Petrogenesis and Tectonic Implications of the Paiku Leucogranites, Northern Himalaya

Abstract

The Himalayan leucogranites provide insights into the partial melting behavior of relatively deeper crustal rocks and tectono-magmatic history of the Himalayan Orogen. The Paiku leucogranites of northern Himalaya can be subdivided into two-mica leucogranite (TML), garnet-bearing leucogranite (GL), cordierite-bearing leucogranite (CL), and tourmaline-bearing leucogranite (TL). All of them are high-K, peraluminous, calc-alkalic to alkali-calcic rocks. They are enriched in light rare earth elements (LREE) and large ion lithophile elements (LILE), and show pronounced negative anomalies of Sr, Ba, K and Ti, but positive anomalies of Nb and Rb. LA-ICP-MS U-Pb zircon dating of one TML, one GL and two CL samples yielded variable ²⁰⁶Pb/²³⁸U ages ranging from 23.6 to 16.1 Ma, indicating the Paiku leucogranites underwent a low degree of partial melting process. Combining with previous studies, we suggest the Paiku leucogranites were derived from partial melting of metasedimentary rocks of the Higher Himalayan Sequence (HHS). The GL and TL mainly resulted from the muscovite-dehydration melting, whereas the TML and CL were mainly derived from the biotite-dehydration melting. Finally, it is concluded that the Paiku leucogranites were probably formed during the subduction of the Indian crust.

Keywords

Paiku leucogranites / petrochemistry / U-Pb geochronology / dehydration melting / tectonic implications / northern Himalaya

References

[1] Andersen T. Correction of Common Lead in U-Pb Analyses that do not Report ²⁰⁴Pb. Chemical Geology, 2002, 192(1/2): 59-79.

[2] Aikman A B, Harrison T M, Hermann J. Age and Thermal History of Eo- and Neohimalayan Granitoids, Eastern Himalaya. Journal of Asian Earth Sciences, 2012, 51: 85-97.

[3] Aoya M, Wallis S R, Terada K, . North-South Extension in the Tibetan Crust Triggered by Granite Emplacement. Geology, 2005, 33(11): 853-856.

[4] Booth A L, Zeitler P, Kidd W, . U-Pb Zircon Constraints on the Tectonic Evolution of Southeastern Tibet, Namche Barwa Area. American Journal of Science, 2004, 304(10): 889-929.

[5] Braun I, Raith M, Kumar G R R. Dehydration-Melting Phenomena in Leptynitic Gneisses and the Generation of Leucogranites: A Case Study from the Kerala Khondalite Belt, Southern India. Journal of Petrology, 1996, 37(6): 1285-1305.

[6] Burchfiel B C, Royden L H. North-South Extension within the Convergent Himalayan Region. Geology, 1985, 13(10): 679-682.

[7] Clemens J D, Vielzeuf D. Constraints on Melting and Magma Production in the Crust. Earth and Planetary Science Letters, 1987, 86(2/3/4): 287-306.

[8] Clemens J D, Stevens G. Comment on ‘Water-Fluxed Melting of the Continental Crust: A Review’ by R. F. Weinberg and P. Hasalová. Lithos, 2015, 100-101.

[9] Deniel C, Vidal P, Fernandez A, . Isotopic Study of the Ma-naslu Granite (Himalaya, Nepal): Inferences on the Age and Source of Himalayan Leucogranites. Contributions to Mineralogy and Petrology, 1987, 96(1): 78-92.

[10] Ding L, Kapp P, Wan X Q. Paleocene-Eocene Record of Ophio-lite Obduction and Initial India-Asia Collision, South Central Tibet. Tectonics, 2005, 24(3): 1-18.

[11] Edwards M A, Harrison T M. When did the Roof Collapse? Late Miocene North-South Extension in the High Himalaya Revealed by Th-Pb Mon-azite Dating of the Khula Kangri Granite. Geology, 1997, 25(6): 543-546.

[12] Frost B R, Barnes C G, Collins W J, . A Geochemical Classification for Granitic Rocks. Journal of Petrology, 2001, 42(11): 2033-2048.

