Genesis of Late Ordovician granite porphyry at Heicigou gold deposit, East Kunlun: constraints from zircon U-Pb age, geochemistry and Sr-Nd-Pb-Hf isotopic systematics
-
摘要:
黑刺沟金矿区位于东昆仑造山带西段, 区内花岗斑岩呈脉状沿北西向构造与金矿化带近平行产出, 是近年勘查工作新圈定的与金矿化有成因关系的酸性岩脉。对研究区花岗斑岩进行LA-ICP-MS锆石U-Pb测年, 全岩地球化学及Sr-Nd-Pb-Hf同位素研究, 探讨其形成时代、岩石成因、构造环境、岩浆源区等。研究结果表明, 花岗斑岩锆石U-Pb年龄为445.8±2.4 Ma (MSWD=0.36), 形成时间为晚奥陶世。岩石SiO2含量在75.17%~78.94%之间, K2O+Na2O含量为5.49%~7.07%, K2O/Na2O=0.01~0.03, 相对贫钾富钠, 贫MnO (0.05%~0.07%)、MgO (0.08%~0.25%)、P2O5(0.07%~0.08%)和TiO2(0.15%~0.18%), 属低钾钙碱性岩石系列。A/CNK值为0.92~0.99, A/NK值为1.1~1.14, 为准铝质岩石。稀土元素总量介于132.4×10-6~183.95×10-6之间, LREE/HREE=8.04~8.78, 微量元素显示Ba、Th、Pb相对富集, K、P、Ti亏损, 微量元素组成特征具有I型花岗岩特征。Sr-Nd-Pb-Hf同位素显示, 样品具有高的ISr值(0.7133~0.7158), 低εNd(t)值(-4.45~-5.15), tDM年龄为1.54~1.6 Ga, 初始铅同位素比值(206Pb/204Pb)i=18.218~18.375, (207Pb/204Pb)i=15.63~15.738, (208Pb/204Pb)i=38.22~38.544, 锆石εHf(t)值为-11.12~+0.13, tDM2=1.42~1.65 Ga。综合认为, 花岗斑岩形成于晚奥陶世原特提斯洋向北俯冲消减环境下的陆缘弧环境, 岩浆来源于下地壳中—古元古代物质的部分熔融。
-
关键词:
- 黑刺沟花岗斑岩 /
- 岩石成因 /
- LA-ICP-MS锆石U-Pb年龄 /
- Sr-Nd-Pb-Hf同位素 /
- 全岩地球化学 /
- 晚奥陶世
Abstract:The Heicigou gold deposit is located in the southern segment of the East Kunlun Orogen.The graniteporphyry in the area which is parallel to the gold metallogenic belt along the NW trending structure, is a newly delineated felsic dike related to the gold mineralization in recent years.Based on LA-ICP-MS zircon U-Pb dating, Sr-Nd-Pb-Hf isotopic systematics, and whole-rock geochemistry, the formation age, petrogenesis, tectonic setting, and magma source of the granite porphyry are discussed in detail.The results show that the zircon U-Pb age of the granite porphyry is 445.8±2.4 Ma(MSWD=0.36), indicating an age of the Late Ordovician.The granite porphyry contains 75.17%~78.94% SiO2, 10.22%~12.8% Al2O3, 5.49%~7.07% K2O+Na2O, K2O/Na2O ranging from 0.01 to 0.03, 0.05%~0.07% MnO, 0.08%~0.25%MgO, 0.07%~0.08% P2O5, and 0.15%~0.18% TiO2, suggesting that the rock belongs to the low-K calc-alkaline rock series.The A/CNK and A/NK values are 0.92~0.99 and 1.1~1.14, respectively, indicating that the rock is metaluminuous.The ΣREE concentration ranges from 132.4×10-6 to 183.95×10-6, with the LREE/HREE ratios varying between 8.04 and 8.78.The primitive mantle-normalized trace element spidergrams are characterized by enrichment in Ba, Th, and Pb and depletion in Nb, Ta, and Ti, similar to I-type granites in volcanic arc settings.The granite porphyry exhibits high ISr(0.7133~0.7158), (207Pb/204Pb)i but low εNd(t)(-4.45~-5.15)and εHf(t)(-11.12~+0.13), similar to magmas derived from the lower crust.It is believed that the granite porphyry was formed in a continental margin arc setting due to the northward subduction of the Proto-Tethys Ocean in the Late Ordovician, and that the magma was originated from the partial melting of the lower crust.
