Geological and geochemical characteristics and age of gran-ite porphyry in the Hongdoushan copper deposit, South Langcangjiang belt, western Yunnan Province
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摘要:
南澜沧江火山弧带红豆山花岗斑岩属于过铝质钾玄岩性S型花岗岩,SiO2含量为71.1%~74.4%,全碱含量高(K2O+Na2O=8.4%~9.4%),富钾(K2O/Na2O=3.9~5.0),铝饱和指数(A/CNK)为1.06~1.21;具轻稀土元素富集特征,负Eu异常(δEu=0.53~0.74);相对富集大离子亲石元素(LILE,如Rb、Ba、Th、U等),但亏损Sr、P、Ti等元素。地球化学特征表明,红豆山花岗斑岩具火山弧花岗岩与同碰撞花岗岩的特征,为活动大陆边缘弧的产物。红豆山花岗斑岩的LA-ICP-MS锆石U-Pb年龄为220.3±3.6Ma,形成于晚三叠世。红豆山花岗斑岩的地球化学特征和形成时代与小定西组基性火山岩非常相似,两者是同一期岩浆活动不同阶段的产物。
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关键词:
- 南澜沧江带 /
- 花岗斑岩 /
- LA-ICP-MS锆石U-Pb年龄 /
- 地球化学 /
- 小定西组
Abstract:The Hongdoushan granite porphyry in the South Langcangjiang volcanic arc zone is a peraluminous and shoshonite Stype granitoid. The granite porphyry contains 71.1%~74.4% of SiO2, high total alkalis (K2O+Na2O=8.4%~9.4%), high K and high A/CNK of 1.06~1.21, and is characterized by enrichment of light rare earth elements with negative europium anomalies (δEu=0.53~0.74), relative enrichment of large ion lithophile elements (LILE) such as Rb, Ba, Th and U, and relative depletion of Sr, P and Ti. Geochemical features indicate that the Hongdoushan granite porphyry has characteristics of volcanic arc granite and syn-collision granite, and is epicontinental arc-volcanic rock. LA-ICP-MS zircon U-Pb dating age of the Hongdoushan granite porphyry is 220.3±3.6Ma, indicating that the rock was formed during Late Triassic. Geochemical features and formation age of the Hongdoushan granite porphyry is very similar to features of basic volcanic rock of Xiaodingxi Formation, which suggests that they are products of different stages of the same magmation.
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Key words:
- South Langcang belt /
- granite porphyry /
- LA-ICP-MS zircon U-Pb age /
- geochemistry /
- Xiaodingxi Formation
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图 1 南澜沧江带区域地质简图[4]
Figure 1.
图 3 红豆山岩体岩石分类图解(底图据参考文献[9])
Figure 3.
图 4 红豆山花岗斑岩SiO2-K2O图解(底图据参考文献[10])
Figure 4.
图 5 稀土元素球粒陨石标准化配分模式图(球粒陨石数据据参考文献[10])
Figure 5.
图 6 红豆山花岗斑岩微量元素原始地幔标准化蛛网图(原始地幔数据据参考文献[12])
Figure 6.
图 7 红豆山花岗斑岩Y-Nb(a)和(Y+Nb)-Rb(b)图解(底图据参考文献[13])
Figure 7.
