Fluvial incision and tectonic uplift across the Himalayas of central Nepal

American Geophysical Union (AGU) - Tập 106 Số B11 - Trang 26561-26591 - 2001
Jérôme Lavé, Jean‐Philippe Avouac1
1School of Geog & Environmental Scs

Tóm tắt

The pattern of fluvial incision across the Himalayas of central Nepal is estimated from the distribution of Holocene and Pleistocene terraces and from the geometry of modern channels along major rivers draining across the range. The terraces provide good constraints on incision rates across the Himalayan frontal folds (Sub‐Himalaya or Siwaliks Hills) where rivers are forced to cut down into rising anticlines and have abandoned numerous strath terraces. Farther north and upstream, in the Lesser Himalaya, prominent fill terraces were deposited, probably during the late Pleistocene, and were subsequently incised. The amount of bedrock incision beneath the fill deposits is generally small, suggesting a slow rate of fluvial incision in the Lesser Himalaya. The terrace record is lost in the high range where the rivers are cutting steep gorges. To complement the terrace study, fluvial incision was also estimated from the modern channel geometries using an estimate of the shear stress exerted by the flowing water at the bottom of the channel as a proxy for river incision rate. This approach allows quantification of the effect of variations in channel slope, width, and discharge on the incision rate of a river; the determination of incision rates requires an additional lithological calibration. The two approaches are shown to yield consistent results when applied to the same reach or if incision profiles along nearby parallel reaches are compared. In the Sub‐Himalaya, river incision is rapid, with values up to 10–15 mm/yr. It does not exceed a few millimeters per year in the Lesser Himalaya, and rises abruptly at the front of the high range to reach values of ∼4–8 mm/yr within a 50‐km‐wide zone that coincides with the position of the highest Himalayan peaks. Sediment yield derived from the measurement of suspended load in Himalayan rivers suggests that fluvial incision drives hillslope denudation of the landscape at the scale of the whole range. The observed pattern of erosion is found to closely mimic uplift as predicted by a mechanical model taking into account erosion and slip along the flat‐ramp‐flat geometry of the Main Himalayan Thrust fault. The morphology of the range reflects a dynamic equilibrium between present‐day tectonics and surface processes. The sharp relief together with the high uplift rates in the Higher Himalaya reflects thrusting over the midcrustal ramp rather than the isostatic response to reincision of the Tibetan Plateau driven by late Cenozoic climate change, or late Miocene reactivation of the Main Central Thrust.

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Tài liệu tham khảo

10.2475/ajs.268.3.243

10.1029/96JB01344

10.1029/93GL00128

Baade J., 1998, 13th Himalayas‐Karakorum‐Tibet International Workshop, 22

10.1007/978-94-011-3066-0_1

Bergman S. C., 1993, Late Cenozoic compressional and extensional cooling and exhumation of the Qomolangma (Mt Everest) region, Nepal, Geol. Soc. Am. Abstr. Programs, 25

10.1038/386061a0

10.1126/science.276.5312.571

10.1029/TC005i002p00247

Brunsden D., 1981, The geomorphological character of part of the Low Himalaya of eastern Nepal, Z. Geomorph., 37, 25

10.1029/96WR03190

Bull W., 1991, Geomorphic Response to Climatic Change

10.1038/357680a0

10.1038/379505a0

Carson B. Erosion and sedimentation processes in the Nepal Himalayas Icimod Occasional Paper 1 International Centre for Integrated Mountain Development (ICIMOD) Kathmandu Nepal 1985.

10.1029/2000JB900032

Chang H. H., 1988, Fluvial Processes in River Engineering

Delcaillau B., 1992, Les Siwaliks de l'Himalaya du Népal Oriental, Fonctionnement et Evolution

10.1007/978-1-4615-5935-1_12

10.1006/qres.1998.1958

10.1130/0091-7613(1994)022<0163:HFIT>2.3.CO;2

10.1130/GSAB-P2-91-2152

10.1130/GSAB-P2-91-2189

Fort M. Etude géomorphologique d'une chaîne de collision intracontinentale mem. de thèse 700 pp. Univ. de Parris VII 1993.

Gansser A., 1964, Geology of the Himalayas

10.5194/gh-30-27-1975

10.1029/GM107p0035

10.1016/S0012-821X(96)00215-4

His Majesty's Government (HMG) of Nepal Undertaking Feasibility study on Sapt Gandaki hydroelectric power development projectreport IINepal Electr. Auth.April 1982.

His Majesty's Government (HMG) of Nepal0 Undertaking Final report on disaster prevention master plan in upper Rapti river basin Second Kulekhani Hydroelect. ProjNepal Electr. Auth.Oct. 1989.

His Majesty's Government (HMG) of Nepal Bagmati command area development projectvol. 2Minist. of Water Resour. Dept. of Irrigat.Dec. 1991a.

His Majesty's Government (HMG) of Nepal Undertaking Feasibility study — phase IINepal Electr. Auth. Upper Arun Hydroelect. Proj.Dec. 1991b.

His Majesty's Government (HMG) of Nepal Undertaking Middle Marsyandi hydroelectric ProjectNepal Electr. Auth. Eng. Dir. Invest. Dept.Aug. 1994.

