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The crystalline units of the High Himalayas in the Lahul–Zanskar region (northwest India): metamorphic–tectonic history and geochronology of the collided and imbricated Indian plate

Published online by Cambridge University Press:  01 May 2009

U. Pognante
Affiliation:
Dipartimento di Scienze della Terra, Via Valperga Caluso 37, 10125 Torino, Italy
D. Castelli
Affiliation:
Dipartimento di Scienze della Terra, Via Valperga Caluso 37, 10125 Torino, Italy
P. Benna
Affiliation:
Dipartimento di Scienze della Terra, Via Valperga Caluso 37, 10125 Torino, Italy
G. Genovese
Affiliation:
Dipartimento di Scienze della Terra, Via Valperga Caluso 37, 10125 Torino, Italy
F. Oberli
Affiliation:
Isotope Geochemistry, Swiss Federal Institute of Technology (ETH), 8092 Zurich, Switzerland
M. Meier
Affiliation:
Isotope Geochemistry, Swiss Federal Institute of Technology (ETH), 8092 Zurich, Switzerland
S. Tonarini
Affiliation:
Laboratorio di Geocronologia e Geochimica Isotopica – C.N.R., Via Cardinale Maffi 36, 56100 Pisa, Italy

Abstract

In the High Himalayan belt of northwest India, crustal thickening linked to Palaeogene collision between India and Eurasia has led to the formation of two main crystalline tectonic units separated by the syn-metamorphic Miyar Thrust: the High Himalayan Crystallines sensu stricto (HHC) at the bottom, and the Kade Unit at the top. These units are structurally interposed between the underlying Lesser Himalaya and the very low-grade sediments of the Tibetan nappes. They consist of paragneisses, orthogneisses, minor metabasics and, chiefly in the HHC, leucogranites. The HHC registers: a polyphase metamorphism with two main stages designated as M1 and M2; a metamorphic zonation with high-temperature recrystallization and migmatization at middle structural levels and medium-temperature assemblages at upper and lower levels. In contrast, the Kade Unit underwent a low-temperature metamorphism. Rb–Sr and U–Th–Pb isotope data point to derivation of the orthogneisses from early Palaeozoic granitoids, while the leucogranites formed by anatexis of the HHC rocks and were probably emplaced during Miocene time.

Most of the complicated metamorphic setting is related to polyphase tectonic stacking of the HHC with the ‘cooler’ Kade Unit and Lesser Himalaya during the Himalayan history. However, a few inconsistencies exist for a purely Himalayan age of some Ml assemblages of the HHC. As regards the crustal-derived leucogranites, the formation of a first generation mixed with quartzo-feldspathic leucosomes was possibly linked to melt-lubricated shear zones which favoured rapid crustal displacements; at upper levels they intruded during stage M2 and the latest movements along the syn-metamorphic Miyar Thrust, but before juxtaposition of the Tibetan nappes along the late- metamorphic Zanskar Fault.

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Articles
Copyright
Copyright © Cambridge University Press 1990

