LA-ICP-MS zircon U-Pb dating of the undeformed granite in eastern Taiwan and its geological significance
-
摘要:
台湾源头山位于台湾岛东部太鲁阁带的北部,主体为花岗闪长岩-辉长岩"浆混岩"组合,发生了强烈变形变质,其中央分布有未变形的侵入体,具有典型岩浆岩特征,代表了变形变质期后的岩浆事件。通过开展野外地质调查和岩石学、同位素年代学研究,揭示了变形变质作用前后侵入岩在岩石特征及主量、微量元素方面存在明显差别,表明二者是不同构造岩浆事件的产物。未变形的侵入岩为石英闪长岩,具有高Pb、Rb、U、Th、Zr轻度富集特征,属典型的I型花岗岩,其LA-ICPMS锆石U-Pb年龄为82±1Ma,属晚白垩世坎潘期。这是台湾东部地区变形变质事件结束的标志,其后台湾东部进入了一个非挤压的新构造作用阶段。
-
关键词:
- 台湾东部 /
- 块状石英闪长岩 /
- LA-ICP-MS锆石U-Pb定年 /
- 晚白垩世坎潘期
Abstract:Yuantoushan is located in the north of Tailuko belt, eastern Taiwan. It is mainly composed of strongly deformed and metamorphosed granodiorite-gabbro "slurry mixed rock" combination. Deformed intrusions are in the center and show typical magmatic features, representing magmatic events after deformation and metamorphism. The authors carried out field geological survey and petrologic as well as isotopic geochronologic studies of metamorphic intrusive rocks and intrusive rocks. It is shown that there are significant differences in rock characteristics and main trace elements between the two kinds of rocks, indicating that the two kinds of rocks are products of different tectonic magmatic events. Undeformed intrusive rock is quartz diorite, with high Pb, Rb, U, Th, Zr, exhibiting mild enrichment characteristics of I type granite, and its LA-ICP-MS zircon U-Pb isotopic age is 82 ±1Ma, suggesting the Late Cretaceous Campanian period. This indicates that the deformation and metamorphism event in eastern Taiwan were ended, and the evolution then entered a non-squeezing neotectonic stage.
-
致谢: 本文在调研工作中得到福建省地质调查研究院陈润生教授级高级工程师的帮助;台湾大学陈正宏、李寄瑀教授,台湾东华大学刘萤三教授,台湾师范大学叶恩肇教授等参加了野外考察及调查工作,审稿专家对论文提出了宝贵修改意见,在此表示衷心感谢。
-
图 1 台湾东部地区地质略图(据参考文献[1]修改)
1-前古近纪(南澳片岩),变粒岩、云母片岩、绿泥石片岩、绿泥钠长片岩等;2-晚白垩世角闪片岩(枫树山岩体);3-源头山岩体(未变形石英闪长岩);4-源头山岩体(片麻状花岗闪长岩);5-绿泥片岩;6-黑云片岩和二云片岩;7-角闪片岩;8-片麻状花岗闪长岩;9-石英闪长岩;10-糜棱岩化;11-取样点
Figure 1. Geological map of eastern Taiwan
表 1 样品位置及岩性
Table 1 Locations and lithology of chemically and chronologically analyzed samples
样号 东经 北纬 岩石名称 采样地点 D0015 121°45′30″ 24°30′29″ 块状石英闪长岩 南澳北溪 D0017 121°46′09″ 24°30′12″ 片麻状糜棱岩化花岗闪长岩 南澳北溪 D0011-1 121°53′08″ 24°30′10″ 角闪片岩(枫树山岩体) 南澳 D0013-1 121°53′08″ 24°30′36″ 微晶角闪片岩(枫树山岩体) 南澳 表 2 花岗岩主量、微量和稀土元素分析数据
Table 2 Major, trace and rare earth elements of granites
岩体 枫树山 源头山岩体 岩体 枫树山 源头山岩体 岩性 角闪片岩 微晶闪长岩(未变形) 细粒石英闪长岩(未变形) 片麻状花岗闪长岩 岩性 角闪片岩 微晶闪长岩(未变形) 细粒石英闪长岩(未变形) 片麻状花岗闪长岩 样号 D0011 D0013-1 D0015 2806 NA6A NA8 D0017 样号 D0011 D0013-1 D0015 2806 NA6A NA8 D0017 SiO2 48.68 54.7 56.7 58.25 65.52 64.88 63.25 Nd 7.15 10.96 23.41 24.5 34.7 34.8 37.28 TiO2 0.98 1.09 1.71 1.69 0.7 0.7 0.9 Sm 2.55 3.12 5 5.29 5.98 6.34 7.59 Al2O3 15.44 15.43 16.99 16.76 16.64 17.18 17.05 Eu 0.94 1.11 1.35 1.48 1.18 1.26 1.52 FeO 6.24 6.38 5.44 6.16 3.66 2.74 2.92 Gd 3.12 3.66 4.05 5.44 4.6 6.88 6.38 Fe2O3 2.1 3.45 1.66 