表 1 红豆山花岗斑岩体主量元素含量及地球化学参数
Table 1. Major element content and geochemical parameters of the Hongdoushan granite porphyry
% 样品号
描述HDC204
长英岩化斑岩HDC213-2
紫红色斑岩HDC218-2
矿化斑岩HDR75-1
紫红色斑岩HDR75-2
紫红色斑岩SiO2 64.2 74.3 71.1 74.4 73.9 TiO2 0.17 0.18 0.25 0.19 0.18 Al2O3 7.64 11.85 11.95 12 11.8 Fe2O3 1.64 1.29 1.3 1.13 1.24 MnO 0.14 0.02 0.03 0.02 0.02 MgO 0.16 0.16 0.16 0.07 0.07 CaO 10.7 1.38 2.51 1.1 1.36 Na2O 0.08 1.72 1.46 1.86 1.84 K2O 6.12 6.7 7.27 7.49 7.39 P2O5 0.05 0.04 0.07 0.04 0.04 BaO 0.08 0.08 0.1 0.1 0.07 CuO 0.01 0.04 0.23 0.08 0.05 SO3 0.08 0.13 0.96 0.16 0.1 LOI 8.72 1.7 2.25 1.34 1.52 Total 99.84 99.67 99.71 99.99 99.61 K2O/Na2O 76.5 3.9 5 4 4 ALK 6.2 8.4 8.7 9.4 9.2 A/CNK 0.45 1.21 1.06 1.15 1.11 注:测试单位为中国地质大学(武汉)地质过程与矿产资源重点实验室,由熔片X射线荧光光谱法(XRF)测定,分析偏差优于5% 表 2 红豆山花岗斑岩微量和稀土元素含量
Table 2. Trace and rare earth element content of the Hongdoushan granite porphyry
10-6 样号 HDC204 HDC213-2 HDC218-2 HDR75-1 HDR75-2 La 18.3 16.9 8.2 12 8.7 Ce 41 35.2 19.5 28.2 21.4 Pr 4.57 4.01 2.35 3.3 2.68 Nd 17.9 14.1 8.8 12.6 10.5 Sm 3.93 2.72 2.05 2.7 2.45 Eu 0.95 0.44 0.44 0.44 0.4 Gd 3.78 2.06 2.19 2.21 2.09 Tb 0.57 0.33 0.4 0.38 0.39 Dy 3.15 2.01 2.69 2.43 2.53 Ho 0.55 0.44 0.61 0.51 0.55 Er 1.51 1.39 1.88 1.67 1.76 Tm 0.22 0.24 0.31 0.27 0.28 Yb 1.52 1.57 2.04 1.89 1.95 Lu 0.22 0.26 0.33 0.3 0.31 Y 32 26.6 31.2 27.1 27.7 ΣREE 98.17 81.67 51.79 68.9 55.99 LR/HR 7.52 8.84 3.96 6.13 4.68 (La/Yb)N 8.14 7.27 2.72 4.29 3.01 δEu 0.74 0.55 0.63 0.53 0.53 δCe 1.03 0.98 1.03 1.04 1.03 Cr 10 10 12 29 29 Ni 1.9 2.6 2.5 1.4 1.7 Co 1.1 1.4 11.4 0.9 0.9 Zn 8 15 21 10 Cu 103.5 263 1850 612 370 Rb 170 199.5 206 214 205 W 1.7 0.9 3 0.7 0.9 Sr 58.2 43.7 56.6 32.2 31.8 Ba 710 850 820 670 630 V 7 28 6 5 Nb 13.3 21.2 21.8 21.2 21.7 Ta 1.08 1.65 1.74 1.58 1.62 Zr 53.4 60.1 116 67.4 68.9 Hf 1.8 2.1 3.3 2.2 2.3 Sn 1.3 1.5 4.7 1.7 1.6 Pb 4.8 7.9 186.5 6 6.7 Ag 0.05 0.04 1.74 0.05 0.03 U 1.4 3.8 3.6 3.8 3.8 Th 12.3 18.5 16.2 22.5 21.8 P 230 150 290 160 150 注:微量、稀土元素分析在中国地质大学(武汉)地质过程与矿产资源重点实验室进行,使用方法为ICP-MS法,分析偏差优于10% 表 3 红豆山花岗斑岩LA-ICP-MS锆石U-Th-Pb测年结果
Table 3. LA-ICP-MS zircon U-Th-Pb results for Hongdoushan granite porphyry
