1 区域地质背景
图1 江南造山带大地构造位置(a)(修改自毛景文等,1997)和湘东北醴陵官庄金矿整装勘查区区域地质简图(b)1.第四系;2.白垩—古近系;3.三叠—侏罗系;4.泥盆—二叠系;5.南华—志留系;6.新元古界青白口系板溪群;7.新元古界青白口系冷家溪群;8.燕山早期二长花岗岩;9.印支期二长花岗岩;10.加里东期英云闪长岩;11.加里东期花岗闪长岩;12.武陵期花岗闪长岩;13.武陵期斜长花岗岩;14.加里东期二长花岗岩;15.印支期花岗岩;16.小横江金矿床范围 Fig. 1 Sketch map of geotectonic location of the Jiangnan orogenic belt(a)(modified after Mao et al,1997) and regional geological map of the Liling Guanzhuang gold exploration district,northeast Hunan Province(b) |
2 矿床地质特征
图2 小横江金矿床主要构造及岩浆岩分布图1.青白口系黄浒洞组第三段;2.青白口系黄浒洞组第二段;3.青白口系黄浒洞组第一段;4.青白口系雷神庙组;5.实测压扭性断层;6.实测逆断层;7.实测性质不明断层;8.推测断层;9.辉绿岩;10.花岗闪长岩;11.实测整合接触地质界线;12.推测整合接触地质界线;13.金矿化蚀变带及编号;14.金矿体及编号;15.岩层产状;16.金矿床范围 Fig. 2 Main structure and distribution map of magmatic rocks in the Xiaohengjiang gold deposit |
3 样品采集与分析测试方法
4 分析结果
图4 小横江金矿床花岗闪长岩锆石U-Pb年龄图(a)锆石阴极发光(CL)图像和206Pb/238U年龄;(b)LA-ICP-MS U-Pb谐和年龄;(c)206Pb/238U加权平均年龄 Fig. 4 Zircon U-Pb age diagrams of granodiorite in the Xiaohengjiang gold deposit |
表1 花岗闪长岩中锆石LA-ICP-MS U-Pb定年结果Table 1 LA-ICP-MS U-Pb dating results of zircons in granodiorite |
| 点位编号 | Th/ (×10-6) | U/ (×10-6) | Th/U | 同位素比值 | 年龄/Ma | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 207Pb/206Pb | 1σ | 207Pb/235U | 1σ | 206Pb/238U | 1σ | 207Pb/235U | 1σ | 206Pb/238U | 1σ | ||||
| TY4020-3 | 199 | 487 | 0.41 | 0.0590 | 0.0009 | 0.5640 | 0.0076 | 0.0696 | 0.0005 | 454 | 5 | 434 | 3 |
| TY4020-6 | 206 | 548 | 0.38 | 0.0567 | 0.0008 | 0.5396 | 0.0079 | 0.0691 | 0.0005 | 438 | 5 | 430 | 3 |
| TY4020-9 | 100 | 284 | 0.35 | 0.0571 | 0.0009 | 0.5517 | 0.0089 | 0.0701 | 0.0005 | 446 | 6 | 437 | 3 |
| TY4020-10 | 144 | 293 | 0.49 | 0.0588 | 0.0008 | 0.5662 | 0.0082 | 0.0700 | 0.0005 | 456 | 5 | 436 | 3 |
| TY4020-27 | 125 | 264 | 0.47 | 0.0560 | 0.0011 | 0.5242 | 0.0117 | 0.0692 | 0.0005 | 428 | 8 | 431 | 3 |
| TY4020-28 | 308 | 547 | 0.56 | 0.0566 | 0.0014 | 0.5371 | 0.0158 | 0.0707 | 0.0005 | 437 | 10 | 440 | 3 |
| TY4020-49 | 92 | 196 | 0.47 | 0.0549 | 0.0006 | 0.5121 | 0.0069 | 0.0675 | 0.0005 | 420 | 5 | 421 | 3 |
| TY4020-11 | 84 | 206 | 0.41 | 0.0559 | 0.0007 | 0.5651 | 0.0079 | 0.0733 | 0.0006 | 455 | 5 | 456 | 3 |
| TY4020-19 | 178 | 386 | 0.46 | 0.0574 | 0.0006 | 0.5792 | 0.0069 | 0.0736 | 0.0005 | 464 | 4 | 458 | 3 |
表2 花岗闪长岩主量元素组成Table 2 Major elements composition of granodiorite(%) |