1.06 1.1 1.03 1.86 Tb 0.6 0.64 0.64 0.84 0.83 0.63 1.05 MnO 0.079 0.11 0.124 0.15 0.11 0.03 0.137 Dy 3.24 3.44 3.04 4.95 MgO 9.32 4.13 4.04 2.16 1.89 1.89 1.92 Ho 0.76 0.84 0.7 1.12 CaO 11.46 7.43 5.8 5.37 2.28 1.1 2.37 Er 2.26 2.37 2.02 3.13 Na2O 2.27 2.18 3.11 3.26 2.78 2.52 3.49 Tm 0.32 0.33 0.3 0.44 K2O 0.17 1.02 1.62 2.1 2.7 4.31 3.53 Yb 2.25 2.28 1.96 2.94 4.2 1.18 2.95 P2O5 0.08 0.11 0.12 0.5 0.09 0.05 0.14 Lu 0.3 0.31 0.27 0.45 0.72 0.13 0.39 总和 99.59 99.62 99.64 99.66 Y 23.1 24.6 20.5 18 29 15 30.9 Co 48.28 32.14 25.65 17 10 5 11.32 AR 1.20 1.33 1.52 1.64 1.82 2.19 2.13 Ni 172.4 15.39 15.51 7 22 9 18.12 SI 46.4 24.1 25.5 14.7 15.6 15.1 14.0 Zn 68.93 100.9 91.09 116 141 97 89.12 FL 17.6 30.1 44.9 50.0 70.6 86.1 74.8 Rb 5.6 60.18 65.87 89 114 155 153.6 A/CNK 0.62 0.85 0.98 0.96 1.43 1.59 1.23 Sr 126 222 306.8 337 252 192 237.6 σ 1.05 0.88 1.63 1.88 1.33 2.13 2.43 Nb 2.23 4.17 9.07 18 15 18 15.31 Na2O+K2O 2.44 3.20 4.73 5.36 5.48 6.83 7.02 Cd 0.243 0.234 0.202 0.161 K2O/Na2O 0.07 0.47 0.52 0.64 0.97 1.71 1.01 Ba 34.03 129.2 303.2 396 546 949 616.5 DI 53.35 71.12 77.21 80.29 86.97 88.88 87.59 Hf 2.92 3.03 5.6 4.02 7.01 9.8 7.76 LREE/HREE 1.66 2.11 4.13 3.89 5.04 8.46 4.54 W 0.48 0.73 1.64 1.2 ΣREE 23.88 42.70 104.63 79.97 158.96 177.63 181.49 Pb 10.03 12.46 14.13 16 35 17 21.22 δEu 1.02 1.00 0.89 0.84 0.66 0.58 0.65 Th 1.04 1.98 7.86 6.9 15 19 17.74 Rb/Sr 0.04 0.27 0.21 0.26 0.45 0.81 0.65 U 0.09 0.45 1.03 2.1 3.7 2.8 3.38 Th/U 11.56 4.40 7.63 3.29 4.05 6.79 5.25 Cr 366.5 38.9 36.6 17 56 52 47.7 Ba/Sr 0.27 0.58 0.99 1.18 2.17 4.94 2.59 V 197.4 261 138.4 56 89 86 73.5 Q_CIPW 0.00 15.12 11.95 14.70 30.12 28.30 21.23 Zr 62.7 85.6 130.6 112 249 346 217.2 C_CIPW 0.00 0.00 0.00 0.57 5.35 6.73 3.60 La 3.26 7.66 22.62 20.6 37.4 44.33 42.27 Or_CIPW 1.04 6.28 9.84 12.74 16.37 26.42 21.38 Ce 8.58 17.48 46.61 28.1 79.7 90.9 83.15 Ab_CIPW 19.84 19.21 27.04 28.30 24.13 22.11 30.27 Pr 1.4 2.37 5.64 9.68 An_CIPW 32.47 30.52 28.37 23.98 11.00 5.32 11.12 注:主量元素含量单位为%,微量和稀土元素含量为10-6 表 3 锆石U-Th-Pb同位素分析数据和计算的年龄值
Table 3 Analytical data of zircon U-Th-Pb isotopes and calculated age values
测点号 总Pb/10-6 232Th/10-6 238U/10-6 Th/U 同位素比值 表面年龄/Ma 207Pb/206Pb 1σ 207Pb/235U 1σ 206Pb/238U 1σ 207Pb/206Pb 1σ 207Pb/235U 1σ 206Pb/238U 1σ D0015-1 6 259 319 0.81 0.0489 0.0026 0.0878 0.0047 0.0130 0.0002 142.7 124.1 85.4 4.4 83.2 1.3 2 4 160 222 0.72 0.0527 0.0034 0.0918 0.0057 0.0129 0.0003 322.3 146.3 89.1 5.3 82.7 1.7 3 13 435 753 0.58 0.0482 0.0019 0.0831 0.0031 0.0124 0.0002 109.4 90.7 81.0 2.9 79.8 1.1 4 5 201 343 0.59 0.0449 0.0023 0.0776 0.0041 0.0126 0.0002 75.9 3.8 80.6 1.6 5 8 334 490 0.68 0.0487 0.0021 0.0824 0.0037 0.0124 0.0003 131.6 101.8 80.4 3.4 79.3 1.8 6 8 354 436 0.81 0.0490 0.0019 0.0860 0.0034 0.0126 0.0002 150.1 88.9 83.8 3.2 80.9 1.2 7 4 122 220 0.56 0.0419 0.0034 0.0758 