Geochronology and petrogenesis of Triassic high-K calc-alkaline granodiorites in the East Kunlun orogen, West China: Juvenile lower crustal melting during post-collisional extension

Abstract

This study reports zircon U-Pb and Hf isotopes and whole-rock elemental data for granodiorites from the East Kunlun orogen. The zircon U-Pb dating defines their crystallization age of 235 Ma. The rocks are characterized by high-K calc-alkaline, magnesian and metaluminous with (K₂O+Na₂O)=6.38 wt.%–7.01 wt.%, Mg#=42–50 [Mg#=100×molar Mg/(Mg+FeO^T)], A/CNK=0.92–0.98, coupled with high ε _Hf(t) values from -0.65 to -1.80. The rocks were derived from partial melting of a juvenile mafic crustal source within normal crust thickness. The juvenile lower crust was generated by mixing lithospheric mantle-derived melt (55%–60%) and supracrustal melt (40%–45%) during the seafloor subduction. Together with available data from the East Kunlun, it is proposed that the studied Middle Triassic granodiorites were formed in post-collisional extension setting, in which melting of the juvenile lower crust in response to the basaltic magma underplating resulted in the production of high-K granodioritic melts.

Keywords

East Kunlun / granodiorite / geochronology / Hf isotope / magmatism

References

[1] Ajaji T., Weis D., Giret A., . Coeval Potassic and Sodic Calc-Alkaline Series in the Post-Collisional Hercynian Tanncherfi Intrusive Complex, Northeastern Morocco: Geochemical, Isotopic and Geochronological Evidence.. Lithos, 1998, 45(1–4): 371-393.

[2] Barbarin B., Didier J. Genesis and Evolution of Mafic Microgranular Enclaves through Various Types of Interaction between Coexisting Felsic and Mafic Magmas.. Transactions of the Royal Society of Edinburgh: Earth Sciences, 1992, 83(1/2): 145-153.

[3] Beard J. S., Lofgren G. E. Dehydration Melting and Water-Saturated Melting of Basaltic and Andesitic Greenstones and Amphibolites at 1, 3, and 6.9 kb.. Journal of Petrology, 1991, 32(2): 365-401.

[4] Beard J., Ragland P., Rushmer T. Hydration Crystallization Reactions between Anhydrous Minerals and Hydrous Melt to Yield Amphibole and Biotite in Igneous Rocks: Description and Implications.. The Journal of Geology, 2004, 112(5): 617-621.

[5] Bellos L. I., Castro A., Díaz-Alvarado J., . Multi-Pulse Cotectic Evolution and In-Situ Fractionation of Calc-Alkaline Tonalite-granodiorite Rocks, Sierra de Velasco Batholith, Famatinian Belt, Argentina.. Gondwana Research, 2015, 27(1): 258-280.

[6] Bergemann C., Jung S., Berndt J., . Generation of Magnesian, High-K Alkali-Calcic Granites and Granodiorites from Amphibolitic Continental Crust in the Damara Orogen, Namibia.. Lithos, 2014, 198/199: 217-233.

[7] Bian Q. T., Li D. H., Pospelov I., . Age, Geochemistry and Tectonic Setting of Buqingshan Ophiolites, North Qinghai-Tibet Plateau, China.. Journal of Asian Earth Sciences, 2004, 23(4): 577-596.

[8] Blichert-Toft J., Albarède F. The Lu-Hf Isotope Geochemistry of Chondrites and the Evolution of the Mantle-Crust System.. Earth and Planetary Science Letters, 1997, 148(1/2): 243-258.

[9] Bouilhol P., Jagoutz O., Hanchar J. M., . Dating the India-Eurasia Collision through Arc Magmatic Records.. Earth and Planetary Science Letters, 2013, 366: 163-175.

[10] Bucholz C. E., Jagoutz O., Schmidt M. W., . Fractional Crystallization of High-K Arc Magmas: Biotite-Versus Amphibole-Dominated Fractionation Series in the Dariv Igneous Complex, Western Mongolia.. Contributions to Mineralogy and Petrology, 2014, 168(5): 1-28.

[11] Castro A. Tonalite-Granodiorite Suites as Cotectic Systems: A Review of Experimental Studies with Applications to Granitoid Petrogenesis.. Earth-Science Reviews, 2013, 124: 68-95.

[12] Castro A. The Off-Crust Origin of Granite Batholiths.. Geoscience Frontiers, 2014, 5(1): 63-75.

[13] Chappell B. W. Aluminium Saturation in I- and S-Type Granites and the Characterization of Fractionated Haplogranites.. Lithos, 1999, 46(3): 535-551.