点号 Th/U Th/10-6 U/10-6 比值(经普通铅校正) 年龄(经普通铅校正)/Ma 207Pb/206Pb ±1σ 207Pb/235U ±1σ 206Pb/238U ±1σ 207Pb/206Pb ±1σ 207Pb/235U ±1σ 206Pb/238U ±1σ 1 0.56 305 550 0.0507 0.0017 0.2499 0.0053 0.0358 0.0005 226 77 227 4 227 3 2 0.67 194 291 0.0512 0.0017 0.2506 0.0048 0.0355 0.0005 251 73 227 4 225 3 3 0.76 323 423 0.0519 0.0016 0.2858 0.0047 0.0400 0.0006 280 70 255 4 253 4 4 0.52 111 214 0.0508 0.0017 0.2606 0.0051 0.0372 0.0005 232 74 235 4 236 3 5 0.86 294 343 0.0517 0.0016 0.2695 0.0046 0.0378 0.0005 270 71 242 4 239 3 6 0.86 658 768 0.0514 0.0016 0.2650 0.0043 0.0374 0.0005 260 69 239 3 236 3 7 0.44 308 702 0.0507 0.0016 0.2542 0.0044 0.0363 0.0005 229 71 230 4 230 3 8 0.37 326 875 0.0534 0.0018 0.2040 0.0043 0.0277 0.0004 347 75 189 4 176 3 9 0.51 162 319 0.0511 0.0018 0.2606 0.0059 0.0370 0.0005 246 78 235 5 234 3 10 0.54 182 336 0.0515 0.0017 0.2682 0.0050 0.0378 0.0005 261 72 241 4 239 3 11 0.75 260 346 0.0512 0.0017 0.2645 0.0051 0.0375 0.0005 248 73 238 4 237 3 12 0.84 240 287 0.0507 0.0016 0.2580 0.0046 0.0369 0.0005 225 72 233 4 234 3 13 0.77 49 63 0.0511 0.0021 0.2661 0.0084 0.0377 0.0006 247 92 240 7 239 4 14 0.98 532 541 0.0504 0.0016 0.2642 0.0043 0.0378 0.0005 229 70 238 3 239 3 15 1.29 688 533 0.0509 0.0016 0.2650 0.0043 0.0378 0.0005 236 69 239 3 239 3 16 0.68 172 252 0.0512 0.0017 0.2703 0.0056 0.0383 0.0006 250 75 243 5 242 3 17 0.55 246 448 0.0513 0.0017 0.2689 0.0054 0.0380 0.0006 253 74 242 4 241 3 18 0.60 136 227 0.0509 0.0019 0.2681 0.0071 0.0382 0.0006 234 84 241 6 242 4 19 1.12 632 566 0.0511 0.0017 0.2647 0.0051 0.0375 0.0005 247 73 239 4 238 3 20 0.33 95 290 0.0509 0.0017 0.2644 0.0055 0.0377 0.0006 234 75 238 4 239 3 21 1.01 628 619 0.0510 0.0016 0.2609 0.0041 0.0371 0.0005 241 69 235 3 235 3 22 0.52 78 148 0.0517 0.0032 0.2630 0.0147 0.0369 0.0007 274 137 237 12 233 4 23 0.46 98 214 0.0521 0.0021 0.3244 0.0094 0.0452 0.0007 288 87 285 7 285 4 24 0.56 238 427 0.0516 0.0017 0.2704 0.0050 0.0380 0.0006 267 72 243 4 241 3 25 1.21 584 483 0.0511 0.0016 0.2639 0.0048 0.0375 0.0005 245 71 238 4 237 3 26 0.80 398 498 0.0509 0.0018 0.2515 0.0060 0.0358 0.0005 236 80 228 5 227 3 27 1.29 816 633 0.0511 0.0016 0.2640 0.0043 0.0375 0.0005 245 69 238 3 237 3 28 0.80 399 501 0.0508 0.0016 0.2581 0.0045 0.0369 0.0005 230 71 233 4 233 3 29 0.87 422 486 0.0521 0.0017 0.2661 0.0051 0.0370 0.0005 291 72 240 4 234 3 30 0.84 239 286 0.0516 0.0017 0.3039 0.0061 0.0428 0.00063 266 74 270 5 270 4 31 0.42 88 209 0.0520 0.0017 0.3056 0.0059 0.0426 0.00062 284 72 271 5 269 4 32 0.49 265 545 0.0522 0.0016 0.2640 0.0047 0.0367 0.00053 295 70 238 4 232 3 33 1.16 646 556 0.0508 0.0016 0.2655 0.0046 0.0379 0.00055 230 70 239 4 240 3 34 0.62 483 784 0.0512 0.0017 0.2843 0.060 0.0403 0.0006 250 75 254 5 254 4 35 0.86 222 258 0.0609 0.0019 0.8746 0.0141 0.1042 0.00151 635 64 638 8 639 9 36 0.73 135 185 0.0508 0.0017 0.2593 0.0058 0.0371 0.00055 229 77 234 5 235 3 表 4 红豆山花岗斑岩HDR-75样品LA-ICP-MS锆石U-Th-Pb测年结果
