SHRIMP zircon U-Pb age of Tashan granitic pluton from Hu'nan Province and its geological significance
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摘要:
塔山花岗岩体位于湘南阳明山-塔山东西向构造-岩浆带东端，为呈近东西向延伸的岩基，出露面积约200km2。岩体侵入于古生代地层中，接触面倾向围岩，倾角30°~50°，由四侵入次岩体组成，之间多为脉动接触关系，主要岩性为黑云母二长花岗岩。第二侵入次岩体SHRIMP锆石U-Pb年龄为218±3Ma，第三侵入次岩体SHRIMP锆石U-Pb年龄为215±3Ma。由此表明，塔山花岗岩形成于晚三叠世，相邻单元之间的时间间隔为3~5Ma。阳明山-塔山东西向构造-岩浆带主要形成于印支期。区内钨、锡、铜、铅、锌等多金属矿床丰富，找矿潜力较大，亦表明南岭地区不仅存在燕山期花岗岩成矿，印支期花岗岩也可成矿。
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关键词:
- 花岗岩 /
- SHRIMP锆石U-Pb年龄 /
- 湖南塔山 /
- 地质意义
Abstract:Tashan granite pluton covering an area of 200km2 is an EW-trending batholith which is located at the eastern end of the Yangmingshan-Tashan tectomagmatic belt in southern Hunan. The pluton intruded into the Paleozoic strata and its interface is inclined to the wall rock, with the dip angle ranges from 30° to 50°. The pluton is composed four periods of pulsation intrusive rock bodies and its main lithology is biotite adamellite. The SHRIMP zircon U-Pb age of the second-stage pluton is 218±3Ma and the third is 215±3Ma, as measured by the Beijing SHRIMP Center of Chinese Academy of Geological Sciences. It is suggested that the Tashan pluton was formed in the Late Triassic period, and the age gap with the neighboring intrusive bodies is 3~5Ma, suggesting that the EW-trending Yangmingshan-Tashan tectomagmatic belt was probably formed in Indo-Chinese epoch. This area is rich in tungsten, tin, copper, lead and zinc polymetallic deposits and has bright future for ore prospect in that the mineralization in the Nanling region occurred not only in Yanshanian epoch but also in Indo-Chinese epoch.
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Key words:
- granite /
- SHRIMP zircon U-Pb age /
- Tashan, Hu'nan Province /
- geological implications
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表 1 塔山花岗岩样品SHRIMP锆石U-Th-Pb分析结果
Table 1. SHRIMP U-Th-Pb analyses of zircons from the Tashan pluton
点号 206Pbc/% U/10-6 Th/10-6 232Th/238U 206Pb*/10-6 206Pb/238U年龄/Ma 207Pb/206Pb年龄/Ma 207Pb*/206Pb* ±% 207Pb*/235U ±% 206Pb*/238U ±% D0232-1.1 0.25 1019 60 0.06 27.7 200.5 ±3.3 243 ±47 0.04972 1.5 0.2162 2.3 0.03154 1.7 D0232-2.1 -- 468 116 0.26 71.0 1050 ±20 1021 ±17 0.07294 0.77 1.778 2.2 0.1768 2.1 D0232-3.1 1.27 600 446 0.77 18.1 219.7 ±3.6 291 ±150 0.05140 3.6 0.2455 3.9 0.03464 1.6 D0232-4.1 1.30 829 92 0.11 24.7 216.8 ±3.4 188 ±120 0.05220 3.6 0.2467 4.0 0.03431 1.6 D0232-5.1 0.38 1440 376 0.27 43.1 219.9 ±4.0 215 ±86 0.05260 3.2 0.2523 3.7 0.03479 1.8 D0232-6.1 0.39 1184 94 0.08 34.0 211.1 ±3.3 262 ±63 0.05018 1.6 0.2300 2.3 0.03324 1.6 D0232-7.1 0.56 743 394 0.55 22.2 219.2 ±3.5 158 ±86 0.05276 1.6 0.2527 2.3 0.03474 1.6 D0232-8.1 0.56 2148 103 0.05 59.6 203.6 ±3.1 234 ±89 0.05202 1.0 0.2305 1.9 0.03214 1.5 D0232-9.1 0.18 2250 142 0.07 67.6 221.0 ±3.4 199 ±46 0.04994 1.5 0.2402 2.2 0.03488 1.6 D0232-10.1 1.81 458 51 0.12 18.3 288.0 ±4.8 377 ±170 0.04490 6.2 0.2800 6.5 0.04519 1.7 D0244-1.1 0.41 2246 65 0.03 67.3 220.0 ±4.4 166 ±33 0.05059 0.83 0.2426 2.2 0.03477 2.0 D0244-2.1 1.94 642 524 0.84 18.8 212.3 ±4.4 88 ±120 0.05420 1.9 0.2525 2.8 0.03376 2.1 D0244-3.1 0.11 486 301 0.64 67.8 968 ±18 1，048 ±20 0.07084 0.99 1.576 2.3 0.1614 2.0 D0244-4.1 0.27 2058 99 0.05 62.2 222.4 ±4.4 238 ±32 0.05089 0.85 0.2463 2.2 0.03511 2.0 D0244-5.1 0.97 527 294 0.58 15.3 212.3 ±4.3 150 ±90 0.05510 1.6 0.2563 2.6 0.03373 2.1 D0244-6.1 0.04 1611 623 0.40 313 1315 ±24 1778.7 ±5.5 0.09201 0.41 2.809 2.1 0.2214 2.0 D0244-7.1 0.28 2352 204 0.09 68.1 213.2 ±4.2 210 ±31 0.05291 0.77 0.2461 2.2 0.03373 2.0 D0244-8.1 0.43 1163 82 0.07 33.3 210.3 ±4.2 181 ±58 0.05037 1.8 0.2305 2.7 0.03319 2.0 D0244-9.1 0.39 849 687 0.84 24.9 215.7 ±4.4 252 ±48 0.05224 1.5 0.2454 2.6 0.03407 2.1 D0244-10.1 4.81 335 111 0.34 62.3 1209 ±29 1186 ±94 0.08570 1.4 2.448 3.0 0.2071 2.6 D0244-11.1 1.24 237 92 0.40 6.97 214.4 ±4.8 116 ±200 0.04820 3.8 0.2245 4.4 0.03382 2.2 D0244-12.1 0.46 1427 586 0.42 42.1 216.7 ±4.4 68 ±89 0.05019 1.1 0.2374 2.3 0.03431 2.0 D0244-13.1 0.29 615 108 0.18 52.5 609 ±12 610 ±29 0.06099 1.0 0.8340 2.4 0.0991 2.1 
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