DOCSLIB.ORG

Sediment Geochemistry of the Yamuna River System in the Himalaya: Implications to Weathering and Transport

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Sediment Geochemistry of the Yamuna River System in the Himalaya: Implications to Weathering and Transport Geochemical Journal, Vol. 38, pp. 441 to 453, 2004 Sediment geochemistry of the Yamuna River System in the Himalaya: Implications to weathering and transport TARUN K. DALAI,1,2* R. RENGARAJAN2 and P. P. PATEL3 1Ocean Research Institute, University of Tokyo, Tokyo 164-8639, Japan 2Physical Research Laboratory, Ahmedabad - 380 009, India 3M.S. University of Baroda, Vadodara - 390 002, India (Received October 23, 2003; Accepted March 24, 2004) Bed sediments of the Yamuna River and its tributaries in the Himalaya (Yamuna River System, YRS) have been analyzed for major elements and trace metals (Sr, Ba, Ni, Cu, Co, Zn, Pb and Cr). These results have been used to charac- terize chemical weathering and transport in the Himalaya, to assess relative mobility of elements during weathering and to understand heavy metal association. Concentrations of major and trace elements of YRS sediments vary between 20 and 50%. In general, elemental variability reduces when data are analyzed individually for the major rivers, suggesting that tributaries draining diverse lithology contribute significant variations. Comparison of sediment chemistry with composi- tion of source rocks and average Upper Continental Crust (UCC) suggests significant loss of Na, K, Ca and Mg from source rocks during weathering, the degree of loss being more for Ca and Na. Chemical index of alteration (CIA) for YRS sediments averages at 59, indicating that weathering in the basin is of moderate intensity. This inference is also supported by major ion chemistry of YRS waters and is attributed to steep gradient and enhanced physical erosion in the basin. Available results seem to indicate that Na and Sr are effectively more mobile than Ba, which is thought to be a combined effect of higher solubility of Na and Sr, and the affinity of Ba to be adsorbed onto solid phase. Heavy metals show significant positive correlation with Al and weak correlation with Fe, Mn and P. These observations suggest that metal concentrations are controlled mainly by clay mineral abundances, and that Fe-Mn oxides and organic matter may be playing less significant role. Heavy metal concentrations of YRS sediments are lower than those of suspended particulates of the Yamuna river, presumably due to higher clay mineral abundances in the latter. Strong association of metals with Al, and lower metal concentrations in bed sediments compared to suspended matter underscores the importance of sediment transport and mineral sorting in influencing the YRS sediment chemistry. Enrichment factor and geo-accumulation index calculated for heavy metals in YRS sediments suggest that they are mainly of natural origin and that anthropogenic activi- ties exert little influence on their abundances. Keywords: Yamuna River, Himalaya, chemical weathering, sediment chemistry, elemental mobility ing the Himalaya (Krishnaswami et al., 1992; Sarin et INTRODUCTION al., 1992; Pande et al., 1994; Galy and France-Lanord, The rivers draining the Himalaya contribute signifi- 1999; Dalai et al., 2002a, 2002b, 2002c, 2003). These cantly to the global sediment and water discharge studies are based mainly on isotopic and major ion com- (Milliman and Meade, 1983). They have recently attracted position of dissolved load of rivers. Available geochemical attention of several workers because of the possible con- studies of river sediments in the Indian Himalaya include nection between chemical weathering in the Himalaya and reconnaissance survey of the Ganga and the Yamuna global climate (Raymo and Ruddiman, 1992) as silicate (Subramanian, 1987; Jha et al., 1990; Chakrapani and weathering is thought to be a global sink for CO2 on geo- Subramanian, 1996; Subramanian and Ramanathan, 1996; logic time scales (Walker et al., 1981; Berner, 1995). Such Ramesh et al., 2000) and the Indus (Ahmad et al., 1998). a hypothesis has led to a number of studies on rivers drain- Geochemical studies of sediments in the headwaters of rivers in the Himalaya are limited. The river Yamuna, draining the southern slopes of the *Corresponding author (e-mail: [email protected]) Himalaya in its upper reaches, is the largest tributary of *Present address: Department of Geology and Geophysics, SOEST, the Ganga (Negi, 1991). At the confluence, water dis- University of Hawaii, Manoa 712 POST, 1680 East-West Road., charge of the Yamuna is one and half times that of the Honolulu, HI 96822, U.S.A. Ganga (Rao, 1975). The Yamuna and its major tributaries Copyright © 2004 by The Geochemical Society of Japan. in the Himalaya constitute the Yamuna River System 441 o o o o 68 76 84 92 780 13 0 0 HIGHER o Are a of 77 50’E 78 13’ 32 N G a Stu d y HIMALAYA R New Delhi n anuman h a tti Y g H C a a m R s u . n Gan o a ga R n R . 