Soil Geochemical Characteristics in the Naqu Area,Chongzuo City, Guangxi,and Their Mineral Prospecting Applications

doi:10.19657/j.geoscience.1000-8527.2023.048

Abstract

Abstract:

The Naqu area has significant potential for uranium mineralization,and the molybdenum ore found in association with uranium has considerable value for comprehensive utilization.However,there has been a lack of systematic exploration work on the molybdenum occurrence in this area,hampering the regional molybdenum ore prospecting.To facilitate regional molybdenum ore prospecting,we conducted a 1:10,000 soil geochemical survey.In the survey,we systematic collected 3,295 soil samples,which were analyzed for 10 elements,including Au,Ag,As,Bi,Hg,W,Mo,Cu,V,and Ti.Multi-variant analysis indicates that Mo is a significant ore-forming element in the study area.The original data were conducted to R-type cluster analysis and R-type factor analysis using the SPSS 22 statistical software.The results yield five ore-forming element assemblages: Ag-Cu-V,Bi-Ti-W,As-Mo,Au,and Hg.The contrast anomaly method was utilized to determine the anomalous lower limit of each individual element and their assemblage.Subsequently,the contrast data of each ore-forming element assemblage were processed with the Geochem Studio 3.5 software,which created an anomaly map.Basing on the geological conditions,we proposed three potential prospecting targets,which were then delineated for further investigation.Engineering verification was conducted on the No.1 target through trenching and drilling,revealing the presence of an industrial-grade molybdenum deposit with a Mo grade of 0.11%-0.15%(average 0.112%).Verification of trench engineering was performed in the No.2 target,and analysis of sampled trenches indicates the presence of mineralized molybdenum grade.These findings point to a substantial molybdenum mineralization potential in the Naqu region.

Key words: soil geochemical characteristics, lining value anomaly method, prospecting potential, Naqu area, Chongzuo city of Guangxi

CLC Number:

LUO Haiyi, LUO Xianrong, LIU Panfeng, MA Mingliang, LU Xiansheng, JIANG Xiaoming, BAO Guangui, JIANG Yuxiong. Soil Geochemical Characteristics in the Naqu Area,Chongzuo City, Guangxi,and Their Mineral Prospecting Applications[J]. Geoscience, 2023, 37(06): 1553-1566.

Figures/Tables 15

Fig.1 Geological map and arrangement of soil survey(a) and schematic structural map(b) of the Naqu area

Fig.2 Aeromagnetic ΔT contour map of the West Damingshan area

Fig.3 Schematic geochemical anomaly map(1:200,000) of major metallogenic elements in the West Damingshan area

Table 1 Precision and accuracy of analytical methods for each element

项目	分析方法	检出限 (10^-6)	准确度 Δlg $C -$ _GBW	精密度 RSD(%)
Au	ICP-MS	0.003	0.614	14.304
Ag	ES	0.005	0.001	4.518
Cu	ICP-MS	0.070	0.004	5.314
Mo	ICP-MS	0.100	0.023	6.401
W	ICP-MS	0.300	-0.018	5.507
As	AFS	0.300	0.006	2.042
Hg	AFS	0.001	0.006	3.520
Bi	AFS	0.030	0.005	3.248
Ti	ICP-OES	6.500	0.001	0.378
V	ICP-OES	0.500	-0.001	1.660

Table 1 Precision and accuracy of analytical methods for each element

项目	分析方法	检出限 (10^-6)	准确度 Δlg $C -$ _GBW	精密度 RSD(%)
Au	ICP-MS	0.003	0.614	14.304
Ag	ES	0.005	0.001	4.518
Cu	ICP-MS	0.070	0.004	5.314
Mo	ICP-MS	0.100	0.023	6.401
W	ICP-MS	0.300	-0.018	5.507
As	AFS	0.300	0.006	2.042
Hg	AFS	0.001	0.006	3.520
Bi	AFS	0.030	0.005	3.248
Ti	ICP-OES	6.500	0.001	0.378
V	ICP-OES	0.500	-0.001	1.660

Table 2 Statistics of parameters related to soil geochemical anomalies in the Naqu area

