结构方程模型在地球化学数据分析中的应用

Application of Structural Equation Modeling in Geochemical Data Analysis

为了实现通过确定地球化学组合元素来反映成矿异常,本文在主成分分析模型的基础上,引入了新的结构方程模型(SEM).与主成分所不同的是,结构模型综合了经典统计方法中的因子分析和路径分析方法,以与研究对象具有较好的拟合度为标准来确定最优解,并通过模型最优解来确定新的成分组合,因此结构模型所确定的成分变量不一定是具有最大变化性,而是与研究对象最接近的因子变量,该因子能够更好地反映研究对象.介绍了结构方程模型方法的原理,并利用加拿大Nova Scotia省西南部湖泊沉积物地球化学数据建立了与热液型金矿有关的地球化学元素结构方程模型,研究了结构方程模型所给出的组合变量空间分布规律以及与金矿床的关系.与主成分分析方法所给出的计算结果进行对比发现,结构模型所计算的与金矿相关的组合变量与矿床的空间相关性较高,并且对金矿床(矿点)也具有较好的预测性.

In order to find a combination of geochemical elements reflecting the abnormal mineralization,this paper provides a method of structural equation modeling（SEM）for geochemical data processing based on principal component analysis（PCA）.Different from the PCA,the structural equation model takes the favorable fitness with studying object as the criterion to determine the optimal solution,through which the new component will be determined;it is a combination of factor analysis and path analysis.Therefore,the component determined by the structural model is not necessarily the one with the largest variability,but the one closest to the object of study,which can thus better reflect the research target.This study not only describes the principle of structural equation modeling,but also makes use of it in the geochemical data analysis experiment.The geochemical data is measured from lake sediments samples obtained from the Southwest Nova Scotia,Canada,a model of geochemical elements related to the hydrothermal fluid gold mine is established.The spatial distribution law of the composite variables given by the structural model,and the relation between those variables and the gold deposits as well,is studied.A comparison with those of the PCA results shows that the factor variables related to the gold mine computed by the structural equation modeling are highly correlated to the space of the gold deposits,and they can also better predict the gold deposits.