Petrogenesis of Yarigong Granodiorite in Batang Area and Constraints on Porphyry Cu Fertility, Eastern Tibetan Plateau
-
摘要:
西藏东部的金沙江古特提斯洋闭合在早‒中三叠世，但碰撞后的地质过程还缺乏细致约束，斑岩Cu成矿潜力还缺乏系统评估.对藏东巴塘地区的亚日贡岩体开展年代学、岩石地球化学和矿物成分分析.锆石U-Pb定年结果表明其形成于~227 Ma.这些岩石具有高SiO2、Mg#特征（53~64），富集的Sr-Nd同位素组成（初始87Sr/86Sr=0.709 8~0.711 8，εNd（t）=-7.4~-8.0）.亚日贡高Mg#花岗闪长岩形成是陆壳熔体混染地幔岩石的结果，与古特提斯洋闭合后的板片断离作用有关.系统的锆石、磷灰石和角闪石成分分析表明，尽管亚日贡岩体的岩浆具有高的H2O含量（>5%）、但其氧逸度比典型斑岩Cu成矿岩浆偏低，且S含量显著低于全球典型成矿斑岩，指示区内形成斑岩型Cu矿床的潜力较低.
Abstract:The Paleo-Tethyan Ocean, represented by the Jinshajiang River suture in eastern Tibetan Plateau, was consumed and closed in the Early-Middle Triassic, but the specific process after the oceanic crust demise is still poorly constrained. The potential for porphyry copper mineralization of magma generated in post-subduction setting remains unclear. In present study, geochronological and geochemical analyses were carried out on the Yarigong pluton in Batang area. Magmas were intruded in Late Triassic as corroborated by zircon U-Pb mean age of about 227 Ma. Rocks from this intrusion were characterized by high SiO2 (65.5% to 67.6%) and Mg# (53 to 64), as well as high initial 87Sr/86Sr values (0.709 8 to 0.711 8) and low εNd(t) values (-7.4 to -8.0). Magma generation of the Yarigong pluton resulted from interaction between melts derived from continental crust and peridotite mantle, and partial melts of the continental crust was likely associated with the break-off of early subducted Paleo-Tethyan oceanic slab. Geochemical compositions of amphibole and zircon suggest high magma H2O contents (>5%), the oxygen fugacity of magma is lower than magma related to typical porphyry Cu deposits, and extremely low S in magma was indicated by consistent low SO3 in apatite. These conditions imply barren magma for porphyry Cu deposit formation.
-
图 1 金沙江古特提斯构造带大地构造单元略图（a）和晚古生代‒早中生代岩浆岩分布（b）
b.根据Hou et al.（2003）修编. GLS.甘孜‒理塘蛇绿混杂岩带；JSS.金沙江缝合带；JWA.江达‒维西岩浆弧；b.岩浆锆石年龄数据来自文献Zhu et al.（2011，2022），Zi et al.（2012）
Fig. 1. Sketch map showing major tectonic units (a) and Late Paleozoic-Early Mesozoic magmatic rocks (b) in the Jinshajiang Paleo-Tethyan belt
图 2 亚日贡花岗闪长岩代表性样品显微图像（a和b）和矿物电子背散射图像（c~f）
图c~f中，红色数据为角闪石（红色圆圈）分析点的MgO和Al2O3含量，蓝色数据为磷灰石（蓝色方块）分析点的Cl和SO3分析值；Amp.角闪石；Ap.磷灰石；Bt.黑云母；Kf.钾长石；Plg.斜长石；Qtz.石英
Fig. 2. Representative photomicrographs of the Yarigong granodiorites (a, b) and backscattered electron images of amphibole, apatite and plagioclase (c‒f)
图 3 亚日贡岩体锆石U-Pb谐和图和206U/238Pb加权平均年龄
Fig. 3. Zircon U-Pb concordia diagram and 206U/238Pb weighted mean age
图 4 K2O-SiO2图（a）和Mg#-SiO2图（b）
准同期的羊拉高Mg#安山岩用作对比，数据引自Fan et al.（2020）；图b中玄武质熔体与橄榄岩地幔反应熔体据Rapp et al.（1999），高压变质玄武质岩石熔融实验熔体范围据Rapp and Watson（1995）；拆沉下地壳起源的埃达克质岩范围据Rapp and Watson（2006）
Fig. 4. K2O-SiO2 (a) and Mg#-SiO2 (b) plots
图 5 球粒陨石标准化稀土元素配分图（a）和原始地幔标准化微量元素蛛网图（b）
标准化值据Sun and McDonough（1989），羊拉高Mg#安山岩数据来自Fan et al.（2020）