His Majesty's Government (HMG) of Nepal, 1995, Climatological records of Nepal 1987–1990

His Majesty's Government (HMG) of Nepal, 1995, Hydrological records of Nepal, Streamflow summary — 1993

Hovius N., 2000, Geomorphology and Global Tectonics, 77

10.1130/0091-7613(1997)025<0231:SFFAMB>2.3.CO;2

10.1029/GM107p0297

10.1130/0016-7606(1983)94<739:CCIB>2.0.CO;2

10.1029/94JB00744

10.1029/1998JB900098

10.1029/WR024i005p00713

Iwata S., 1986, River terraces and crustal movement in the area around Narayanghat, Central Nepal, J. Nepal Geol. Soc., 5, 33

10.3126/jngs.v2i0.36176

Iwata S., 1984, A preliminary report on geomorphology of central Nepal and Himalayan uplift, J. Nepal Geol. Soc., 4, 141

10.1029/94JB00714

10.1029/1999GL900416

Keller E. A., 1986, Active tectonics, 136

10.2475/ajs.289.9.1041

10.1086/624985

10.1086/626370

Kuhle M., 1982, Der Dhaulagiri und Annapurna Himalaya. Ein Beitrag zur Geomorphologie extremer Hochgebirge, Z. Geomorph., Suppl., 41

Laban P. Field measurements on erosion and sedimentation in Nepal Integrated Watershed Management Working Pap. 5 Min. of For. Dep. of Soil and Water Conserv. Kathmandu Nepal 1978.

10.1029/1998JB900043

Lavé J. Tectonique et érosion: L'apport de la dynamique fluviale a l'étude sismotectonique de l'Himalaya du Népal central thèse de 3eme cycle 225 pp. Univ. Paris VII 1997.

10.1029/1999JB900292

10.1144/GSL.SP.1986.019.01.08

Leopold L. B., 1994, A View of the River

Leopold L. B. J. P.Miller Ephemeral streams‐hydraulics factors and their relation to the drainage net U.S. Geol. Surv. Prof. Pap. 282A 1–37 1956.

10.1029/JB088iB10p08171

10.1029/TC004i006p00513

10.1029/94JB00461

10.1016/0012-821X(75)90222-8

10.1029/94JB00857

10.1046/j.1365-2117.1999.00101.x

10.1046/j.1365-246X.1999.00802.x

Mezaki S., 1984, Channel morphology of the Kali Gandaki and the Narayani rivers in central Nepal, J. Nepal Geol. Soc., 4, 161

Molnar P., 1987, Inversion of profiles of uplift rates for the geometry of dip‐slip faults at depth, with examples from the Alps and the Himalayas, Ann. Geophys., 5, 663

Molnar P., 1990, A review of the seismicity and rates of active underthrusting and deformation at the Himalayas, J. Himalayan Geol., 1, 131

10.1038/346029a0

10.1029/94JB00122

10.1016/0040-1951(94)90056-6

Nakata T. Geomorphic history and crustal movements of the foothills of the HimalayasSci. Rep. Tohoku Univ. Ser. 2 22 177 1972.

10.1130/SPE232-p243

Nautiyal S. P. P. N.Sharma A geological report on the ground water investigation of Kathmandu valley reportGeol. Surv. of India 1961.

10.1029/94GL02971

10.1046/j.1365-2117.1996.00253.x

10.1017/S0022112078002505

10.1029/96JB02698

10.1029/TC007i003p00563

10.1130/0016-7606(1998)110<1010:SASOTK>2.3.CO;2

10.1038/359117a0

10.1130/0091-7613(1988)016<0649:IOLCMB>2.3.CO;2

10.1029/92TC00213

10.1029/91TC01011

10.1126/science.270.5236.617

10.1144/gsjgs.156.2.0227

10.1086/515924

10.1029/ME004p0259

10.1016/0040-1951(83)90201-9

10.1130/0016-7606(1974)85<257:ESORI>2.0.CO;2

10.1029/GM107p0237

Slingerland R., 1998, Slope‐area scaling as a test of fluvial bedrock erosion laws, EOS Trans. AGU, 79, F358

10.1130/0016-7606(2000)112<1250:LRTTFD>2.0.CO;2

10.1029/98JB02139

10.1144/gsjgs.137.1.0001

Stöcklin J. Geological map of Kathmandu area and central Mahabarat range sacle 1:250 000 Dep. of Mines and Geol. Népal 1987.

10.1029/94JB00715

Wadia D. N., 1951, The transitional passage of Pliocene into the Pleistocene in the Northwestern Sub‐Himalaya, Proc. 18th Int. Geol. Congr. London, 1948, 43

Weldon R. J. Late Cenozoic geology of Cajon Pass: Implications for tectonics and sedimentation along the San Andreas fault Ph.D. thesis 400 pp. Calif. Inst. of Technol. Pasadena 1986.

10.1029/1999TC900026

West R. M., 1981, Neogene vertebrate paleontology and stratigraphy of Nepal, J. Nepal Geol. Soc., 1, 1

10.1038/43375

10.1130/0091-7613(1993)021<0371:MMFTTO>2.3.CO;2

10.3126/jngs.v2i0.36191

Yanbin W., 1998, 13th Himalaya‐Karakorum‐ Tibet International Workshop, 218

10.1029/JC094iC06p08146

Yoshida M., 1988, Magnetostratigraphy of Plio‐Pleistocene lacustrine deposits in the Kathmandu valley, central Nepal, Proc. Indian Nat. Sci. Acad, 54, 410

Yoshida M., 1984, Neogene to Quaternary lacustrine sediments in the Kathmandu valley, J. Nepal Geol. Soc., 4, 73

10.1038/366557a0

Zollinger F., 1979, The Sapt Kosi unsolved problems of flood control in the Nepalese Terai, integrated watershed management, torrent control and use development of soil and water conservation

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American Geophysical Union (AGU)

Tập 106 Số B11

26561-26591

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