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| Geochemical characteristics of strata of Lower Cambrian Shuigoukou Formation in Southern Qinling and their implications for prospecting |
| Jun YOU1,2, Hong-Yuan CAO1, Feng-Jun ZHANG1, Wen-Chun CAI1, Jing-Chen LI1, Peng-Tao SHE1 |
1. Shaanxi Center of Geological Survey, Xi'an 710068, China
2. Shaanxi Institute of Geological Survey, Xi'an 710054, China |
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Abstract The black rock series of the lower Cambrian Shuigoukou Formation exposed in Zhongcun-Xianghe area lies in the middle belt of Qinling area, and constitutes the typical strata of the black rock series and the main ore-bearing layer for gold and vanadium ore deposits in this area. The strata consist of a set of carbon, silica, argillite and carbonite formations, and the rocks include silicalite, carbonaceous silicalite, claystone, carbonaceous limestone, and carbonaceous-siliceous slate, which contain P-Mn nodules locally. Geochemical research on the strata reveals the following phenomena: Firstly, rocks are obviously rich in V, Au, Ag, Cu, Zn, Mo, Ni, Pt and Pd, and experienced intense differentiation and obvious superimposition-reformation, which was geochemically favorable for mineralization. Secondly, P-Mn nodules, claystones and silicalites are the most advantageous types of ore-bearing rocks. Thirdly, the values of ore-forming elements, especially V, Ni, Zn, Cu, Ag, U, PGE and the grade of ores are closely related to the content of carbon (TOC%) in the rocks. What's more, the distribution of deposits related to the black rock series of the Shuigoukou Formation is characterized by Au (Ag) in the western part and V in the eastern part, Au-V in the northern part and and Ag-V in the southern part. Grade of ores and content of carbon in rocks are featured by higher in the west and lower in the east, higher in the north and lower in the south, which indicates that the northern belt is much more favorable than the southern belt in prospecting, and that the western belt is more favorable than the eastern belt. These opinions are much significant for choosing the main and associated mineral types, indicators and ore-prospecting directions in further prospecting work in this area.
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Received: 17 May 2017
Published: 04 June 2018
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| 元素 | 最小值
Xmin | 最大值
Xmax | 平均值
| 标准离差
δ1 | 背景值
C0 | 标准离差
δ2 | 变化系数
Cv | 区域背景
X1 | 富集系数
k1 | 叠加强度
系数k2 | | V | 46 | 34969 | 3781 | 5105 | 105 | 40 | 1.4 | 70 | 54.0 | 4595 | | Co | 0.9 | 165.0 | 7.9 | 16.3 | 3.2 | 1.7 | 2.1 | 10.5 | 0.8 | 23.7 | | Au | 0.5 | 110.0 | 5.3 | 11.4 | 1.8 | 3.6 | 2.2 | 0.8 | 6.6 | 9.3 | | Ag | 0.02 | 7.97 | 1.91 | 1.52 | 1.91 | 1.52 | 0.8 | 0.05 | 38.2 | 1.0 | | U | 1.0 | 131.0 | 20.4 | 24.8 | 9.2 | 23.2 | 1.2 | | | 2.4 | | Cu | 10 | 1907 | 176 | 281 | 65 | 179 | 1.6 | 12 | 14.7 | 4.3 | | Pb | 1.0 | 257.0 | 24.8 | 30.8 | 10.4 | 3.3 | 1.2 | 11.3 | 2.2 | 22.3 | | Zn | 2 | 24516 | 507 | 2199 | 74 | 166 | 4.3 | 32 | 15.8 | 90.8 | | W | 0.4 | 12.5 | 2.3 | 2.1 | 1.4 | 0.5 | 0.9 | 1.1 | 2.1 | 6.9 | | Mo | 0.3 | 202.1 | 16.7 | 32.3 | 2.4 | 2.1 | 1.9 | 0.4 | 41.8 | 107 | | Ni | 11 | 2049 | 117 | 244 | 28 | 13 | 2.1 | 23 | 5.1 | 78.4 | | Ru | 0.03 | 4.36 | 0.67 | 0.9 | 0.37 | 0.4 | 1.3 | | | 4.1 | | Rh | 0.02 | 3.62 | 0.48 | 0.6 | 0.23 | 0.5 | 1.2 | | | 2.5 | | Pd | 0.02 | 159.70 | 22.07 | 28.4 | 9.57 | 28.5 | 1.3 | | | 2.3 | | Os | 0.01 | 24.44 | 2.30 | 3.4 | 0.29 | 0.2 | 1.5 | | | 134.8 | | Ir | 0.02 | 3.09 | 0.20 | 0.4 | 0.12 | 0.1 | 2.1 | | | 6.7 | | Pt | 0.01 | 48.06 | 6.45 | 7.8 | 1.00 | 0.6 | 1.2 | | | 83.9 |
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| 元素 | 黏土岩类
(n=35) | 硅质岩类
(n=41) | 碳酸盐岩类
(n=14) | 炭硅质板岩类
(n=63) | 磷锰结核
(n=4) | 水沟口组
(n=149) | | TOC | 0.77 | 1.05 | 0.46 | 2.43 | 1.95 | 1.54 | | V | 4450 | 3494 | 1186 | 4158 | 3546 | 3781 | | Co | 13.1 | 5.3 | 5.5 | 7.5 | 9.5 | 7.9 | | Au | 9.4 | 5.9 | 2.0 | 3.3 | 4.1 | 5.3 | | Ag | 1.74 | 2.34 | 0.66 | 1.75 | 5.32 | 1.91 | | U | 20.4 | 16.7 | 7.1 | 21.4 | 76.1 | 20.4 | | Cu | 291 | 149 | 24 | 148 | 338 | 176 | | Pb | 29.6 | 20.1 | 12 | 27.6 | 34.7 | 24.8 | | Zn | 1328 | 301 | 90 | 169 | 2364 | 507 | | W | 2.7 | 2.1 | 2.1 | 2.4 | 2.1 | 2.3 | | Mo | 15.0 | 22.3 | 23.6 | 12.7 | 17.5 | 16.7 | | Ni | 186 | 90.5 | 48.6 | 86.8 | 531 | 117 | | Ru | 0.91 | 0.89 | 0.38 | 0.38 | 1.43 | 0.67 | | Rh | 0.76 | 0.52 | 0.12 | 0.35 | 0.90 | 0.48 | | Pd | 26.55 | 23.85 | 4.3 | 21.02 | 49.5 | 22.07 | | Os | 3.94 | 1.85 | 0.79 | 1.92 | 4.19 | 2.30 | | Ir | 0.24 | 0.33 | 0.13 | 0.07 | 0.52 | 0.20 | | Pt | 8.77 | 5.84 | 1.60 | 6.29 | 13.97 | 6.45 |
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