分析元素	Ag	As	Au	Bi	Cu	Hg	Mo	Ti	W	V
样品数(件)	3295	3295	3295	3295	3295	3295	3295	3295	3295	3295
最大值	8.28	12035.00	165.00	14.00	396.00	53.90	231.00	12128.00	153.00	5323.30
最小值	0.02	1.70	0.30	0.03	9.28	0.03	0.26	782.00	0.88	58.67
算术平均值	0.49	89.54	4.34	0.55	61.07	0.56	5.59	3767.59	13.08	409.34
标准差	0.68	286.50	4.67	0.37	41.92	2.12	12.64	1794.05	15.41	505.36
变异系数CV₁	1.40	3.20	1.08	0.67	0.69	3.76	2.26	0.48	1.18	1.24
有效样品数(件)	2919	3032	3129	3265	3095	2935	2821	3273	2243	2971
剔除率(%)	11.41	7.98	5.04	0.91	6.07	10.93	14.39	0.67	31.93	9.83
剔除后最大值	0.99	187.00	10.50	1.31	131.00	0.71	7.58	8889.00	10.50	729.30
剔除后最小值	0.02	1.70	0.30	0.03	9.28	0.03	0.26	782.00	0.88	58.67
剔除后标准差	0.23	44.66	2.27	0.26	25.98	0.15	1.67	1733.63	2.00	148.84
剔除后变异系数CV₂	0.78	0.84	0.61	0.48	0.49	0.58	0.65	0.47	0.44	0.52
研究区背景值	0.30	53.11	3.72	0.54	53.16	0.26	2.57	3728.32	4.56	283.86
广西区域背景值	0.07	15.40	1.42	0.45	23.00	0.11	1.03	4533.00	2.33	93.30
区域浓集系数RCC	4.14	3.45	2.62	1.19	2.31	2.35	2.49	0.82	1.96	3.04

Fig.4 Dispersion diagram of soil elements in the Naqu area

Fig.5 Cluster analysis pedigree of related elements in the Naqu area

Table 3 Rotated orthogonal factors and cumulative variance contributions

元素	F₁	F₂	F₃	F₄	F₅
Ag	0.918	-0.195	0.039	-0.012	0.039
As	-0.041	0.124	0.904	0.056	-0.007
Au	0.079	0.130	0.050	0.949	0.001
Bi	0.031	0.775	0.052	0.043	-0.017
Cu	0.702	0.117	0.006	0.501	-0.020
Hg	0.044	-0.009	0.073	-0.003	0.995
Mo	0.139	-0.026	0.899	0.001	0.093
Ti	-0.211	0.873	0.026	-0.027	-0.006
W	-0.059	0.871	0.033	0.210	0.010
V	0.939	-0.092	0.070	0.011	0.036
特征值	2.665	2.304	1.554	0.970	0.865
方差贡献率(%)	26.647	23.040	15.539	9.700	8.655
累积方差贡献率(%)	26.647	49.687	65.226	74.926	83.581

Table 4 Statistical characteristics of soil geochemical contrast parameters in the Naqu area

分析元素	平均值	标准差	衬度平均值	衬度标准差	衬度外带值	衬度中带值	衬度内带值
Ag	1.630	2.281	0.993	0.766	2.525	5.050	10.100
As	1.686	5.394	1.000	0.841	2.682	5.364	10.728
Au	1.167	1.254	1.000	0.611	2.222	4.444	8.888
Bi	1.025	0.684	1.001	0.484	1.969	3.938	7.876
Cu	1.149	0.788	1.000	0.489	1.978	3.956	7.912
Hg	2.174	8.176	0.998	0.576	2.150	4.300	8.600
Mo	2.178	4.925	1.000	0.652	2.304	4.608	9.216
Ti	1.011	0.481	1.000	0.465	1.930	3.860	7.720
W	2.866	3.377	1.000	0.439	1.878	3.756	7.512
V	1.442	1.780	1.000	0.524	2.048	4.096	8.192
Ag-Cu-V	—	—	3.066	1.668	6.402	12.804	25.608
W-Bi-Ti	—	—	4.716	3.831	12.378	24.756	49.512
As-Mo	—	—	2.223	1.541	5.305	10.610	21.220

Fig.6 Contrast anomaly maps of F1(a) and F2(b) in the Naqu area

Fig.7 Anomaly of factor score for F3(a) and contrast anomaly map of F3(b) in the Naqu area

Fig.8 Contrast anomaly maps of F4(a) and F5(b) in the Naqu area

Fig.9 Prospecting target area prediction and engineering verification map of the Naqu area

Table 5 Analysis results of TC1901,TC1908 and TC1910 grooved chemical samples from the Naqu area

工程编号	样品号	岩性	Mo含量(%)
TC1901	TC1901H1	泥岩蚀变带	0.150
	TC1901H2	泥岩蚀变带	0.049
	TC1901H3	泥岩蚀变带	0.050
	TC1901H4	泥岩蚀变带	0.074
TC1908	TC1908H2	硅质岩	0.019
TC1910	TC1910H3	硅质岩	0.026
	TC1910H4	硅质岩	0.030
	TC1910H7	硅质岩	0.016

Fig.10 ZK001 drilling cores of molybdenum orebody

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