Abstract
Various shaped mafic microgranular enclaves (MMEs) together with several mafic massifs are developed within the Yuegelu granitoid pluton in the eastern part of the Eastern Kunlun. On the basis of detailed field geological surveying and of the results of the petrological and geochemical studies it is suggested that there must be some genetic relationship among the granodiorite host, the MMEs and the hornblende (Hb)-gabbro massifs. Magmatic zircon grains are extracted from samples of granodiorite host rock, Hb-gabbro and the MMEs for U-Pb dating. The U-Pb ages are determined by using SHRIMP II technique, which yields the ages of 242 ± 6 Ma, 239 ± 6 Ma and 241 ± 5 Ma, respectively. The overall correspondence in the U-Pb dating results of them excludes the possibility that the MMEs in the granitoids are solid refractory relics from the source region or that they are xenoliths from the wall rocks. It can also rule out the possibility of a later emplacement of basic magma after the solidification of the granitoids. This dating result indicates that they are the products of magma mixing in early-mid Triassic epoch. Among them the granitoid host is chemically akin to the acidic end member during the magma mixing process, the Hb-gabbro is akin to the basic ones while the MMEs are the incompletely mixed basic magma clots trapped in the acidic magma. Combined with the results from other researches on this pluton it is reasonable to consider that in the mid-Triassic the Eastern Kunlun granitoid belt had undergone a process of magma mixing between the mantle-derived basic magma and the crustal acidic magma which indicates that the injection of mantle materials and energy into the crust and the reactions between them played an important role in the formation of the granitoid rocks.
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Wang, D. Z., Zhou, X. M., Origin of the Late Mesozoic Granitic Volcano-intrusive Complex in Southeastern China and Implications for the Crust Evolution (in Chinese), Beijing: Science Press, 2002, 1–5.
Chappell, B. W., White, A. J. R., Restite enclaves and the restite model, Collection in Enclaves and Granite Petrology (eds. Didier, J., Barbarin, B.), Amsterdam: Elsevier, 1991, 375–381.
Didier, J., Granites and Their Enclaves: The Bearing of Enclaves on the Origin of Granites, Collection in Development in Petrology, Amsterdam: Elsevier, 1973, 393.
Didier, J., Barbarin, B., Enclaves and Granite Petrology, Amsterdam: Elsevier, 1991, 1–625.
Liu, C. D., Zhang, W. Q., Mo, X. X. et al., Characteristics and origin of mafic microgranular enclaves in Yuegelu granitic pluton in Eastern Kunlun, Geological Bulletin of China (in Chinese), 2002, 21(11): 739–744.
Li, Y. W., Deng, J. F., Luo, Z. H. et al., Discovery of cumulus crystal bojite and its significance in Sonid Zuoqi area, Inner Mongolia, Geoscience (in Chinese), 1995, 9(2): 212–219.
Mo, X.X., Luo, Z.H., Xiao, Q.H. et al., Evidence of magma mixing in granitoids plutons and the ways of investigation, Collection in the Ways of Investigation on Granitoids (ed. Xiao, Q. H.) (in Chinese), Beijing: Geological Publishing House, 2002, 53–70.
Williams, I. S., Claesson, S., Isotope evidence for the Precambrian province and Caledonian metamorphism of high grade paragneiss from the Seve Nappes, Scandinavian Caledonides, II. Ion microprobe zircon U-Th-Pb, Contrib. Mineral. Petrol., 1987, 97: 205–217.
Compston, W., Williams, I. S., Krischvink, J. L. et al., Zircon U-P ages of early Cabbrian time-scale, J. Geol. Soc., 1992, 149: 171–184.
Claoue-Long, J. C., Compston, W., Roberts, J. et al., Two carboniferous ages: a comparison of SHRIMP zircon dating with conventional zircon ages and40Ar/39Ar analysis, Collection in Geochronology, Time Scales and Global Stratigraphic Correlation: SEPM Special Publication (eds. Berggren, W. A., Kent, D. V., Aubry, M. P. et al.), 1995, 5(4): 3–31.
Williams, I. S., Buick, C. I., An extended episode of early Mesoproterozoic metamorphic fluid flow in the Reylolds Range, central Australia, J. Metamorphic Geol., 1996, 14: 29–47.
Luo, Z. H., Ke, S., Cao, Y. Q. et al., Late Indosinian mantle-derived magmatism in East Kunlun, Geological Bulletin of China (in Chinese), 2002, 21(6): 292–297.
Jiang, C. F., Some questions about tectonic in Qinghai Ayimaqing mountain area, Geology Study (in Chinese), 1995, 28: 15–26.
Guo, Z. F., Deng, J. F., Xu, Z. Q. et al., Late Palaeozoic-Mesozoic intracontinental orogenic process and intermediate-acid igneous rocks from the Eastern Kunlun Mountians of northwestern China, Geoscience (in Chinese), 1998, 12(3): 345–352.
Deng, J. F., Zhao, H. L., Mo, X. X. et al., Root and Pillar Tectonic of China—the Key to the Continental Dynamics (in Chinese), Beijing: Geological Publishing House, 1996, 14–82.
Jin, Z. M., Gao, S., Underplating and its geodynamical significances for the evolution of cruse-mantle boundary, Geological Science and Technology Information (in Chinese), 1996, 15(2): 1–7.
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Liu, C., Mo, X., Luo, Z. et al. Mixing events between the crust- and mantle-derived magmas in eastern kunlun: Evidence from zircon SHRIMP II chronology. Chin. Sci. Bull. 49, 828–834 (2004). https://doi.org/10.1007/BF02889756
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DOI: https://doi.org/10.1007/BF02889756