-
-
表 1 黑刺沟金矿区花岗斑岩地球化学数据
Table 1. Whole-rock geochemical data of the granite porphyry in the Heicigou gold deposit
样品号 HCG-1 HCG-2 HCG-3 HCG-4 样品号 HCG-1 HCG-2 HCG-3 HCG-4 SiO2 76.83 76.66 78.94 75.17 F 138.60 126.70 126.30 150.30 TiO2 0.17 0.18 0.15 0.17 Au 256.00 458.00 424.00 285.00 Al2O3 12.02 11.92 10.22 12.80 Cu 204.50 662.00 198.70 20.33 Fe2O3 1.64 1.87 1.15 1.45 Pb 318.30 1199.00 878.90 1328.00 FeO 0.42 0.27 0.58 0.40 Zn 59.02 21.84 57.84 2502.00 MnO 0.05 0.06 0.06 0.07 Ag 2.58 8.58 11.35 4.04 MgO 0.12 0.08 0.22 0.25 La 38.74 33.88 26.97 41.15 CaO 0.74 0.87 1.01 0.82 Ce 71.07 63.67 54.04 75.91 Na2O 6.55 6.53 5.42 6.89 Pr 8.30 7.33 6.63 8.72 K2O 0.08 0.06 0.07 0.19 Nd 30.25 26.67 24.50 31.65 P2O5 0.08 0.08 0.07 0.07 Sm 6.32 5.87 5.32 6.69 烧失量 0.90 1.03 1.51 1.27 Eu 0.67 0.63 0.66 0.53 总计 99.61 99.63 99.40 99.56 Gd 5.52 5.51 4.58 6.07 Rb 2.99 1.34 3.33 2.30 Tb 0.94 0.89 0.76 1.01 Ba 1567.00 2152.65 6144.29 795.32 Dy 5.02 4.85 4.02 5.48 Th 19.22 24.41 23.42 22.35 Ho 0.89 0.85 0.72 1.00 U 2.89 4.11 4.39 2.31 Er 2.37 2.27 1.84 2.58 Nb 12.28 15.48 12.02 14.46 Tm 0.36 0.34 0.29 0.39 Ta 1.57 2.37 1.97 2.27 Yb 2.24 2.15 1.81 2.41 Sr 83.85 97.40 125.77 86.67 Lu 0.35 0.32 0.28 0.36 Zr 96.03 99.20 80.98 104.25 Y 26.20 25.23 20.22 29.30 Hf 2.99 3.65 2.99 3.49 ΣREE 173.06 155.22 132.40 183.95 Sc 5.78 5.17 4.98 4.77 LREE 155.36 138.04 118.11 164.64 W 14.74 13.41 9.78 20.47 HREE 17.70 17.18 14.29 19.30 Sn 6.65 7.54 6.07 11.68 LREE/HREE 8.78 8.04 8.26 8.53 Bi 1.67 9.56 3.46 0.31 LaN/YbN 12.41 11.32 10.68 12.26 Mo 0.18 0.26 0.15 0.42 δEu 0.35 0.34 0.41 0.25 V 19.88 19.29 16.45 18.99 δCe 0.97 0.99 0.99 0.98 Li 3.45 3.52 4.11 1.92 A/CNK 0.99 0.96 0.92 0.99 Be 0.81 0.88 0.63 1.08 σ 1.30 1.28 0.84 1.55 注: A/CNK=(Al2O3)/(CaO+K2 O+Na2O)摩尔分数比；里特曼指数σ=(K2O+Na2O)2/(SiO2 -43)。主量元素含量单位为%，微量元素中Au含量单位为10-9，其余元素及稀土元素含量单位为10-6 
下载: 导出CSV
表 2 黑刺沟金矿区花岗斑岩LA-ICP-MS锆石U-Th-Pb同位素分析结果
Table 2. LA-ICP-MS zircon U-Th-Pb isotopic dating results of the Heicigou granite porphyry
