移研究一直受到科学界的重视，形成的深穿透地球化学方法在深部找矿中发挥了独特的作用，基于多重分形理论的覆盖区地表弱缓异常识别和提取方法和技术取得了大量标志性成果。本研究选择厚黄土覆盖为特定对象，将已知矿床上方纵向长岩芯中混合粒级和分粒级按埋深顺序的矿源地球化学元素的含量组成的空间序列视作多尺度元素迁移机制的耦合和叠加的结果，其耦合和叠加是串级过程，其结果是多重分形，用空间统计建模的方法研究地球化学元素在(元素×深度×粒级)三个维度上的相关性，用幂率关系和多重分形谱检验空间序列的分形和多重分形分布特征，进而尝试用多种多重分形谱分解的方法分解元素和元素组合的含量序列，反演驱动矿源地球化学元素在黄土介质中长程迁移的不同尺度机制的特征和多尺度机制的耦合特征，为解释黄土覆盖区地表地球化学异常的形成和识别提供理论支持，也为其它类型覆盖层中地球化学元素的迁机制研究提供方法借鉴。

按照项目的设计进行了充分的野外勘察、研究区地质背景研究，在此基础上定位采样131个、将每个样本筛成4个粒级，对每个粒级的样品测试了Mn 、Cu 、Zn 、As、 Mo 、Pb、S、K等40种元素的含量，得到131×4×40顺序含量数据库。用非参数Kendall-τ方法研究了覆盖层纵向剖面40种元素与埋深的非线性相关关系，发现18种主要成矿元素存在明显的迁移趋势。用HP滤波法提取18种元素的迁移趋势，用函数聚类法对其进行了模式分类。用多种多重分形谱分解的方法分解元素和元素组合的含量序列，反演驱动矿源地球化学元素在黄土介质中长程迁移的不同尺度机制的特征和多尺度机制的耦合特征，发现单一成矿元素或成矿因子在呈纵向上呈不同单分形分布，而多种成矿元素单分形在空间上扭结形成多重分形，它是多尺度耦合、叠加过程形成的串级过程结果，也是覆盖层表层的地球化学弱缓异常形成的原因。用机器学习的方法研究纵向剖面矿源地球化学元素地球物理和地球化学性质，发现与矿化相关性前10强频段的反射强度以方差贡献率为权重的线性组合对矿化的识别程度高。 . 以上成果可以作为相关研究的理论基础，也可以作为发展覆盖区地球化学弱缓异常识别方法的依据，开辟了很有前景的新研究方向。课题组将研究范围延拓到与成矿过程相关的矿产资源领域，吸收了大量的新兴研究方法，取得了丰富的研究成果。. 在Journal of Geophysical Research，Renewable and Sustainable Energy Reviews，Energy，Minerals，Natural Resources Research，Geophysical Research Letters，Energies, Resources Policy，International journal of environmental research public health，资源科学等期刊发表论文24篇，其中SCI或SSCI检索18篇；会议论文4篇；国际会议论文摘要5篇。参加国际地质大会IGC，国际数学地球科学学会年会IAMG，国际能源经济大会IAEE等8人次。培养硕士研究生8人，博士研究生6人，2人获得国家奖学金，2人获得国家留学基金委资助在国外知名大学联合培养。期间项目组两名年轻学者获得国家自然科学基金资助并晋升为副教授。