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Volume 32 Issue 6
Dec.  2021
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Wenbo Fan, Neng Jiang, Mingguo Zhai, Jun Hu. Origin of the Low δ18O Signals in Zircons from the Early Cretaceous A-Type Granites in Eastern China: Evidence from the Kulongshan Pluton. Journal of Earth Science, 2021, 32(6): 1415-1427. doi: 10.1007/s12583-021-1515-y
Citation: Wenbo Fan, Neng Jiang, Mingguo Zhai, Jun Hu. Origin of the Low δ18O Signals in Zircons from the Early Cretaceous A-Type Granites in Eastern China: Evidence from the Kulongshan Pluton. Journal of Earth Science, 2021, 32(6): 1415-1427. doi: 10.1007/s12583-021-1515-y

Origin of the Low δ18O Signals in Zircons from the Early Cretaceous A-Type Granites in Eastern China: Evidence from the Kulongshan Pluton

doi: 10.1007/s12583-021-1515-y
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  • The origin of low δ18O signals in zircons from the Early Cretaceous A-type granites in eastern China has long been disputed. It is uncertain whether the 18O-depleted features were inherited from high-temperature hydrothermal altered source rock or resulted from water-rock interaction after emplacement. In this paper, zircon oxygen isotopes in the ~130 Ma Kulongshan A-type granites in the northern North China Craton are analyzed. The zircons could be subdivided into 5 types based on their luminescent intensity and internal structures in CL images. Their δ18O values also vary in different types and show negative correlation with U and Th contents and accompanying cumulative α-decay doses, implying that their δ18O values may have been modified to various degrees by meteoric water-rock interaction after the accumulation of radiation damage. The idea is further confirmed by oxygen isotopic equilibrium calculation between co-existing mineral pairs. It is inferred that only the least-influenced zircons, with slightly elevated δ18O values than normal mantle, have preserved the magmatic oxygen isotopes. In combination with other evidences, it is proposed that the A-type granites are lower-crustal-derived, unnecessarily invoking a high-temperature hydrothermal altered source. The proposition is applicable to many other Cretaceous A-type granites that have similar zircon behaviors.
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  • Amelin, Y., Lee, D. C., Halliday, A. N., et al., 1999. Nature of the Earth's Earliest Crust from Hafnium Isotopes in Singledetrital Zircons. Nature, 399: 1497-1503. https://doi.org/10.1038/20426 doi:  10.1038/20426
    Bibikova, Y. V., Ustinov, V. I., Gracheva, T. V., et al. 1982. Variations of Isotopic Composition of Oxygen in Accessory Zircons. Doklady Akademii Nauk SSR, 264(3): 698-700
    Bindeman, I., 2008. Oxygen Isotopes in Mantle and Crustal Magmas as Revealed by Single Crystal Analysis. Reviews in Mineralogy and Geochemistry, 69(1): 445-478. https://doi.org/10.2138/rmg.2008.69.12 doi:  10.2138/rmg.2008.69.12
    Bindeman, I. N., Schmitt, A. K., Lundstrom, C. C., et al., 2018. Stability of Zircon and Its Isotopic Ratios in High-Temperature Fluids: Long-Term (4 Months) Isotope Exchange Experiment at 850℃ and 50 MPa. Frontiers in Earth Science, 6: 59. https://doi.org/10.3389/feart.2018.00059 doi:  10.3389/feart.2018.00059
    Bonin, B., 2007. A-Type Granites and Related Rocks: Evolution of a Concept, Problems and Prospects. Lithos, 97(1/2): 1-29. https://doi.org/10.1016/j.lithos.2006.12.007 doi:  10.1016/j.lithos.2006.12.007
    Booth, A. L., Kolodny, Y., Chamberlain, C. P., et al., 2005. Oxygen Isotopic Composition and U-Pb Discordance in Zircon. Geochimica et Cosmochimica Acta, 69(20): 4895-4905. https://doi.org/10.1016/j.gca.2005.05.013 doi:  10.1016/j.gca.2005.05.013
    Butera, K. M., Williams, I. S., Blevin, P. L., et al., 2001. Zircon U-Pb Dating of Early Palaeozoic Monzonitic Intrusives from the Goonumbla Area, New South Wales. Australian Journal of Earth Sciences, 48(3): 457-464. https://doi.org/10.1046/j.1440-0952.2001.00870.x doi:  10.1046/j.1440-0952.2001.00870.x
    Chakoumakos, B. C., Murakami, T., Lumpkin, G. R., et al., 1987. Alpha-Decay-Induced Fracturing in Zircon: The Transition from the Crystalline to the Metamict State. Science, 236(4808), 1556-1559. https://doi.org/10.1126/science.236.4808.1556 doi:  10.1126/science.236.4808.1556
    Charoy, B., Raimbault, L., 1994. Zr-, Th-and REE-Rich Biotite Differentiates in the A-Type Granite Pluton of Suzhou (Eastern China): The Key Role of Fluorine. Journal of Petrology, 35(4): 919-962. https://doi.org/10.1093/petrology/35.4.919 doi:  10.1093/petrology/35.4.919
    Clemens, J. D., Holloway, J. R., White, A. J. R., 1986. Origin of an A-Type Granite: Experimental Constraints. American Mineralogist, 71(3/4): 317-324 http://rruff.info/doclib/am/vol71/AM71_317.pdf
    Collins, W. J., Beams, S. D., White, A. J. R., et al., 1982. Nature and Origin of A-Type Granites with Particular Reference to Southeastern Australia. Contributions to Mineralogy and Petrology, 80: 189-200. https://doi.org/10.1007/bf00374895 doi:  10.1007/BF00374895
    Collins, W. J., Huang, H. Q., Bowden, P., et al., 2019. Repeated S-I-A-Type Granite Trilogy in the Lachlan Orogen and Geochemical Contrasts with A-Type Granites in Nigeria: Implications for Petrogenesis and Tectonic Discrimination. Geological Society, London, Special Publications, 491(1). https://doi.org/10.1144/sp491-2018-159 doi:  10.1144/sp491-2018-159
    Deng, X. Q., Peng, T. P., Zhou, Y. Y., et al., 2020. Origin of the Late Paleoproterozoic Low-δ18O A-Type Granites on the Southern Margin of the North China Craton and Their Geodynamic Mechanism. Precambrian Research, 351: 105960. https://doi.org/10.1016/j.precamres.2020.105960 doi:  10.1016/j.precamres.2020.105960
    Erdmann, S., Wodicka, N., Jackson, S. E., et al., 2013. Zircon Textures and Composition: Refractory Recorders of Magmatic Volatile Evolution? Contributions to Mineralogy and Petrology, 165: 45-71. https://doi.org/10.1007/s00410-012-0791-z doi:  10.1007/s00410-012-0791-z
    Ewing, R. C., Meldrum, A., Wang, L. M., et al., 2003. Radiation Effects in Zircon. Reviews in Mineralogy & Geochemistry, 53(1): 387-425. https://doi.org/10.2113/0530387 doi:  10.2113/0530387
    Fan, W. B., Jiang, N., Xu, X. Y., et al., 2017. Petrogenesis of the Middle Jurassic Appinite And Coeval Granitoids in the Eastern Hebei Area of North China Craton. Lithos, 278-281: 331-346. https://doi.org/10.1016/j.lithos.2017.01.030 doi:  10.1016/j.lithos.2017.01.030
    Fan, W. B., Jiang, N., Zhai, M. G., et al., 2020. Zircon Constraints on Granite Provenance in the Northern North China Craton. Lithos, 356/357: 105370. https://doi.org/10.1016/j.lithos.2020.105370 doi:  10.1016/j.lithos.2020.105370
    Farnan, I., Salje, E. K. H., 2001. The Degree and Nature of Radiation Damage in Zircon Observed by 29Si Nuclear Magnetic Resonance. Journal of Applied Physics, 89(4): 2084-2090. https://doi.org/10.1063/1.1343523 doi:  10.1063/1.1343523
    Geisler, T., Schaltegger, U., Tomaschek, F., 2007. Re-equilibration of Zircon in Aqueous Fluids and Melts. Elements, 3(1): 43-50. https://doi.org/10.2113/gselements.3.1.43 doi:  10.2113/gselements.3.1.43
    Griffin, W. L., Wang, X., Jackson, S. E., et al., 2002. Zircon Chemistry and Magma Mixing: SE China: in-situ Analysis of Hf Isotopes, Tonglu and Pingtan Igneous Complexes. Lithos, 61: 237-269. https://doi.org/10.1016/s0024-4937(02)00082-8 doi:  10.1016/S0024-4937(02)00082-8
    Gao, Y. Y., Li, X. H., Griffin, W. L., et al., 2014. Screening Criteria for Reliable U-Pb Geochronology and Oxygen Isotope Analysis in Uranium-Rich Zircons: A Case Study from the Suzhou A-Type Granites, SE China. Lithos, 192-195: 180-191. https://doi.org/10.1016/j.lithos.2014.02.002 doi:  10.1016/j.lithos.2014.02.002
