Zircon U-Pb age, petrogenesis and tectonic model of Miocene quartz monzonite in Zuozuoxiang area, Western Lhasa terrane
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摘要:
中新世的岩浆活动对于判别青藏高原新生代的构造演化具有重要意义，本文在拉萨地体西部左左乡地区新厘定出一套中新世石英二长岩。通过LA-ICP-MS测年，获得锆石206Pb/238U年龄为22.38±0.46 Ma(n=13，MSWD=0.71)，此年龄可代表石英二长岩的形成时代。全岩化学成分显示，其具有高的SiO2(65.87%~66.90%)、K2O(6.19%~6.41%)含量、K2O/Na2O值(1.7~1.8)及低的MgO(1.71%~1.76%)含量，岩石类型属于拉萨地体中新世钾质中酸性岩系列。依据岩石高的Mg#(56.5~57.8)值、Nb/Ta(16.0~16.4)值、Cr(46.0×10-6~48.9×10-6)、Ni(32.6×10-6~34.8×10-6)含量及大量的暗色包体，推测左左乡中新世石英二长岩形成于壳源岩浆与幔源岩浆的混合。依据区域内的隆升研究结果，推测印度板片分段俯冲及撕裂模型相比于岩石圈地幔对流减薄模型、增厚岩石圈拆沉模型、俯冲印度板片断裂模型能够更合理地解释拉萨地体中新世钾质-超钾质火山岩的成因。
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关键词:
- 拉萨地体 /
- 中新世 /
- 钾质中酸性岩 /
- 印度板片撕裂 /
- LA-ICP-MS锆石U-Pb测年
Abstract:The Miocene magmatism is of great significance to distinguish the Cenozoic tectonic evolution of the Tibetan Plateau.In this paper, a new set of Miocene quartz monzonite has been redefined in Zuozuoxiang area, western Lhasa terrane.Zircon U-Pb dating shows that the age of quartz monzonite is 22.38±0.46 Ma.Whole rock geochemical test shows that quartz monzonite has high SiO2 (65.87%~66.90%), K2O(6.19%~6.41%)contents, K2O/Na2O(1.7~1.8)ratios and low MgO(1.71%~1.76%)contents, belonging to potassic intermediate-acid rock.According to the high Mg#(56.5~57.8), Nb/Ta(16.0~16.4), Cr(46.0×10-6~48.9×10-6), Ni(32.6×10-6~34.8×10-6)and a large number of dark inclusions in the rocks, we believe that Miocene quartz monzonite from Zuozuoxiang area was formed by partial melting of thickened lower crust with the addition of mantle material.In addition, based on the results of uplift studies, we believe that the tearing of Indian plate is more suitable for the interpretation of Miocene potassic-ultrapotassic rocks in Lhasa terrane than the convective thinning of lithospheric mantle, the delamination of thickened lithosphere and the break-off of Indian plate.
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Key words:
- Lhasa terrane /
- Miocene /
- Potassic rocks /
- Tearing of Indian plate /
- LA-ICP-MS zircon U-Pb dating
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表 1 左左乡中新世石英二长岩锆石U-Th-Pb同位素数据
Table 1. U-Th-Pb isotope composition of zircon in the Miocene quartz monzonite at Zuozuoxiang area
编号 元素/10-6 Th/U 同位素比值 同位素年龄/Ma Th U Pb 207Pb/235U 1σ 206Pb/238U 1σ 207Pb/235U 1σ 206Pb/238U 1σ 1 1437 750 4.16 1.92 0.0211 0.0016 0.0036 0.0001 21.00 2.00 23.00 0.70 2 1751 905 5.06 1.93 0.0222 0.0015 0.0035 0.0001 22.00 1.00 22.30 0.60 3 1497 679 4.05 2.20 0.0268 0.0018 0.0035 0.0001 27.00 2.00 22.30 0.60 4 1341 551 3.43 2.43 0.0241 0.0020 0.0036 0.0001 24.00 2.00 23.00 0.70 5 314 363 4.08 0.87 0.0568 0.0037 0.0088 0.0003 56.00 4.00 57.00 2.00 