24 . o 0 T INDIA 77 50 E 0 16o . Mori 30 49 N s R on R T r 27 LESSER Kuthnaur a b 26 28 G Hanuman C hatti HIMALAYA a o Mori R P Tiuni d d R. u a a P a Gad G n u n . i u Purola r Tiuni R l m o mu . 29 a a l R a P Y a a Purola l Y s o 18 R arkot Sh n r 19 Did B ej o u ar Ga Kh T P 20 d ad 22 Naugaon d 21 25 0 rni Ga 31 Barkot 30 49’ Ba 30 Naugaon S R Minas 14 Kuwa h . Barni G ad s e R n . j 12 13 o R K T a Kuwa h w a . a Mina s a n R l u d G s ir m i R. n m o Kalsi A a T Y A 5 8 m Bata R. 32 9 lawa Paonta 6 Aglar R. 2 R Dakpathar Sahib R lar R Mussoorie a g 1 A 3 n A u sa Batamandi 4 n N m R. a Y 300 11’ N Tajewala 11 Dehradun Mussoorie 300 11 R R a Giri n R Kalsi u a m n Ya u m Dehradun a km Y 0 15 To Saharanpur ( # 33) Sampling Locations Crysta lline s boundary Towns LH-HH Carbonates Fig. 1. Map showing sediment sampling locations in the Yamuna Oth e r Sedimentaries and its tributaries in the Himalaya. Fig. 2. General lithology of the YRS drainage basin. Only some of the tributaries are shown. (Negi, 1991). This work, which builds on our earlier stud- ies (Dalai et al., 2002a, b, c), forms a part of detailed fractions were powdered either in an agate mortar or in a geochemical and isotopic investigation of the Yamuna Spex ball mill with acrylic container and methylacrate River System (YRS) in the Himalaya. Reported here are balls, and were sieved to <100 mesh size using nylon the concentrations of major and trace elements in sieves. Samples >100 mesh size were repeatedly pow- sediments of the Yamuna and its tributaries in the dered to bring all the materials to <100 mesh size. Dur- Himalaya. Results obtained in this study, in conjunction ing powdering, care was taken to ensure that samples did with those available on bed rocks in the basin and dis- not come in contact with any metal surface. After thor- solved load of the YRS (Dalai et al., 2002a, b), are used ough homogenization, powdered samples were stored in to (i) characterize chemical weathering in the YRS basin, clean plastic bottles. About 500 mg of sample was (ii) assess relative mobility of elements during weather- weighed and dissolved in PTFE dish by repeatedly treat- ing and transport, and (iii) determine the origin and asso- ing with hot HF-HCl-HNO3-HClO4 mixture and finally ciation of heavy metals in river sediments. dissolving in 1N HNO3. These solutions were used for elemental analysis after suitable dilution. Some samples were digested in replicates and analyzed to assess the pre- SAMPLING AND ANALYSIS cision of measurements. Reagents used for sample disso- Riverbed sediments were collected from the Yamuna lution were analyzed to assess their blank contribution. mainstream and its tributaries (Fig. 1) during October USGS rock standard (G-2) and an in-house laboratory 1998. Details of the sampling and analysis are given in standard (NOVA, prepared from the Pacific sediments, Dalai (2001) and Dalai et al. (2002a, b). Samples were Agnihotri, 2001) were also dissolved along with the sam- collected in zip-lock polythene bags using a plastic scoop. ples and analyzed to check the accuracy of the measure- In the laboratory, they were oven-dried at ~90°C and ments. Ca, Mg, Al, Sr, Ba, Fe, P, Ti, Pb, Zn and Cr were sieved to <1 mm size using nylon sieves. The <1 mm size measured by ICP-AES (Jobin Yvon 38S), and Na, K, Mn, 442 T. K. Dalai et al. Table 1. Results of analysis of reference standards G-2 and NOVA G-2 NOVA Element Measured Reported* Measured ICP-AES** ICP-MS** Cu 10.13 12 407 ± 2 392 ± 20 403 Ni 20.7 ± 0.9 13.7 244 ± 1 206 ± 15 224 Co 33.95 20.7 134 104 ± 7 101 Ti n.m. n.m. 3787 ± 234 3810 ± 245 4076 P n.m. n.m. 2009 ± 87 1875 ± 34 1702 Cr 5.89 ± 0.11 9 61 ± 2 63 ± 484 Zn 77 ± 2 85 137 ± 5 152 ± 10 146 Pb 23.3 ± 0.4 31 33.4 ± 1.2 n.m. 35.5 *Reported value from Potts et al. (1992). **ICP-AES and ICP-MS data of NOVA from Agnihotri (2001). n.m.: not measured. Cu, Ni and Co by flame-AAS (Perkin Elmer 4000). Car- river flows past the Higher Himalaya, it drains quartz- bonate contents were determined by coulometric titration.