    Guo, J. L., Wu, J. H., Niu, Z. L., et al., 2019. Petrogenesis of the Kulongshan Complex Pluton in Northern Hebei: Chronologic and Geochemical Constraints. Acta Metallurgica Sinica, 25(1): 33-50. https://doi.org/10.16108/j.issn1006-7493.2018048 (in Chinese with English Abstract) doi:  10.16108/j.issn1006-7493.2018048
    Hiess, J., Bennett, V. C., Nutman, A. P., et al., 2011. Archaean Fluid-Assisted Crustal Cannibalism Recorded by Low δ18O and Negative εHf(t) Isotopic Signatures of West Greenland Granite Zircon. Contributions to Mineralogy and Petrology, 161: 1027-1050. https://doi.org/10.1007/s00410-010-0578-z doi:  10.1007/s00410-010-0578-z
    Holland, H. D., Gottfried, D., 1955. The Effect of Nuclear Radiation on the Structure of Zircon. Acta Crystallographica, 8(6): 291-300 doi:  10.1107/S0365110X55000947
    Hoskin, P. W. O., 2005. Trace-Element Composition of Hydrothermal Zircon and the Alteration of Hadean Zircon from the Jack Hills, Australia. Geochimica et Cosmochimica Acta, 69(3): 637-648. https://doi.org/10.1016/j.gca.2004.07.006 doi:  10.1016/j.gca.2004.07.006
    Jahn, B. M., Condie, K. C., 1995. Evolution of the Kaapvaal Craton as Viewed from Geochemical and Sm-Nd Isotopic Analyses of Intracratonic Pelites. Geochimica et Cosmochirnica Acta, 59: 2239-2258. https://doi.org/10.1016/0016-7037(95)00103-7 doi:  10.1016/0016-7037(95)00103-7
    Jahn, B. M., Wu, F. Y., Hong, D., 2000. Important Crustal Growth in the Phanerozoic: Isotopic Evidence of Granitoids from East-Central Asia. Journal of Earth System Science, 109: 5-20. https://doi.org/10.1007/bf02719146 doi:  10.1007/BF02719146
    Jahn, B. M., Wu, F. Y., Capdevila, R., et al., 2001. Highly Evolved Juvenile Granites with Tetrad REE Patterns: The Woduhe and Baerzhe Granites from the Great Xing'an Mountains in NE China. Lithos, 59(4): 171-198. https://doi.org/10.1016/s0024-4937(01)00066-4 doi:  10.1016/S0024-4937(01)00066-4
    Javoy, M., Weis, D., 1987. Oxygen Isotopic Composition of Alkaline Anorogenic Granites as a Clue to Their Origin: The Problem of Crustal Oxygen. Earth and Planetary Science Letters, 84(4): 415-422. https://doi.org/10.1016/0012-821x(87)90006-9 doi:  10.1016/0012-821X(87)90006-9
    Jiang, N., Guo, J. H., Zhai, M. G., et al., 2010. ~2.7 Ga Continental Crust Growth in the North China craton. Precambrian Research, 179(1-4): 27-49. https://doi.org/10.1016/j.precamres.2010.02.010 doi:  10.1016/j.precamres.2010.02.010
    Jiang, N., Guo, J. H., Chang, G. H., 2013. Nature and Evolution of the Lower Crust in the Eastern North China Craton: A Review. Earth-Science Reviews, 122: 1-9. https://doi.org/10.1016/j.earscirev.2013.03.006 doi:  10.1016/j.earscirev.2013.03.006
    Li, X. H., Liu, Y., Li, Q. L., et al., 2009. Precise Determination of Phanerozoic Zircon Pb/Pb Age by Multi-Collector SIMS without External Standardization. Geochemistry Geophysical Geosystem, 10: Q04010. https://doi.org/10.1029/2009gc002607 doi:  10.1029/2009gc002607
    Li, X. H., Long, W. G., Li, Q. L., et al., 2010. Penglai Zircon Megacrysts: A Potential Newworking Reference Material for Micro Beam Determination of Hf-O Isotopes and U-Pb Age. Geostandards and Geoanalytical Research, 34: 117-134. https://doi.org/10.1111/j.1751-908x.2010.00036.x doi:  10.1111/j.1751-908X.2010.00036.x
    Li, S. L., Hao, J. J., 2017. REE Ore Mineralization of the Kulongshan A-Type Granites in Eastern Hebei. Huabei Land and Resources, 77: 53-62 (in Chinese)
    Liebmann, J., Spencer, C. J., Kirkland, C. L., et al., 2021. Effect of Water on δ18O in Zircon. Chemical Geology, 574: 120243. https://doi.org/10.1016/j.chemgeo.2021.120243 doi:  10.1016/j.chemgeo.2021.120243
    Liu, J. X., 1990. Preparation of Reference Materials for Oxygen Isotope Determination in Silicates. Rock and Mineral Analysis, 9(4): 276-282 (in Chinese with English Abstract) http://en.cnki.com.cn/Article_en/CJFDTOTAL-YKCS199004008.htm
    Liu, Y., Hou, Z. Q., Zhang, R. Q., et al., 2019. Zircon Alteration as a Proxy for Rare Earth Element Mineralization Processes in Carbonatite-Nordmarkite Complexes of the Mianning-Dechang Rare Earth Element Belt, China. Economic Geology, 114(4): 719-744. https://doi.org/10.5382/econgeo.4660 doi:  10.5382/econgeo.4660
    Loiselle, M. C., Wones, D. R., 1979. Characteristics and Origin of Anorogenic Granites. Geological Society of America, Abstracts, 11: 468 http://ci.nii.ac.jp/naid/10019593683
    Ludwig, K. R., 2012. User's Manual for Isoplot 3.75: A Geochronological Toolkit for Microsoft Excel. Special Publication No. 5. Berkeley Geochronology Center, Berkeley
    McDonough, W. F., Sun, S. S., 1995. The Composition of the Earth. Chemical Geology, 120: 223-253. https://doi.org/10.1016/0009-2541(94)00140-4 doi:  10.1016/0009-2541(94)00140-4
    Monani, S., Valley, J. W., 2001. Oxygen Isotope Ratios of Zircon: Magma Genesis of Low δ18O Granites from the British Tertiary Igneous Province, Western Scotland. Earth and Planetary Science Letters, 184(2): 377-392. https://doi.org/10.1016/s0012-821x(00)00328-9 doi:  10.1016/S0012-821X(00)00328-9
    Murakami, T., Chakoumakos, B. C., Ewing, R. C., et al., 1991. Alpha-Decay Event Damage in Zircon. American Mineralogist, 76(9/10): 1510-1532 http://ammin.geoscienceworld.org/content/76/9-10/1510
    Nasdala, L., Wenzel, M., Vavra, G., et al., 2001. Metamictisation of Natural Zircon: Accumulation versus Thermal Annealing of Radioactivity-Induced Damage. Contributions to Mineralogy and Petrology, 141(2): 125-144. https://doi.org/10.1007/s004100000235 doi:  10.1007/s004100000235
    Patiño Douce, A. E., 1997. Generation of Metaluminous A-Type Granites by Low-Pressure Melting of Calc-Alkaline Granitoids. Geology, 25(8): 743-746. https://doi.org/10.1130/0091-7613(1997)025<0743:gomatg>2.3.co;2 doi:  10.1130/0091-7613(1997)025<0743:GOMATG>2.3.CO;2
    Peck, W. H., Valley, J. W., Graham, C. M., 2003. Slow Oxygen Diffusion Rates in Igneous Zircons from Metamorphic Rocks. American Mineralogist, 88(7): 1003-1014. https://doi.org/10.2138/am-2003-0708 doi:  10.2138/am-2003-0708
    Pidgeon, R. T., Nemchin, A. A., Cliff, J., 2013. Interaction of Weathering Solutions with Oxygen and U-Pb Isotopic Systems of Radiation-Damaged Zircon from an Archean Granite, Darling Range Batholith, Western Australia. Contributions to Mineralogy and Petrology, 166(2): 511-523. https://doi.org/10.1007/s00410-013-0888-z doi:  10.1007/s00410-013-0888-z
    Qiu, K. F., Yu, H. C., Wu, M. Q., et al., 2019. Discrete Zr and REE Mineralization of the Baerzhe Rare-Metal Deposit, China. American Mineralogist, 104(10): 1487-1502. https://doi.org/10.2138/am-2019-6890 doi:  10.2138/am-2019-6890
    Silver, L. T., Deutsch, S., 1963. Uranium-Lead Isotopic Variations in Zircons: A Case Study. The Journal of Geology, 71(6): 721-758 doi:  10.1086/626951
    Steiger, R. H., Jager, E., 1977. Subcommission on Geochronology: Convention on the Use of Decay Constants in Geo-and Cosmochronology. Earth and Planetary Science Letters, 36: 359-362. https://doi.org/10.1016/0012-821x(77)90060-7 doi:  10.1016/0012-821X(77)90060-7
    Sun, J. F., Yang, J. H., 2009. Early Cretaceous A-Type Granites in the Eastern North China Block with Relation to Destruction of the Craton. Earth Science, 34: 137-147 (in Chinese with English Abstract)
    Sun, J. F., 2011. Petrogenesis of Early Cretaceous A-Type Granites in the Northern Liaodong Peninsula: Implications for Decratonization of the North China Craton: [Dissertation]. University of Chinese Academy of Sciences, Beijing. 103-105 (in Chinese)
    Tang, J., Xu, W. L., Wang, F., et al., 2018. Subduction History of the Paleo-Pacific Slab beneath Eurasian Continent: Mesozoic-Paleogene Magmatic Records in Northeast Asia. Science China Earth Sciences, 61: 527-559. https://doi.org/10.1007/s11430-017-9174-1 doi:  10.1007/s11430-017-9174-1
    Taylor, H. P., 1988. Oxygen, Hydrogen and Stronium Isotope Constaints on the Origin of Granite. Transactions of the Royal Society of Edinburg: Earth Science, 79: 317-338 doi:  10.1017/S0263593300014309