6 1151 581 3.30 1.98 0.0211 0.0018 0.0036 0.0001 21.00 2.00 22.80 0.70 7 4444 1147 8.27 3.87 0.0221 0.0014 0.0034 0.0001 22.00 1.00 22.10 0.60 8 857 1026 6.87 0.83 0.0353 0.0019 0.0055 0.0002 35.00 2.00 35.30 1.00 9 1923 778 4.86 2.47 0.0219 0.0015 0.0035 0.0001 22.00 2.00 22.70 0.60 10 2391 964 5.47 2.48 0.0213 0.0025 0.0033 0.0001 21.00 3.00 21.20 0.80 11 1225 594 3.46 2.06 0.0207 0.0018 0.0036 0.0001 21.00 2.00 22.90 0.70 12 291 366 13.08 0.79 0.2546 0.0147 0.0288 0.0008 230.00 12.00 183.00 5.00 13 750 641 2.91 1.17 0.0222 0.0025 0.0033 0.0001 22.00 2.00 21.20 0.80 14 5634 1605 10.91 3.51 0.0242 0.0013 0.0034 0.0001 24.00 1.00 22.00 0.60 15 240 307 5.22 0.78 0.1057 0.0144 0.0148 0.0007 102.00 13.00 94.00 4.00 16 4363 1509 8.85 2.89 0.0214 0.0015 0.0033 0.0001 22.00 2.00 21.00 0.60 17 250 258 7.85 0.97 0.1534 0.0087 0.0229 0.0006 145.00 8.00 146.00 4.00 18 241 642 18.19 0.38 0.2173 0.0106 0.0273 0.0007 200.00 9.00 173.00 5.00 19 107 102 11.27 1.04 0.6624 0.0510 0.0837 0.0028 516.00 31.00 518.00 16.00 20 5113 1292 9.47 3.96 0.0238 0.0016 0.0035 0.0001 24.00 2.00 22.40 0.60 
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表 2 左左乡中新世石英二长岩主量、微量和稀土元素含量
Table 2. Analytical results of major, trace and rare earth elements of Miocene quartz monzonite in Zuozuoxiang area
编号 B19T11H1 B19T11H2 B19T11H3 编号 B19T11H1 B19T11H2 B19T11H3 SiO2 66.90 65.87 66.41 La 90.7 95.2 94.3 Al2O3 14.69 14.36 14.79 Ce 186.3 197.0 195.0 MgO 1.76 1.71 1.73 Pr 22.6 24.1 23.8 Na2O 3.65 3.47 3.60 Nd 87.9 94.1 92.6 K2O 6.30 6.19 6.41 Sm 14.2 15.1 15.0 P2O5 0.36 0.38 0.36 Eu 2.5 2.6 2.6 TiO2 0.68 0.69 0.67 Gd 7.2 7.4 7.4 CaO 2.16 2.80 2.33 Tb 0.7 0.8 0.8 TFe2O3 3.00 3.07 2.98 Dy 3.3 3.5 3.4 MnO 0.05 0.05 0.05 Ho 0.5 0.6 0.6 烧失量 0.79 1.69 0.95 Er 1.2 1.3 1.3 Cr 46.8 48.9 46.0 Tm 0.2 0.2 0.2 Ni 32.6 34.8 33.0 Yb 1.1 1.1 1.1 Rb 477.0 476.7 476.7 Lu 0.2 0.2 0.2 Sr 627.3 524.6 699.3 Hf 13.6 13.8 13.7 Y 12.9 13.6 13.5 Ta 1.5 1.5 1.5 Zr 458.4 466.6 471.5 Pb 87.4 97.4 97.7 Nb 23.4 24.6 24.2 Th 113.9 122.7 117.7 Cs 25.4 27.8 27.0 U 12.4 14.1 12.4 Ba 1837.0 2090.2 2090.6 注：主量元素含量单位为%，微量和稀土元素含量单位为10-6
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[1] 赵志丹, 莫宣学, Nomade S, 等. 青藏高原拉萨地块碰撞后超钾质岩石的时空分布及其意义[J]. 岩石学报, 2006, 22: 787-794. https://www.cnki.com.cn/Article/CJFDTOTAL-YSXB200604003.htm
[2] Foley S F, Venturelli G, Green D H. The ultrapotassic rocks: characteristics, classification, and constraints for petrogenetic models[J]. Earth Science Reviews, 1987, 24(2): 81-134. doi: 10.1016/0012-8252(87)90001-8
[3] Chen J L, Zhao W X, Xu J F, et al. Geochemistry of Miocene trachytes in Bugasi, Lhasa block, Tibetan Plateau: Mixing products between mantle- and crust-derived melts?[J]. Gondwana Research, 2012, 21: 112-122. doi: 10.1016/j.gr.2011.06.008