0.0058 0.0132 0.0003 error error 74.2 5.5 84.6 1.8 8 6 241 336 0.72 0.0477 0.0031 0.0841 0.0052 0.0129 0.0002 87.1 148.1 82.0 4.9 82.9 1.5 9 8 377 459 0.82 0.0483 0.0021 0.0855 0.0036 0.0129 0.0002 122.3 -93.5 83.3 3.4 82.7 1.3 10 6 171 334 0.51 0.0449 0.0024 0.0802 0.0040 0.0132 0.0002 error 78.4 3.8 84.8 1.5 11 5 229 298 0.77 0.0476 0.0023 0.0842 0.0040 0.0129 0.0002 76.0 114.8 82.1 3.8 82.5 1.5 12 4 149 220 0.68 0.0498 0.0028 0.0891 0.0047 0.0131 0.0002 183.4 126.8 86.7 4.4 84.1 1.5 13 6 142 349 0.41 0.0483 0.0032 0.0822 0.0052 0.0125 0.0002 122.3 142.6 80.2 4.9 79.8 1.5 14 7 293 391 0.75 0.0527 0.0028 0.0899 0.0045 0.0125 0.0002 322.3 122.2 87.4 4.2 79.8 1.3 15 9 404 549 0.74 0.0485 0.0026 0.0805 0.0041 0.0122 0.0003 124.2 131.5 78.6 3.8 77.9 2.1 16 5 178 280 0.64 0.0476 0.0031 0.0802 0.0052 0.0122 0.0002 76.0 157.4 78.3 4.9 78.0 1.5 17 5 170 273 0.62 0.0524 0.0027 0.0938 0.0046 0.0131 0.0003 301.9 114.8 91.0 4.2 84.1 1.6 18 3 126 196 0.64 0.0500 0.0034 0.0846 0.0051 0.0126 0.0003 194.5 157.4 82.5 4.8 81.0 1.6 19 4 160 258 0.62 0.0520 0.0032 0.0884 0.0051 0.0127 0.0003 283.4 110.2 86.0 4.8 81.1 1.6 20 6 223 364 0.61 0.0512 0.0029 0.0850 0.0048 0.0121 0.0002 250.1 126.8 82.8 4.5 77.2 1.4 21 8 380 448 0.85 0.0500 0.0026 0.0911 0.0046 0.0133 0.0002 194.5 122.2 88.6 4.3 84.9 1.3 22 8 343 477 0.72 0.0507 0.0029 0.0860 0.0052 0.0123 0.0003 233.4 125.0 83.8 4.9 78.6 1.9 23 4 133 221 0.60 0.0548 0.0030 0.0953 0.0056 0.0127 0.0002 466.7 124.1 92.5 5.2 81.1 1.6 24 3 87 154 0.56 0.0599 0.0055 0.1046 0.0085 0.0136 0.0004 598.2 200.0 101.1 7.8 87.2 2.6 25 5 152 343 0.44 0.0485 0.0029 0.0891 0.0049 0.0137 0.0002 120.5 133.3 86.7 4.5 87.4 1.6 26 4 175 266 0.66 0.0513 0.0033 0.0877 0.0054 0.0126 0.0002 257.5 148.1 85.4 5.0 80.5 1.6 27 6 273 356 0.77 0.0497 0.0033 0.0829 0.0050 0.0122 0.0003 183.4 147.2 80.9 4.7 78.5 2.0 28 5 115 305 0.38 0.0894 0.0399 0.1572 0.0693 0.0129 0.0003 1413.0 963.8 148.3 60.9 82.8 2.0 29 5 170 257 0.66 0.0482 0.0036 0.0868 0.0061 0.0133 0.0003 109.4 166.6 84.5 5.7 85.0 2.0 30 5 193 280 0.69 0.0483 0.0030 0.0849 0.0048 0.0131 0.0003 122.3 131.5 82.7 4.5 83.9 1.9 -
福建省地质调查研究院.台湾省区域地质志[M].北京:地质出版社, 2015. Yui T F, Maki K, Lan C Y, et al. Detrital zircons from the Tananao metamorphic complex of Taiwan:Implications for sediment provenance and Mesozoic tectonics[J]. Tectonophysics, 2012, 541/543:31-42. doi: 10.1016/j.tecto.2012.03.013
Yui T F, Wu T W, Jahn B M. Geochemistry and plate-tectonic significance of the metabasites from the Tananao schist complex of Taiwan[J]. Journal of southeast Asian Earth Science, 1990, 4:357-368. doi: 10.1016/0743-9547(90)90006-Y
Yui T F, Lu C Y, Lo A.Tectonic evolution of the Tananao schist Complex of Taiwan[C]//Aubouin A, Bourgois J. Tectonics of Circum-Pacific Continental Margins.VSP, the Nethirlands, 1990:193-209.