| 样品编号 | SiO2 | Al2O3 | Fe2O3 | CaO | MgO | K2O | Na2O | TiO2 | P2O5 | MnO | LOI | 总计 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| TSJ-H1 | 68.31 | 14.91 | 4.01 | 0.19 | 1.71 | 2.52 | 2.94 | 0.43 | 0.06 | 0.06 | 3.04 | 98.18 |
| TSJ-H2 | 67.72 | 15.62 | 3.80 | 0.39 | 1.59 | 2.61 | 3.06 | 0.42 | 0.06 | 0.06 | 3.13 | 98.46 |
| TSJ-H3 | 66.43 | 16.60 | 3.49 | 0.15 | 1.94 | 3.35 | 2.45 | 0.44 | 0.09 | 0.05 | 3.12 | 98.11 |
| TSJ-H4 | 68.40 | 15.21 | 3.50 | 0.34 | 1.72 | 2.94 | 2.42 | 0.44 | 0.08 | 0.05 | 3.22 | 98.32 |
| TSJ-H5 | 67.21 | 15.89 | 3.33 | 0.32 | 1.84 | 3.15 | 2.63 | 0.45 | 0.10 | 0.06 | 2.95 | 97.93 |
| TSJ-H6 | 67.97 | 15.10 | 3.51 | 1.62 | 1.63 | 2.56 | 2.51 | 0.43 | 0.06 | 0.05 | 3.01 | 98.45 |
| TSJ-H7 | 66.83 | 16.17 | 3.42 | 0.16 | 1.87 | 3.05 | 2.55 | 0.42 | 0.06 | 0.05 | 2.96 | 97.54 |
| TSJ-H8 | 68.02 | 14.90 | 3.89 | 0.21 | 1.69 | 2.54 | 2.66 | 0.41 | 0.07 | 0.06 | 3.06 | 97.51 |
表3 花岗闪长岩微量和稀土元素组成Table 3 Trace elements and rare earth elements composition of granodiorite(×10-6) |
| 样品编号 | Sc | V | Cr | Mn | Co | Ni | Cu | Zn | Ga | Ge | Rb | Sr | Y | Zr |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| TSJ-H1 | 10.8 | 68.1 | 187 | 496 | 29.0 | 118 | 5.00 | 77.9 | 18.6 | 1.58 | 135 | 84.4 | 6.73 | 150 |
| TSJ-H2 | 10.7 | 68.1 | 172 | 469 | 27.2 | 108 | 5.78 | 76.0 | 18.6 | 1.55 | 144 | 93.8 | 7.17 | 147 |
| TSJ-H3 | 11.0 | 74.0 | 176 | 358 | 28.9 | 120 | 19.90 | 59.2 | 21.6 | 1.63 | 181 | 71.3 | 10.40 | 154 |
| TSJ-H4 | 10.4 | 70.3 | 173 | 386 | 30.6 | 126 | 7.95 | 57.8 | 20.0 | 1.55 | 152 | 65.6 | 8.02 | 141 |
| TSJ-H5 | 11.3 | 76.6 | 171 | 484 | 34.7 | 138 | 15.20 | 72.7 | 20.3 | 1.61 | 166 | 75.7 | 9.85 | 153 |
| TSJ-H6 | 10.6 | 74.3 | 180 | 463 | 29.2 | 131 | 14.60 | 63.3 | 20.6 | 1.59 | 157 | 83.5 | 8.44 | 150 |
| TSJ-H7 | 10.9 | 73.9 | 169 | 367 | 29.3 | 112 | 17.60 | 73.1 | 21.1 | 1.62 | 175 | 73.4 | 10.10 | 151 |
| TSJ-H8 | 11.1 | 68.4 | 182 | 481 | 31.4 | 126 | 5.23 | 66.5 | 19.9 | 1.57 | 141 | 86.3 | 6.93 | 149 |
| 样品编号 | Nb | Ba | La | Ce | Pr | Nd | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm |
| TSJ-H1 | 2.18 | 517 | 36.8 | 63.5 | 6.97 | 23.5 | 3.63 | 0.86 | 3.27 | 0.369 | 1.44 | 0.264 | 0.833 | 0.126 |
| TSJ-H2 | 1.99 | 553 | 40.8 | 69.7 | 7.61 | 25.8 | 4.05 | 0.94 | 3.52 | 0.407 | 1.50 | 0.280 | 0.876 | 0.132 |