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References

Baig, M.S., Lawrence, R. D. & Snee, L.W. 1988. Evidence for late Precambrian to early Cambrian orogeny in northwest Himalaya, Pakistan. Geological Magazine 125, 83–6.CrossRefGoogle Scholar
Barth, S., Oberli, F. & Meier, M. 1989. Age and U–Th–Pb systematics of zircon and allanite; a high resolution isotopic study of the Periadriatic Rensen Pluton (Northern Italy). Earth and Planetary Science Letters (submitted).CrossRefGoogle Scholar
Baud, A. 1988. The nappe and thrust tectonics in Zanskar area (NW Himalaya), review of the so called ‘autochthony’ of the Tethys-Tibetan zone. Himalayan-Karakoram–Tibet Workshop Meeting,Lausanne, 43–4.Google Scholar
Baud, A., Gaetani, M., Garzanti, E., Nicora, A. & Tintiri, A. 1984. Geological observations in south-eastern Zanskar and adjacent Lahul area (northwestern Himalaya). Eclogae Geologicae Helvetiae 77, 171–97.Google Scholar
Bhanot, V. B., Bhandari, A., Singh, V.P. & Kansal, A.K. 1979. Geochronological and geological studies on a granite of High Himalaya, Northeast of Manikaran, Himachal-Pradesch. Journal of the Geological Society of India 20, 90–4.Google Scholar
Bossart, P.J., Mejer, M., Oberli, F. & Steiger, R.H. 1986. Morphology versus U–Pb systematics in zircon: a high resolution isotopic study of a zircon population from a Variscan dike in the Central Alps. Earth and Planetary Science Letters 78, 339–54.CrossRefGoogle Scholar
Brunel, M. & Kienast, J. R., 1986. Etude petro-structurale des chevauchements ductiles himalayens sur la trasversale de l'Everest-Makalu (Nepal oriental). Canadian Journal of Earth Sciences 23, 1117–37.CrossRefGoogle Scholar
Caby, R., Pecher, A. & Le Fort, P., 1983. Le grand chevauchement central himalayen: nouvelles données sur le metamorphisme inverse á la base de la Dalle du Tibet. Revue de Géologie dynamique et de Géographic Physique 24, 89100.Google Scholar
Castelli, D. & Lombardo, B. 1988. The Gophu La and Western Lunana granites: Miocene muscovite leucogranites of the Bhutan Himalaya. Lithos 21, 211–25.CrossRefGoogle Scholar
Cumming, G. L. & Richards, J. R. 1975. Ore lead isotope ratios in a continuously changing earth. Earth and Planetary Science Letters 28, 155–71.CrossRefGoogle Scholar
Ellis, D. J. & Green, D. H. 1979. An experimental study of the effect of Ca upon garnet–clinopyroxene Fe–Mg exchange equilibria. Contributions to Mineralogy and Petrology 71, 1322.CrossRefGoogle Scholar
Ferrara, G., Lombardo, B. & Tonarini, S. 1983. Rb/Sr geochronology of granites and gneisses from the Mount Everest Region, Nepal Himalaya. Geologische Rundschau 72, 119–36.CrossRefGoogle Scholar
Ferrara, G., Lombardo, B., Tonarini, S. & Turi, B. 1987. New Rb/Sr data on granitoids from Gumburanjon and Kade Chu (High Himalaya). Himalayan-Karakoram Workshop Meeting,Nancy, 33.Google Scholar
Ferry, J. M. & Spear, F. S. 1978. Experimental calibration of the partitioning of Fe and Mg between biotite and garnet. Contributions to Mineralogy and Petrology 66, 113–17.CrossRefGoogle Scholar
Frank, W., Hoinkes, G., Miller, C., Purtscheller, F., Richter, W. & Thoni, M. 1973. Relations between metamorphism and orogeny in a typical section of Indian Himalayas. Tschermaks Mineralogische und Petrographische Mitteilugen 20, 303–32.CrossRefGoogle Scholar
Frank, W., Thoni, M. & Purtscheller, F. 1977. Geology and petrology of Kulu–South Lahul area. Colloquie International C.N.R.S. no. 268: Ecologie et Géologie de l' Himalaya, Sèvres, 1976, 147–72.Google Scholar
Fuchs, G. 1988. Arguments for the autochthony of the Tibetan Zone. Himalayan-Karakoram-Tibet Workshop Meeting,Lausanne, 41.Google Scholar
Gaetani, M., Garzanti, E. & Jadoul, F. 1985. Main structural elements of Zanskar, Nw Himalaya (India). Rendiconti della Società Geologica Italiana 8, 38.Google Scholar
Garzanti, E., Casnedi, R. & Jadoul, F. 1986. Sedimentary evidence of a Cambro-Ordovician orogenic event in the northwestern Himalaya. Sedimentary Geology 48, 237–65.CrossRefGoogle Scholar