点号 元素含量/10-6 Th/U 同位素比值 同位素年龄/Ma Th U 207Pb/206Pb 207Pb/235U 206Pb/238U 207Pb/206Pb 207Pb/235U 206Pb/238U 1 260 976 0.27 0.0691±0.001 0.6819±0.0098 0.0716±0.0008 900.5±29.8 527.9±5.9 446±4.6 2 190 704 0.27 0.0565±0.0007 0.5572±0.0074 0.0717±0.001 472±27.1 449.7±4.8 446.2±6 3 313 1057 0.30 0.056±0.0005 0.5555±0.0073 0.0717±0.0007 453.7±19.6 448.6±4.8 446.4±4.2 4 357 649 0.55 0.0662±0.0009 0.6606±0.0094 0.0723±0.0006 813.2±27.6 515±5.7 450±3.5 5 216 913 0.24 0.0563±0.0005 0.5581±0.0054 0.0718±0.0006 463.6±21 450.3±3.5 446.8±3.3 6 184 856 0.21 0.0649±0.0007 0.6449±0.0083 0.0722±0.0008 771.1±23.5 505.4±5.1 449.1±5 7 373 1609 0.23 0.0564±0.0012 0.5526±0.0133 0.071±0.0012 468.7±46.2 446.7±8.7 442.2±7.2 8 320 1593 0.20 0.0568±0.0007 0.5593±0.0063 0.0714±0.0006 484±26.6 451.1±4.1 444.3±3.7 9 120 582 0.21 0.0551±0.0006 0.5486±0.0058 0.0721±0.0006 417.1±25.1 444.1±3.8 448.8±3.6 10 93 650 0.14 0.0576±0.0011 0.5694±0.01 0.0715±0.001 514.4±43 457.6±6.5 445.4±5.7 11 226 1111 0.20 0.0565±0.0007 0.557±0.0094 0.0713±0.0007 472.1±27.3 449.6±6.1 444.1±4.1 12 153 876 0.17 0.0559±0.0007 0.5548±0.0063 0.0719±0.0005 448.2±26.3 448.1±4.1 447.7±2.8
下载: 导出CSV
表 3 黑刺沟金矿区花岗斑岩Sr和Nd同位素组成
Table 3. Sr and Nd isotopic compositions of the granite porphyry in the Heicigou gold deposit
样品号 87Rb/86Sr 87Sr/86Sr (87Sr/86Sr)i 147Sm/144Nd 143Nd/144Nd (143Nd/144Nd)i εNd(t) fSm/Nd tDM/Ma HCG-1 0.103 0.7143 0.7136 0.1264 0.5122 0.5118 -5.13 -0.36 1711 HCG-2 0.040 0.7142 0.7140 0.1330 0.5122 0.5118 -4.45 -0.32 1747 HCG-3 0.077 0.7138 0.7133 0.1312 0.5122 0.5118 -5.15 -0.33 1787 HCG-4 0.077 0.7162 0.7158 0.1278 0.5122 0.5118 -4.74 -0.35 1696 注: (87Sr/86Sr)CHUR=0.7045，(87Rb/86Sr)CHUR=0.0827，λRb=0.0142Ga-1，(143Nd/144Nd)CHUR=0.5126，(147Sm/144Nd)CHUR=0.1967，(143Nd/144Nd)DM=0.5132，(147Sm/144Nd)DM=0.2137，λSr=0.0065Ga-1，t=445.8 Ma，fSm/Nd=(147Sm/144Nd)s/(147Sm/144Nd)CHUR-1，s(代表样品)
下载: 导出CSV
表 4 黑刺沟金矿区花岗斑岩Pb同位素组成
Table 4. Pb isotopic compositions of the granite porphyry in the Heicigou gold deposit
