Chronology, Geochemistry and Geological Significance of Epo Granite Intrusion, Southern Jiangxi
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摘要: 赣南鹅婆岩体位于南岭东西向构造岩浆带与武夷山北北东向构造带结合部位,地处于都—青塘古生代盆地西缘,出露面积达200 km2。岩体主体为黑云母二长花岗岩,其构造位置特殊,周边成矿条件有利,西侧银坑矿田内部和外围分别发育金银铅锌贵多金属矿和钨多金属矿。本文在岩体地质工作的基础上,应用激光剥蚀多接收器电感耦合等离子体质谱(LA-MC-ICP-MS)技术对鹅婆黑云母二长花岗岩进行了锆石U-Pb定年;结合元素地球化学数据讨论了其岩浆系列和岩石成因;并与区内成矿岩浆岩进行对比,探讨其成矿潜力。鹅婆花岗岩体的侵入年龄为(412.5±1.7) Ma,花岗岩中含富铝矿物,主量和微量元素地球化学显示其属于高钾钙碱性-钾玄岩系列,为强过铝质的S型花岗岩,是新元古代壳层沉积变质泥岩在加里东晚期重熔侵入的产物。与加里东期和燕山期成钨锡花岗岩的对比研究表明,鹅婆岩体在形成过程中发生了W、Sn等成矿元素的富集。本文研究结果一方面证明前人获得的全岩Rb-Sr等时线年龄(307 Ma)代表的是成岩期后所经历的一次地质事件;同时表明加里东期花岗岩也有钨锡矿成矿的潜力。
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关键词:
- 赣南 /
- 鹅婆岩体 /
- LA-MC-ICP-MS /
- 加里东晚期 /
- 成矿作用
Abstract: The Epo intrusion with an exposed area of 200 km2, is mainly composed of biotite monzonitic granite, and is located on the western margin of the Yudu-Qingtang basin, the conjunction of E-W trending Nanling tectonic-magmatic belt and the NNE trending Wuyishan tectonic belt. Situated in such a special tectonic position, this region is advantageous to mineralization. The Yinkeng ore field, which lies to the west of the Epo intrusion, consists of Au-Ag-Pb-Zn and W polymetallic deposits. On the basis of field survey, zircon U-Pb dating for Epo biotite monzonitic granite has been carried out by Laser Ablation-Multicollector-Inductively Coupled Plasma-Mass Spectrometry (LA-MC-ICP-MS). Magma series and petrogenesis have been discussed according to geochemical data, and metallogenetic potentiality of the intrusion has been studied by comparing with other metallogenetic granitic bodies in the district. Analysis results show that the diagenetic age of Epo granite is (412.5±1.7) Ma. The granite contains abundant aluminium minerals, such as muscovite and sillimanite. Major and trace elements indicate that Epo granite is strongly peraluminous S-type granite, and belongs to the High potassium calc alkaline-shoshonite series. The pluton stemmed from Neoproterozoic metamorphic shale by remelting and intruding during the Late Caledonian period. Comparative research with Caledonian and Yanshanian W-Sn metallogenetic granites shows that W and Sn had been concentrated during the formation of Epo granite. Proof that the previous Rb-Sr whole rock isochron age (307 Ma) represents a late geological event after the diagenesis period is given in this paper, and Caledonian granites have potential for W-Sn mineralization.-
Key words:
- southern Jiangxi /
- Epo intrusion /
- LA-MC-ICP-MS /
- Late Caledonian /
- metallogenesis
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图 1 鹅婆岩体地质图(据1:20万兴国幅地质图和徐明[9]修改)
Figure 1.
图 5 鹅婆花岗岩球粒陨石标准化稀土元素配分曲线(球粒陨石标准化值来自McDonough等[15])
Figure 5.
图 6 鹅婆花岗岩A/MF-C/MF源区判别图(据Alther等[18])
Figure 6.