Load more

Recommended publications
  • The Geographic, Geological and Oceanographic Setting of the Indus River
    16 The Geographic, Geological and Oceanographic Setting of the Indus River Asif Inam1, Peter D. Clift2, Liviu Giosan3, Ali Rashid Tabrez1, Muhammad Tahir4, Muhammad Moazam Rabbani1 and Muhammad Danish1 1National Institute of Oceanography, ST. 47 Clifton Block 1, Karachi, Pakistan 2School of Geosciences, University of Aberdeen, Aberdeen AB24 3UE, UK 3Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA 4Fugro Geodetic Limited, 28-B, KDA Scheme #1, Karachi 75350, Pakistan 16.1 INTRODUCTION glaciers (Tarar, 1982). The Indus, Jhelum and Chenab Rivers are the major sources of water for the Indus Basin The 3000 km long Indus is one of the world’s larger rivers Irrigation System (IBIS). that has exerted a long lasting fascination on scholars Seasonal and annual river fl ows both are highly variable since Alexander the Great’s expedition in the region in (Ahmad, 1993; Asianics, 2000). Annual peak fl ow occurs 325 BC. The discovery of an early advanced civilization between June and late September, during the southwest in the Indus Valley (Meadows and Meadows, 1999 and monsoon. The high fl ows of the summer monsoon are references therein) further increased this interest in the augmented by snowmelt in the north that also conveys a history of the river. Its source lies in Tibet, close to sacred large volume of sediment from the mountains. Mount Kailas and part of its upper course runs through The 970 000 km2 drainage basin of the Indus ranks the India, but its channel and drainage basin are mostly in twelfth largest in the world. Its 30 000 km2 delta ranks Pakiistan.
    [Show full text]
  • Clift Final.Indd
    http://oceanusmag.whoi.edu/v42n2/clift.html Moving Earth and Heaven Colliding continents, the rise of the Himalayas, and the birth of the monsoons By Peter Clift, Associate Scientist, clues to reconstruct when and how fast out of trees and upright onto two feet. Geology and Geophysics Department, their mountain sources rose to great All of these developments in recent Woods Hole Oceanographic Institution heights millions of years ago, and how Earth history ultimately may be attributed the climate and other environmental con- to the land masses now known as India Therefore will not we fear, though the earth ditions may have changed in response. and Arabia, which began moving north be removed, and though the mountains be carried into the midst of the sea. —Psalm 46 some 100 million years ago, on a collision Linking mountains and monsoons course with what is now Eurasia. Accord- s a geologist, I do not fear the pro- Tens of millions of years ago, a geo- ing to plate tectonic theory, Earth’s crust is Acesses that carry earth and mountain logical process was set in motion that composed of interlocking, moving oceanic into the sea. I rejoice in them. changed the planet. It produced some of and continental plates. Scientists consider The mountains rise, are lashed by the world’s most dramatic and extensive the collision of the Indian and Eurasian wind and weather, and erode. The rivers mountain ranges. It probably created one Plates the classic example of how plate carry mud and debris from the moun- of the planet’s most intense and important tectonics can alter the circulation of the tains into the ocean, where they settle climate phenomena—the Asian mon- oceans and atmosphere.
