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Synorogenic extension in the Tethyan Himalaya documented by structural studies and the Kübler index, Lachung La area, NW India

Published online by Cambridge University Press:  09 July 2018

M. Girard ,
P. Thélin  and
A. Steck
M. Girard*
Affiliation:
Institut de Minéralogie et Petrographie, Université de Lausanne, BFSH2, CH-1015 Lausanne, Switzerland
P. Thélin
Affiliation:
Institut de Minéralogie et Petrographie, Université de Lausanne, BFSH2, CH-1015 Lausanne, Switzerland
A. Steck
Affiliation:
Institut de Minéralogie et Petrographie, Université de Lausanne, BFSH2, CH-1015 Lausanne, Switzerland
*
*E-mail: [email protected]
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Abstract

Tectonic observations in the Tethyan Himalaya reveal an important extensional event that succeeds the emplacement of SW-verging nappes. A major thrust, called the Kum Tso Thrust, has been backfolded and reactivated by normal faulting associated with this event.

Measurements of the Kübler index, coupled with characterization of clay-size paragenesis show the effect of normal faulting on the regional metamorphic zonation and indicate that important extension zones, like the Sarchu-Lachung La Normal Fault Zone (SLFZ), exist within the Tethyan Himalaya. Diagenetic limestones from within the SLFZ are characterized by the occurrence of mixed-layered clay phases, kaolinite and an illite with a 001 peak >0.4 Δ°2θ. This zone is bordered by two anchizonal-to-epizonal zones, where illite peaks become narrower. Further to the NE the successive appearance of biotite, chloritoid, garnet and garnet-staurolite-kyanite assemblages testifies to an increase in metamorphic grade. The cataclastic samples from the normal faults contain kaolinite, smectite and a ‘broad’ illite, indicating that extension occurs under diagenetic conditions.

Keywords

Tethyan HimalayaKübler indexIndiamixed-layer clay phases
Type
Research Article
Information
Clay Minerals , Volume 36 , Issue 2 , June 2001 , pp. 237 - 247
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2001

