Баруунбүрэн орчмын Сэлэнгэ бүрдлийн геохими, геохронологийн судалгаа
Keywords:
Selenge complex, geology, geochemistry, geochronologyAbstract
The Selenge Complex, situated in the Orkhon–Selenge region of Northern Mongolia within the Central Asian Orogenic Belt (CAOB), constitutes a significant archive of Late Paleozoic to Early Mesozoic tectono-magmatic evolution. This study integrates petrographic obsevations, whole-rock major and trace element geochemistry, rare earth element (REE) characteristics, and zircon U–Pb geochronology to constrain the petrogenesis and geodynamic setting of the granitoid assemblages.
The investigated granitoid are characterized as calc-alkaline, metaluminous, and belong to the I-type intrusive suite. They exhibit enrichment in large-ion lithophile elements (LILE; e.g., Rb, Ba, Sr) and light rare earth elements (LREE), coupled with depletion in high field strength elements (HFSE; e.g., Nb, Ta, Ti), and display pronounced negative Nb–Ta–Ti anomalies. These geochemical features are indicative of magmatism in a subduction-related continental arc environment, generated from a mantle wedge source metasomatized by slab-derived fluids. Systematic geochemical variations further suggest that the magmatic evolution was predominantly controlled by fractional crystallization, progressing from a basaltic parental magma toward more evolved granodioritic to granitic compositions.
Zircon U–Pb geochronological data obtained from granodiorite and biotite granite samples in the Baruunburen area yield crystallization ages ranging from 258 to 252 Ma. These ages correspond to Late Permian–Early Triassic tectono-magmatic activity, consistent with regionally documented events throughout the CAOB.
Collectively, the results support a model in which the Selenge granitoids formed within a subduction-related magmatic arc during the terminal stages of subduction. This magmatic activity records a transitional geodynamic regime, marking the shift from active convergence to post-collisional evolution.
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References
Berzina, N. P., & Sotnikov, V. N. (1989). [Geo¬chronology and petrology of Erdenet-type por¬phyry associations]. Moscow: Nauka.
Chappell, B.J., and White, A.J.R., 1974. Two con¬trasting granite types: Pacific Geology, v. 8, p. 173-174.
Irvine, T.N., Baragar, W.R.A., (1971). A Guide to the Chemical Classification of the Common Volcanic Rocks. Can. J. Earth Sci. 8, 523– 548. https://doi.org/10.1139/e71-055Mid¬dlemost, E.A.K. (1994) Naming Materials in the Magma/Igneous Rock System. Earth-Sci¬ence Reviews, 37, 215-244. http://dx.doi. org/10.1016/0012-8252(94)90029
Jahn, B. M., Wu, F., & Chen, B. (2000). Geo¬chemistry of subduction-related granites. Journal of Petrology, 41(10), 1471-1492.
Kovalenko, V. I., Sotnikov, V. N., & Berzina, N. P. (2004). Geochemistry of Late Paleozoic intrusive complexes in Mongolia. Lithos, 74(1- 2), 109-132.
Lamb, W. M., & Cox, R. A. (1998). Ar–Ar dating of hydrotherсая.жилl systems. Geochim¬ica et Cosmochimica Acta, 62, 421-433.
Li, X., Tang, G., Wang, Q., & Zhang, H. (2023). Geochemical constraints on the ori¬gin of calc-alkaline granitoids in Central Asia. Gondwana Research, 120, 102–118.
Middlemost, E.A.K. (1994) Naming Materials in the Magma/Igneous Rock System. Earth-Sci ence Reviews, 37, 215-244. http://dx.doi. org/10.1016/0012-8252(94)90029
Munkhtsengel, T. (2007). SHRIMP U-Pb zircon dating of Erdenet porphyry copper–molybde¬num deposit and host intrusions. Mongolian Journal of Geology, 5(1), 33–45.
Munkhtsengel, T., et al. (2009). SHRIMP U-Pb zircon geochronology of the Erdenet Ovoo area. Mongolian Geoscience Reports, 7, 12–28.
Pearce J.A., (2008). Geochemical fingerprinting of oceanic basalts with applications to ophiolite classification and the search for Archean oceanic crust. Lithos, 100: p.14-48.
Pearce J.A., Harris N.B.W., Tindle A.G., (1984). Trace element discrimination diagrams for the tectonic interpretation of granitic rocks, J. Pet¬rol., Vol.25, № 4, p.956-983
Peccerillo, A. and Taylor, S.R. (1976) Geo¬chemistry of Eocene Calc Alkaline Volcanic Rocks from Kastamonu Area, Northern Tur¬key. Contribution to Mineralogy and Petrol-ogy,58,63-81. http://dx.doi.org/10.1007/ BF00384745
Shand, S.J., (1943). Eruptive Rocks. Their Gen¬esis, Composition, Classification, and Their Relation to Ore-Deposits with a Chapter on Meteorite. New York: John Wiley & Sons.
Sotnikov, V. N., Berzina, N. P., & Ivanov, A. V. (2005). 40Ar/39Ar geochronology of intrusive and metamorphic rocks in Mongolia. Russian Geology and Geophysics, 46, 412-430.
Sun S.S., McDonogh W.F., (1989). Chemical and Isotopic Systematics of Ocean Basalts: Implica¬tion for Mantle Composition and Processes. In: Magmatism in Ocean Basins, Saunders, A.D. and M.J. Norry (Eds.). Geol. Soc. London Special Publication, London, p.313-345.
Tang, G., Li, X., Wang, J., & Chen, Y. (2023). Geochemistry and geochronology of Permo Tri¬assic granitoids in Northern Mongolia. Journal of Petrological Research, 35(2), 45–66.
Taylor, S.R., McLennan, S.M., (1985). The Con¬tinental Crust: its Composition and Evolution. Blackwell Scientific Publications, Oxford
Wang, J., Tang, G., Li, X., & Zhou, Y. (2024). Late Paleozoic–Early Mesozoic tectono-сая. жилgсая.жилtic evolution of Northern Mon¬golia. Journal of Asian Earth Sciences, 235, 105–128.
Watanabe, Y., & Stein, H. J. (2000). Re-Os geochronology of porphyry copper–molybde-num deposits in Mongolia. Economic Geology, 95(3), 497–506.
Windley, B. F., Alexeiev, D., Xiao, W., & Kröner, A. (2007). Tectonic evolution of the Central Asian Orogenic Belt. Journal of Asian Earth Sciences, 30, 115-129.
Xiao, W., Windley, B. F., & Allen, M. B. (2009). Geodynamic evolution of the CAOB: A review. Lithos, 112S, 1-22.
А.А.Моссаковский ., нар 1976, Орогенные структуры и вулканизм палеозоид Евразии иихместо в процессе формирования континентальной земнойкоры. М: Наука, с.318
Г.Дэжидмаа., (2008) УГЗ-200 иж бүрдлийн геологийн 1:200000-ны масштабын зураг, Хөвсгөл-Булганы сери M-48-XXVII.
Р. А. Хасин, В. А. Благонравов, Ю. А. Борзаковский и др. Геология Монгольской Народной Республики Текст : В 3 т. / Гл. ред. Н. А. Маринов; М-во геологии СССР. Науч.-исслед. лаб. геологии зарубеж. стран Т. 2
Э. В. Михайлов Интрузивные комплексы Северо-Восточной Монголии // Магматизм и металлогения Монгольской Народной Республики, Москва, Недра, 1971, с.60-77.
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