Greco, A. 1988. Tectonics and metamorphism in the Himalayas of NE Pakistan (Kaghan valley and Azad Kashmir). Himalayan-Karakoram-Tibet Workshop Meeting,Lausanne, 24–5.Google Scholar
Green, T. & Ringwood, A. E. 1967. An experimental investigation of the gabbro-eclogite transformation and some petrological applications. Geochimica and Cosmochimica Acta 31, 767833.CrossRefGoogle Scholar
Herren, E. 1987. The Zanskar shear zone: northeast- southwest extension within the Higher Himalayas (Ladakh, India). Geology 15, 409–13.2.0.CO;2>CrossRefGoogle Scholar
Hodges, K. & Silverberg, D. S. 1988. Thermal evolution of the greater Himalaya, Garhwal, India. Tectonics 7, 583600.CrossRefGoogle Scholar
Hollister, L. S. & Crawford, M. L. 1986. Melt-enhanced deformation: a major tectonic process. Geology 14, 555–61.2.0.CO;2>CrossRefGoogle Scholar
Honegger, K., Dietrich, V., Frank, W., Gansser, A., Thoni, M. & Trommsdorff, V. 1982. Magmatism and metamorphism in the Ladakh Himalayas (the Indus-Tsangpo suture zone). Earth and Planetary Science Letters 60, 253–92.CrossRefGoogle Scholar
Hoschek, G. 1969. The stability of staurolite and chloritoid and their significance in the metamorphism of pelitic rocks. Contributions to Mineralogy and Petrology 22, 208–32.CrossRefGoogle Scholar
Krogh, T. E. 1973. A low-contamination method for hydrothermal decomposition of zircon and extraction of U and Pb for isotopic age determinations. Geochimica et Cosmochimica Acta 37, 485–94.CrossRefGoogle Scholar
Kündig, R. 1989. Domal structures and high grade metamorphism in the Higher Himalayan Crystalline-Zanskar region (NW India). Journal of Metamorphic Geology 7, 4355.CrossRefGoogle Scholar
Leake, B. E. 1978. Nomenclature of amphiboles. American Mineralogist 63, 1023–52.Google Scholar
Le Fort, P. 1975. Himalaya: the collided range – Present knowledge of the continental arc. American Journal of Science 275A, 144.Google Scholar
Le Fort, P. 1981. Manaslu leucogranite: a collision signature of the Himalaya – A model for its genesis and emplacement. Journal of Geophysical Research 86, 10545–68.CrossRefGoogle Scholar
Le Fort, P. 1986. Metamorphism and magmatism during the Himalayan collision. In Collision Tectonics (ed. Coward, M. P. and Ries, A. C.), pp. 159–72. Geological Society Special Publication no. 19.Google Scholar
Le Fort, P., Debon, F. & Sonet, J. 1980. The ‘Lesser Himalayan’ cordierite granite belt, typology and age of the pluton of Mansehra, Pakistan. Special Issue of the Geological Bulletin of the University of Peshawar 13, 5161.Google Scholar
Ludwig, K. R. 1980. Calculation of uncertainties of U–Pb isotope data. Earth and Planetary Science Letters 46, 212–20.CrossRefGoogle Scholar
Ludwig, K. R. 1988. A plotting and regression program for radiogenic-isotope data for IBM-PC compatible computers. USGS Open-File report no. 88–557.CrossRefGoogle Scholar
Mehta, P. K. 1977. Rb/Sr geochronology of the Kulu–Mandi belt: its implications for the Himalayan Tectogenesis. Geologische Rundschau 66, 156–75.CrossRefGoogle Scholar
Merrill, R. B., Robertson, J. K. & Wyllie, P. J. 1970. Melting reactions in the system NaAISi3O8–KAISi3O8–SiO2–H2O to 20 kilobars compared with results for other feldspar–quartz–H2O and rock–H2O systems. Journal of Geology 78, 558–69.CrossRefGoogle Scholar
Mueller, R. F. & Saxena, S. K. 1977. Chemical Petrology. New York Heidelberg Berlin: Springer-Verlag. 394 pp.CrossRefGoogle Scholar
Newton, R. C. & Haselton, H. T. 1981. Thermodynamics of the garnet–plagioclase–Al2SiO5–quartz geobarometer. In Thermodynamics of Minerals and Melts (ed. Newton, R. C., Navrotsky, A. and Wood, B. J.), pp. 129–45. New York: Springer-Verlag.CrossRefGoogle Scholar
Newton, R. C. & Perkins, D. 1982. Thermodynamic calibration of geobarometers based on the assemblages garnet–plagioclase–orthopyroxene (clinopyroxene)–quartz. American Mineralogist 67, 203–22.Google Scholar