[14] Chappell B. W., White A. J. R. Two Contrasting Granite Types.. Pacific Geology, 1974, 8: 173-174.

[15] Chappell B. W., White A. J. R. Two Contrasting Granite Types: 25 Years Later.. Australian Journal of Earth Sciences, 2001, 48(4): 489-499.

[16] Chen N. S., Wang X. Y., Zhang H. F., . Geochemistry and Nd-Sr-Pb Isotopic Compositions of Granitoids from Qaidam and Oulongbuluke Micro-Blocks, NW China: Constraints on Basement Nature and Tectonic Affinity.. Earth Science––Jorunal of China University of Geosciences, 2007, 32(1): 7-21.

[17] Chen N. S., Xia X. P., Li X. Y., . Timing of Magmatism of the Gneissic-Granite Plutons along North Qaidam Margin and Implications for Precambrian Crustal Accretions: Zircon U-Pb Dating and Hf Isotope Evidences.. Acta Petrologica Sinica, 2007, 23(2): 501-512.

[18] Chen X. H., Gehrels G., Yin A., . Paleozoic and Mesozoic Basement Magmatisms of Eastern Qaidam Basin, Northern Qinghai-Tibet Plateau: LA-ICP-MS Zircon U-Pb Geochronology and Its Geological Significance.. Acta Geologica Sinica––English Edition, 2012, 86(2): 350-369.

[19] Chen X. H., Gehrels G., Yin A., . Geochemical and Nd-Sr-Pb-O Isotopic Constrains on Permo-Triassic Magmatism in Eastern Qaidam Basin, Northern Qinghai-Tibetan Plateau: Implications for the Evolution of the Paleo-Tethys.. Journal of Asian Earth Sciences, 2015, 114: 674-692.

[20] Chen Y. X., Pei X. Z., Li R. B., . Zircon U-Pb Age of Xiaomiao Formation of Proterozoic in the Eastern Section of the East Kunlun Orogenic Belt.. Geoscience, 2011, 25(3): 510-521.

[21] Cocherie A., Rossi P., Fouillac A. M., . Crust and Mantle Contributions to Granite Genesis—An Example from the Variscan Batholith of Corsica, France, Studied by Trace-Element and Nd-Sr-O Isotope Systematics.. Chemical Geology, 1994, 115(3/4): 173-211.

[22] Condie K. C. Growth of Continental Crust: A Balance between Preservation and Recycling.. Mineralogical Magazine, 2014, 78(3): 623-637.

[23] Corfu F. Atlas of Zircon Textures.. Reviews in Mineralogy and Geochemistry, 2003, 53(1): 469-500.

[24] DePaolo D. J. Trace Element and Isotopic Effects of Combined Wallrock Assimilation and Fractional Crystallization.. Earth and Planetary Science Letters, 1981, 53(2): 189-202.

[25] Ding Q. F., Jiang S. Y., Sun F. Y. Zircon U-Pb Geochronology, Geochemical and Sr-Nd-Hf Isotopic Compositions of the Triassic Granite and Diorite Dikes from the Wulonggou Mining Area in the Eastern Kunlun Orogen, NW China: Petrogenesis and Tectonic Implications.. Lithos, 2014, 205: 266-283.

[26] Ding S., Huang H., Niu Y. L., . Geochemistry, Geochronology and Petrogenesis of East Kunlun High Nb-Ta Rhyolites.. Acta Petrologica Sinica, 2011, 27: 3603-3614.

[27] Eyal M., Litvinovsky B., Jahn B. M., . Origin and Evolution of Post-Collisional Magmatism: Coeval Neoproterozoic Calc-Alkaline and Alkaline Suites of the Sinai Peninsula.. Chemical Geology, 2010, 269(3/4): 153-179.

[28] Frost B. R. A Geochemical Classification for Granitic Rocks.. Journal of Petrology, 2001, 42(11): 2033-2048.

[29] Gerdes A., Kemp A. I. S., Hanchar J. M., . Accessory Minerals as Tracers of Crustal Processes.. Chemical Geology, 2009, 261(3/4): 197-198.

[30] Gong S. L., Chen N. S., Geng H. Y., . Zircon Hf Isotopes and Geochemistry of the Early Paleoproterozoic High-Sr Low-Y Quartz-Diorite in the Quanji Massif, NW China: Crustal Growth and Tectonic Implications.. Journal of Earth Science, 2014, 25(1): 74-86.