表 1 鹅婆钾长花岗岩(XGep-1)锆石U-Pb年代学分析测试结果
Table 1. Analytical results of LA-MC-ICPMS U-Pb dating for zircons from Epo biotite monzonitic granite
点号 含量(μg/g) 207Pb/ 206Pb 207Pb/ 235U 206Pb/ 238U 207Pb/ 206Pb 207Pb/ 235U 206Pb/ 238U 谐和度(%) 232Th 238U 比值 1 σ 比值 1 σ 比值 1 σ 年龄 (Ma) 1 σ 年龄 (Ma) 1 σ 年龄 (Ma) 1 σ XGep-1-1 173.15 206.52 0.84 0.0574 0.0006 0.5312 0.0093 0.0672 0.0009 505.6 22.2 432.6 6.1 419.1 5.6 96 XGep-1-2 38.57 43.08 0.90 0.0565 0.0033 0.5205 0.0302 0.0670 0.0022 472.3 129.6 425.5 20.2 418.0 13.2 98 XGep-1-3 165.95 157.76 1.05 0.0568 0.0007 0.5275 0.0109 0.0674 0.0014 483.4 27.8 430.2 7.3 420.7 8.2 97 XGep-1-4 76.66 106.12 0.72 0.0576 0.0018 0.5327 0.0238 0.0671 0.0024 522.3 70.4 433.6 15.8 418.8 14.5 96 XGep-1-5 122.83 392.29 0.31 0.0573 0.0005 0.5279 0.0164 0.0669 0.0025 505.6 20.4 430.4 10.9 417.4 14.9 96 XGep-1-6 95.26 60.57 1.57 0.0587 0.0004 0.5394 0.0015 0.0666 0.0006 566.7 16.7 438.0 1.0 415.8 3.5 94 XGep-1-7 132.05 139.21 0.95 0.0585 0.0006 0.5365 0.0132 0.0666 0.0020 550.0 24.1 436.1 8.7 415.7 11.9 95 XGep-1-8 186.52 275.48 0.68 0.0578 0.0007 0.5319 0.0117 0.0667 0.0011 524.1 25.9 433.1 7.7 416.2 6.8 96 XGep-1-9 267.04 343.82 0.78 0.0571 0.0006 0.5283 0.0050 0.0671 0.0009 498.2 20.4 430.7 3.3 418.6 5.4 97 XGep-1-10 197.93 681.45 0.29 0.0557 0.0003 0.5177 0.0046 0.0674 0.0005 442.6 9.3 423.6 3.1 420.5 3.3 99 XGep-1-11 65.19 134.31 0.49 0.0583 0.0024 0.5222 0.0177 0.0649 0.0005 542.6 88.9 426.6 11.8 405.5 2.9 94 XGep-1-12 104.59 126.13 0.83 0.0565 0.0015 0.5156 0.0289 0.0661 0.0020 472.3 57.4 422.2 19.4 412.8 12.1 97 XGep-1-13 64.93 164.18 0.40 0.0565 0.0018 0.5123 0.0168 0.0657 0.0002 472.3 38.0 420.0 11.3 410.5 1.1 97 XGep-1-14 79.31 329.87 0.24 0.0580 0.0004 0.5282 0.0070 0.0661 0.0009 527.8 12.0 430.6 4.6 412.5 5.4 95 XGep-1-15 175.89 144.69 1.22 0.0573 0.0018 0.5192 0.0210 0.0657 0.0008 501.9 68.5 424.6 14.0 410.2 5.1 96 XGep-1-16 119.11 146.39 0.81 0.0578 0.0007 0.5270 0.0079 0.0662 0.0007 520.4 27.8 429.8 5.2 413.0 4.0 96 XGep-1-17 105.57 421.72 0.25 0.0577 0.0015 0.5256 0.0123 0.0662 0.0006 516.7 59.3 428.9 8.2 413.0 3.5 96 XGep-1-18 58.17 164.46 0.35 0.0570 0.0005 0.5227 0.0066 0.0665 0.0008 500.0 18.5 426.9 4.4 415.2 4.8 97 XGep-1-19 51.14 47.11 1.09 0.0563 0.0055 0.5157 0.0474 0.0665 0.0004 464.9 216.6 422.3 31.8 415.0 2.3 98 XGep-1-20 73.93 309.55 0.24 0.0571 0.0005 0.5250 0.0080 0.0667 0.0007 494.5 23.1 428.5 5.3 416.2 4.4 97 表 2 鹅婆花岗岩及潭头群变质岩的主量元素和微量元素含量
