Current Science

Open Access Open Access  Restricted Access Subscription Access

Migmatization, Granite Generation and Melt Accumulation in the Himalayan Orogenic Channel, Central and Eastern Bhutan


Affiliations
1 CSIR-Central Building Research Institute, Roorkee 247 667, India
2 Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee 247 667, India
3 Department of Geosciences, Texas Tech University, Lubbock, TX 79409, United States
 

In Central and Eastern Bhutan Himalaya, the Great Himalayan Sequence (GHS) reveals mesoscopic structures within the migmatite–leucogranite association due to crustal anataxis above the Main Central Thrust (MCT). The first phase of dominant melting generates stromatitic migmatite along the main foliation during high grade of metamorphism, possibly by dehydration melting. Subsequent ductile strike–slip shearing caused in situ melting in dilatational sites to produce structureless, non-foliated patchy leucogranite leucosome as well as in boudin necks and post-tectonic patches. In addition, melt-enhanced deformation caused doming of accumulated melt and subsidiary ductile shear zones on either margins of these domes. Surrounded by biotite-rich melanosome, leucosomes destroy the pre-existing foliation during new anatectic phase, which post-dates earlier stromatitic migmatite. These migmatites are the snapshot of mutual relations between newly-developed migmatite and leucogranite melt, and signify the transportation of Himalayan Orogenic Channel to the extreme south in Central and Eastern Bhutan over the Lesser Himalayan sedimentary belt along the MCT.

Keywords

Bhutan, Channel, Himalayan Orogenic Migmatite, Leucogranite.
User
Notifications
Font Size

  • Brown, M., The definition of metatexis, diatexis and migmatite. Proc. Geol. Assoc., 1973, 84(4), 371–382.

  • Harris, N. B. W., Ayres, M. and Massey, J., Geochemistry of granitic melts produced during the incongruent melting of muscovite: Implications for the extraction of Himalayan leucogranite magmas. J. Geophys. Res., 1995, 100, 15767–15777; doi:10.1029/94JB02623.

  • Sawyer, E. W., Atlas of migmatites. Can. Miner. Spec. Publ., 2008, 9, 386.

  • Mehnert, K. R., Migmatites and the Origin of Granitic Rocks, Elsevier Publ. Co, Amsterdam, 1968, p. 405.

  • Wimmenauew, W. and Bryhni, I., Migmatite and related rocks: a proposal on behalf of the IUGS Subcommission on the Systematics of Metamorphic Rocks, 2007, www.bgs.uk/scmr/home.html (web version 1 February 2007).

  • Searle, M. P., Crustal melting, ductile flow, and deformation in mountain belts: Cause and effect relationships. Lithosphere, 2013, 5(6), 547–554; doi:10.1130/RF.L006.1.

  • St-Onge, M. R., Searle, M. P. and Wodicka, N., Trans-Hudson orogen of North America and Himalaya-Karakoram-Tibet orogen of Asia: Structural and thermal characteristics of the lower and upper plates. Tectonics, 2006, 25, TC4006; doi:10.1029/2005TC 001907.

  • Harris, N. and Massey, J., Decompression and anataxis of Himalayan metapelites. Tectonics, 1994, 13(6), 1537–1546; doi:10.1029/94TC01611.

  • Neogi, S., Dasgupta, S. and Fukuoka, M., High P–T polymetamorphism, dehydration melting, and generation of migmatites and granites in the Higher Himalayan Crystalline Complex, Sikkim, India. J. Petrol., 1998, 39, 61–99.

  • Singh, S., Status of magmatic ages in the Himalaya: a review of geochronological studies. J. Indian Geophys. Union, 2001, 5(1), 57–72.

  • Searle, M. P., Cottle, J. M., Streule, M. J. and Waters, D. J., Crustal melt granites and migmatites along the Himalaya: melt source, segregation, transport and granite emplacement mechanisms. Earth Environ. Sci. Trans. R. Soc. Edinb., 2010, 100, 219–233.

  • Guo, Z. and Wilson, M., The Himalayan leucogranites: constraints on the nature of their crustal source region and geodynamic setting. Gondwana Res., 2012, 22(2), 360–376.

  • Imayama, T., Takeshita, T., Yi, K., Cho, D. L., Kitajima, K., Tsutsumi, Y. and Sano, Y., Two-stage partial melting and contrasting cooling history within the Higher Himalayan Crystalline Sequence in the far-eastern Nepal Himalaya. Lithos, 2012, 134, 1–22.

  • Visona, D., Carosi, R., Montomoli, C., Peruzzo, L. and Tiepolo, M., Miocene andalusite leucogranite in central-east Himalaya (Everest–Masang Kang area): low-pressure melting during heating. Lithos, 2012, 144, 194–208.

  • Jain, A. K., Seth, P., Shreshtha, M., Mukherjee, P. K. and Singh, K., Structurally-controlled melt accumulation: Himalayan migmatites and related deformation, Dhauli Ganga Valley, Garhwal Himalaya. J. Geol. Soc. India, 2013, 82, 313–318.

  • Weinberg, R. F., Himalayan leucogranites and migmatites: nature, timing and duration of anataxis. J. Metamorph. Geol., 2016, doi:10.1111/jmg.12204.