[31] Griffin W. L., Pearson N. J., Belousova E., . The Hf Isotope Composition of Cratonic Mantle: LAM-MC-ICPMS Analysis of Zircon Megacrysts in Kimberlites.. Geochimica et Cosmochimica Acta, 2000, 64(1): 133-147.

[32] Griffin W. L., Wang X., Jackson S. E., . Zircon Chemistry and Magma Mixing, SE China: In-Situ Analysis of Hf Isotopes, Tonglu and Pingtan Igneous Complexes.. Lithos, 2002, 61(3/4): 237-269.

[33] Harris N. B. W., Xu R. H., Lewis C. L., . Isotope Geochemistry of the 1985 Tibet Geotraverse, Lhasa to Golmud.. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 1988, 327(1594): 263-285.

[34] Harrison T. M., Watson E. B. The Behavior of Apatite during Crustal Anatexis: Equilibrium and Kinetic Considerations.. Geochimica et Cosmochimica Acta, 1984, 48(7): 1467-1477.

[35] Hawkesworth C. J., Dhuime B., Pietranik A. B., . The Generation and Evolution of the Continental Crust.. Journal of the Geological Society, 2010, 167(2): 229-248.

[36] Honarmand M., Omran N. R., Neubauer F., . Geochemistry of Enclaves and Host Granitoids from the Kashan Granitoid Complex, Central Iran: Implications for Enclave Generation by Interaction of Cogenetic Magmas.. Journal of Earth Science, 2015, 26(5): 626-647.

[37] Hoskin P. W. O., Schaltegger U. The Composition of Zircon and Igneous and Metamorphic Petrogenesis.. Reviews in Mineralogy and Geochemistry, 2003, 53(1): 27-62.

[38] Hu Y., Niu Y. L., Li J. Y., . Petrogenesis and Tectonic Significance of the Late Triassic Mafic Dikes and Felsic Volcanic Rocks in the East Kunlun Orogenic Belt, Northern Tibet Plateau.. Lithos, 2015, 245(2): 205-222.

[39] Hu Z. C., Liu Y. S., Gao S., . Improved in Situ Hf Isotope Ratio Analysis of Zircon Using Newly Designed X Skimmer Cone and Jet Sample Cone in Combination with the Addition of Nitrogen by Laser Ablation Multiple Collector ICP-MS.. Journal of Analytical Atomic Spectrometry, 2012, 27: 1391-1399.

[40] Jagoutz O., Schmidt M. W., Enggist A., . TTG-Type Plutonic Rocks Formed in a Modern Arc Batholith by Hydrous Fractionation in the Lower Arc Crust.. Contributions to Mineralogy and Petrology, 2013, 166(4): 1099-1118.

[41] Jung S., Masberg P., Mihm D., . Partial Melting of Diverse Crustal Sources—Constraints from Sr-Nd-O Isotope Compositions of Quartz Diorite-granodioriteleucogranite Associations (Kaoko Belt, Namibia).. Lithos, 2009, 111(3/4): 236-251.

[42] Li X., Huang X., Luo M., . Petrogenesis and Geodynamic Implications of the Mid-Triassic Lavas from East Kunlun, Northern Tibetan Plateau.. Journal of Asian Earth Sciences, 2015, 105: 32-47.

[43] Liu B., Ma C. Q., Zhang J., . ⁴⁰Ar-³⁹Ar Age and Geochemistry of Subduction-Related Mafic Dikes in Northern Tibet, China: Petrogenesis and Tectonic Implications.. International Geology Review, 2014, 56(1): 57-73.

[44] Liu Y. S., Gao S., Hu Z. C., . Continental and Oceanic Crust Recycling-Induced Melt-Peridotite Interactions in the Trans-North China Orogen: U-Pb Dating, Hf Isotopes and Trace Elements in Zircons from Mantle Xenoliths.. Journal of Petrology, 2010, 51(1/2): 537-571.

[45] Ludwig K. R. User’s Manual for Isoplot/Ex Version 3.00: A Geochronological Toolkit for Microsoft Excel. Berkeley Geochronology Center, Special Publication, 2003

[46] Ma C. Q., Zhang J. Y., Xiong F. H., . Mantle Evolution from Plate Subduction to Post-Orogenic Extension: Evidence from Permo-Triassic Mafic Dike Swarms in Northern Tibet Plateau.. Mineralogical Magazine, 2012, 76 2046.

[47] Maniar P. D., Piccoli P. M. Tectonic Discrimination of Granitoids.. Geological Society of America Bulletin, 1989, 101(5): 635-643.

[48] Martin R. F. Amphiboles in the Igneous Environment.. Reviews in Mineralogy and Geochemistry, 2007, 67(1): 323-358.