[4] 陈建林, 许继峰, 康志强, 等. 青藏高原西南部查孜地区中新世钾质火山岩地球化学及其成因[J]. 地球化学, 2007, 36: 457-466. https://www.cnki.com.cn/Article/CJFDTOTAL-DQHX200705003.htm
[5] 孙晨光, 赵志丹, 莫宣学, 等. 青藏高原拉萨地块西部中新世赛利普超钾质岩石的地球化学与岩石成因[J]. 岩石学报, 2007, 23: 2715-2726. doi: 10.3969/j.issn.1000-0569.2007.11.004
[6] 刘栋, 赵志丹, 朱弟成, 等. 青藏高原拉萨地块西部雄巴盆地后碰撞钾质-超钾质火山岩年代学与地球化学[J]. 岩石学报, 2011, 27(7): 2045-2059. https://www.cnki.com.cn/Article/CJFDTOTAL-YSXB201107014.htm
[7] 刘栋. 青藏高原后碰撞钾质-超钾质岩石的地球化学特征与岩石成因[D]. 中国地质大学(北京)博士学位论文, 2017.
[8] Chung S L, Lo C H, Lee T Y, et al. Diachronous uplift of the Tibetan plateau starting 40 Myr ago[J]. Nature, 1998, 394: 769-773. doi: 10.1038/29511
[9] Turner S, Arnaud N, Liu J, et al. Post-collision, shoshonitic volcanism on the Tibetan Plateau: Implications for convective thinning of the lithosphere and the source of ocean island basalts[J]. Journal of Petrology, 1996, 37: 45-71. doi: 10.1093/petrology/37.1.45
[10] Chen J L, Zhao W X, Xu J F, et al. Geochemistry of Miocene trachytes in Bugasi, Lhasa block, Tibetan Plateau: Mixing products between mantle- and crust-derived melts?[J]. Gondwana Research, 2012, 21: 112-122. doi: 10.1016/j.gr.2011.06.008
[11] 侯增谦, 赵志丹, 高永丰, 等. 印度大陆板片前缘撕裂与分段俯冲: 来自冈底斯新生代火山-岩浆作用证据[J]. 岩石学报, 2006, 22(4): 761-774. https://www.cnki.com.cn/Article/CJFDTOTAL-YSXB200604001.htm
[12] Hao L L, Wang Q, Wyman D A, et al. First identification of postcollisional A-type magmatism in the Himalayan-Tibetan orogeny[J]. Geology, 2019, 47: 187-190.
[13] Chung S L, Lo C H, Lee T Y, et al. Diachronous uplift of the Tibetan plateau starting 40 Myr ago[J]. Nature, 1998, 394: 769-773. doi: 10.1038/29511
[14] Wang C S, Dai J G, Zhao X X, et al. Outward-growth of the Tibetan Plateau during the Cenozoic: a review[J]. Tectonophysics, 2014, 621: 1-43. doi: 10.1016/j.tecto.2014.01.036
[15] Yin A, Harrison T M. Geologic evolution of the Himalayan-Tibetan Orogen[J]. Annual Review of Earth and Planetary Sciences, 2000, 28: 211-280. doi: 10.1146/annurev.earth.28.1.211
[16] 李才, 翟庆国, 董永胜, 等. 青藏高原羌塘中部榴辉岩的发现及其意义[J]. 科学通报, 2006, 51(1): 70-74. https://www.cnki.com.cn/Article/CJFDTOTAL-KXTB200601013.htm
[17] Zhu D C, Zhao Z D, Niu Y L, et al. The origin and pre-Cenozoic evolution of the Tibetan Plateau[J]. Gondwana Research, 2013, 23: 1429-1454. doi: 10.1016/j.gr.2012.02.002
[18] Yuan H L, Gao S, Liu X M, et al. Accurate U-Pb Age and Trace Element Determinations of Zircon by Laser Ablation- Inductively Coupled Plasma-Mass Spectrometry[J]. Geostandards and Geoana-lytical Research, 2004, 28: 353-370. doi: 10.1111/j.1751-908X.2004.tb00755.x
[19] Ludwig K R. User's Manual for Isoplot 3.00: A Geochronological Toolkit for Microsoft Excel[M]. Berkeley Geochronology Center Special Publication, Berkeley, 2003.