Table 2. Analyitical results of major and trace elements in Epo granites and metamorphic rocks from Tantou Group
主量元素 主量元素含量(%) XGep-1 (斑状黑云母 二长花岗岩) XGep-2 (粗中粒多斑黑云母 二长花岗岩) XGep-3 (粗中粒斑状黑云母 二长花岗岩) XGep-4 (中细粒斑状黑云母 二长花岗岩) XGep-5 (似斑状黑云母 二长花岗岩) XGep-6 (潭头群变沉积岩, 七个数据平均值) SiO 2 79.7 72.62 71.3 66.44 71.09 68.31 TiO 2 0.46 0.4 0.39 0.44 0.35 0.48 Al 2O 3 8.79 13.54 14.09 16.96 14.78 14.81 Fe 2O 3 0.63 1.13 1.07 0.43 0.88 1.89 FeO 1.92 1.59 1.43 2.51 1.71 2.18 MnO 0.05 0.05 0.08 0.06 0.07 0.17 MgO 1.21 0.96 0.53 1.25 0.77 1.86 CaO 0.35 0.42 0.58 0.37 0.66 0.96 Na 2O 0.55 2.35 2.62 1.28 2.77 2.58 K 2O 3.73 5.53 5.25 5.97 4.83 3.64 P 2O 5 0.12 0.16 0.18 0.14 0.18 0.12 CO 2 0.56 0.43 0.46 0.64 - - H 2O + 1.54 1.13 1.35 3.45 0.88 - LOI 1.47 1.16 0.78 3.74 1.56 2.99 总计 101.08 101.47 100.11 103.68 100.53 99.97 K 2O+Na 2O 4.28 7.88 7.87 7.25 7.60 - K 2O/Na 2O 6.78 2.35 2.00 4.66 1.74 - A/CNK 1.57 1.27 1.27 1.83 1.34 - A/NK 1.77 1.37 1.41 1.98 1.51 - AR 1.67 2.36 2.39 1.66 2.33 - 微量元素 微量元素含量(μg/g) XGep-1 (斑状黑云母 二长花岗岩) XGep-2 (粗中粒多斑黑云母 二长花岗岩) XGep-3 (粗中粒斑状黑云母 二长花岗岩) XGep-4 (中细粒斑状黑云母 二长花岗岩) XGep-5 (似斑状黑云母 二长花岗岩) XGep-6 (潭头群变沉积岩, 七个数据平均值) Rb 192.00 250.00 250.00 210.00 - - Sr 39.40 233.00 87.00 230.00 - - Rb/Sr 4.87 1.07 2.87 0.91 - - Nb 6.98 15.3 11.5 13.5 - - Y 20.60 40.84 25.44 9.26 - - La 25.10 62.30 17.56 44.94 - 51.97 Ce 50.00 124.46 43.86 85.98 - 98.41 Pr 5.56 11.81 3.33 7.85 - 11.65 Nd 21.10 50.74 13.95 34.92 - 42.07 Sm 4.18 9.88 2.83 6.20 - 8.10 Eu 1.05 1.13 0.28 1.02 - 1.19 Gd 4.07 8.06 2.70 3.98 - 6.91 Tb 0.71 1.21 0.58 0.43 - 1.06 Dy 3.70 7.42 3.99 2.20 - 6.45 Ho 0.76 1.49 0.88 0.39 - 1.24 Er 2.28 4.28 2.90 1.01 - 3.80 Tm 0.32 0.64 0.49 0.15 0.70 Yb 1.93 4.09 2.88 0.88 - 3.82 Lu 0.29 0.80 0.43 0.13 - 0.60 Y 20.60 40.84 25.44 9.26 - 35.63 (La/Yb) N 8.83 10.35 4.14 34.69 - 9.25 (La/Sm) N 3.75 3.94 3.87 4.53 - 4.00 (Gd/Yb) N 1.71 1.59 0.76 3.66 - 1.46 δEu 0.78 0.39 0.31 0.63 - 0.48 ∑REEs 121.05 288.31 96.65 190.09 - 237.98 数据来源 本文 [9] [9] [9] [12] [17] 表 3 鹅婆岩体与南岭地区部分成钨黑云母花岗岩成矿元素含量
Table 3. Contents of ore-forming elements in granite from Epo and some other tungsten mineralization-related intrusions
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[1] 陈毓川,裴荣富,张宏良,林新多,白鸽,李崇佑,胡永嘉,刘姤群,冼柏琪.南岭地区与中生代花岗岩类有关的有色及稀有金属矿床地质[M].北京:地质出版社,1989:1-508.
[2] 毛景文,谢桂青,郭春丽,陈毓川.南岭地区大规模钨锡多金属成矿作用:成矿时限及地球动力学背景[J].岩石学报,2007,23(10):2329-2338. doi: 10.3969/j.issn.1000-0569.2007.10.002
[3] 郭春丽.赣南崇义—上犹地区与成矿有关中生代花岗岩类的研究及对南岭地区中生代成矿花岗岩的探讨[D].北京:中国地质科学院,2010.