  • Bhargava, O. N., The Bhutan Himalaya: a geological account. Spec. Publ. Ser. Geol. Surv. India, Director General, Geological Survey of India, Kolkata, 1995, vol. 39, p. 245.

  • Long, S. and McQuarrie, N. and Tobgay, T., Tectonostratigraphy of the Lesser Himalaya of Bhutan: implications for the along strike stratigraphic continuity of the northern Indian margin. Geol. Soc. Am. Bull., 2011, 123, 1406–1426; doi:10.1130/B30202.1.

  • McQuarrie, N., Long, S. P. and Tobgay, T., Documenting basin scale, geometry, and provenance through detrital geochemical data: lesson from the Neoproterozoic to Ordovician Lesser, Greater, and Tethyan Himalayan strata of Bhutan. Gondwana Res., 2013, 23, 1491–1510; doi:10.1016/j.gr.2012.09.002.

  • Dasgupta, S, Jaishidanda Formation. In Bhutan Himalaya: A Geological Account (ed. Bhargava, O. N.), Geol. Surv. India Spec. Publ., Director General, Geological Survey of India, Kolkata, 1995, vol. 39, pp. 79–88.

  • Davidson, C., Grujic, D. E., Hollister, L. S. and Schmid, S. M., Metamorphic reactions related to decompression and synkinematic intrusion of leucogranite, High Himalayan Crystalllines, Bhutan. J. Metamorph. Geol., 1997, 15(5), 593–612.

  • Daniel, C. G., Hollister, L. S., Parrish, R. R. and Grujic, D., Exhumation of the Main Central Thrust from lower crustal depths, eastern Bhutan Himalaya. J. Metamorph. Geol., 2003, 21, 317–334; doi:10.1046/j.1525-1314.2003.00445.x.

  • Grujic, D., Hollister, L. S. and Parrish, R. R., Himalayan metamorphic sequence as an orogenic channel: insight from Bhutan. Earth Planet. Sci. Lett., 2002, 198, 177–191.

  • Zeiger, K., Gordon, S. M., Long, S. P., Kylander-Clark, A. R. C., Agustsson, K. and Penfold, M., Timing and conditions of metamorphism and melt crystallization in Greater Himalayan rocks, eastern and central Bhutan: insight from U–Pb zircon and monazite geochronology and trace-element analyses. Contrib Mineral. Petrol., 2015, 169, 47; doi:10.1007/s00410-015-1143-6.

  • Grujic, D., Channel flow and continental collision tectonics. In Channel Flow, Ductile Extrusion and Exhumation in Continental Collision Zones (eds Law, R. D., Searle, M. P. and Godin, L.), Geol. Soc. Spec. Publ., vol. 268, 2006, pp. 25–37.

  • Yin, A., Cenozoic tectonic evolution of the Himalayan orogen as constrained by along-strike variation of structural geometry, exhumation history, and foreland sedimentation. Earth-Sci. Rev., 2006, 76, 1–131; doi:10.1016/j.earscirev.2005.05.004.

  • Brown, M., The generation, segregation, ascent and emplacement of granite magma: the migmatite-tocrustally-derived granite connection in thickened orogens. Earth-Sci. Rev., 1994, 36, 83–130.

  • Brown, M., Averkin, Y. A., McLellan, E. L. and Sawyer, E. W., Melt segregation in migmatites. J. Geophys. Res., 1995, 100(B8), 15655–15679.

  • Platt, J. P. and Vissers, R. L. M., Extensional structures in anisotropic rocks. J. Struct. Geol., 1980, 2, 397–410.

  • Jain, A. K., Sushmita and Singh, Sandeep, Photograph of the month. J. Struct. Geol., 2014, 59, 50.

  • Arslan, A., Passchier, C. W. and Koehn, D., Foliation boudinage. J. Struct. Geol., 30, 291–309.

  • Davidson, C., Hollister, L. S. and Schmid, S. M., Role of melt during deformation in the deep crust. Terra Nova, 1994, 6, 133–142.

  • Brown, M. and Solar, G. S., Shear-zone systems and melts: feedback relations and self- organization in orogenic belts. J. Struct. Geol., 1997, 20(2/3), 211–227.

  • Berger, A. and Kalt, A., Structures and melt fractions as indicators of rheology in cordierite- bearing migmatites of the Bayersche Wald (Variscan Belt, Germany). J. Petrol., 1999, 40, 1699–1719.

  • Brown, M., Orogeny, migmatites and leucogranites: a review. Earth Planet. Sci. Lett., 2001, 110(4), 313–336.

  • Sawyer, E. W., Melt segregation in the continental crust. Geology, 1994, 22, 1019–1022.

  • Jung, S., Hoernes, S., Masberg, P. and Hoffer, E., The petrogenesis of some migmatites and granites (Central Damara Orogen, Namibia): evidence for disequilibrium melting, wall-rock contamination and crystal fractionation. J. Petrol., 1999, 40(8), 1241–1269.