Fig. 5. Chondrite-normalized REE pattern (a) and primitive mantle-normalized trace element spider diagram (b)
图 6 Sr-Nd同位素
红色实心圆点代表亚日贡花岗闪长岩.图中二元混合拟合曲线上的标记指示5%端元增量. 金沙江古特提斯软流圈地幔值据Xu and Castillo（2004），羊拉高Mg#安山岩和人支雪山组玄武岩数据引自Fan et al.（2020）和Wang et al.（2014a，2014b），人支雪山组和攀天阁组流纹岩数据引自Wang et al.（2014a，2014b）和Zi et al.（2012），扬子下地壳和上地壳范围据Zhu et al.（2011）及其中参考文献
Fig. 6. Sr-Nd isotope plots
图 7 （a）Dy/Yb-SiO2协变图，（b）Nb/La-εNd(t)，（c）Th/La-εNd(t)，（d）Ba/Th-La/Sm图
据Tatsumi（2001）. 红色实心圆点代表亚日贡花岗闪长岩，羊拉高Mg#安山岩来自Fan et al.（2020）. 图a中角闪石分异趋势据Davidson et al.（2007），图d中全球沉积物平均成分、沉积物流体和熔体成分据Plank and Langmuir（1998）
Fig. 7. (a) Dy/Yb vs. SiO2 covariant diagram, (b) Nb/La-εNd(t), (c) Th/La vs. εNd(t) values, and (d) Ba/Th vs. La/Sm plots
图 8 根据角闪石（a. Ridolfi et al., 2010）和锆石（b. Ge et al., 2023）成分计算的平衡熔体H2O含量，根据锆石（c. Loucks et al., 2020）和角闪石（d. Ridolfi et al., 2010）计算的平衡熔体ΔFMQ氧逸度，磷灰石SO3（e）和Cl含量与F/Cl比值（f）
图e~f中黑色（字母简写指代依次为B：Bumolo；BM：Black Mountain；C：Clifton；Cor：Coroccohuayco；Cq：Chuquicamata；ES：El Salvador；RB：Rio Blanco；RC：Red Chirs；ST：Santo Tomas Ⅱ）和红色五星分别代表俯冲和碰撞阶段斑岩系统Cu矿床，根据Huang et al.（2023）文中整理数据绘制
Fig. 8. (a) and (b) showing calculated melt H2O contents in equilibrium with amphibole (Ridolfi et al., 2010) and zircon (Ge et al., 2023), (c) and (d) showing calculated ΔFMQ values of equilibrated melt crystallized zircon (Loucks et al., 2020) and amphibole (Ridolfi et al., 2010); apatite SO3 (e) and Cl contents (f) vs. F/Cl values
-
Aydin, F., Sönmez, M., Siebel, W., et al., 2022. Slab Break-off-Related Magnesian Andesites and Dacites with Adakitic Affinity from the Early Quaternary Keçiboyduran Stratovolcano, Cappadocia Province, Central Turkey: Evidence for Slab/Sediment Melt- Mantle Interaction and Magma Mixing. Contributions to Mineralogy and Petrology, 177(7): 65. https://doi.org/10.1007/s00410-022-01931-8 Davidson, J., Turner, S., Handley, H., et al., 2007. Amphibole "Sponge" in Arc Crust? Geology, 35(9): 787. https://doi.org/10.1130/g23637a.1 Davis, J. H., von Blanckenburg, F., 1995. Slab Breakoff: A Model of Lithosphere Detachment and Its Test in the Magmatism and Deformation of Collisional Orogens. Earth and Planetary Science Letters, 129(1-4): 85-102. https://doi.org/10.1016/0012-821X(94)00237-S Fan, H. P., Li, B., Zhou, J. X., et al., 2020. Subduction-Modified Mantle-Derived Triassic High-Mg Andesites in the Sanjiang Tethys, Eastern Tibet. Journal of Asian Earth Sciences, 191: 104216. https://doi.org/10.1016/j.jseaes.2019.104216 Gao, S., Rudnick, R. L., Yuan, H. L., et al., 2004. Recycling Lower Continental Crust in the North China Craton. Nature, 432(7019): 892-897. https://doi.org/10.1038/nature03162 Ge, R. F., Wilde, S. A., Zhu, W. B., et al., 2023. Earth's Early Continental Crust Formed from Wet and Oxidizing Arc Magmas. Nature, 623(7986): 334-339. https://doi.org/10.1038/s41586-023-06552-0 Gómez-Tuena, A., Langmuir, C. H., Goldstein, S. L., et al., 2007. Geochemical Evidence for Slab Melting in the