Table 4. LA-ICP-MS zircon U-Th-Pb results for sample HDR-75 from Hongdoushan granite porphyry
点号 Th/U Th/10-6 U/10-6 比值(经普通铅校正) 年龄(经普通铅校正)/Ma 207Pb/206Pb ±1σ 207Pb/235U ±1σ 206Pb/238U ±1σ 207Pb/206Pb ±1σ 207Pb/235U ±1σ 206Pb/238U ±1σ 1 0.23 55 234 0.0603 0.0031 0.2828 0.0144 0.0340 0.0004 616 114 253 11 215 3 2 0.52 212 409 0.0542 0.0009 0.2191 0.0036 0.0291 0.0004 380 27 201 3 185 3 3 0.43 166 389 0.0465 0.0008 0.2128 0.0033 0.0331 0.0006 23 26 196 3 210 4 4 0.43 212 489 0.0536 0.0008 0.2213 0.0033 0.0298 0.0001 354 25 203 3 189 1 5 0.48 213 442 0.0738 0.0033 0.3066 0.0134 0.0302 0.0004 1035 91 272 10 191 2 6 0.55 228 418 0.0681 0.0012 0.2903 0.0048 0.0310 0.0002 873 24 259 4 196 1 7 0.44 186 418 0.0494 0.0007 0.2390 0.0037 0.0349 0.0004 168 23 218 3 221 3 8 0.38 142 375 0.0479 0.0008 0.2334 0.0037 0.0352 0.0005 95 25 213 3 223 3 9 0.38 146 388 0.0500 0.0008 0.2422 0.0034 0.0350 0.0005 197 22 220 3 222 3 10 0.60 363 608 0.0651 0.0008 0.2652 0.0031 0.0294 0.0004 777 15 239 2 187 2 0.35 142 409 0.0499 0.0007 0.2350 0.0032 0.0340 0.0005 191 22 214 3 215 3 12 0.38 194 513 0.0578 0.0008 0.2692 0.0037 0.0336 0.0005 521 21 242 3 213 3 13 0.44 281 643 0.0524 0.0007 0.2600 0.0034 0.0357 0.0004 304 20 235 3 226 2 14 0.43 218 509 0.0542 0.0009 0.2593 0.0041 0.0345 0.0005 380 26 234 3 219 3 15 0.39 214 547 0.0518 0.0014 0.2451 0.0065 0.0343 0.0005 278 63 223 5 217 3 16 0.46 220 477 0.0626 0.0011 0.3144 0.0052 0.0364 0.0005 693 26 278 4 230 3 17 0.47 137 293 0.0536 0.0019 0.2547 0.0090 0.0345 0.0004 354 83 230 7 218 3 18 0.22 77 359 0.0555 0.0010 0.5144 0.0092 0.0673 0.0003 431 42 421 6 420 2 19 0.39 212 548 0.0544 0.0008 0.2684 0.0037 0.0356 0.0005 387 22 241 3 225 3 20 0.55 260 473 0.0519 0.0008 0.2660 0.0038 0.0370 0.0005 281 22 240 3 234 3 21 0.75 548 727 0.0676 0.0009 0.3098 0.0040 0.0331 0.0007 855 17 274 3 210 4 22 0.30 104 347 0.0508 0.0019 0.2702 0.0097 0.0386 0.0003 230 86 243 8 244 2 23 0.42 283 677 0.0579 0.0024 0.2644 0.0106 0.0331 0.0006 527 91 238 9 210 4 24 0.40 182 451 0.0518 0.0019 0.2353 0.0084 0.0330 0.0007 274 86 215 7 209 5 -
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