    [Show full text]
  • Suspended Sediment Transport in the Ganges-Brahmaputra
    SUSPENDED SEDIMENT TRANSPORT IN THE GANGES-BRAHMAPUTRA RIVER SYSTEM, BANGLADESH A Thesis by STEPHANIE KIMBERLY RICE Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 2007 Major Subject: Oceanography SUSPENDED SEDIMENT TRANSPORT IN THE GANGES-BRAHMAPUTRA RIVER SYSTEM, BANGLADESH A Thesis by STEPHANIE KIMBERLY RICE Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Co-Chairs of Committee, Beth L. Mullenbach Wilford D. Gardner Committee Members, Mary Jo Richardson Head of Department, Robert R. Stickney August 2007 Major Subject: Oceanography iii ABSTRACT Suspended Sediment Transport in the Ganges-Brahmaputra River System, Bangladesh. (August 2007) Stephanie Kimberly Rice, B.S., The University of Mississippi Co-Chairs of Advisory Committee: Dr. Beth L. Mullenbach Dr. Wilford D. Gardner An examination of suspended sediment concentrations throughout the Ganges- Brahmaputra River System was conducted to assess the spatial variability of river sediment in the world’s largest sediment dispersal system. During the high-discharge monsoon season, suspended sediment concentrations vary widely throughout different geomorphological classes of rivers (main river channels, tributaries, and distributaries). An analysis of the sediment loads in these classes indicates that 7% of the suspended load in the system is diverted from the Ganges and Ganges-Brahmaputra rivers into southern distributaries. Suspended sediment concentrations are also used to calculate annual suspended sediment loads of the main river channels. These calculations show that the Ganges carries 262 million tons/year and the Brahmaputra carries 387 million tons/year.
    [Show full text]
  • Ganges Strategic Basin Assessment
    Public Disclosure Authorized Report No. 67668-SAS Report No. 67668-SAS Ganges Strategic Basin Assessment A Discussion of Regional Opportunities and Risks Public Disclosure Authorized Public Disclosure Authorized Public Disclosure Authorized GANGES STRATEGIC BASIN ASSESSMENT: A Discussion of Regional Opportunities and Risks b Report No. 67668-SAS Ganges Strategic Basin Assessment A Discussion of Regional Opportunities and Risks Ganges Strategic Basin Assessment A Discussion of Regional Opportunities and Risks World Bank South Asia Regional Report The World Bank Washington, DC iii GANGES STRATEGIC BASIN ASSESSMENT: A Discussion of Regional Opportunities and Risks Disclaimer: © 2014 The International Bank for Reconstruction and Development / The World Bank 1818 H Street NW Washington, DC 20433 Telephone: 202-473-1000 Internet: www.worldbank.org All rights reserved 1 2 3 4 14 13 12 11 This volume is a product of the staff of the International Bank for Reconstruction and Development / The World Bank. The findings, interpretations, and conclusions expressed in this volume do not necessarily reflect the views of the Executive Directors of The World Bank or the governments they represent. The World Bank does not guarantee the accuracy of the data included in this work. The boundaries, colors, denominations, and other information shown on any map in this work do not imply any judgment on part of The World Bank concerning the legal status of any territory or the endorsement or acceptance of such boundaries. Rights and Permissions The material in this publication is copyrighted. Copying and/or transmitting portions or all of this work without permission may be a violation of applicable law.
    [Show full text]
  • Magnetic Fabric of Bengal Fan Sediments Holocene Record Of
    Marine Geology 430 (2020) 106347 Contents lists available at ScienceDirect Marine Geology journal homepage: www.elsevier.com/locate/margo Invited research article Magnetic fabric of Bengal fan sediments: Holocene record of sedimentary T processes and turbidite activity from the Ganges-Brahmaputra river system ⁎ Eva Morenoa, , Fabien Caroirb, Lea Fournierc, Kelly Fauquemberguec, Sébastien Zaragosic, Ronan Joussaind, Christophe Colind, Marie-Madeleine Blanc-Vallerone, François Baudinf, Thibault de Garidel-Thorong, Jean Pierre Valeth, Franck Bassinoti a Laboratoire d'Océanographie et du Climat: Expérimentations et approches numériques, UMR 7159 CNRS, IRD, Sorbonne Université/MNHN/IPSL. Boîte 100 - 4, place Jussieu, 75252 Paris cedex 05, France b UMR 8187, LOG, Laboratoire d'Océanologie et de Géosciences, Université Lille, CNRS, Université Littoral Côte d'Opale, F 59000 Lille, France c UMR CNRS 5805 EPOC, OASU, Université de Bordeaux, Allée Geoffroy Saint-Hilaire - CS 50023, 33615 Pessac cedex, France d CNRS, GEOPS, Université Paris-Saclay, 91405, Orsay, France e CR2P, UMR 7207, Muséum National d'Histoire Naturelle, 43 Rue Buffon - CP38, Paris, France f ISTeP - Institut des Sciences de la Terre Paris, Sorbonne Université, 4 place Jussieu, CP 117, 75005 Paris, France g CNRS, IRD, Coll. de France, INRAE, CEREGE, Aix-Marseille Université, Technopôle de l'Arbois - BP80, 13545 Aix-en-Provence cedex 04, France h Institut De Physique Du Globe De Paris, 1, Université de Paris, 1 rue Jussieu, 75238 Paris cedex 05, France i Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France ARTICLE INFO ABSTRACT Keywords: We present here a study based on the Anisotropy of Magnetic Susceptibility (AMS) and magnetic mineralogy Bengal fan carried out on the composite core MD17&18taken from the eastern levee of the active channel of the middle Holocene Bengal Fan in the Indian Ocean.