    Taylor, S. R., McLennan, S. M., 1985. The Continental Crust: Its Composition and Evolution. Blackwell Scientific Publications, Oxford
    Trail, D., Bindeman, I. N., Watson, E. B., et al., 2009. Experimental Calibration of Oxygen Isotope Fractionation between Quartz and Zircon. Geochimica et Cosmochimica Acta, 73(23): 7110-7126. https://doi.org/10.1016/j.gca.2009.08.024 doi:  10.1016/j.gca.2009.08.024
    Troch, J., Ellis, B. S., Schmitt, A. K., et al., 2018. The Dark Side of Zircon: Textural, Age, Oxygen Isotopic and Trace Element Evidence of Fluid Saturation in the Subvolcanic Reservoir of the Island Park Mount Jackson Rhyolite, Yellowstone (USA). Contributions to Mineralogy and Petrology, 173(7): 54. https://doi.org/10.1007/s00410-018-1481-2 doi:  10.1007/s00410-018-1481-2
    Valley, J. W., Kinny, P. D., Schulze, D. J., et al., 1998. Zircon Megacrysts from Kimberlite: Oxygen Isotope Variability among Mantle Melts. Contributions to Mineralogy and Petrology, 133: 1-11. https://doi.org/10.1007/s004100050432 doi:  10.1007/s004100050432
    Valley, J. W., 2003. Oxygen Isotopes in Zircon. Reviews in Mineralogy and Geochemistry, 53(1): 343-385. https://doi.org/10.2113/0530343 doi:  10.2113/0530343
    Wang, X. L., Coble, M. A., Valley, J. W., et al., 2014. Influence of Radiation Damage on Late Jurassic Zircon from Southern China: Evidence from in situ Measurements of Oxygen Isotopes, Laser Raman, U-Pb Ages, and Trace Elements. Chemical Geology, 389: 122-136. https://doi.org/10.1016/j.chemgeo.2014.09.013 doi:  10.1016/j.chemgeo.2014.09.013
    Wang, R. C., Zhao, G. T., Wang, D. Z., et al., 2000. The Aggregation of Fractionated Fluid in A-Type Granite: Evidences from Accessory Mineral. Chinese Science Bulletin, 45(7): 771-774 (in Chinese) doi:  10.1360/csb2000-45-7-771
    Watson, E. B., Cherniak, D. J., 1997. Oxygen Diffusion in Zircon. Earth and Planetary Science Letters, 148(3/4): 527-544. https://doi.org/10.1016/s0012-821x(97)00057-5 doi:  10.1016/s0012-821x(97)00057-5
    Watson, E. B., Harrison, T. M., 1983. Zircon Saturation Revisited: Temperature and Composition Effects in a Variety of Crustal Magma Types. Earth and Planetary Science Letters, 64(2): 295-304. https://doi.org/10.1016/0012-821x(83)90211-x doi:  10.1016/0012-821X(83)90211-X
    Wei, C. S., Zheng, Y. F., Zhao, Z. F., 2001a. Nd-Sr-O Isotopic Geochemistry Constraints on the Age and Origin of the A-Type Granites in Eastern China. Acta Petrologica Sinica, 17(1): 95-111 (in Chinese with English Abstract) http://www.researchgate.net/profile/Yong-Fei_Zheng/publication/279653468_Nd-Sr-O_isotopic_geochemistry_constraints_on_the_age_and_origin_of_the_A-type_granites_in_Eastern_China/links/55ceae5a08ae118c85bed286.pdf
    Wei, C. S., Zheng, Y. F., Zhao, Z. F., 2001b. Oxygen Isotopic Evidences for the Two Stages of Water-Rock Interaction in Nianzishan A-Type Granites. Chinese Science Bulletin, 46(1): 8-13 (in Chinese) doi:  10.1360/csb2001-46-1-8
    Wei, C. S., Zheng, Y. F., Zhao, Z. F., et al. 2002. Oxygen and Neodymium Isotope Evidence for Recycling of Juvenile Crust in Northeast China. Geology, 30(4): 375-378. https://doi.org/10.1130/0091-7613(2002)030<0375:oanief>2.0.co;2 doi:  10.1130/0091-7613(2002)030<0375:OANIEF>2.0.CO;2
    Wei, C. S., Zhao, Z. F., Spicuzza, M. J., 2008. Zircon Oxygen Isotopic Constraint on the Sources of Late Mesozoic A-Type Granites in Eastern China. Chemical Geology, 250(1-4): 1-15. https://doi.org/10.1016/j.chemgeo.2008.01.004 doi:  10.1016/j.chemgeo.2008.01.004
    Wen, X., 2013. The Origin of the Houshihushan Alkaline Ring Complex in the Yanshan Orogenic Belt and Its Tectonic Implications: [Dissertation]. China University of Geosciences, Wuhan. 46-49 (in Chinese)
    Whalen, J. B., Currie, K. L., Chappell, B. W., 1987. A-Type Granites: Geochemical Characteristics, Discrimination and Petrogenesis. Contributions to Mineralogy and Petrology, 95: 407-419. https://doi.org/10.1007/bf00402202 doi:  10.1007/BF00402202
    White, L. T., Ireland, T. R., 2012. High-Uranium Matrix Effect in Zircon and Its Implications for SHRIMP U-Pb Age Determinations. Chemical Geology, 306/307(19): 78-91. https://doi.org/10.1016/j.chemgeo.2012.02.025 doi:  10.1016/j.chemgeo.2012.02.025
    Wu, W. F., Sun, D. Y., Li, H. M., et al., 2002. A-Type Granites in Northeastern China: Age and Geochemical Constraints on Their Petrogenesis. Chemical Geology, 187(1/2): 143-173. https://doi.org/10.1016/s0009-2541(02)00018-9 doi:  10.1016/s0009-2541(02)00018-9
    Xu, B. L., Chen, Y. G., Huang, F. S., 1993. Two Types of Granites of the Fengning District, Hebei Province. Aeta Seientiarum Naturalium Universitatis Pekinensis, 29(2): 213-224 (in Chinese with English Abstract) http://en.cnki.com.cn/Article_en/CJFDTOTAL-BJDZ199302013.htm
    Yang, J. H., Wu, F. Y., Chung, S. L., et al., 2006. A Hybrid Origin for the Qianshan A-Type Granite, Northeast China: Geochemical and Sr-Nd-Hf Isotopic Evidence. Lithos, 89: 89-106. https://doi.org/10.1016/j.lithos.2005.10.002 doi:  10.1016/j.lithos.2005.10.002
    Yang, J. H., Wu, F. Y., Wilde, S. A., et al., 2008. Petrogenesis of an Alkali Syenite-Granite-Rhyolite Suite in the Yanshan Fold and Thrust Belt, Eastern North China Craton: Geochronological, Geochemical and Nd-Sr-Hf Isotopic Evidence for Lithospheric Thinning. Journal of Petrology, 49: 315-351. https://doi.org/10.1093/petrology/egm083 doi:  10.1093/petrology/egm083
    Yang, W. B., Niu, H. C., Sun, W. D., et al., 2013. Isotopic Evidence for Continental Ice Sheet in Mid-Latitude Region in the Supergreenhouse Early Cretaceous. Scientific Reports, 3(39): 2732. https://doi.org/10.1038/srep02732 doi:  10.1038/srep02732
    Yang, W. B., Niu, H. C., Hollings, P., et al., 2017. The Role of Recycled Oceanic Crust in the Generation of Alkaline A-Type Granites. Journal of Geophysical Research-Solid Earth, 122(12): 9775-9783. https://doi.org/10.1002/2017jb014921 doi:  10.1002/2017JB014921
    Zeng, L. J., Niu, H. C., Bao, Z. W., et al., 2017. Chemical Lattice Expansion of Natural Zircon during the Magmatic-Hydrothermal Evolution of A-Type Granite. American Mineralogist, 102: 655-665. https://doi.org/10.2138/am-2017-5840 doi:  10.2138/am-2017-5840
    Zhang, J. F., Liu, H. B., Shi, X., et al., 2019. Study on Influence Factors for Determination of Oxygen Isotopic Composition of Silicates and Oxide Minerals by BrF5 Method. Rock and Mineral Analysis, 38(1): 45-54. https://doi.org/10.15898/j.cnki.11-2131/td.201805170062 (in Chinese with English abstract) doi:  10.15898/j.cnki.11-2131/td.201805170062
    Zhang, S. B., Zheng, Y. F., 2011. On the Origin of Low δ18O Magmatic Rocks. Acta Petrologica Sinica, 27(2): 320-530 (in Chinese with English Abstract) http://www.researchgate.net/publication/279675937_On_the_origin_of_low_d_18O_magmatic_rocks
    Zhang, X. H., Yuan, L., Xue, F., et al., 2015. Early Permian A-Type Granites from Central Inner Mongolia, North China: Magmatic Tracer of Post-Collisional Tectonics and Oceanic Crustal Recycling. Gondwana Research, 28(1): 311-327. https://doi.org/10.1016/j.gr.2014.02.011 doi:  10.1016/j.gr.2014.02.011
    Zhao, Z. F., Zheng, Y. F., Wei, C. S., 2001. Kinetics of Oxygen Isotope Exchange between Water and Minerals of Miarolitic Alkaline Granite from Nianzishan. Geochimica, 30(2): 177-185. https://doi.org/10.19700/j.0379-1726.2001.02.010 (in Chinese with English Abstract) doi:  10.19700/j.0379-1726.2001.02.010
    Zheng, Y. F., 1993. Calculation of Oxygen Isotope Fractionation in Anhydrous Silicate Minerals. Geochimica et Cosmochimica Acta, 57(13): 1079-1091. https://doi.org/10.1016/0016-7037(93)90042-u doi:  10.1016/0016-7037(93)90042-u
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Origin of the Low δ18O Signals in Zircons from the Early Cretaceous A-Type Granites in Eastern China: Evidence from the Kulongshan Pluton