样品号 206Pb/204Pb 1σ 207Pb/204Pb 1σ 208Pb/204Pb 1σ t/Ma (206Pb/204Pb)i (207Pb/204Pb)i (208Pb/204Pb)i HCG-1 18.416 0.0002 15.741 0.0002 38.633 0.0008 445.8 18.375 15.738 38.544 HCG-2 18.371 0.0003 15.723 0.0004 38.551 0.0012 445.8 18.355 15.722 38.522 HCG-3 18.294 0.0021 15.632 0.0026 38.259 0.0085 445.8 18.272 15.630 38.220 HCG-4 18.226 0.0002 15.662 0.0002 38.567 0.0008 445.8 18.218 15.662 38.543 注: (206Pb/204Pb)i=(206Pb/204Pb)实测-μ(eλt-1)，(207Pb/204Pb)i=(207Pb/204Pb)实测-μ/137.88(eλt-1)，(208Pb/204Pb)i=(208Pb/204Pb)实测-ω(eλt-1)，式中t为侵位年龄445.8 Ma，λ238U=1.55125×10－10/a，λ235U=9.8485×10－10/a，λ232Th=4.9475×10－11/a
下载: 导出CSV
表 5 黑刺沟金矿区花岗斑岩锆石原位Hf同位素数据
Table 5. Zircon in situ Hf isotopic data of the granite porphyry in the Heicigou gold deposit
点号 176Yb/177Hf 2σ 176Lu/177Hf 2σ 176Hf/177Hf 2σ t/Ma εHf(t) TDM1/Ma TDM2/Ma fLu/Hf 1 0.020843 0.000248 0.000708 0.000012 0.282450 0.000020 445.8 -1.8 1124 1538 -0.98 2 0.010521 0.000460 0.000371 0.000017 0.282429 0.000021 -2.4 1142 1577 -0.99 3 0.011578 0.000106 0.000360 0.000004 0.282395 0.000019 -3.6 1189 1654 -0.99 4 0.033064 0.000839 0.001149 0.000025 0.282462 0.000021 -1.4 1121 1521 -0.97 5 0.007096 0.000114 0.000227 0.000004 0.282466 0.000020 -1.0 1088 1493 -0.99 6 0.016727 0.000233 0.000558 0.000007 0.282461 0.000023 -1.3 1103 1509 -0.98 7 0.015343 0.000573 0.000513 0.000022 0.282503 0.000021 0.1 1045 1416 -0.98 8 0.021738 0.000395 0.000655 0.000010 0.282503 0.000017 0.1 1048 1417 -0.98 9 0.022948 0.000830 0.000793 0.000031 0.282420 0.000020 -2.8 1168 1606 -0.98 10 0.015647 0.000335 0.000519 0.000011 0.282490 0.000019 -0.3 1063 1445 -0.98 11 0.044412 0.000721 0.001445 0.000017 0.282462 0.000021 -1.6 1129 1525 -0.96 12 0.013922 0.000546 0.000447 0.000017 0.282183 0.000037 -11.1 1483 2128 -0.99 注: 176Lu的衰变常数为1.865×10－11 a－1；球粒陨石标准值: (176Lu/177Hf)CHUR=0.0332±0.0002，(176Hf/177Hf)CHUR=0.282772±0.000029，(176Lu/177Hf)DM=0.0384，(176Hf/177Hf)DM=0.28325；tDM=1/λ×ln{1+[(176Hf/177Hf)sample－(176Hf/177Hf)DM]/[(176Lu/177Hf)sample－(176Lu/177Hf)DM]
下载: 导出CSV
-
[1] 潘彤, 王秉璋, 李东生, 等. 青海东昆仑成矿环境成矿规律与找矿方向[M]. 北京: 地质出版社, 2016.