| TSJ-H3 | 2.10 | 726 | 49.4 | 74.9 | 9.00 | 30.3 | 4.74 | 1.16 | 4.13 | 0.497 | 1.93 | 0.358 | 1.040 | 0.156 |
| TSJ-H4 | 1.48 | 620 | 42.0 | 68.4 | 7.93 | 26.7 | 4.11 | 1.00 | 3.72 | 0.437 | 1.78 | 0.310 | 0.952 | 0.145 |
| TSJ-H5 | 2.08 | 680 | 46.7 | 73.0 | 8.71 | 29.8 | 4.75 | 1.12 | 4.14 | 0.511 | 2.13 | 0.376 | 1.110 | 0.166 |
| TSJ-H6 | 1.86 | 675 | 43.3 | 70.2 | 7.16 | 27.1 | 4.32 | 1.01 | 3.93 | 0.508 | 2.01 | 0.298 | 1.030 | 0.162 |
| TSJ-H7 | 2.06 | 711 | 49.1 | 74.4 | 8.37 | 28.6 | 4.70 | 1.09 | 4.06 | 0.493 | 1.90 | 0.361 | 1.050 | 0.152 |
| TSJ-H8 | 2.01 | 540 | 38.6 | 67.9 | 7.55 | 25.4 | 3.92 | 0.92 | 3.36 | 0.401 | 1.40 | 0.278 | 0.859 | 0.136 |
| 样品编号 | Yb | Lu | Hf | Ta | W | Tl | Pb | Th | U | ΣREE | LREE | HREE | LREE/HREE | |
| TSJ-H1 | 0.844 | 0.129 | 3.69 | 0.180 | 149 | 0.730 | 41.3 | 18.9 | 3.68 | 143 | 135 | 7.27 | 18.6 | |
| TSJ-H2 | 0.910 | 0.140 | 4.22 | 0.231 | 145 | 0.774 | 37.6 | 20.6 | 4.09 | 157 | 149 | 7.77 | 19.2 | |
| TSJ-H3 | 1.030 | 0.157 | 3.95 | 0.228 | 153 | 0.982 | 17.1 | 20.7 | 4.59 | 179 | 170 | 9.30 | 18.2 | |
| TSJ-H4 | 0.954 | 0.143 | 3.72 | 0.154 | 117 | 0.819 | 21 698.0 | 19.5 | 4.60 | 159 | 150 | 8.44 | 17.8 | |
| TSJ-H5 | 1.060 | 0.167 | 3.74 | 0.242 | 162 | 0.923 | 20.9 | 20.3 | 4.16 | 174 | 164 | 9.66 | 17.0 | |
| TSJ-H6 | 0.976 | 0.154 | 3.76 | 0.190 | 127 | 0.830 | 21.1 | 19.2 | 4.33 | 162 | 153 | 9.07 | 16.9 | |
| TSJ-H7 | 1.010 | 0.148 | 3.88 | 0.223 | 146 | 0.911 | 18.5 | 20.5 | 4.52 | 175 | 166 | 9.17 | 18.1 | |
| TSJ-H8 | 0.878 | 0.131 | 4.04 | 0.211 | 150 | 0.749 | 40.2 | 19.6 | 3.97 | 152 | 144 | 7.45 | 19.4 |
图5 花岗闪长岩地球化学分类图解(a)TAS图解(Middlemost,1994);(b)Zr/TiO2-SiO2图解(Rickwood,1989);(c)SiO2-K2O图解(Rickwood,1989);(d)Zr-TiO2图解(Chappell,1999) Fig. 5 Geochemical classification diagrams of the granodiorite |
图6 花岗闪长岩稀土元素球粒陨石标准化配分曲线(a)和微量元素原始地幔标准化蛛网图(b) Fig. 6 Rare earth elements chondrite-normalized pattern(a) and trace elements primitive mantle-normalized spider diagram(b) of granodiorite |
5 讨论
5.1 成岩年代
5.2 岩石成因
5.3 构造背景及金成矿潜力
图9 花岗闪长岩的Y+Nb-Rb(a)和Y-Nb(b)判别图解(Pearce et al,1984)Fig. 9 Discrimination diagram of Y+Nb-Rb(a) and Y-Nb(b) of the granodiorite(Pearce et al,1984) |

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