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References

Berthelsen, A. (1953) On the Geology of the Rupshu District, NW Himalaya. Bull. Geol. Soc. Denmark, 12, 350–414.Google Scholar
Brindley, G. & Brown, G. (1980) Crystal Structures of Clay Minerals and their X-ray Identification. Monograph, 5. Mineralogical Society, London.Google Scholar
Burchfiel, B.C. & Royden, L.H. (1985) North-south extension within the convergent Himalayan region. Geology, 13, 679–682.2.0.CO;2>CrossRefGoogle Scholar
Burchfiel, B.C., Chen, Z., Hodges, K.V., Liu, Y., Royden, L.H. & Deng, C. (1992) The South Tibetan Detachment System, Himalayan orogen: extension contemporaneous with and parallel to shortening in a collisional mountain belt. Geol. Soc. Am. Spec. Paper, 269, 41.Google Scholar
Chemenda, A.I., Matauer, M. & Bokun, A.I. (1996) Continental subduction and a mechanism for exhumation of HP metamorphic rocks: new modeling and field data from Oman. Earth Planet. Sci. Lett. 143, 173–182.CrossRefGoogle Scholar
Dèzes, P., Vannay, J.C., Steck, A., Bussy, F. & Cosca, M. (1999) Synorogenic extension: Quantitative constraints on the age and displacement of the Zanskar Shear Zone (NW Himalaya). Geol. Soc. Am. Bull. 111, 364–374.2.3.CO;2>CrossRefGoogle Scholar
Frank, W., Hoinkes, G., Miller, C., Purtscheller, F., Richter, W. & Thöni, M. (1973) Relations between metamorphism and orogeny in a typical section of the Indian Himalayas. Tschermaks Miner. Petrogr. Mitt. 20, 303–332.Google Scholar
Frank, W., Graseman, B., Guntli, P. & Miller, C. (1995) Geological map of the Kishtwar-Chamba- Kulu region (NW Himalaya, India ). Jahrb. Geol. Bundesanstalt, 138, 299–308.Google Scholar
Frey, M. (1988) Discontinuous inverse metamorphic zonation, Glarus Alps, Switzerland: evidence from illite “crystallinity” data. Schweiz. Mineral. Petrogr. Mitt. 68, 171–183.Google Scholar
Frey, M. & Robinson, D. (1999) Low-Grade Metamorphism. Blackwell Science, Oxford, UK.Google Scholar
Garzanti, E., Jadoul, F., Nicora, A. & Berra, F. (1995) Triassic of Spiti (Thetys Himalaya, N India). Riv. It. Paleonto. Stratigraphia, 101/3, 267–300.Google Scholar
Girard, M. & Bussy, F. (1999) Late Pan-African magmatism in the Himalaya: new geochronological and geochemical data from the Ordovician Tso Morari metagranites (Ladakh, NW India). Schweiz. Mineral. Petrogr. Mitt. 79, 399–417.Google Scholar
Girard, M., Steck, A. & Thélin, P. (1999) The Dutung- Thaktote extensional fault zone and nappe structures documented by illite crystallinity and clay-mineral paragenesis in the Tethys Himalaya between Spiti river and Tso Morari, NW India. Schweiz. Mineral. Petrogr. Mitt. 79, 419–430.Google Scholar
Herren, E. (1987) Zanskar shear zone; northeast-southwest extension within the Higher Himalayas (Ladakh, India). Geology, 15, 409–413.Google Scholar
Jaboyedoff, M. (1998) QUICK WIDTH, a computer program to measure FWHM of 10 Å illite peak (Windows ). XRD Laboratory, Institute of Mineralogy, Lausanne University.Google Scholar
Jaboyedoff, M. & Thélin, P. (1996) New data on lowgrade metamorphism in the Briançonnais domain of the Prealps, Western Switzerland. Eur. J. Mineral. 8, 577–592.Google Scholar
Jaboyedoff, M., Kübler, B. & Thélin, P. (1999a) An empirical Scherrer equation for weakly swelling mixed-layer minerals, especially illite-smectite. Clay Miner. 34, 601–617.Google Scholar
Jaboyedoff, M., Kübler, B. & Thélin, P. (1999b) La cristallinité de l’illite: les probables raisons d’un succès. Schweiz. Mineral. Petrogr. Mitt. 79, 323–324.Google Scholar
Kübler, B. (1967) La cristallinité de l’illite et les zones tout à fait supérieur du métamorphisme. Colloque de Neuchâtel, 1966. La Baconnière, Neuchâtel, Switzerland.Google Scholar
Kübler, B. (1990) “Cristallinité” de l’illite et mixedlayers: brève révision. Schweiz. Mineral. Petrogr. Mitt. 70, 89–93.Google Scholar
Kübler, B. & Goy-Eggenberger, D. (2001) La cristallinité de l’illite revisitée: un bilan des connaissances acquises ces trente dernières années. Clay Miner. 36, 143–157.CrossRefGoogle Scholar
Moore, D.M. & Reynolds, R.C.J. (1997) X-ray Diffraction and the Identification and Analysis of Clay Minerals, 2nd edition. Oxford University Press, Oxford and New York.Google Scholar
Spring, L., Masson, H., Stutz, E., Thélin, P., Marchant, R. & Steck, A. (1993) Inverse metamorphic zonation in very low-grade Tibetan zone series of Zanskar and its tectonic consequences (NW India, Himalaya). Schweiz. Mineral. Petrogr. Mitt. 73, 85–95.Google Scholar
Środoń, J. & Eberl, D.D. (1984) Illite. Pp. 495–544 in. Micas (Bailey, S.W., editor). Reviews in Mineralogy, 13. Mineralogical Society of America, Washington, D.C.Google Scholar
Steck, A., Spring, L., Vannay, J.C., Masson, H., Stutz, E., Bucher, H., Marchant, R. & Tieche, J.C. (1993) Geologic al transec t across the northwe stern Himalaya in eastern Ladakh and Lahul (a model for the continental collision of India and Asia). Eclogae Geol. Helv. 86, 219–263.Google Scholar
Steck, A., Epard, J.L., Vannay, J.C., Hunziker, J., Girard, M., Morard, A. & Robyr, M. (1998) Geological transect across the Tso Morari and Spiti areas: The nappe structures of the Tethys Himalaya. Eclogae Geol. Helv. 91, 103–121.Google Scholar
Thélin, P., Jaboyedoff, M. & Kübler, B. (1999) Towards a more objective understanding of illite crystallinity (IC). P. 137 in: Abst. Conf. Eur. Clay Groups Assoc. Kraków.Google Scholar
Vannay, J.C. (1993) Géologie des chaõˆnes du Haut Himalaya et du Pir Panjal au Haut-Lahul (NW Himalaya, Inde). Mémoires de géologie (Lausanne), 16, 148 pp.Google Scholar
Vannay, J.C. & Grasemann, B. (1998) Inverted metamorphism in the High Himalaya of Himachal Pradesh (NW India): phase equilibria versus thermobarometry. Schweiz. Mineral. Petrogr. Mitt. 78, 107–132.Google Scholar
Vannay, J.C. & Steck, A. (1995) Tectonic evolution of the High Himalaya in Upper Lahul (NW Himalaya, India). Tectonics, 14, 253–263.Google Scholar
Wyss, M., Hermann, J. & Steck, A. (1999) Structural and metamorphic evolution of the northern Himachal Himalaya, NW India. Eclogae Geol. Helv. 92, 3–44.Google Scholar