doi: 10.1007/s12583-021-1515-y

Abstract: The origin of low δ18O signals in zircons from the Early Cretaceous A-type granites in eastern China has long been disputed. It is uncertain whether the 18O-depleted features were inherited from high-temperature hydrothermal altered source rock or resulted from water-rock interaction after emplacement. In this paper, zircon oxygen isotopes in the ~130 Ma Kulongshan A-type granites in the northern North China Craton are analyzed. The zircons could be subdivided into 5 types based on their luminescent intensity and internal structures in CL images. Their δ18O values also vary in different types and show negative correlation with U and Th contents and accompanying cumulative α-decay doses, implying that their δ18O values may have been modified to various degrees by meteoric water-rock interaction after the accumulation of radiation damage. The idea is further confirmed by oxygen isotopic equilibrium calculation between co-existing mineral pairs. It is inferred that only the least-influenced zircons, with slightly elevated δ18O values than normal mantle, have preserved the magmatic oxygen isotopes. In combination with other evidences, it is proposed that the A-type granites are lower-crustal-derived, unnecessarily invoking a high-temperature hydrothermal altered source. The proposition is applicable to many other Cretaceous A-type granites that have similar zircon behaviors.

Wenbo Fan, Neng Jiang, Mingguo Zhai, Jun Hu. Origin of the Low δ18O Signals in Zircons from the Early Cretaceous A-Type Granites in Eastern China: Evidence from the Kulongshan Pluton. Journal of Earth Science, 2021, 32(6): 1415-1427. doi: 10.1007/s12583-021-1515-y
Citation: Wenbo Fan, Neng Jiang, Mingguo Zhai, Jun Hu. Origin of the Low δ18O Signals in Zircons from the Early Cretaceous A-Type Granites in Eastern China: Evidence from the Kulongshan Pluton. Journal of Earth Science, 2021, 32(6): 1415-1427. doi: 10.1007/s12583-021-1515-y
  • A-type granites comprise an important group in granites because of their distinctive mineralogical and geochemical compositions as well as geodynamic context (Whalen et al., 1987; Clemens et al., 1986; Collins et al, 1982; Loiselle and Wones, 1979). They are dominated by alkaline feldspar and quartz, with high alkaline, halogen, high field strength elements (HFSE), Ga/Al, Fe/Mg ratios and low CaO, Ba, Sr and Eu contents. Besides, they often appear at the late stage of regional magmatic cycle with typical anorogenic or postorogenic extensional tectonic setting (Collins et al., 2019, 1982; Loiselle and Wones, 1979).

    A number of Early Cretaceous A-type granites in eastern China have been found to be characterized by depleted 18O signatures based on whole rock and/or major rock-forming oxygen isotope analyses (Guo et al., 2019; Wei et al., 2001a; Zhao et al., 2001). Subsequent studies show that many of the Early Cretaceous A-type granites have extremely low zircon δ18O values when analyzed by laser fluorination technique (Wei et al., 2008, 2002, 2001b) or ion microprobe (Yang et al., 2017; Sun, 2011). It is thus suggested that the A-type granites were crystallized from low δ18O magmas that had originated from partial melting of either high-temperature hydrothermally altered oceanic crust or altered recycled crustal igneous rocks (Yang et al., 2017; Sun, 2011; Wei et al., 2008). However, it is argued recently that zircon oxygen isotopes in some Cretaceous A-type granites may have been affected greatly by later metamictization (Gao et al., 2014) or incorporation of meteoric water during the post- magmatic hydrothermal evolution stage (Yang et al., 2013). Similar scenario has also been proposed in zircons from other types of igneous rock (Liu et al., 2019; Wang et al., 2014; Pidgeon et al., 2013; Booth et al., 2005). Therefore, it is necessary to reevaluate the origin of the low δ18O signals and their implications on petrogenesis.

    In this paper, the Early Cretaceous Kulongshan (KLS) granites in Fengning area of northern North China Craton (NCC) (Fig. 1) are taken as an example to explore the possible origin of the low δ18O signals in the A-type granites. Based on zircon internal texture observation, in situ ion microprobe oxygen isotopes and U-Pb age analyses were performed. For comparison, their whole rock and major rock-forming minerals were also analyzed for oxygen isotopes. The comparison of zircons in KLS granites with those from not only other Early Cretaceous A-type granites but also other types of igneous rocks makes it possible for us to better understand the formation mechanism of the 18O-depleted signals in such A-type granites.

    Figure 1.  (a), (b) Sketch maps showing the distribution of the Early Cretaceous plutons and A-type granites in the eastern part of the northern NCC. Figure 1a modified after the national standard map of No. GS(2020)4631, and Fig. 1b modified after Fan et al. (2017); the A-type granites are marked with their name abbreviations nearby, some other Cretaceous A-type granites in eastern China are also shown. (c) Sketch geological map of the Kulongshan A-type granites in Fengning area, with sampling localities indicated by yellow stars (modified after Fan et al., 2020). KLS. Kulongshan; NQZB. Niuquanziba; BZ. Baizha; QCB. Qiancengbei; XS. Xiangshan; SHG. Shanhaiguan; QS. Qianshan; SKS. Sankuaishi; SPJ. Sipingjie; GS. Gushan; XF. Xingfu; SLSQ. Shanglvshuiqiao; YWBZ. Yanwangbizi; NZS. Nianzishan; BEZ. Baerzhe; LS. Laoshan; SZ. Suzhou; KQ. Kuiqi.