[2] 李瑞保, 裴先治, 李佐臣, 等. 东昆仑南缘布青山构造混杂带得力斯坦南MOR型玄武岩地质、地球化学特征及岩石成因[J]. 地球科学, 2015, 40(7): 1148-1162. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX201507004.htm
[3] 莫宣学, 罗照华, 邓晋福, 等. 东昆仑造山带花岗岩及地壳生长[J]. 高校地质学报, 2007, 13(3): 403-414. doi: 10.3969/j.issn.1006-7493.2007.03.010
[4] 陈加杰, 付乐兵, 魏俊浩, 等. 东昆仑沟里地区晚奥陶世花岗闪长岩地球化学特征及其对原特提斯洋演化的制约[J]. 地球科学, 2016, 41(11): 1863-1882. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX201611004.htm
[5] 陈邦学, 徐胜利, 杨有生, 等. 东昆仑西段其木来克一带晚二叠世侵入岩的成因及其构造意义[J]. 地质通报, 2019, 38(6): 1040-1051. http://dzhtb.cgs.cn/gbc/ch/reader/view_abstract.aspx?file_no=20190614&flag=1
[6] 高晓峰, 校培喜, 谢从瑞, 等. 东昆仑阿牙克库木湖北巴什尔希花岗岩锆石LA-ICP-MS U-Pb定年及其地质意义[J]. 地质通报, 2010, 29(7): 1001-1008. doi: 10.3969/j.issn.1671-2552.2010.07.005 http://dzhtb.cgs.cn/gbc/ch/reader/view_abstract.aspx?file_no=20100705&flag=1
[7] 刘彬. 东昆仑跃进山早泥盆世侵入杂岩体岩石学、锆石U-Pb年代学及岩石成因[D]. 中国地质大学硕士学位论文, 2011.
[8] Anderson T. Correction of common lead in U-Pb analyses that do not report 204Pb[J]. Chemical Geology, 2002, 192(1/2): 59-79.
[9] Ludwig K R. User's manual for Isoplot 3.0: A geochronologicaltoolkit for Microsoft Excel[M]. Berkeley Geochronology CenterSpecial Publication, 2003: 1-20.
[10] Middlemost E A K. Naming materials in the magma/igneous rock system [J]. Earth Science Reviews, 1994, 37(3/4): 215-224.
[11] Irvine T N, Barager W R A. A guide to the chemical classification of the common volcanic rocks[J]. Canadian Journal of Earth Sciences, 1971, 8: 523-548. doi: 10.1139/e71-055
[12] Maniar P D, Piccoli P M. Tectonic discrimination of granitoids[J]. Geological Society of America Bulletin, 1989, 101(5): 635-643. doi: 10.1130/0016-7606(1989)101<0635:TDOG>2.3.CO;2
[13] O'Connor J A. classification for quartz-rich igneous rock based on feldspar ratios[J]. US Geol Surv Prof Paper, 1965, 525: B79-B84.
[14] Sun S S, McDonough W F. Chemical and isotopic systematic of oceanic basalts: Implications for mantle composition and processes[C]//Saunders A D, Norry M J. Magmatism in the Ocean Basins. Geological Society, London, Special Publication, 1989, 42(1): 313-345.
[15] 吴元保, 郑永飞. 锆石成因矿物学研究及其对U-Pb年龄解释的制约[J]. 科学通报, 2004, 49(16): 1589-1604. doi: 10.3321/j.issn:0023-074X.2004.16.002
[16] Slama J, Kosler J, Condon D J, et al. Plesovice zircon-A new natural reference material for U-Pb and Hf isotopic microanalysis[J]. Chemical Geology, 2008: 1-35.
