Physical property characterization of rocks in the Bayan Obo REE-Nb-Fe deposit, China

IF 3 2区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Geophysics Pub Date : 2023-12-06 DOI:10.1190/geo2023-0439.1

Lili Zhang, Hongrui Fan, Jian Wang, Liang Zhao, Kuifeng Yang, Ya Xu, Yonggang Zhao, Xingwang Xu, Meizhen Hao, Zhanfeng Yang, Xianhua Li

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引用次数: 0

Abstract

Bayan Obo ore deposit is the world’s largest rare-earth element (REE) resource, the second largest niobium (Nb) resource, and also a significant iron (Fe) resource in China. Evaluating resource potential for the deposit has become a focus of global interest. Rock physical properties bridge geophysical exploration and geological modeling; variation in these parameters is necessary for successful geophysical application. REE, Nb, iron, and potassium are mainly hosted in dolomite and slate in the Bayan Obo Group, and REE mineralization is genetically associated with carbonatite. Three physical properties (resistivity, polarizability, and magnetic susceptibility (MS)) of iron ore, slate, dolomite, and carbonatite dike outcrop samples at Bayan Obo are measured and statistically analyzed using three-dimensional reconstruction, one-/two-/three-dimensional kernel density estimation, scatterplot matrix, three-dimensional histogram, and Pearson- and maximum-information-coefficient-based correlation analysis. It is evident that iron ore, iron-mineralized fine-grained dolomite, and iron-mineralized slate are mainly of low resistivity, and iron ore and iron-mineralized fine-grained dolomite have high MS. MS favorably distinguishes iron ore from slate; MS and resistivity distinguish between iron-mineralized fine-grained dolomite and carbonatite dikes. The physical properties and whole rock geochemistry (major and trace elements) jointly demonstrate that MS of iron ore, slate, and dolomite is positively correlated with TFe2O3 content, polarizability is correlated with TFe2O3, SiO2 content is correlated with K2O, and resistivity is correlated with MS and polarizability respectively. Resistivity of iron ore and dolomite is negatively correlated with TFe2O3 content. Resistivity of iron ore is negatively correlated with TFe2O3, total rare-earth element (REE), and Nb, respectively, and correlated with thorium. The methods used have intuitive visual expression and reflect the characteristics of the physical properties and their correlation with the mineralogical composition. The results will be beneficial to determining the geometry of ore-hosting rock masses and providing crucial evidence for the resource evaluation.

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中国巴彦鄂博 REE-Nb-Fe 矿床岩石的物理性质表征

巴彦奥博矿床是世界上最大的稀土元素（REE）资源、第二大铌（Nb）资源，也是中国重要的铁（Fe）资源。评估该矿床的资源潜力已成为全球关注的焦点。岩石物理性质是地球物理勘探和地质建模的桥梁；这些参数的变化是地球物理应用取得成功的必要条件。REE 、Nb、铁和钾主要赋存于巴彦奥博组的白云岩和板岩中，REE 矿化在遗传上与碳酸盐岩有关。利用三维重建、一/二/三维核密度估计、散点图矩阵、三维直方图以及基于皮尔逊和最大信息系数的相关分析，对巴彦奥博的铁矿、板岩、白云岩和碳酸盐岩堤露头样品的三种物理性质（电阻率、极化率和磁感应强度（MS））进行了测量和统计分析。结果表明，铁矿石、铁矿化细粒白云岩和铁矿化板岩的电阻率主要较低，铁矿石和铁矿化细粒白云岩的 MS 值较高。MS值可将铁矿石与板岩区分开来；MS值和电阻率可将铁矿化细粒白云岩与碳酸盐岩尖晶石区分开来。物理性质和全岩地球化学（主要元素和微量元素）共同表明，铁矿石、板岩和白云岩的MS与TFe2O3含量成正相关，极化率与TFe2O3成正相关，SiO2含量与K2O成正相关，电阻率分别与MS和极化率成正相关。铁矿石和白云石的电阻率与 TFe2O3 含量呈负相关。铁矿石的电阻率分别与 TFe2O3、稀土元素总量和铌呈负相关，与钍呈正相关。所采用的方法具有直观形象的表达效果，反映了物理性质的特点及其与矿物成分的相关性。研究结果将有助于确定矿床岩体的几何形状，为资源评价提供重要依据。

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来源期刊

Geophysics 地学-地球化学与地球物理

CiteScore

6.90

自引率

18.20%

发文量

354

审稿时长

3 months

期刊介绍： Geophysics, published by the Society of Exploration Geophysicists since 1936, is an archival journal encompassing all aspects of research, exploration, and education in applied geophysics. Geophysics articles, generally more than 275 per year in six issues, cover the entire spectrum of geophysical methods, including seismology, potential fields, electromagnetics, and borehole measurements. Geophysics, a bimonthly, provides theoretical and mathematical tools needed to reproduce depicted work, encouraging further development and research. Geophysics papers, drawn from industry and academia, undergo a rigorous peer-review process to validate the described methods and conclusions and ensure the highest editorial and production quality. Geophysics editors strongly encourage the use of real data, including actual case histories, to highlight current technology and tutorials to stimulate ideas. Some issues feature a section of solicited papers on a particular subject of current interest. Recent special sections focused on seismic anisotropy, subsalt exploration and development, and microseismic monitoring. The PDF format of each Geophysics paper is the official version of record.