    [Show full text]
  • Deep Sea Drilling Project Initial Reports Volume 22
    16. STRATIGRAPHIC-SEISMIC SECTION CORRELATIONS AND IMPLICATIONS TO BENGAL FAN HISTORY David G. Moore, Naval Undersea Research and Development Center Joseph R. Curray, Russel W. Raitt, and Frans J. Emmel, Scripps Institution of Oceanography, La Jolla, California ABSTRACT Two drilling sites were proposed in the Bay of Bengal (Sites 217 and 218) in areas of anomalously thin section as determined by earlier seismic work. Although possibilities for characterizing the sediments in the normal thick section of the Bengal Fan were precluded, these holes were, nevertheless, successful in determin- ing the ages of two unconformity-refracting horizons which had been traced throughout the entire bay. These horizons, which subdivide the sedimentary section into three units, probably mark times of both plate-edge and mid-plate deformation. The oldest sediments in the Bay of Bengal were deposited on new sea floor formed after rifting of India from Antarctica and Australia, probably as a Cretaceous and Paleocene passive continental rise up to 12 km thick. First collision of India with the subduction zone lying off the southern margin of Asia occurred at the end of the Paleocene, causing both uplift of ancestral mountains in the eastern Himalayan region and defor- mation and unconformity across the bay. The first phase of Bengal Fan deposition was from middle Eocene into uppermost Miocene. At this time important further tectonism occurred, causing uplift of the modern Himalayas, deformation of the sea floor, and changes in sedimentation in the bay. Subsequent deposits of the modern Bengal Fan are largely undeformed. INTRODUCTION unconformably on apparently older deformed fan and pelagic deposits, and these in turn unconformably overlay The international Indian Ocean expeditions of 1960 to still older deposits of unknown origin.
    [Show full text]
  • LETTER 613C of Organic Carbon in the Bengal
    Geochimica et Cosmochimica Acta, Vol. 58, No. 21, pp. 4809-4814, 1994 Copyright 0 1994 ElsevierScience Ltd Pergamon Printed in the USA. All rightsreserved 0016-7037/94 $6.00 + .OO 0016-7037(94)00234-7 LETTER 613C of organic carbon in the Bengal Fan: Source evolution and transport of C3 and C4 plant carbon to marine sediments CHRISTIAN FRANCE-LANORD’ and LOUIS A. DERRY’ ‘Centre de Recherches Pktrographiques et G&ochimiques, CNRS, BP20 54501, Vandoeuvre-les-Nancy, France *Cornell University, Department of Geological Sciences, Ithaca, NY 14853, USA (Received July 8, 1994; accepted in revisedform August 29, 1994) Abstract-Carbon isotopic measurements on organic carbon (oc) in sediment cores from the Bengal Fan (ODP Leg 116) show a dramatic 10 %Oincrease beginning ca. 7 Ma ago, and a rapid decrease after 0.9 Ma. These shifts reflect changes in the mixing ratio of terrigenous carbon derived from C3 and C4 plants. The rapid increase in 613C of Bengal Fan OC at 7 Ma shows that Late Miocene expansion of C4 plants already documented in the Siwaliks was widespread over all the Himalayan foreland. After 7 Ma, relations of 613C with sedimentological parameters show that C4 plants dominate in the foreland whereas C3 plants remain abundant in the mountain range. Variations in the source of the sediments and of the OC appear to be sensitive to climate-hydrologic conditions in the basin. Major changes in the isotopic composition of the carbon flux in one of the worlds largest river systems modify the isotopic budgets of both marine dissolved carbon and the sedimentary carbon mass.