[17] 吴福元, 李献华, 郑永飞, 等. Lu-Hf同位素体系及其岩石学应用[J]. 岩石学报, 2007, 23(2): 185-220. https://www.cnki.com.cn/Article/CJFDTOTAL-YSXB200702002.htm
[18] 祁生胜. 青海省东昆仑造山带火成岩岩石构造组合与构造演化[D]. 中国地质大学博士学位论文, 2015.
[19] 张耀玲, 张绪教, 胡道功, 等. 东昆仑造山带纳赤台群流纹岩SHRIMP锆石U-Pb年龄[J]. 地质力学学报, 2010, 16(1): 21-27. doi: 10.3969/j.issn.1006-6616.2010.01.003
[20] 李献华, 李武显, 李正祥, 等. 再论南岭燕山早期花岗岩的成因类型与构造意义[J]. 科学通报, 2007, 52(9): 981-991. doi: 10.3321/j.issn:0023-074X.2007.09.001
[21] Collins W, Beams S, White A, et al. Nature and Origin of A-type Granites with Particular Reference to Southeastern Australia[J]. Contributions to Mineralogy and Petrology, 1982, 80(2): 189-200. doi: 10.1007/BF00374895
[22] Whalen J B, Currie K L, Chappell B W. A-type granites: geochemical characteristics, discriminatuon and petrogenesis[J]. Contributions to Mineralogy and Petrology, 1987, 95: 407-419. doi: 10.1007/BF00402202
[23] Alther R, Holl A, Hegner E, et al. High-potassium, calc-alkaline Ⅰ-type plutonism in the European Variscides: Northern Vosges(France)and northern Schwarzwald(Germany)[J]. Lithos, 2000, 50(1): 51-73. http://www.sciencedirect.com/science/article/pii/S0024493799000523
[24] 彭勃, 李宝龙, 秦广洲, 等. 西藏拉萨地块盐湖石英闪长岩成因: 锆石SHRIMP U-Pb年代学、地球化学及Sr-Nb-Pb-Hf同位素的制约[J]. 地质学报, 2019, 93(3): 606-621. https://www.cnki.com.cn/Article/CJFDTOTAL-DZXE201903007.htm
[25] Chappell B W, White A J R. Two contrasting granite types[J]. Pacific Geoglogy, 1974, 8: 173-174.
[26] Beard J S, Lofgren G E. Dehydration melting and water saturated melting of basaltic and andesitic greenstones and amphibolites at 1, 3 and 6.9kb[J]. Journal of Petrology, 1991, 32: 365-401. doi: 10.1093/petrology/32.2.365
[27] Clemens J D. Stype granitic magmas petrogenetic issues, models and evidence[J]. Earth Science Reviews, 2003, 61(1/2): 1-18.
[28] 张旗, 王元龙, 张福勤, 等. 埃达克岩与斑岩铜矿[J]. 华南地质与矿产, 2002, 3: 85-90. doi: 10.3969/j.issn.1007-3701.2002.03.012
[29] 孙立新, 任邦方, 赵凤清, 等. 内蒙古锡林浩特地块中元古代花岗片麻岩的锆石U-Pb年龄和Hf同位素特征[J]. 地质通报, 2013, 32(2/3): 327-340. https://www.cnki.com.cn/Article/CJFDTOTAL-ZQYD2013Z1011.htm
[30] 李婷, 李猛, 胡朝斌, 等. 东昆仑祁漫塔格阿确墩地区侵入岩U-Pb年代学、地球化学及其地质意义[J]. 地球科学, 2018, 43(12): 4350-4363. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX201812006.htm
[31] Pearce J A, Harris N B W, Tindle A G. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[J]. Journal of Petrology, 1984, 25: 956-983. doi: 10.1093/petrology/25.4.956
① 王秉璋, 王瑾, 叶占福, 等. 布喀达坂峰幅(J46C004001) 1∶25万区域地质调查. 2004.
-
图(10)
表(5)
计量
- 文章访问数: 1204
- PDF下载数: 74
- 施引文献: 0