Zhiqiang Xu, Bin Liang, Hui Jiang, Ting Liu, Qiubo Wang, Jiaxin Duan, Bangqiao Chen, Yangpiao He
{"title":"Factor analysis of geogas data for concealed lithium deposits detection and false anomalies identification in Jiajika area","authors":"Zhiqiang Xu, Bin Liang, Hui Jiang, Ting Liu, Qiubo Wang, Jiaxin Duan, Bangqiao Chen, Yangpiao He","doi":"10.1016/j.gexplo.2024.107511","DOIUrl":null,"url":null,"abstract":"<div><p>The Jiajika hardrock-type rare metal deposit in western Sichuan, China, is considered the largest spodumene deposit in Asia. The quaternary overburden of this area leads to ineffectiveness for ore prospecting using geochemical soil and geochemical stream sediment surveys. Although geogas prospecting has been proven to be effective in exploring buried orebodies, it is seldom deployed to explore concealed lithium deposits. In this work, the geogas samples were collected using the dynamic collection technique along the traverses over three concealed lithium deposits, namely, V-804, V-X03 (Line 7 and Line 35 were selected for sampling, denoted as V-X03–7 and V-X03–35, respectively), and V-STG. The samples were also collected from a Li-poor pegmatite (V-CLZ). The concentrations of Li, Be, Rb, Cs, Nb, Ta, Sn, B, Sr, Ba, and W in the nitric acid collector were measured by performing inductively coupled plasma-mass spectrometry (ICP-MS) measurements. The nanoparticles in geogas were analysed by using a transmission electron microscope coupled with performing energy dispersive spectroscopy (TEM-EDS) measurements. Apparent anomalies of Li, Be, Rb, Cs, B, and Sr were observed on all the traverses. These elements are regarded as pathfinders for the detection of concealed lithium deposits. Clear anomalies of Li, Be, Rb, Sn, B, and Sr were also found over V-CLZ. The concentrations of these elements in the nitric acid solutions were close to those over V-X03–35 and V-STG. The pathfinders are thus not effective in accurately recognizing the false anomalies over Li-poor pegmatite. The TEM-EDS measurements are not suitable for the characterization of nanoparticles in the Jiajika area because the particles from Li-rich and Li-poor pegmatites exhibited similarities in their morphologies. In addition, Li and Be cannot be detected by studying the EDS spectra, and the disturbance from the high background was non-negligible. To effectively address these issues, factor analysis (FA) was conducted on the concentrations of Li, Be, Rb, Cs, Nb, Ta, and Sn in geogas. The synthesis score (SSC) was computed based on three factors extracted by FA. At some sampling sites over V-804, V-X03, and V-STG, the SSC values were larger than 0.25, whereas the maximum SSC over V-CLZ was 0.15. Therefore, FA of geogas data is arising as a feasible method to detect concealed lithium deposits and identify false anomalies in the Jiajika area. The elemental concentrations in the samples from V-X03–7 were much higher than those from the other veins. This effect was attributed to the migration of the elements from buried orebodies to the ground surface, which was possibly promoted by the tourmalinized hornfels.</p></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":null,"pages":null},"PeriodicalIF":3.4000,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Geochemical Exploration","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0375674224001274","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
The Jiajika hardrock-type rare metal deposit in western Sichuan, China, is considered the largest spodumene deposit in Asia. The quaternary overburden of this area leads to ineffectiveness for ore prospecting using geochemical soil and geochemical stream sediment surveys. Although geogas prospecting has been proven to be effective in exploring buried orebodies, it is seldom deployed to explore concealed lithium deposits. In this work, the geogas samples were collected using the dynamic collection technique along the traverses over three concealed lithium deposits, namely, V-804, V-X03 (Line 7 and Line 35 were selected for sampling, denoted as V-X03–7 and V-X03–35, respectively), and V-STG. The samples were also collected from a Li-poor pegmatite (V-CLZ). The concentrations of Li, Be, Rb, Cs, Nb, Ta, Sn, B, Sr, Ba, and W in the nitric acid collector were measured by performing inductively coupled plasma-mass spectrometry (ICP-MS) measurements. The nanoparticles in geogas were analysed by using a transmission electron microscope coupled with performing energy dispersive spectroscopy (TEM-EDS) measurements. Apparent anomalies of Li, Be, Rb, Cs, B, and Sr were observed on all the traverses. These elements are regarded as pathfinders for the detection of concealed lithium deposits. Clear anomalies of Li, Be, Rb, Sn, B, and Sr were also found over V-CLZ. The concentrations of these elements in the nitric acid solutions were close to those over V-X03–35 and V-STG. The pathfinders are thus not effective in accurately recognizing the false anomalies over Li-poor pegmatite. The TEM-EDS measurements are not suitable for the characterization of nanoparticles in the Jiajika area because the particles from Li-rich and Li-poor pegmatites exhibited similarities in their morphologies. In addition, Li and Be cannot be detected by studying the EDS spectra, and the disturbance from the high background was non-negligible. To effectively address these issues, factor analysis (FA) was conducted on the concentrations of Li, Be, Rb, Cs, Nb, Ta, and Sn in geogas. The synthesis score (SSC) was computed based on three factors extracted by FA. At some sampling sites over V-804, V-X03, and V-STG, the SSC values were larger than 0.25, whereas the maximum SSC over V-CLZ was 0.15. Therefore, FA of geogas data is arising as a feasible method to detect concealed lithium deposits and identify false anomalies in the Jiajika area. The elemental concentrations in the samples from V-X03–7 were much higher than those from the other veins. This effect was attributed to the migration of the elements from buried orebodies to the ground surface, which was possibly promoted by the tourmalinized hornfels.
期刊介绍:
Journal of Geochemical Exploration is mostly dedicated to publication of original studies in exploration and environmental geochemistry and related topics.
Contributions considered of prevalent interest for the journal include researches based on the application of innovative methods to:
define the genesis and the evolution of mineral deposits including transfer of elements in large-scale mineralized areas.
analyze complex systems at the boundaries between bio-geochemistry, metal transport and mineral accumulation.
evaluate effects of historical mining activities on the surface environment.
trace pollutant sources and define their fate and transport models in the near-surface and surface environments involving solid, fluid and aerial matrices.
assess and quantify natural and technogenic radioactivity in the environment.
determine geochemical anomalies and set baseline reference values using compositional data analysis, multivariate statistics and geo-spatial analysis.
assess the impacts of anthropogenic contamination on ecosystems and human health at local and regional scale to prioritize and classify risks through deterministic and stochastic approaches.
Papers dedicated to the presentation of newly developed methods in analytical geochemistry to be applied in the field or in laboratory are also within the topics of interest for the journal.