[49] Middlemost E. A. K. Naming Materials in the Magma/Igneous Rock System.. Earth-Science Reviews, 1994, 37(3/4): 215-224.

[50] Mo X. X., Dong G. C., Zhao Z. D., . Mantle Input to the Crust in Southern Gangdese, Tibet, during the Cenozoic: Zircon Hf Isotopic Evidence.. Journal of Earth Science, 2009, 20(2): 241-249.

[51] Niu Y. L., Batiza R. Trace Element Evidence from Seamounts for Recycled Oceanic Crust in the Eastern Pacific Mantle.. Earth and Planetary Science Letters, 1997, 148(3/4): 471-483.

[52] Ostendorf J., Jung S., Berndt-Gerdes J., . Syn-Orogenic High-Temperature Crustal Melting: Geochronological and Nd-Sr-Pb Isotope Constraints from Basement-Derived Granites (Central Damara Orogen, Namibia).. Lithos, 2014, 192–195: 21-38.

[53] Pearce J. A., Norry M. J. Petrogenetic Implications of Ti, Zr, Y, and Nb Variations in Volcanic Rocks.. Contributions to Mineralogy and Petrology, 1979, 69(1): 33-47.

[54] Pitcher W. S. Granites and yet more Granites Forty Years on.. Geologische Rundschau, 1987, 76(1): 51-79.

[55] Rapp R. P. Amphibole-out Phase Boundary in Partially Melted Metabasalt, Its Control over Liquid Fraction and Composition, and Source Permeability.. Journal of Geophysical Research, 1995, 100(B8): 15601-15610.

[56] Rapp R. P., Watson E. B. Dehydration Melting of Metabasalt at 8–32 kbar: Implications for Continental Growth and Crust-Mantle Recycling.. Journal of Petrology, 1995, 36(4): 891-931.

[57] Rapp R. P., Watson E. B., Miller C. F. Partial Melting of Amphibolite/Eclogite and the Origin of Archean Trondhjemites and Tonalites.. Precambrian Research, 1991, 51(1–4): 1-25.

[58] Roger F., Arnaud N., Gilder S., . Geochronological and Geochemical Constraints on Mesozoic Suturing in East Central Tibet.. Tectonics, 2003, 22 4 1037

[59] Rudnick R. L., Gao S. Composition of the Continental Crust.. Treatise on Geochemistry, 2003, 33: 1-64.

[60] Simon J. I., Weis D., DePaolo D. J., . Assimilation of Preexisting Pleistocene Intrusions at Long Valley by Periodic Magma Recharge Accelerates Rhyolite Generation: Rethinking the Remelting Model.. Contributions to Mineralogy and Petrology, 2014, 167(1): 1-34.

[61] Sisson T. W., Ratajeski K., Hankins W. B., . Voluminous Granitic Magmas from Common Basaltic Sources.. Contributions to Mineralogy and Petrology, 2004, 148(6): 635-661.

[62] Söderlund U., Patchett P. J., Vervoort J. D., . The ¹⁷⁶Lu Decay Constant Determined by Lu-Hf and U-Pb Isotope Systematics of Precambrian Mafic Intrusions.. Earth and Planetary Science Letters, 2004, 219(3/4): 311-324.

[63] Soesoo A. Fractional Crystallization of Mantle-Derived Melts as a Mechanism for some I-Type Granite Petrogenesis: An Example from Lachlan Fold Belt, Australia.. Journal of the Geological Society, London, 2000, 157(1): 135-149.

[64] Sun S. S., McDonough W. F. Chemical and Isotopic Systematics of Oceanic Basalts: Implications for Mantle Composition and Processes.. Geological Society, London, Special Publications, 1989, 42(1): 313-345.

[65] Taylor S. R., McLennan S. M. The Continental Crust: Its Composition and Evolution, 1985 Oxford: Blackwell Scientific Publications

[66] Tiepolo M., Oberti R., Zanetti A., . Trace-Element Partitioning between Amphibole and Silicate Melt.. Reviews in Mineralogy and Geochemistry, 2007, 67(1): 417-452.

[67] Wang G. C., Wang Q. H., Jian P., . Zircon SHRIMP Ages of Precambrian Metamorphic Basement Rocks and Their Tectonic Significance in the Eastern Kunlun Mountains, Qinghai Province, China.. Earth Science Frontiers, 2004, 11(4): 481-490.

[68] Wolf M. B., Wyllie P. J. Dehydration-Melting of Amphibolite at 10 kbar: The Effects of Temperature and Time.. Contributions to Mineralogy and Petrology, 1994, 115(4): 369-383.