Trans-Mexican Volcanic Belt. Journal of Petrology, 48(3): 537-562. https://doi.org/10.1093/petrology/egl071 Hou, Z. Q., Wang, L. Q., Zaw, K., et al., 2003. Post- Collisional Crustal Extension Setting and VHMS Mineralization in the Jinshajiang Orogenic Belt, Southwestern China. Ore Geology Reviews, 22(3-4): 177-199. https://doi.org/10.1016/S0169-1368(02)00141-5 Huang, M. L., Zhu, J. J., Bi, X. W., et al., 2022. Low Magmatic Cl Contents in Giant Porphyry Cu Deposits Caused by Early Fluid Exsolution: A Case Study of the Yulong Belt and Implication for Exploration. Ore Geology Reviews, 141: 104664. https://doi.org/10.1016/j.oregeorev.2021.104664 Huang, M. L., Zhu, J. J., Chiaradia, M., et al., 2023. Apatite Volatile Contents of Porphyry Cu Deposits Controlled by Depth-Related Fluid Exsolution Processes. Economic Geology, 118(5): 1201-1217. https://doi.org/10.5382/econgeo.5000 Jian, P., Liu, D. Y., Kröner, A., et al., 2009. Devonian to Permian Plate Tectonic Cycle of the Paleo-Tethys Orogen in Southwest China (Ⅰ): Geochemistry of Ophiolites, Arc/back-Arc Assemblages and Within-Plate Igneous Rocks. Lithos, 113(3-4): 748-766. https://doi.org/10.1016/j.lithos.2009.04.004 Jian, P., Liu, D. Y., Sun, X. M., 2003. SHRIMP Dating of Carboniferous Jinshajiang Ophiolite in Western Yunnan and Sichuan: Geochronological Constraints on the Evolution of the Paleo-Tethys Oceanic Crust. Acta Geologica Sinica, 77(2): 217-228, 291-292 (in Chinese with English abstract). Jugo, P. J., 2009. Sulfur Content at Sulfide Saturation in Oxidized Magmas. Geology, 37(5): 415-418. https://doi.org/10.1130/G25527A.1 Liu, Y. S., Hu, Z. C., Gao, S., et al., 2008. In Situ Analysis of Major and Trace Elements of Anhydrous Minerals by LA-ICP-MS without Applying an Internal Standard. Chemical Geology, 257(1-2): 34-43. https://doi.org/10.1016/j.chemgeo.2008.08.004 Loucks, R. R., Fiorentini, M. L., Henríquez, G. J., 2020. New Magmatic Oxybarometer Using Trace Elements in Zircon. Journal of Petrology, 61(3): egaa034. https://doi.org/10.1093/petrology/egaa034 Lu, Y. J., Loucks, R. R., Fiorentini, M., et al., 2016. Zircon Compositions as A Pathfinder for Porphyry Cu± Mo±Au Deposits. In: Richards, J. P., ed., Tectonics and Metallogeny of the Tethyan Orogenic Belt. Society of Economic Geologists, Colorado, 329-347. https://doi.org/10.5382/sp.19.13 Ludwig, K. R., 2012. A Geochronological Toolkit for Microsoft Excel. Berkeley Geochronology Center Special Publications, Berkeley, 75. Mo, X. X., Deng, J. F., Lu, F. X., 1994. Volcanism and the Evolution of Tethys in Sanjiang Area, Southwestern China. Journal of Asian Earth Sciences, 9(4): 325-333. https://doi.org/10.1016/0743-9547(94)90043-4 Plank, T., Langmuir, C. H., 1998. The Chemical Composition of Subducting Sediment and Its Consequences for the Crust and Mantle. Chemical Geology, 145(3-4): 325-394. https://doi.org/10.1016/S0009-2541(97)00150-2 