[20] 于红. 陕西商南松树沟橄榄岩矿物地球化学特征及成因机理示踪[D]. 中国地质大学(北京)博士学位论文, 2011.
[21] 吴福元, 李献华, 杨进辉, 等. 花岗岩成因研究的若干问题[J]. 岩石学报, 2007, 23: 1217-1238. doi: 10.3969/j.issn.1000-0569.2007.06.001
[22] Lee C T A, Tang M. How to make a copper porphyry ore deposit[J]. Earth and Planetary Science Letters, 2020, 529: 115868. doi: 10.1016/j.epsl.2019.115868
[23] Baker M B, Hischmann M M, Ghiorso M S, et al. Compositions of near solidus predictive melts from experiments and thermodynamic calculations[J]. Nature, 1995, 375: 308-311. doi: 10.1038/375308a0
[24] Defant M J, Drummond M S. Derivation of some modern arc magmas by melting of young subducted lithosphere[J]. Nature, 1990, 347(6294): 662-665. doi: 10.1038/347662a0
[25] Castillo P R, Janney P E, Solidum R U. Petrology and geochemistry of Camiguin Island, southern Philippines: insights to the source of adakites and other lavas in a complex arc setting[J]. Contributions to Mineralogy & Petrology, 1999, 134(1): 33-51.
[26] Rapp R P, Watson E B. Dehydration melting of metabasalt at 8-32 kbar: implications for continental growth and crust-mantle recycling[J]. Journal of Petrology, 1995, 36: 891-931. doi: 10.1093/petrology/36.4.891
[27] Chen J L, Xu J F, Kang Z Q, et al. Origin of Cenozoic alkaline potassic volcanic rocks at Konglongxiang, Lhasa terrane, Tibetan Plateau: products of partial melting of a mafic lower-crustal source?[J]. Chemical Geology, 2010, 273: 286-299. doi: 10.1016/j.chemgeo.2010.03.003
[28] Münker C, Pfnder J A, Weyer S, et al. Evolution of planetary cores and the earth-moon system from Nb/Ta systematics[J]. Science, 2003, 301(5629): 84-87. doi: 10.1126/science.1084662
[29] Pfnder J A, Münker C, Stracke A, et al. Nb/Ta and Zr/Hf in ocean island basalts: Implications for crust-mantle differentiation and the fate of niobium[J]. Earth and Planetary Science Letters, 2007, 254(1-2): 158-172. doi: 10.1016/j.epsl.2006.11.027
[30] 黄思华, 陈建林, 曾云川, 等. 拉萨地块西北部早白垩世岩浆岩地球化学特征及其对高原南部早期地壳生长的指示[J]. 地球化学, 2020, 49: 21-35. https://www.cnki.com.cn/Article/CJFDTOTAL-DQHX202001002.htm
[31] 李勇, 张士贞, 李奋其, 等. 西藏拉萨地块西段狮泉河地区晚侏罗世花岗岩年代学、地球化学与岩石成因[J]. 地球科学, 2020. doi: 10.3799/dqkx.2020.102.