[69] Wyllie P. J., Wolf M. B. Amphibolite Dehydration-Melting: Sorting out the Solidus.. Geological Society, London, Special Publications, 1993, 76(1): 405-416.

[70] Xia R., Wang C. M., Deng J., . Crustal Thickening Prior to 220 Ma in the East Kunlun Orogenic Belt: Insights from the Late Triassic Granitoids in the Xiao-Nuomuhong Pluton.. Journal of Asian Earth Sciences, 2014, 93: 193-210.

[71] Xiong F. H., Ma C. Q., Jiang H. A., . Petrogenetic and Tectonic Significance of Permian Calc-Alkaline Lamprophyres, East Kunlun Orogenic Belt, Northern Qinghai-Tibet Plateau.. International Geology Review, 2013, 55(14): 1817-1834.

[72] Xiong F. H., Ma C. Q., Zhang J. Y., . Zircon LA-ICP-MS U-Pb Dating and Geological Significance of Bairiqili Gabbro Pluton in Eastern Kunlun, Northern Qinghai-Tibet Plateau.. Geological Bulletin of China, 2011, 30(8): 1196-1202.

[73] Xiong F. H., Ma C. Q., Zhang J. Y., . LA-ICP-MS Zircon U-Pb Dating, Elements and Sr-Nd-Hf Isotope Geochemistry of the Early Mesozoic Mafic Dyke Swarms in Eastern Kunlun Orogenic Belt.. Acta Petrologica Sinica, 2011, 27: 3350-3364.

[74] Xiong F. H., Ma C. Q., Zhang J. Y., . The Origin of Mafic Microgranular Enclaves and Their Host Granodiorites from East Kunlun, Northern Qinghai-Tibet Plateau: Implications for Magma Mixing during Subduction of Paleo-Tethyan Lithosphere.. Mineralogy and Petrology, 2012, 104(3/4): 211-224.

[75] Xiong F. H., Ma C. Q., Zhang J. Y., . Reworking of Old Continental Lithosphere: An Important Crustal Evolution Mechanism in Orogenic Belts, as Evidenced by Triassic I-Type Granitoids in the East Kunlun Orogen, Northern Tibetan Plateau.. Journal of the Geological Society, 2014, 171(6): 847-863.

[76] Xu M. J., Li C., Xu W., . Petrology, Geochemistry and Geochronology of Gabbros from the Zhongcang Ophiolitic Mélange, Central Tibet: Implications for an Intra-Oceanic Subduction Zone within the Neo-Tethys Ocean.. Journal of Earth Science, 2014, 25(2): 224-240.

[77] Xu Z. Q., Yang J. S., Jiang M., . Deep Structure and Lithospheric Shear Faults in the East Kunlun-Qiangtang Region, Northern Tibetan Plateau.. Science in China Series D: Earth Sciences, 2001, 44(S1): 1-9.

[78] Yang J. S., Robinson P. T., Jiang C. F., . Ophiolites of the Kunlun Mountains, China and Their Tectonic Implications.. Tectonophysics, 1996, 258(1–4): 215-231.

[79] Yang J. S., Shi R. D., Wu C. L., . Dur’ngoi Ophiolite in East Kunlun, Northeast Tibetan Plateau: Evidence for Paleo-Tethyan Suture in Northwest China.. Journal of Earth Science, 2009, 20(2): 303-331.

[80] Yang J. S., Xu Z. Q., Li H. B., . The Paleo-Tethyan Volcanism and Plate Tectonic Regime in the A’nyemaqen Region of East Kunlun, Northern Tibet Plateau.. Acta Petrologica et Mineralogica, 2005, 24(5): 369-380.

[81] Yuan C., Sun M., Xiao W. J., . Garnet-Bearing Tonalitic Porphyry from East Kunlun, Northeast Tibetan Plateau: Implications for Adakite and Magmas from the MASH Zone.. International Journal of Earth Sciences, 2009, 98(6): 1489-1510.

[82] Zhang J. Y., Ma C. Q., Xiong F. H., . Petrogenesis and Tectonic Significance of the Late Permian–Middle Triassic Calc-Alkaline Granites in the Balong Region, Eastern Kunlun Orogen, China.. Geological Magazine, 2012, 149(5): 892-908.

[83] Zhu Y. H., Zhu Y. S., Lin Q. X., . Characteristics of Early Jurassic Volcanic Rocks and Their Tectonic Significance in Haidewula, East Kunlun Orogenic Belt, Qinghai Province.. Earth Science––Jorunal of China University of Geosciences, 2003, 28(6): 653-659.