[13] Gao L E, Zeng L S. Fluxed Melting of Metapelite and the Formation of Miocene High-CaO Two-Mica Granites in the Malashan Gneiss Dome, Southern Tibet. Geochimica et Cosmochimica Acta, 2014, 130: 136-155.

[14] Gao L E, Zeng L S, Hou K J, . Episodic Crustal Anatexis and the Formation of Paiku Composite Leucogranitic Pluton in the Malashan Gneiss Dome, Southern Tibet. Chinese Science Bulletin, 2013, 58(28/29): 3546-3563.

[15] Gao L E, Zeng L S, Xie K J. Eocene High Grade Metamorphism and Crustal Anatexis in the North Himalaya Gneiss Domes, Southern Tibet. Chinese Science Bulletin, 2011, 57(36): 3078-3090. (in Chinese)

[16] Gou Z B, Zhang Z M, Dong X, . Petrogenesis and Tectonic Implications of the Yadong Leucogranites, Southern Himalaya. Lithos, 2016, 300-310.

[17] Groppo C, Rubatto D, Rolfo F, . Early Oligocene Partial Melting in the Main Central Thrust Zone (Arun Valley, Eastern Nepal Himalaya). Lithos, 2010, 118(3/4): 287-301.

[18] Groppo C, Rolfo F, Indares A. Partial Melting in the Higher Himalayan Crystallines of Eastern Nepal: The Effect of Decompression and Implications for the ‘Channel Flow’ Model. Journal of Petrology, 2012, 53(5): 1057-1088.

[19] Guillot S, Le Fort P, Pêcher A, . Contact Metamorphism and Depth of Emplacement of the Manaslu Granite (Central Nepal). Implications for Himalayan Orogenesis. Tectonophysics, 1995, 241(1/2): 99-119.

[20] Guillot S, Le Fort P. Geochemical Constraints on the Bimodal Origin of High Himalayan Leucogranites. Lithos, 1995, 35(3/4): 221-234.

[21] Guilmette C, Indares A, Hébert R. High-Pressure Anatectic Paragneisses from the Namche Barwa, Eastern Himalayan Syntaxis: Textural Evidence for Partial Melting, Phase Equilibria Modeling and Tectonic Implications. Lithos, 2011, 124(1/2): 66-81.

[22] Guo Z F, Wilson M. The Himalayan Leucogranites: Constraints on the Nature of Their Crustal Source Region and Geodynamic Setting. Gondwana Research, 2012, 22(2): 360-376.

[23] Harris N, Inger S. Trace Element Modelling of Pelite-Derived Granites. Contributions to Mineralogy and Petrology, 1992, 110(1): 46-56.

[24] Harris N, Massey J, Inger S. The Role of Fluids in the Formation of High Himalayan Leucogranites. Geological Society, London, Special Publications, 1993, 74(1): 391-400.

[25] Harris N, Massey J. Decompression and Anatexis of Himalayan Metape-lites. Tectonics, 1994, 13(6): 1537-1546.

[26] Harris N, Caddick M, Kosler J, . The Pressure-Temperature-Time Path of Migmatites from the Sikkim Himalaya. Journal of Metamorphic Geology, 2004, 22(3): 249-264.

[27] Harrison M T, Grove M, McKeegan K D, . Origin and Episodic Emplacement of the Manaslu Intrusive Complex, Central Himalaya. Journal of Petrology, 1999, 40(1): 3-19.

[28] 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.

[29] Hou Z Q, Zheng Y C, Zeng L S, . Eocene-Oligocene Granitoids in Southern Tibet: Constraints on Crustal Anatexis and Tectonic Evolution of the Himalayan Orogen. Earth and Planetary Science Letters, 2012, 349(350): 38-52.

[30] Huang C M, Zhao Z D, Li G M, . Leucogranites in Lhozag, Southern Tibet: Implications for the Tectonic Evolution of the Eastern Himalaya. Lithos, 2017, 246-262.