  • Brown, M. and Rushmer, T., The role of deformation in the movement of granitic melt: views from the laboratory and the field. In Deformation-Enhanced Fluid Transport in the Earth′s Crust and Mantle (ed. Holness, M. B.), Chapman & Hall, London, 1997, pp. 111–144.

  • Snoke, A. W., Kalakay, T. J., Quick, J. E. and Sinigoi, S., Deep-crustal shear zone as a result of mafic igneous intrusion in the lower crust, Ivrea-Verbano Zone, Southern Alps, Italy. Earth Planet. Sci. Lett., 1999, 166, 31–45.

  • Hutton, D. H. W., Depster, T. J., Brown, P. E. and Becker, S. D., A new mechanism of granite emplacement: intrusion in active extensional shear zones. Nature, 1990, 343, 452–455.

  • Vernon, R. H. and Paterson, S. R., Axial-surface leucosomes in anatectic migmatites. Tectonophysics, 2001, 335, 183–192.

  • Ord, A., Mechanical controls on dilatant shear zones. In Deformation Mechanisms, Rheology and Tectonics (eds Knipe, R. J. and Rutter, E. H.), Geol. Soc. London Spec. Publ., 1990, 54, 183–192.

  • D’Eramo, F., Tubía, J. M., Pinotti, L., Vegas, N., Coniglio, J., Demartis, M., Aranguren, A. and Basei, M., Granite emplacement by crustal boudinage: example of the Calmayo and El Hongo plutons (Córdoba, Argentina). Terra Nova, 2015, 25, 423–430.

  • Hollister, L. S. and Crawford, M. L., Melt enhanced deformation: a major tectonic process. Geology, 1986, 14, 558–561.

  • Webb, A. A. G., Yin, A., Harrison, T. M., Célérier, J. and Burgess, W. P., The leading edge of the Greater Himalayan Crystallines revealed in the NW Indian Himalaya: Implications for the evolution of the Himalayan Orogen. Geology, 2007, 35, 955–958; doi:10.1130/G23931A.1.

  • Jain, A. K. and Manickavasagam, R. M., Inverted metamorphism in the intracontinental ductile shear zone during Himalayan collision tectonics. Geology, 1993, 21, 407–410.

  • Beaumont, C., Jamieson, R. A., Nguyen, M. H. and Lee, B., Himalayan tectonics explained by extrusion of a low-viscosity crustal channel coupled to focused surface denudation. Nature, 2001, 414, 738–742.

  • Jain, A. K. and Manickavasagam, R. M., Singh, Sandeep and Mukherjee, S., Himalayan collision zone: new perspectives-its tectonic evolution in a combined ductile shear zone and channel flow model. Himal. Geol., 2005, 26(1), 1–18.

  • Godin, L., Grujic, D., Law, R. D. and Searle, M. P., Channel flow, ductile extrusion and exhumation in continental collision zones; an introduction. In Channel Flow, Ductile Extrusion and Exhumation in Continental Collision Zones (eds Law, R. D., Searle, M. P. and Godin, L.), Geol. Soc. London Spec. Publ., 2006, vol. 268, pp. 1–23.

  • Hollister, L. S. and Grujic, D., Pulsed channel flow in Bhutan. Geol. Soc. Spec. Publ., 2006, 268, 415–423; doi:10.1144/GSL.SP.2006.268.01.19.

  • Gansser, A., Geology of the Bhutan Himalaya, Birkäuser, Basel, 1983, p. 181.


Abstract Views: 402

PDF Views: 138




  • Migmatization, Granite Generation and Melt Accumulation in the Himalayan Orogenic Channel, Central and Eastern Bhutan

Abstract Views: 402  |  PDF Views: 138

Authors

A. K. Jain
CSIR-Central Building Research Institute, Roorkee 247 667, India
Sushmita
Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee 247 667, India
Sandeep Singh
Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee 247 667, India
P. K. Mukherjee
Department of Geosciences, Texas Tech University, Lubbock, TX 79409, United States

Abstract


In Central and Eastern Bhutan Himalaya, the Great Himalayan Sequence (GHS) reveals mesoscopic structures within the migmatite–leucogranite association due to crustal anataxis above the Main Central Thrust (MCT). The first phase of dominant melting generates stromatitic migmatite along the main foliation during high grade of metamorphism, possibly by dehydration melting. Subsequent ductile strike–slip shearing caused in situ melting in dilatational sites to produce structureless, non-foliated patchy leucogranite leucosome as well as in boudin necks and post-tectonic patches. In addition, melt-enhanced deformation caused doming of accumulated melt and subsidiary ductile shear zones on either margins of these domes. Surrounded by biotite-rich melanosome, leucosomes destroy the pre-existing foliation during new anatectic phase, which post-dates earlier stromatitic migmatite. These migmatites are the snapshot of mutual relations between newly-developed migmatite and leucogranite melt, and signify the transportation of Himalayan Orogenic Channel to the extreme south in Central and Eastern Bhutan over the Lesser Himalayan sedimentary belt along the MCT.

Keywords


Bhutan, Channel, Himalayan Orogenic Migmatite, Leucogranite.

References





DOI: https://doi.org/10.18520/cs%2Fv114%2Fi09%2F1903-1912