Rapp, R. P., Shimizu, N., Norman, M. D., et al., 1999. Reaction between Slab-Derived Melts and Peridotite in the Mantle Wedge: Experimental Constraints at 3.8 GPa. Chemical Geology, 160(4): 335-356. https://doi.org/10.1016/S0009-2541(99)00106-0 Rapp, R. P., Watson, E. B., 1995. Dehydration Melting of Metabasalt at 8-32 kbar: Implications for Continental Growth and Crust-Mantle Recycling. Journal of Petrology, 36(4): 891-931. https://doi.org/10.1093/petrology/36.4.891 Richards, J. P., 2015. The Oxidation State, and Sulfur and Cu Contents of Arc Magmas: Implications for Metallogeny. Lithos, 233: 27-45. https://doi.org/10.1016/j.lithos.2014.12.011 Ridolfi, F., Renzulli, A., Puerini, M., 2010. Stability and Chemical Equilibrium of Amphibole in Calc-Alkaline Magmas: An Overview, New Thermobarometric Formulations and Application to Subduction-Related Volcanoes. Contributions to Mineralogy and Petrology, 160(1): 45-66. https://doi.org/10.1007/s00410-009-0465-7 Streck, M. J., Leeman, W. P., 2018. Petrology of "Mt. Shasta" High-Magnesian Andesite (HMA): A Product of Multi-Stage Crustal Assembly. American Mineralogist, 103(2): 216-240. https://doi.org/10.2138/am-2018-6151 Sun, S. S., McDonough, W. F., 1989. Chemical and Isotopic Systematics of Oceanic Basalts: Implications for Mantle Composition and Processes. Geological Society, London, Special Publications, 42(1): 313-345. https://doi.org/10.1144/GSL.SP.1989.042.01.19 Tang, Y., Qin, Y. D., Gong, X. D., et al., 2023. Petrology, Geochemistry and Ar-Ar Geochronology of Eclogites in Jinshajiang Orogenic Belt, Gonjo Area, Eastern Tibet and Restriction on Paleo-Tethyan Evolution. China Geology, 6(2): 285-302. https://doi.org/10.31035/cg2023025 Tatsumi, Y., 2001. Geochemical Modeling of Partial Melting of Subducting Sediments and Subsequent Melt-Mantle Interaction: Generation of High-Mg Andesites in the Setouchi Volcanic Belt, Southwest Japan. Geology, 29(4): 323-326. https://doi.org/10.1130/0091-7613(2001)029<0323:GMOPMO>2.0.CO;2 doi: 10.1130/0091-7613(2001)029<0323:GMOPMO>2.0.CO;2 Wang, B. D., Wang, L. Q., Chen, J. L., et al., 2014a. Triassic Three-Stage Collision in the Paleo-Tethys: Constraints from Magmatism in the Jiangda-Deqen-Weixi Continental Margin Arc, SW China. Gondwana Research, 26(2): 475-491. https://doi.org/10.1016/j.gr.2013.07.023 Wang, R., Richards, J. P., Hou, Z. Q., et al., 2014b. Increasing Magmatic Oxidation State from Paleocene to Miocene in the Eastern Gangdese Belt, Tibet: Implication for Collision-Related Porphyry Cu-Mo Au Mineralization. Economic Geology, 109(7): 1943-1965. https://doi.org/10.2113/econgeo.109.7.1943 Wang, D. Z., Hu, R. Z., Hollings, P., et al., 2021a. Remelting of a Neoproterozoic Arc Root: Origin of the Pulang and Songnuo Porphyry Cu Deposits, Southwest China. Mineralium Deposita, 56(6): 1043-1070. https://doi.org/10.1007/s00126-021-01049-0 Wang, J., Dan, W., Wang, Q., et al., 2021b. High-Mg# Adakitic