高斯混合模型在水系沉积物地球化学异常圈定中的应用:以湖南省溆浦地区为例  

Gaussian mixture model in geochemical anomaly delineation of stream sediments:A case study of Xupu,Hunan Province

作　　者：刘旭洋 赵玉岩[2] LIU Xuyang;ZHAO Yuyan(School of Earth Resources,China University of Geosciences(Wuhan),Wuhan 430074 China;College of Geo-Exploration Science and Technology,Jilin University,Changchun 130026,China)

机构地区：[1]中国地质大学(武汉)资源学院,武汉430074 [2]吉林大学地球探测科学与技术学院,长春130026

出　　处：《地质科技通报》2024年第1期122-134,共13页Bulletin of Geological Science and Technology

基　　金：“湖南省国土资源信息中心地球化学找矿信息挖掘服务”项目(湘财采计[2014D]0326号)。

摘　　要：化探数据的正确处理和解译对于区域矿产勘查工作具有重要意义。然而,由于不同类型的岩石具有不同的元素丰度,在处理复杂岩性区化探数据时如果采用统一的异常下限,会导致高背景区被误判为异常区,而部分低弱地球化学异常被忽略。所以复杂岩性区的化探数据需按岩性分类后再划分地球化学背景与异常,从而更准确地圈定化探异常。提出了基于因子得分高斯混合模型的化探异常圈定方法,首先将化探数据做对数比转换后进行因子分析,然后利用因子得分完成高斯混合模型岩性分类,再进行分类标准化处理以消除岩性背景的影响,最后使用处理后的数据圈定化探异常。利用该方法对湖南溆浦地区1∶20万水系沉积物化探数据进行研究,结果表明,成矿元素在研究区不同岩性中的含量存在一定差异,若采用统一的异常下限是不合理的;而本研究提出的方法能准确地进行岩性分类、消除不同岩性的背景和强化低弱异常,且异常位置与已知矿点相吻合。因此,高斯混合模型方法可以准确地圈定复杂岩性区的化探异常,并为研究区下一步的矿产勘查工作提供一些参考依据。[Objective]The correct processing and interpretation of geochemical exploration data are critical for regional mineral exploration.High backgrounds may be misjudged as anomalies or low and weak geochemical anomalies may be ignored,if a unified anomaly threshold is adopted for geochemical exploration data in lithologically complex regions due to different elemental abundances in different lithologies.Therefore,it is essential to identify geochemical backgrounds and anomalies in lithologically complex regions based on lithologic classification.[Methods]Here,we propose a method for delineating geochemical anomalies based on a Gaussian mixture model of factor scores.The geochemical exploration data are subjected to factor analysis after a log-ratio transformation,and then the lithologic classification is completed by the Gaussian mixture model with factor scores.Subsequently,the standardization is performed to eliminate the lithologic background,and geochemical exploration anomalies are delineated with the processed data.This method is used to the geochemical exploration data of 1∶200000 stream sediments in Xupu,Hunan Province.[Results]The results show that the contents of the metallogenic elements in various lithologies of the study area are partly different,and consequently,it would be unreasonable to adopt a uniform anomaly threshold.In contrast,the method advanced in this paper can accurately classify lithology,eliminate the background of different lithologies,and enhance low and weak anomalies,with the location of the anomalies corresponding to known deposits.[Conclusion]Hence,the Gaussian mixture model enables effective delineation of geochemical exploration anomalies in lithologically complex regions and provides certain information for further mineral prospecting in this region.

关 键 词：水系沉积物 岩性背景 化探异常 因子分析 高斯混合模型 湖南溆浦 

分 类 号：P632[天文地球—地质矿产勘探] P628[天文地球—地质学]