Jahn B M, Martineau F, Peucat J J, et al. Geochronology of the Tananao schist complex, Tawan, and its regional tectonic significance[J]. Tectonophysics, 1986, 125:103-124. doi: 10.1016/0040-1951(86)90009-0
Yen T P. Some geological problems on the Tananao Schist[J]. Bull. Geol. Surv. Taiwan, 1954, 7:47-50. http://www.sciencedirect.com/science/article/pii/074395479090006Y
侯可军, 李延河, 田有荣. LA-MC-ICP-MS锆石微区原位U-Pb定年技术[J].矿床地质, 2009, 28(4):481-492. http://d.wanfangdata.com.cn/Periodical/kcdz200904010 Liu Y S, Gao S, Hu Z C, et al. Continental and oceanic crust recycling-induced melt-peridotite interactions in the Trans-North China Orogen:U-Pb dating, Hf isotopes and trace elements in zircons from mantle xenoliths[J]. Journal of Petrology, 2010, 51:537-571. doi: 10.1093/petrology/egp082
Le Maitre R W. A Classification of igneous rocks and glossary of terms[M]. Oxford:Blackwell Sci. Pub., 1989:1-193.
邓晋福, 刘翠, 冯艳芳, 等.关于火成岩常用图解的正确使用:讨论与建议[J].地质论评, 2015, 61(4):717-734. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=dzlp201504002&dbname=CJFD&dbcode=CJFQ 邱家骧, 林景仟.岩石化学[M].北京:地质出版社, 1991. 李昌年.火成岩微量元素岩石学[M].武汉:中国地质大学出版社, 1992. Masuda A, Nakamura N, Tanaka T. Fine structure of mutually normalized rare earth patterns of chondrites[J]. Geochim. Cosmochim. Acta, 1973, 49:2051-2067. http://www.sciencedirect.com/science/article/pii/0016703773901312
黄长煌.福建东山晚中生代花岗岩的LA-ICP-MS锆石同位素定年及其地质意义[J].福建地质, 2015, 34(4):261-271. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=fjdz201504001&dbname=CJFD&dbcode=CJFQ 黄长煌.福建东山变质岩LA-ICP-MS同位素年龄及其地质意义[J].中国地质, 2016, 43(3):738-750. doi: 10.12029/gc20160304 黄长煌.福建龙海深澳变质岩锆石U-Pb同位素年代学及地质意义[J].华东地质, 2016, 37(1):28-35. http://d.wanfangdata.com.cn/Periodical/hsdzykc201601004 黄长煌.福建港里地区变质岩与南园组火山岩地球化学特征及锆石U-Pb年龄对比[J].华东地质, 2017, 38(1):12-20. http://d.wanfangdata.com.cn/Periodical/hsdzykc201701002 冯艳芳, 邓晋福, 肖庆辉, 等.长乐-南澳构造带花岗岩类年代学岩石组合与构造演化[M].北京:地质出版社, 2013. 毛建仁, 厉子龙, 叶敏.华南中生代构造-岩浆活动研究:现状与前景[J].中国科学:地球科学, 2014, 44(12):2593-2617. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=jdxk201412001&dbname=CJFD&dbcode=CJFQ 徐先兵, 张岳桥, 贾东等.华南早中生代大地构造过程[J].中国地质, 2009, 36(3):573-593. http://d.wanfangdata.com.cn/Periodical/zgdizhi200903007 林启文, 高铭建. 1: 5万台湾地质图说明书. 苏澳幅(第二版). 经济部中央地质调查所.2009. 陈肇夏. 台湾的变质岩. 经济部中央地质调查所. 1998.