[31] Icenhower J, London D. An Experimental Study of Element Partitioning among Biotite, Muscovite, and Coexisting Peraluminous Silicic Melt at 200 MPa (H₂O). American Mineralogist, 1995, 80(11/12): 1229-1251.

[32] Imayama T, Suzuki K. Carboniferous Inherited Grain and Age Zoning of Monazite and Xenotime from Leucogranites in Far-Eastern Nepal: Constraints from Electron Probe Microanalysis. American Mineralogist, 2013, 98(8/9): 1393-1406.

[33] Inger S, Harris N. Geochemical Constraints on Leucogranite Mag-matism in the Langtang Valley, Nepal Himalaya. Journal of Petrology, 1993, 34(2): 345-368.

[34] King J, Harris N, Argles T, . Contribution of Crustal Anatexis to the Tectonic Evolution of Indian Crust beneath Southern Tibet. Geological Society of America Bulletin, 2011, 123(1/2): 218-239.

[35] Liu Y S, Hu Z C, Zong K Q, . Reappraisement and Refinement of Zircon U-Pb Isotope and Trace Element Analyses by LA-ICP-MS. Chinese Science Bulletin, 2010, 55(15): 1535-1546.

[36] Liu Z C, Wu F Y, Ji W Q, . Petrogenesis of the Ramba Leu-cogranite in the Tethyan Himalaya and Constraints on the Channel Flow Model. Lithos, 2014, 118-136.

[37] Ludwig K R. Isoplot/Ex Version 3.00: A Geochronological Toolkit for Microsoft Excel, 2003, 1-73.

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

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

[40] Patino Douce A E, Harris N. Experimental Constraints on Himalayan Anatexis. Journal of Petrology, 1998, 39(4): 689-710.

[41] Patino Douce A E, Humphreys E D, Johnston A D. Anatexis and Metamorphism in Tectonically Thickened Continental Crust Exemplified by the Sevier Hinterland, Western North America. Earth and Planetary Science Letters, 1990, 97(3/4): 290-315.

[42] Paul A, Jung S, Romer R L, . Petrogenesis of Synorogenic High-Temperature Leucogranites (Damara Orogen, Namibia): Constraints from U-Pb Monazite Ages and Nd, Sr and Pb Isotopes. Gondwana Research, 2014, 25(4): 1614-1626.

[43] Rubatto D, Chakraborty S, Dasgupta S. Timescales of Crustal Melting in the Higher Himalayan Crystallines (Sikkim, Eastern Himalaya) Inferred from Trace Element-Constrained Monazite and Zircon Chronology. Contributions to Mineralogy and Petrology, 2013, 165(2): 349-372.

[44] Scaillet B, France-Lanord C, Le Fort P. Badrinath-Gangotri Plu-tons (Garhwal, India): Petrological and Geochemical Evidence for Fractionation Processes in a High Himalayan Leucogranite. Journal of Volcanology and Geothermal Research, 1990, 44(1/2): 163-188.

[45] Schärer U. The Effect of Initial ²³⁰Th Disequilibrium on Young U-Pb Ages: The Makalu Case, Himalaya. Earth and Planetary Science Letters, 1984, 67(2): 191-204.

[46] Searle M P, Godin L. The South Tibetan Detachment and the Ma-naslu Leucogranite: A Structural Reinterpretation and Restoration of the Annapurna-Manaslu Himalaya, Nepal. The Journal of Geology, 2003, 111(5): 505-523.

[47] Searle M P, Szulc A G. Channel Flow and Ductile Extrusion of the High Himalayan Slab—The Kangchenjunga-Darjeeling Profile, Sikkim Himalaya. Journal of Asian Earth Sciences, 2005, 25(1): 173-185.

[48] Searle M P, Cottle J M, Streule M J, . Crustal Melt Granites and Migmatites along the Himalaya: Melt Source, Segregation, Transport and Granite Emplacement Mechanisms. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 2009, 100(1/2): 219-233.