  • The Kulongshan (KLS) granite is exposed in the Fengning area, which is located in the middle-eastern segment of the northern margin of the NCC (Figs. 1a, 1b). The area is composed of predominantly ~1.8 Ga basement rocks, Late Paleozoic to Mesozoic granitic intrusions and some Early Cretaceous volcanic and lacustrine strata (Fan et al., 2020). Similar to many other regions in eastern China, voluminous Early Cretaceous igneous rocks formed in the eastern part of the northern NCC in response to the subduction and roll-back of the Paleo- Pacific plate. The latter resulted in an extensional setting and intensive mantle-crust interaction, both of which facilitated the formation of A-type granites (Tang et al., 2018; Sun and Yang, 2009; Wu et al., 2002). The flare-up of Early Cretaceous A-type granites (about 130–120 Ma) nearly terminated the Mesozoic igneous activity accompanied with some contemporaneous alkaline igneous rocks. In the Fengning area, a large amount of Early Cretaceous I-type granites intruded before the final appearance of A-type granites (Fan et al., 2020).

    The KLS pluton is another A-type granite in the Fengning area besides the previously reported NQZB granite porphyry which was also suggested to belong to the Cretaceous A-type granites in eastern China (Fan et al., 2020) (Fig. 1b). The KLS pluton crops out about 120 km2 and intruded into the Early Cretaceous rhyolite of Zhangjiakou Formation (Figs. 1c and 2a). The emplacement depth is about 3 km based on the thickness of the overlying strata, which is also supported by the appearance of miarolitic cavity in the granites. It appears as a composite body of two batches of granites, with the inner medium-fine grained granite surrounded by an earlier-intruded outer medium-coarse grained zone (Xu et al., 1993; Fig. 1c). Apart from the obviously intruding contact relationship between the two zones in the field (Fig. 2b), there is no mineral distinction between them. The rocks are all composed of alkali feldspar (perthite dominantly, 60%–65%), quartz (30%–35%), annite (2%–3%) and minor plagioclase (0–2%) (Fig. 2c). The occurrence of euhedral arfvedsonite (Fig. 2d) is found in the southeastern margin of the pluton (samples FN1421 and FN1422 in Fig. 1c). Microprobe analysis shows that both the annite and arfvedsonite have high F and Fe concentrations, with formula of (K0.97Na0.04){(Mn0.15Ti0.08Fe2.38Mg0.08) [Al1.11Si3.18O10](OH0.83F1.17)} and (K0.21Na2.63)(Mg0.12Fe4.41Mn0.38 Al0.2)[Al0.05Si7.95O22](F1.04OH0.96), respectively. The graphic intergrowths of quartz and perthite are very common, indicating that they are hypersolvus granites crystallized near eutectic point at high temperature and high intruding level. All these mineral behaviors are strikingly similar to typical A-type granites, such as those in southeastern Australia (Collins et al., 1982; Loiselle and Wones, 1979). Zircon is the major accessory mineral besides fluorite, magnetite, cyrtolite, thorite and columbite (Guo et al., 2019; Li and Hao, 2017; Xu et al., 1993). No enclave has been found or reported in the pluton.

    Figure 2.  Field and microscopic photographs of the KLS granites showing (a) the intrusion into the rhyolite of Zhangjiakou Formation, (b) the contact between the medium-fine grained and medium-coarse grained granites, and (c), (d) the major mineral assemblages. Q. quartz; Pth. perthite; Ann. annite; Arf. arfvedsonite.

  • The major element compositions of minerals were measured on a Jeol JXA-8100 electron microprobe (EMPA) at the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS), Beijing. Whole rock major elements were measured by X-ray fluorescence (XRF) at Northwest University, Xiʼ an. Whole rock trace element compositions were determined by an Agilent 7500a inductively coupled plasma mass spectrometer at China University of Geosciences, Wuhan. Whole rock Nd isotopes for selected samples were analyzed by isotope dilution on a Finnigan MAT 262 thermal ionization multi-collector mass spectrometer at IGGCAS, for which the data reduction processes are similar to those described in Fan et al. (2017). Whole rock Sr isotopes were not analyzed due to their very high Rb/Sr ratios. Oxygen isotopes of whole rock, alkali feldspar and quartz were measured by the BrF5 method at Beijing Research Institute of Uranium Geology, following the procedures presented in Zhang et al. (2019). The results are presented in the normal delta notation relative to the Vienna standard mean ocean water (δ18OVSMOW).

    Zircons were separated, mounted in epoxy resin together with reference zircons and then polished to nearly half thickness. Prior to analyses, reflected and transmitted light photomicrographs as well as cathodoluminescence (CL) images using scanning electron microscope (SEM) were obtained. Zircon was analyzed following the sequence of oxygen isotopes, U-Pb ages and finally Hf isotopes because their gradual increasing consumption. In situ zircon oxygen isotope analyses and U-Pb dating were conducted on the CAMECA IMS-1280 ion microprobe (SIMS) at IGGCAS, following the analytical procedures described in Li et al.(2010, 2009). For oxygen isotope analyses, the spot size was about 10 μm×15 μm. The results are also reported in the form of δ18OVSMOW. The U-Pb dating was performed on the same spots as oxygen isotope analyses, with spot diameter of about 20 μm×30 μm. Age calculations and plots were made using ISOPLOT 3.75 (Ludwig, 2012). After O and U-Pb analyses, the analyzed pits were re-imaged in microscope in order to check the exactly targeted domains. In situ Hf isotopes were analyzed using the Neptune multi-collector ICP-MS at IGGCAS. The εHf(t) values and depleted mantle model ages (THf, CDM) are calculated as those described in Fan et al. (2017).

    Details on the standard/reference materials and replicate analyses are the same as those reported in Fan et al. (2020), except for the whole rock and mineral separate oxygen isotopic analyses. For the latter, the quartz standard GBW04409 resulted in δ18OVSMOW value of 11.03‰±0.08‰, consistent with the recommended value of 11.11‰ (Liu, 1990). Data for the analyzed granites and zircons are presented in Tables S1 and S2, respectively.

  • Both the KLS samples and their wall-rocks are typical of granite in composition (Fig. 3a). The KLS granites range gradually from weakly peraluminous to metaluminous and tend to have peralkaline affinity, with very low CaO contents (0.07 wt.%–0.75 wt.%) (Fig. 3b). Consistent with their mineral assemblages and compositions, the KLS granites mirror the typical geochemical characters of A-type granites, such as high Na2O+K2O (> 8.19 wt.%), REE3+, HFSE (such as Nb, Ta, Zr, Hf) abundance, flat and weakly tetrad REE patterns ((La/Yb)N=2.1–4.5), extremely depleted elements compatible in plagioclase (Ba, Sr and Eu; (Eu/Eu*)N as low as 0.02–0.05) and mafic silicates (Cr < 3.19 ppm, Ni < 1.24 ppm) (Fig. 4 and Table S1) (Collins et al., 1982; Loiselle and Wones, 1979). In the A-type granites discrimination diagrams (Whalen et al., 1987), all the samples are plotted as typical A-type granites because of their high Nb (> 70 ppm), Zr (> 271 ppm), 10 000×Ga/Al (> 3.21), Zr+Nb+Ce+Y (> 510 ppm) and FeO/MgO (> 19.5) (Figs. 3c3d). The KLS samples also present high whole rock Zr saturation temperatures (890–996 ℃; Table S1) (Watson and Harrison, 1983), which agrees well with the high-temperature property of A-type granites (Clemens et al., 1986; Collins et al., 1982; Loiselle and Wones, 1979). No composition distinction exists between samples from the outer and inner zones, indicating that they shared similar magmatic supply and derivation.

    Figure 3.  (a) Total alkali versus silica diagram, (b) alumina saturation indices, (c) Zr and Nb vs. 10 000×Ga/Al, and (d) FeO/MgO vs. Zr+Nb+Ce+Y plots for the KLS granites (after Whalen et al., 1987).

    Figure 4.  (a) Chondrite-normalized REE patterns and (b) primitive mantle-normalized trace element diagrams for the KLS granites. Normalization values for the chondrite and primitive mantle are from Taylor and McLennan (1985) and McDonough and Sun (1995), respectively.

    The rhyolite sample FN1420, which was sampled from the wall-rock (Figs. 1c and 2a), has completely different geochemistry from the KLS granites (Figs. 3, 4 and Table S1). It possesses also lower whole rock Zr saturation temperatures (838 ℃) than the KLS samples.