Rocks Formed by Lower-Crustal Magma Differentiation: Mineralogical and Geochemical Evidence from Garnet-Bearing Diorite Porphyries in Central Tibet. Journal of Petrology, 62(4): egaa099. https://doi.org/10.1093/petrology/egaa099 Wang, R., Luo, C. H., Xia, W. J., et al., 2021. Progresses in the Study of High Magmatic Water and Oxidation State of Post-Collisional Magmas in the Gangdese Porphyry Deposit Belt. Bulletin of Mineralogy, Petrology and Geochemistry, 40(5): 1061-1077, 997 (in Chinese with English abstract). Wang, Q., Xu, J. F., Jian, P., et al., 2006. Petrogenesis of Adakitic Porphyries in an Extensional Tectonic Setting, Dexing, South China: Implications for the Genesis of Porphyry Copper Mineralization. Journal of Petrology, 47(1): 119-144. https://doi.org/10.1093/petrology/egi070 Xu, J. F., Castillo, P. R., 2004. Geochemical and Nd-Pb Isotopic Characteristics of the Tethyan Asthenosphere: Implications for the Origin of the Indian Ocean Mantle Domain. Tectonophysics, 393(1-4): 9-27. https://doi.org/10.1016/j.tecto.2004.07.028 Yang, Z. M., Goldfarb, R., Chang, Z. S., 2016. Generation of Postcollisional Porphyry Copper Deposits in Southern Tibet Triggered by Subduction of the Indian Continental Plate. In: Richards, J. P., ed., Tectonics and Metallogeny of the Tethyan Orogenic Belt. Society of Economic Geologists, Colorado, 279-300. https://doi.org/10.5382/sp.19.11 Zhu, J. J., Hu, R. Z., Bi, X. W., et al., 2011. Zircon U-Pb Ages, Hf-O Isotopes and Whole-Rock Sr-Nd-Pb Isotopic Geochemistry of Granitoids in the Jinshajiang Suture Zone, SW China: Constraints on Petrogenesis and Tectonic Evolution of the Paleo-Tethys Ocean. Lithos, 126(3-4): 248-264. https://doi.org/10.1016/j.lithos.2011.07.003 Zhu, J. J., Hu, R. Z., Bi, X. W., et al., 2022. Porphyry Cu Fertility of Eastern Paleo-Tethyan Arc Magmas: Evidence from Zircon and Apatite Compositions. Lithos, 424: 106775. https://doi.org/10.1016/j.lithos.2022.106775 Zhu, J. J., Hu, R. Z., Richards, J. P., et al., 2015. Genesis and Magmatic-Hydrothermal Evolution of the Yangla Skarn Cu Deposit, Southwest China. Economic Geology, 110(3): 631-652. https://doi.org/10.2113/econgeo.110.3.631 Zhu, J. J., Richards, J. P., Rees, C., et al., 2018. Elevated Magmatic Sulfur and Chlorine Contents in Ore-Forming Magmas at the Red Chris Porphyry Cu-Au Deposit, Northern British Columbia, Canada. Economic Geology, 113(5): 1047-1075. https://doi.org/10.5382/econgeo.2018.4581 Zi, J. W., Cawood, P. A., Fan, W. M., et al., 2012. Triassic Collision in the Paleo-Tethys Ocean Constrained by Volcanic Activity in SW China. Lithos, 144: 145-160. https://doi.org/10.1016/j.lithos.2012.04.020 简平, 刘敦一, 孙晓猛, 2003. 滇川西部金沙江石炭纪蛇绿岩SHRIMP测年: 古特提斯洋壳演化的同位素年代学制约. 地质学报, 77(2): 217-228, 291-292. 王瑞, 罗晨皓, 夏文杰, 等, 2021. 冈底斯后碰撞斑岩成矿带高水、高氧逸度岩浆成因研究进展. 矿物岩石地球化学通报, 40(5): 1061-1077, 997. -
下载:
点击查看大图
计量
- 文章访问数: 306
- HTML全文浏览量: 17
- PDF下载量: 41
- 被引次数: 0