Pinet, C. & Jaupart, C. 1987. A thermal model for the distribution in space and time of the Himalayan granites. Earth and Planetary Science Letters 84, 8799.CrossRefGoogle Scholar
Pognante, U. & Lombardo, B. 1989. Metamorphic evolution of the High Himalayan Crystallines in SE Zanskar, India. Journal of Metamorphic Geology 7, 917.CrossRefGoogle Scholar
Pognante, U., Genovese, G., Lombardo, B. 1987. Preliminary data on the High Himalaya Crystallines along the Padum–Darcha Traverse (South-Eastern Zanskar, India). Rendiconti delta Societá Italiana di Mineralogia e Petrologia 42, 95105.Google Scholar
Powell, C. M. A. & Conaghan, P. J. 1973. Polyphase deformation in Phanerozoic rocks of the central Himalayan gneiss, northwest India. Journal of Geology 81, 127–43.CrossRefGoogle Scholar
Pupin, J. P. 1980. Zircon and granite petrology. Contributions to Mineralogy and Petrology 73, 207–20.CrossRefGoogle Scholar
Rao, B. B. & Johannes, W. 1979. Further data on the stability of staurolite+quartz and related assemblages. Neues Jahrbuch für Mineralogie Abhandlungen 10, 437–47.Google Scholar
Richardson, S. W. 1968. Staurolite stability in a part of the system Fe–A1–Si–O–H. Journal of Petrology 9, 468–88.CrossRefGoogle Scholar
Searle, M. P. 1986. Structural evolution and sequence of thrusting in the High Himalayan, Tibetan-Tethys and Indus suture zones of Zanskar and Ladakh, Western Himalaya. Journal of Structural Geology 8, 923–36.CrossRefGoogle Scholar
Searle, M. P. & Fryer, B. J., 1986. Garnet, tourmaline and muscovite-bearing leucogranites, gneisses and migmatites of the Higher Himalayas from Zanskar, Kulu, Lahoul and Kashmir. In Collision Tectonics (eds Coward, M. P. and Ries, A. C.), pp. 185201. Geological Society of London Special Publication no. 19.Google Scholar
Searle, M. P. & Rex, A. J. 1989. Thermal model for the Zanskar Himalaya. Journal of Metamorphic Geology 7, 127–34.CrossRefGoogle Scholar
Srikantia, S. V., Ganesan, T. M., Rao, R. N., Sinha, P. H. & Tirkey, P., 1980. Geology of the Zanskar area, Ladakh Himalaya. Himalayan Geology 8, 1009–33.Google Scholar
StÄubli, A. 1989. Polyphase metamorphism and the development of the Main Central Thrust (M.C.T.) at the Kishtwar window (NW India). Journal of Metamorphic Geology 7, 7393.CrossRefGoogle Scholar
Steiger, R. H. & Jäger, E. 1977. Subcommission on Geochronology: convention on the use of decay constants in geo- and cosmochronology. Earth and Planetary Science Letters 36, 359–62.CrossRefGoogle Scholar
Storre, B. & Karotke, E. 1971. An experimental determination of the upper stability limit of muscovite+quartz in the range 7–20 kb water pressure. Neues Jahrbuch für Mineralogie Monatshefte 115, 237–40.Google Scholar
Thakur, V. C. 1980. Tectonics of the central crystallines of western Himalaya. Tectonophysics 62, 141–54.CrossRefGoogle Scholar
Thakur, V. C. 1987. Plate tectonic interpretation of the Western Himalaya. Tectonophysics 134, 91102.CrossRefGoogle Scholar
Tracy, R. J. 1982. Compositional zoning and inclusions in metamorphic minerals. In Characterization of Metamorphism through Mineral Equilibria (ed. Ferry, J. M.), pp. 355–97. Mineralogical Society of America: Reviews in Mineralogy Series no. 10.Google Scholar
Treloar, P. J., Williams, M. P., Coward, M. P., Broughton, R. D. & Windley, B. F. 1989. Deformation, metamorphism and imbrication of the Indian plate, south of the Main Mantle Thrust, north Pakistan. Journal of Metamorphic Geology 7, 111–25.CrossRefGoogle Scholar
Ulmer, P. 1986. Norm-program for cation and oxygen mineral norms. Computer Library IKP-ETH, Zürich.Google Scholar
Villa, I. & Oddone, M. 1988. 39Ar/40Ar ages of Himalayan leucogranites decrease eastward. Himalayan–Karakoram–Tibet Workshop Meeting,Lausanne,1988, 16.Google Scholar
Williams, M. P., Treloar, P. J. & Coward, M. P. 1988. More evidence of pre-Himalayan orogenesis in Northern Pakistan. Geological Magazine 125, 651–2.CrossRefGoogle Scholar
York, D. 1969. Least squares fitting of a straight line with correlated errors. Earth and Planetary Science Letters 5, 320–4.CrossRefGoogle Scholar