  • Three samples from different locations of the KLS pluton, including two medium-fine grained granites (JN0984 and JN0989) and one medium-coarse grained sample (JN0990), were chosen for zircon analyses. Zircons from sample JN0984 are mostly cloudy and brown in transmitted light, with stubby and subhedral morphology and cracked and pitted appearance (Fig. S1). In CL images, they show very weak zoning and can be descriptively grouped into five types according to their variable luminescent intensity and internal textures (Fig. 5a). Type-1 zircons, which are very scarce in this sample, are nearly completely bright in CL images due to extremely high luminescence, while type-2 zircons are light gray with moderate CL intensity and visible rhythmic zonation. Type-3 zircons are gray with weak oscillatory zoning, while type-4 zircons are entirely dark in CL images. The gradually decreasing luminescence from type-1 to type-4 zircons agrees well with their increasing U and Th concentration from tens of ppm to thousands of ppm (Figs. 6a and 6b). Type-5 zircons, although with very high U and Th contents, are characterized by cauliflower-like internal texture due to the irregular distribution of dark and bright domains inside. Twenty-eight analyses reveal U of 238 ppm– 7 086 ppm, Th of 83 ppm–5 090 ppm and Th/U ratios of 0.1–2.3 (Table S2 and Fig. S2). Among the 28 analyses, 11 spots are discarded in age calculation due to either abnormally elevated U and Th contents (mostly type-4 and type-5 zircons) or large age errors. The rest 17 spots yield a concordia age of 132.1±1.2 Ma (95% confidence level), which is taken as the age of the granite (Fig. 7a).

    Figure 5.  Representative zircon CL images for the KLS granites and rhyolite of Zhangjiakou Formation, with oxygen isotopes, age and Hf analysis points marked by red ellipse, green ellipse and yellow circle, respectively. The spot Nos. are also shown by blue number nearby.

    Figure 6.  The concentrations of U and Th, δ18O and Dα values of different types of zircon in KLS granites. The α-decay constants of 238U, 235U and 232Th are 4.468×109, 0.703 81×109 and 14.01×109 (Steiger and Jager, 1977) in calculation, respectively.

    Figure 7.  Zircon U-Pb concordia diagrams for the KLS granites (a)–(c) and their intruding country rock, i.e., the rhyolite of Zhangjiakou Formation (d). Both data-point error ellipses and bars are 2σ.

    Zircons from JN0989 and JN0990 are mostly transparent to semi-transparent with well-developed prismatic and pyramidal crystal faces (Figs. 5b, 5c and S1). According to their CL behaviors, zircons in JN0989 are dominated by type-2 with a few type-1 and type-4 zircons, while those in JN0990 include type-1, type-2 and type-3 zircons. Sixteen spots for JN0989 show U content of 16 ppm–1 145 ppm and Th of 21 ppm–542 ppm, which are mostly much lower than those for JN0984 (Table S2 and Fig. S2). However, their Th/U ratios are similar. The U and Th contents also increase from type-1 through type-2 to type-3 zircons (Figs. 6a and 6b). For JN0990, the ranges of zircon U, Th contents and Th/U ratios are similar to those in JN0989. Fourteen analyses for JN0989 and 13 spots for JN0990 result in a concordia age of 132.0±1.6 Ma (95% confidence level) and a weighted mean 206Pb/238U age of 129.0±3.0 Ma (95% confidence level), respectively (Figs. 7b and 7c). The ages for the three analyzed samples (JN0984, JN0989 and JN0990) are nearly identical within errors.

    Contrastingly, zircons from rhyolite FN1420 are mostly euhedral elongated or stubby prisms with pronounced oscillatory zoning (Fig. 5d), typical of magmatic origin. Except for two pre-magmatic spots which may be xenocrystic in origin, the rest 8 analyses yield U of 71 ppm–1 110 ppm, Th of 98 ppm–798 ppm and Th/U ratios of 0.31–2.56, comparable to those of KLS samples JN0989 and JN0990 (Table S2). The data form a tight group and yield concordant age of 143.8±4.5 Ma (95% confidence level) (Fig. 7d), similar to the previously reported Cretaceous I-type granites in Fengning area (Fan et al., 2020).

  • The KLS granites have zircon δ18O values (from 1.19±0.56 to 6.39±0.33, 2σ) mostly overlapping or lower than those equilibrium with the normal mantle (5.3‰±0.6‰, 2σ; Valley et al., 1998), while zircons in the rhyolite possess δ18O values (from 5.63±0.39 to 6.51±0.48, 2σ) of commonly crustal-derived igneous rocks (Valley, 2003) (Fig. 8; Table S2). As a result, although both the granites and the rhyolite share similar upper limit of δ18O values, the KLS granites have much variable zircon δ18O values. Besides, the δ18O values for all the KLS samples show a decreasing trend from type-1 to type-2, then to type-3, and finally to type-4 and type-5 zircons (Fig. 6c). The pristine type-1 and some type-2 zircons have the highest δ18O values that are close to those of the rhyolite. Considering the correlation of zircon types with U and Th contents, it is reasonable to connect δ18O values with zircon composition. This is indeed the case, as shown in Fig. 9a.

    Figure 8.  Histogram of zircon δ18O values for the KLS granites (a) and rhyolite of Zhangjiakou Formation (b). The values for igneous zircon in equilibrium with magmas from the normal mantle peridotite (5.3‰±0.6‰, 2σ), presented as shaded yellow areas, are from Valley et al. (1998).

    Figure 9.  (a) δ18O vs. U contents, (b) 206Pb/238U apparent age vs. U contents, and (c) δ18O vs. Dα values plots of zircon from the KLS granites. Only the spots with both U-Pb ages and oxygen isotopes analyzed are shown.

    There is no difference in Hf isotopes among the three KLS granites or different zircon types within each sample. They exhibit similar εHf(t) of -14.8 to -10.2. Corresponding model ages (TDMHf, C) fall into the range of 1.8–2.2 Ga (Table S2; Fig. 10). The data are similar to the Mesozoic I-type granites which were proposed to be lower-crustal derived in the region (Fan et al., 2020).

    Figure 10.  Whole rock εNd(t) and zircon εHf(t) values versus ages diagrams for the KLS granites. The isotopic evolution curves of the Late Archean crust are modified after Fan et al. (2017), in which the average continental crust is assuming to have 147Sm/144Nd of 0.118 (Jahn and Condie, 1995) and 176Lu/177Hf ratio of 0.015 (Griffin et al., 2002), while the lower crust is assuming to have 176Lu/177Hf ratio of 0.022 (Amelin et al., 1999). The suggested values of the lower crust at 130 Ma in the northern NCC are cited from Jiang et al. (2013). The range of the Early Cretaceous (K1A) A-type granites in the northern NCC is compiled from Yang et al.(2008, 2006), Sun (2011), Fan et al. (2020) and also this study.

  • The three analyzed samples (JN0984, JN0989 and JN0990) have nearly identical εHf(t) values of -13.7 to -13.1 (Table S1). The corresponding two stages depleted mantle model ages (T2DMNd) are concentrated at ~2.0 Ga, which are comparable with zircon Hf model ages (Fig. 10).

    The medium-fine grained granite JN0984 and its adjacent sample FN1403 preserve lower whole rock δ18O values of 5.4‰, while the medium-fine grained JN0989 and medium-coarse grained JN0990 show higher δ18O values (7.0‰ and 6.4‰) (Table S1 and Fig. 11). As for the major rock-forming minerals, quartzes present δ18O values of 7.3‰ to 8.1‰ which are consistent with the previously reported results for the Early Cretaceous Suzhou A-type granites (7.1‰ to 8.3‰) in eastern China (Fig. 1; Gao et al., 2014) and also for some A-type granites worldwide (Javoy and Weis, 1987). However, the alkali feldspars have obviously lower δ18O values which range from 3.9‰ to 4.8‰ for JN0984 and FN1403, and from 5.6‰ to 5.8‰ for JN0989 and JN0990. Mass balance calculation based on the relative proportion of quartz and alkaline feldspar confirms that the decreased whole rock δ18O values are mostly controlled by alkali feldspar, which is less stable than quartz and thus likely to be modified by later fluids (Zhao et al., 2001; Taylor, 1988; Javoy and Weis, 1987). Theoretical oxygen isotopic fractionation between quartz and alkali feldspar is calculated further, with fractionation factors cited from Zheng (1993). Considering the hypersolvus behaviors of the KLS samples and the suggested solvus temperature of 725 ℃ at 100 MPa in such systems (Zeng et al., 2017), the equilibrium temperature of 750 ℃ is chosen here. The temperature also resembles the closed temperature of oxygen isotopes exchange between quartz and alkali feldspar in A-type granites proposed (Zhao et al., 2001). As a result, the oxygen isotopic fractionation between them (δ18O quartz-alkali feldspar) is about 1.0‰ in theory, which is not only lower than the measured δ18O values for JN0984 and FN1403 (2.5‰ and 3.4‰), but also lower than those in JN0989 and JN0990 (2.3‰ and 2.1‰) (Fig. 11). The isotopic disequilibrium between quartz and feldspar implies that the oxygen isotopes of the KLS granites may have been altered, probably by meteoric water (Taylor, 1988).