[4] 华仁民,张文兰,陈培荣,翟伟,李光来.初论华南加里东花岗岩与大规模成矿作用的关系[J].高校地质学报,2013,19(1):1-11. http://www.cnki.com.cn/Article/CJFDTOTAL-GXDX201301002.htm
[5] 程顺波,付建明,马丽艳,陈希清,张利国,卢友月.南岭地区加里东期花岗岩地球化学特征、岩石成因及含矿性评价[J].华南地质与矿产,2013,29(1):1-11. http://www.cnki.com.cn/Article/CJFDTOTAL-HNKC201301002.htm
[6] 侯可军,陈振宇,王登红,陈郑辉,赵正.赣南兴国杨村岩体锆石U-Pb年龄测定及其地质意义[J].岩矿测试,2012,31(3):549-553. http://www.cnki.com.cn/Article/CJFDTOTAL-YKCS201203033.htm
[7] 于扬,陈振宇,陈郑辉,侯可军,赵正,许建祥,张家菁,曾载淋.赣南印支期清溪岩体的锆石U-Pb年代学研究及其含矿性评价[J].大地构造与成矿学,2013,36(3):413-421. http://www.cnki.com.cn/Article/CJFDTOTAL-DGYK201203016.htm
[8] 刘善宝,李鹏,陈振宇,陈郑辉,侯可军,赵正,王成辉.赣南于都万田花岗岩锆石铀-铅定年及启示[J].岩矿测试,2012,31(4):724-729. http://www.cnki.com.cn/Article/CJFDTOTAL-YKCS201204031.htm
[9] 徐明.赣南鹅婆岩体地质特征及演化程序[J].江西地质,1998,12(1):20-26. http://www.cnki.com.cn/Article/CJFDTOTAL-JXDZ801.003.htm
[10] 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):484-492. http://www.cnki.com.cn/Article/CJFDTOTAL-KCDZ200904009.htm
[11] 江西省地质局区域地质调查大队.1/20万区域地质调查报告书(兴国幅)[R].1974:1-50.
[12] 陈祖兴,徐明.鹅婆复式深成岩体成岩时代初探[J].江西地质,1999,13(2):100-105. http://www.cnki.com.cn/Article/CJFDTOTAL-JXDZ902.004.htm
[13] 洪大卫,王涛,童英.中国花岗岩概述[J].地质论评,2007,53(增刊):9-16. http://www.cnki.com.cn/Article/CJFDTOTAL-DZLP2007S1004.htm
[14] 舒良树.华南构造演化的基本特征[J].地质通报,2012,31(7):1035-1053. http://www.cnki.com.cn/Article/CJFDTOTAL-ZQYD201207004.htm
[15] McDonough W F, Sun S S.The composition of the Earth [J].Chemical Geology, 1995, 120: 223-253. doi: 10.1016/0009-2541(94)00140-4
[16] Chappell B W.Aluminium saturation in I- and S-type granites and the characterization of fractionated haplogranites [J].Lithos, 1999, 46:535-551. doi: 10.1016/S0024-4937(98)00086-3
[17] 张芳荣,吴富江,黄新曙.赣中南新元古代潭头群变质沉积岩物源及构造背景[J].东华理工大学学报(自然科学版),2009,32(2):134-140. http://www.cnki.com.cn/Article/CJFDTOTAL-HDDZ200902007.htm
[18] Alther R, Holl A, Hegner E, Langer C, Kreuzer H.High-potassium, calc-alkaline I-type plutonism in the European Variscides: Northern Vosges (France) and northern Schwarzwald (Germany) [J].Lithos,2000,50(1-3):51-73. doi: 10.1016/S0024-4937(99)00052-3
[19] 沈渭洲,凌洪飞,李武显,黄小龙,王德滋.中国东南部花岗岩Nd-Sr同位素研究[J].高校地质学报,1999,5(1):22-32. http://www.cnki.com.cn/Article/CJFDTOTAL-GXDX901.003.htm
[20] 胡恭仁,张邦桐.赣中变质基底的Nd同位素组成和物质来源[J].岩石矿物学杂志,1998,17(1):35-39. http://www.cnki.com.cn/Article/CJFDTOTAL-YSKW801.005.htm
[21] 陈郑辉.南岭东段钨矿成矿潜力评价及找矿方向建议[D].北京:中国地质科学院,2006.
[22] 地质部江西省地质局区域测量队.1/20万地质矿产图说明书(赣州幅)[R].1967:32-60.
[23] 中国科学院贵阳地球化学研究所.华南花岗岩类的地球化学[M].北京:科学出版社,1979:1-421.
[24] 吴永乐.西华山钨矿地质[M].北京:地质出版社,1987:1-317.
[25] 赵正.南岭东段银坑矿田构造岩浆活动与成矿规律研究[D].北京:中国地质科学院,2012.
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