[49] Sorcar N, Hoppe U, Dasgupta S, . High-Temperature Cooling Histories of Migmatites from the High Himalayan Crystallines in Sik-kim, India: Rapid Cooling Unrelated to Exhumation?. Contributions to Mineralogy and Petrology, 2014, 167(2): 1-34.

[50] 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.

[51] Thompson A B, Connolly J A D. Melting of the Continental Crust: Some Thermal and Petrological Constraints on Anatexis in Continental Collision Zones and other Tectonic Settings. Journal of Geophysical Research: Solid Earth, 1995, 100(B8): 15565-15579.

[52] Vielzeuf D, Holloway J R. Experimental Determination of the Fluid-Absent Melting Relations in the Pelitic System. Contributions to Mineralogy and Petrology, 1988, 98(3): 257-276.

[53] Vielzeuf D, Montel J M. Partial Melting of Metagreywackes. Part I. Fluid-Absent Experiments and Phase Relationships. Contributions to Mineralogy and Petrology, 1994, 117(4): 375-393.

[54] Visonà D, Lombardo B. Two-Mica and Tourmaline Leucogranites from the Everest-Makalu Region (Nepal-Tibet). Himalayan Leu-cogranite Genesis by Isobaric Heating?. Lithos, 2002, 62(3/4): 125-150.

[55] Wang L X, Ma C Q, Zhang C, . Genesis of Leucogranite by Prolonged Fractional Crystallization: A Case Study of the Mufushan Complex, South China. Lithos, 2014, 147-163.

[56] Wang X X, Zhang J J, Wang J M. Geochronology and Formation Mechanism of the Paiku Granite in Northern Himalaya, and Its Tectonic Implications. Earth Science, 2016, 41: 982-998. (in Chinese with English Abstract)

[57] Wu F Y, Liu Z C, Liu X C, . Himalayan Leucogranites: Petrogenesis and Implications to Orogenesis and Plateau Uplift. Acta Petrologica Sinica, 2015, 31: 1-36. (in Chinese with English Abstract)

[58] Yin A. Cenozoic Tectonic Evolution of the Himalayan Orogen as Constrained by Along-Strike Variation of Structural Geometry, Exhumation History, and Foreland Sedimentation. Earth-Science Reviews, 2006, 76(1/2): 1-131.

[59] Zeng L S, Gao L E, Xie K J, . Mid-Eocene High Sr/Y Granites in the Northern Himalayan Gneiss Domes: Melting Thickened Lower Continental Crust. Earth and Planetary Science Letters, 2011, 303(3/4): 251-266.

[60] Zeng L S, Gao L E, Tang S H, . Eocene Magmatism in the Tethyan Himalaya, Southern Tibet. Geological Society, London, Special Publications, 2014, 412(1): 287-316.

[61] Zhang H F, Harris N, Parrish R, . U-Pb Ages of Kude and Sajia Leucogranites in Sajia Dome from North Himalaya and Their Geological Implications. Chinese Science Bulletin, 2004, 49 19 2017.

[62] Zhang Z M, Dong X, Santosh M, . Metamorphism and Tectonic Evolution of the Lhasa Terrane, Central Tibet. Gondwana Research, 2014, 25(1): 170-189.

[63] Zhang Z M, Xiang H, Dong X, . Long-Lived High-Temperature Granulite-Facies Metamorphism in the Eastern Himalayan Orogen, South Tibet. Lithos, 2015, 1-15.

[64] Zhang Z M, Xiang H, Dong X, . Oligocene HP Metamor-phism and Anatexis of the Higher Himalayan Crystalline Sequence in Yadong Region, East-Central Himalaya. Gondwana Research, 2017, 41: 173-187.

[65] Zhang Z M, Kang D Y, Ding H X, . Partial Melting of Himalayan Orogen and Formation Mechanism of Leucogranites. Earth Science, 2018, 43(1): 82-98. in Chinese with English Abstract)

[66] Zhang Z M, Ding H X, Dong X, . High-Temperature Metamorphism, Anataxis and Tectonic Evolution of a Mafic Granulite from the Eastern Himalayan Orogen. Journal of Earth Science, 2018, 29(5): 1010-1025.