    Figure 11.  Comparison of δ18O values for whole rock, quartz, alkali feldspar and zircon in the analyzed KLS granites. The values for zircon in equilibrium with quartz at 900 ℃, alkali feldspar in equilibrium with quartz at 750 ℃ and the weighted mean of type-1 zircon are also shown.

  • Since the resistance to later hydrothermal alteration, metamorphism or anatexis, zircon oxygen isotopes have been regarded as the most robust records of magmatic compositions (Bindeman et al., 2018; Peck et al., 2003; Valley, 2003; Watson and Cherniak, 1997). The 18O-depleted zircons have been reported in various granitic rocks in earth history, especially those formed in extensional environments (Deng et al., 2020; Zhang et al., 2015; Hiess et al., 2011; Valley, 2003; Monani and Valley, 2001). The possible mechanisms proposed for low δ18O zircons can be categorized into (1) crystallized from magmas derived from pre-existing low δ18O rocks that had experienced high- temperature hydrothermal alteration of meteoric water or sea water, (2) crystallized from magmas assimilated by 18O- depleted wallrock whose δ18O values had been decreased by syn-magmatic high-temperature water-rock interaction, (3) infiltration of meteoric water into the magmatic systems and (4) influenced by post-magmatic modification and isotopic exchange due to radiation-induced metamictization (Zhang and Zheng, 2011; Valley, 2003; Taylor, 1988; Bibikova et al., 1982). Among the mechanisms mentioned above, the effect of radiation damage on oxygen isotopes are mostly neglected although recognized very early (Bibikova et al., 1982). By comparison, the discordance of U-Pb ages in high-U and -Th zircons, which results in the deviation of 206Pb/238U apparent ages (Fig. 9b), has long been considered in U-Pb dating (Erdmann et al., 2013; White and Ireland, 2012; Butera et al., 2001; Silver and Deutsch, 1963), as performed in the KLS granites in which such spots are discarded in ages calculation (see Section 3.2.1). It is also reported that the discordant zircon with high-U content may preserve lighter δ18O values (Gao et al., 2014; Wang et al., 2014; Pidgeon et al., 2013; Booth et al., 2005; Bibikova et al., 1982). Water-rock interaction facilitated by crystal lattice-damage due to metamictization has been suggested to be responsible for the depletion of 18O.

    The relevance of δ18O values with zircon types and their co-variation with zircon U and Th contents in the KLS samples imply the probable influence of radiation damage on their oxygen isotopes (Figs. 6a6c and 9a). The radiation damage in zircon, usually caused by α-decay of 238U, 235U, 232Th and their daughter nuclides, can be quantitatively measured by the parameter of cumulative α-decay doses per milligram (Dα), which is dependent on the age and radionuclide content in zircon crystals (Holland and Gottfried, 1955). Previous studies on natural and synthetic zircons revealed that the increasing Dα will induce the apparent transformation of zircon from crystalline to aperiodic and metamict state when Dα exceeds ~1×1015 α-events/mg (Ewing et al., 2003; Nasdala et al., 2001; Chakoumakos et al., 1987; Holland and Gottfried, 1955). For example, it has been proved that the accumulation of isolated point defects due to α-recoil will cause the unit-cell expansion and distortion when Dα < 3×1015 α-events/mg (Murakami et al., 1991). With Dα from 3×1015 to 8×1015 α-events/mg, distorted crystalline regions and amorphous tracks will appear. If Dα > 8×1015 α-events/mg, the zircon microstructure will no longer exist and be fully metamict, i.e., amorphous state. Similar results were also proposed by Farnan and Salje (2001) in which the relative proportions of amorphous phases in zircon increases from < 0.05% to nearly 97% with increase Dα from about 1×1015 to 10×1015 α-events/mg.

    For the KLS samples, the calculated Dα values range from 10-2×1015 to 101×1015 α-events/mg and increase from type-1 to type-2, then to type-3 and finally to type-4 and type-5 zircons (Fig. 6d). The last three types of zircon plus some type-2 ones have Dα values comparable to or exceed 1×1015 α-events/mg, suggesting they occupy the radioactive dose enough for metamictization. The non-luminescent type-4 zircons show nearly the most depleted δ18O values, consistent with their extremely high-U contents and probable amorphous phase, while the most pristine type-1 and some type-2 zircons have normal magmatic δ18O values. The inverse correlation of δ18O with both U contents and Dα values (Figs. 9a and 9c) implies that the zircons in KLS A-type granites may have acquired their depleted oxygen isotopes after the radiation damage accumulated to a certain degree. The deviation of 206Pb/238U apparent ages at extremely higher U contents also supports the idea (Fig. 9b). The Self-irradiation of zircon will loosen the lattice, destroy the crystal structure and produce metamict domains with nanoscale pores and cracks that will be easily permeated by hydrothermal fluids and even weathering solutions, both of which mainly come from meteoric water (Gao et al., 2014; Wang et al., 2014; Pidgeon et al., 2013; Booth et al., 2005; Bibikova et al., 1982). The metamict domains are susceptible to fluid-assisted alteration (Geisler et al., 2007; Hoskin, 2005) and will not be closed for oxygen isotopes (Watson and Cherniak, 1997). As a result, later water-rock interaction and accompanying oxygen isotopes exchanges result in the depleted-18O signals in zircons. The alkali feldspar in the KLS granites may be modified at the same time. Recently, it is reported that the radiation-damaged parts of natural zircon show elevated 16O1H/16O values based on the newly developed analysis technique for zircon water content by SIMS (Liebmann et al., 2021; Pidgeon et al., 2013). Therefore, it is suggested the uptake of water or OH facilitated by radiation damage may contribute to the decreasing δ18O values in zircons, besides isotopes exchanges with meteoric water. Whether similar effect exists in the KLS zircons is unclear so far. Further study is still needed.

  • The internal textures of zircon provide further evidence for the origin of their light δ18O signals. Except for the bright to intermediate luminescent type-1 and type-2 zircons which are typical of magmatic origin, the obviously elevated U and Th contents in other types of zircons, especially the dark type-4 zircons (Figs. 6a6b), mirror exactly the characters of zircons crystallized from the late-stage granitic melt enriched in fluids, incompatible elements such as LREE, U and Th and other impurity elements (Fan et al., 2020; Gao et al., 2014; Wang et al., 2014; Yang et al., 2013; Hoskin, 2005). The type-5 zircons, with cauliflower-like texture (Figs. 5 and S1) which has also been described as mottled, patchy, spongy or sieved textures in literature, were either interpreted as metamict zircons with probably hydrothermal altered imprints (Booth et al., 2005) or as hydrothermal-crystallized zircons with abundant inclusions or nanopores due to the saturation of volatile in the fractionated melts (Liu et al., 2019; Troch et al., 2018; Zeng et al., 2017; Erdmann et al., 2013). For many Early Cretaceous A-type granites in eastern China, it has been proposed indeed that the magmatic crystallization and accompanying evolution resulted in the occurrence of aqueous hydrothermal fluids with high halogen (F), REE and HFES (Nb, Ta, Zr, Hf, Th and U) based on whole rocks, accessory mineral assemblage, biotite (Jahn et al., 2001; Wang et al., 2000; Charoy and Raimbault, 1994) and zircon analyses (Qiu et al., 2019; Zeng et al., 2017; Gao et al., 2014). Considering the cracked and pitted surface of type-4 and type-5 zircons in transmitted light (Fig. S1), it is better to interpret them as metamict zircons that originally crystallized from the late- solidified melts and were modified later by meteoric water after the accumulation of crystal defects in response to radioactive disintegration, rather than hydrothermal-crystallized zircons with abundant inclusions. The weakly tetrad REE patterns, high F content in annite (1.9% to 4.5%) and arfvedsonite (~2%), and the existence of accessory minerals such as fluorite, cyrtolite, thorite and columbite support the enrichment of fluids and incompatible elements in the KLS granites due to progressive crystallization (Jahn et al., 2001; Wang et al., 2000; Charoy and Raimbault, 1994). The gradually increasing U and Th contents from type-1 to type-5 zircons also agree with the trend.