[32] Wang Q, Xu J F, Jian P, et al. Petrogenesis of Adakitic Porphyries in an Extensional Tectonic Setting, Dexing, South China: Implications for the Genesis of Porphyry Copper Mineralization[J]. Journal of Petrology, 2006, 47(1): 119-144. doi: 10.1093/petrology/egi070
[33] Bouilhol P, Jagoutz O, Hanchar J M, et al. Dating the India-Eurasia collision through arc magmatic records[J]. Earth and Planetary Science Letters, 2013, 366: 163-175. doi: 10.1016/j.epsl.2013.01.023
[34] Lippert P C, van Hinsbergen D J J, Dupont-Nivet G. Early Cretaceous to present latitude of the central proto-Tibetan Plateau: A paleomagnetic synthesis with implications for Cenozoic tectonics, paleogeography, and climate of Asia[J]. Geol. Soc. Am. Spec. Pap., 2014, 507: 1-21.
[35] Tapponnier P, Xu Z, Roger F, et al. Oblique stepwise rise and growth of the Tibet Plateau[J]. Science, 2001, 294: 1671-1677. doi: 10.1126/science.105978
[36] Turner S, Arnaud N, Liu J, et al. Post-collision, shoshonitic volcanism on the Tibetan Plateau: Implications for convective thinning of the lithosphere and the source of ocean island basalts[J]. Journal of Petrology, 1996, 37: 45-71. doi: 10.1093/petrology/37.1.45
[37] Hao L L, Wang Q, Wyman D A, et al. First identification of postcollisional A-type magmatism in the Himalayan-Tibetan orogeny[J]. Geology, 2019, 47: 187-190.
[38] Wang R, Richards J P, Zhou L M, et al. The role of Indian and Tibetan lithosphere in spatial distribution of Cenozoic magmatism and porphyry Cu-Mo deposits in the Gangdesebelt, southern Tibet[J]. Earth-Science Reviews, 2015, 150: 68-94. doi: 10.1016/j.earscirev.2015.07.003
[39] Copley A, Avouac J P, Royer J Y. India-Asia collision and the Cenozoic slowdown of the Indian plate: Implications for the forces driving plate motions[J]. Journal of Geophysical Research B: Solid Earth, 2010, 115: B03410.
[40] Kirstein L A. Thermal evolution and exhumation of the Ladakh Batholith, northwest Himalaya, India. Tectonophysics, 2011, 503(3/4): 222-233.
[41] Ding L, Xu Q, Yue Y, et al. The Andeantype Gangdese Mountains: paleoelevation record from the Paleocene-Eocene Linzhou Basin[J]. Earth and Planetary Science Letters, 2014, 392: 250-264. doi: 10.1016/j.epsl.2014.01.045
[42] Enkelmann E, Ehlers T A, Zeitler P K, et al. Denudation of the Namche Barwa antiform, eastern Himalaya[J]. Earth and Planetary Science Letters, 2011, 307: 323-333. doi: 10.1016/j.epsl.2011.05.004
[43] Dai J G, Wang C S, Hourigan J, et al. Exhumation history of the Gangdese Batholith, Southern Tibetan Plateau: evidence from apatite and zircon(U-Th)/He thermochronology[J]. J. Geol., 2013, 121(2): 155-172. doi: 10.1086/669250
[44] Ji W Q, Wu F Y, Liu C Z, et al. Early Eocene crustal thickening in southern Tibet: New age and geochemical constraints from the Gangdese batholith[J]. Journal of Asian Earth Sciences, 2012, 53: 82-95. doi: 10.1016/j.jseaes.2011.08.020
[45] Harrison T M, Copeland P, Kidd W S F, et al. Raising Tibet[J]. Science, 1992, 255: 1663-1670. doi: 10.1126/science.255.5052.1663
[46] Chung S L, Chu M F, Zhang Y, et al. Tibetan tectonic evolution inferred from spatial and temporal variations in post-collisional magmatism[J]. Earth-Science Reviews, 2005, 68: 173-196.
[47] Chen Y, Li W, Yuan X H, et al. Tearing of the Indian lithospheric slab beneath southern Tibet revealed by SKS-wave splitting measurements[J]. Earth and Planetary Science Letters, 2015, 413: 13-24. doi: 10.1016/j.epsl.2014.12.041
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