    Besides the KLS A-type granites, zircons with similar CL behaviors and high-U or -Th contents have also been reported in some other Cretaceous A-type granites in eastern China, such as the Sipingjie (Sun, 2011), Shanhaiguan (Wen, 2013), Suzhou (Gao et al., 2014), Xiangshan (Zeng et al., 2017), Baerzhe (Qiu et al., 2019; Yang et al., 2013) and Niuquanziba plutons (Fan et al., 2020) (Fig. 1). This similarity suggests that many, if not all, Cretaceous A-type granites in eastern China may share similar secondary origin for their depleted 18O signals. The progressive crystallization and accompanying evolution of the granitic melts enriched the late-crystallized zircons with U, Th and other non-formula elements. The impurity elements created more crystal defects (and thus less crystallinity of the lattice) in primary zircons that would be further expanded by radiation damage with time, resulting in the decreasing degree of crystallinity for zircons whose oxygen isotopes were readily to be modified finally by water-rock interaction. Therefore, it is concluded that the formation of low δ18O signals in zircons from the Cretaceous A-type is facilitated by progressive magmatic crystallization and evolution. What's more, their accessibility to meteoric water is also assisted by the shallow intruding level of A-type granites at extensional geodynamic contexts (Bonin, 2007; Collins et al., 1982). The high-level A-type intrusions cool quickly and produce radioactivity-induced damage that will be accumulated but unable to be thermally annealed (Nasdala et al., 2001). Similar processes also exist in other felsic igneous rocks (Fan et al., 2020; Liu et al., 2019; Wang et al., 2014; Pidgeon et al., 2013), besides the A-type granites discussed here.

  • The secondary origin of the low δ18O signals in zircons from many Early Cretaceous A-type granites in eastern China argues against the contribution of high-temperature hydrothermally altered oceanic or continental crustal rocks in their derivation. For the analyzed zircons, only those with very low U contents and well-developed crystal forms may have preserved the magmatic δ18O values. Besides, quartz may also be useful in determining the oxygen isotopes of the magma due to its slow isotopes-exchanging rate (Gao et al., 2014; Bindeman, 2008; Taylor, 1988; Javoy and Weis, 1987), which is supported by their narrow range of δ18O values (7.3‰ to 8.1‰) in the KLS samples (Fig. 11). In contrast, the δ18O values of alkali feldspar have been altered by meteoric water as discussed above (see Section 3.3). In this regard, the most pristine zircons and quartzes may serve as the best candidate for magmatic oxygen isotopes research. Among the 23 type-1 zircons analyzed, 20 with δ18O values ranging from 5.25‰±0.25‰ to 6.08‰±0.34‰ yield a weighted mean value of 5.68‰±0.12‰ (95% confidence level) except for three anonymously lower spots (Fig. 11). The value is identical to mean value for those with Dα < 0.1×1015 α-events/mg (5.45‰± 0.29‰) (Fig. S3) and also resembles the δ18O values of many less-altered type-2 zircons (Fig. 6).

    We further calculate the δ18O values of zircon in equilibrium with quartzes in theory based on the oxygen isotopes fractionation factors between quartz and zircon stated in Trail et al. (2009) at 900 ℃ (Table S1). The temperature is not only supported by the whole rock Zr saturation temperatures (890–996 ℃) of all KLS samples, but also consistent with the suggested magma temperature for typical A-type granites (Zhao et al., 2001; Patiño Douce, 1997; Clemens et al., 1986). The calculated δ18O results for zircon in equilibrium with quartz are in the range of 5.60‰±0.17‰ to 6.41‰±0.17‰, overlapping with those of the type-1 zircons (Fig. 11). Even if the equilibrium temperature is assumed to be 800 ℃, the resulted δ18O values are also not lower than ~5.3‰ (5.28‰±0.21‰ to 6.08‰±0.21‰; Table S1). It can thus be inferred that both the most pristine zircons and quartzes do record the oxygen isotopic compositions of the magma from which they crystallized. The quartz δ18O values are also similar to the Cretaceous Suzhou A-type granites in eastern China, whose zircon δ18O values have also been decreased mostly because of radiation damage (Gao et al., 2014).

    The slightly higher δ18O values than normal mantle (5.3‰±0.6‰; Valley et al., 1998) in KLS primary zircons are very similar to the Jurassic lower-crustal derived I-type granites or those with hybrid origin (Fan et al., 2017). The values are also indistinguishable from the ~144 Ma rhyolites into which the KLS granites intruded (Fig. 8). Combined with their whole rock εNd(t) and zircon εHf(t) values that are indistinguishable from the range for the Mesozoic lower crustal rocks (Fig. 10), the KLS samples are proposed to be derived mainly from the ancient lower crustal rocks with normal oxygen isotopes. Although dominated by ancient crustal source rocks, the large range of the Nd-Hf isotopes for the compiled Cretaceous A-type granites in the northern NCC implies that both ancient crust and some mantle components contributed to their derivation (Fan et al., 2020; Wen, 2013; Sun, 2011; Sun and Yang, 2009; Yang et al., 2008, 2006), consistent with the intensive mantle-crust interaction and extensional setting at this time (Tang et al., 2018; Sun and Yang, 2009; Wu et al., 2002). Different from those in the NCC, the contemporary A-type granites in the Central Asian Orogen are mainly juvenile crustal-derived (Wei et al., 2002; Wu et al., 2002; Jahn et al., 2001), which accords with the major crustal growth episodes in Archean for the NCC (Jiang et al., 2010) and Phanerozoic for the orogen (Jahn et al., 2000), respectively. The scenario is consistent with the commonly proposed model of partial melting of infracrustal rocks under high-temperature and water-poor conditions for A-type granites (Whalen et al., 1987; Clemens et al., 1986; Collins et al., 1982), whose formation is also facilitated by the extensional setting and intensive mantle-upwelling in the anorogenic or postorogenic context. The rollback of the subducted Paleo-Pacific plate resulted in the flare-up of the voluminous Early Cretaceous A-type granites in the eastern China (Tang et al., 2018; Sun and Yang, 2009; Wu et al., 2002). Considering all of these, the key points for the origin of A-type granites seem to be unrelated with either ancient or juvenile crustal source rocks, to be unrelated with either hydrothermal altered or not for their source rocks. However, A-type granites with probably originally low δ18O values do have been reported in earth history (Deng et al., 2020; Zhang et al., 2015), implying the existence of high-temperature altered crustal rocks in some A-type granites worldwide.

  • The KLS pluton in northern NCC is a typical Early Cretaceous A-type granites in eastern China with low δ18O zircons. The low δ18O values of the zircons are related to magma evolution and also later radiation damage, rather than hydrothermal altered magmatic sources. The crystallization-induced magmatic evolution resulted in the enrichment of U and Th in the zircons, which facilitated the accumulation of radiation damage and metamictazation. For the metamict zircon domains, their oxygen isotopes were no longer resistant to later isotopic exchanging with meteoric water which yielded their variably depleted-18O signals. The similarity of zircons between the KLS and some other contemporaneous A-type granites in eastern China suggests that their very low zircon δ18O values may be formed by similar mechanism. Oxygen isotopic equilibrium calculation between zircon and quartz shows that the most pristine zircon and quartz have preserved their slightly higher δ18O values relative to normal mantle, which argues for the lower- crustal derivation of the A-type granites when whole rock Nd and zircon Hf isotopic data are considered at the same time. Therefore, there is no need for the Cretaceous A-type granites in eastern China to be sourced from hydrothermal altered crustal rocks.

  • We would like to thank Xianhua Li, Qiuli Li, Hongxia Ma, Jiao Li and Guoqiang Tang for their assistance with zircon U-Pb and O isotopes, Xin Yan and Saihong Yang for zircon SEM, Yueheng Yang and Liewen Xie for LA-MC-ICPMS zircon Hf isotopes, Qian Mao and Di Zhang for EPMA, Jianqi Wang, Yongsheng Liu and Keqing Zong for whole rock geochemistry, Chaofeng Li, Youlian Li and Weiyi Li for Nd isotopes and for Hanbin Liu, Jun Yan and Mingyan Zhu for oxygen isotopes analysis. The anonymous reviewers are also thanked for their constructive comments. This study was supported by the National Natural Science Foundation of China (No. 41973034) and the Postdoctoral Initiation Fund of Northwestern University (No. 208521). The final publication is available at Springer via https://doi.org/10.1007/s12583-021-1515-y.

    Electronic Supplementary Materials: Supplementary materials containing Tables S1 and S2 (ESM1), Figs. S1–S3 (ESM2) are available in the online version of this article at https://doi.org/10.1007/s12583-021-1515-y.

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