    [Show full text]
  • Sri Lanka: Is It a Mid-Plate Platelet?
    Sri Lanka: is it a mid-plate platelet? Item Type article Authors Curray, J.R. Download date 25/09/2021 19:54:47 Link to Item http://hdl.handle.net/1834/32912 J. NARA, 31 (1984) 30-50 Sri Lanka: is it a. - Plate Platelet? By JOSEPH R. CURRAY* ABSTRACT Two observations suggest the possibility that Sri La:1..\:a is acting as a small-mid-plate platelet moving very slowly within and relative to the larger Indian plate. First, sediments of the Bengal Deep-Sea Fan off the SSE continental margin are folded and uplifted in a manner simibr to the deformation from front of accretionary prisms where thick sediment columns are passing into subduction zones. i\nd second, subsidence rates in the area of presumed spreading or continuing stretching of continental crust, the Cauvery-Palk Strait-Gulf of Mannar Basin, have not decreased during the Cenozoic as would be predicted by an aborted rift or aulacogen model, but instead appear to have accelerated during the Neogene. Information available on other phenomena which are predicted by the model is at the present time i..""l.adequate for evaluation. INTRODUCTION Sri Lanka (Fig. x) .is an island measuring about 225x435 km, lying just southeast of the southern tip of the Indian Peninsula. Geologically, it bears a very dose resemblance to the Precambrian high-grade crystalline metamorphic rocks of adjacent India. Although this makes Sri Lanka's po:~ition in reconstruction of Gondwanaland obviously close to India, its precise position has never been defined. Smith and Hallam (1970) adjusted Sri Lanka's position relative to India rather arbitrarily and in relatively small scale to constitute a best possible geometric fit.
    [Show full text]
  • Distribution of Rare Earth Elements and Heavy Metals in the Surficial Sediments of the Himalayan River System
    Geochemical Journal, Vol. 34, pp. 295 to 319, 2000 Distribution of rare earth elements and heavy metals in the surficial sediments of the Himalayan river system R. RAMESH,1 AL. RAMANATHAN,2 S. RAMESH,1 R. PURVAJA1 and V. SUBRAMANIAN3 1Institute for Ocean Management, Anna University, Chennai 600 025, India 2Department of Geology, Annamalai University, Annamalai Nagar 608 002, India 3School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110 067, India (Received May 25, 1999; Accepted March 23, 2000) Rare earth elements (REEs) are considered as useful tracers of various surface geological processes in the river system. REEs and heavy metals (V, Pb, Cr, Co, Ag, Zn, Cd, Ni) were analyzed from the sus- pended sediments of Ganges and surficial sediments of Yamuna, Brahmaputra, Jamuna, Padma and Meghna, using VG Thermal Ionization Mass Spectrometer. Physical weathering process seems to be a major con- trolling factor for the distribution of REE and trace metals in the sediments of the Himalayan rivers. Weathering of the surface crustal area in the drainage basin shows significant variations due to changes in lithology and influence of tributaries. The distribution of REE shows an almost uniform pattern due to factors such as river transportation processes and high level of terrigenous mixing in the bed sediments. The results show that finer grain size and high content of clay mineral (illite) in these sediments are possible traps for the accumulation of metals. Anthropogenic activities seem to have very little influence in controlling the elemental distribution in the Himalayan rivers. predominantly in the solid phase during transport INTRODUCTION in the river systems.
    [Show full text]
  • Geologic, Geomorphic and Hydrologic Framework and Evolution of the Bengal Basin, India and Bangladesh
    Journal of Asian Earth Sciences 34 (2009) 227–244 Contents lists available at ScienceDirect Journal of Asian Earth Sciences journal homepage: www.elsevier.com/locate/jaes Geologic, geomorphic and hydrologic framework and evolution of the Bengal basin, India and Bangladesh Abhijit Mukherjee a,*, Alan E. Fryar b, William A. Thomas b a Bureau of Economic Geology, Jackson School of Geosciences, University of Texas at Austin, University Station, Box X, Austin, TX 78713-8924, USA b Department of Earth and Environmental Sciences, University of Kentucky, KY 40506-0053, USA article info abstract Article history: The Bengal basin, the largest fluvio-deltaic sedimentary system on Earth, is located in Bangladesh and Received 7 June 2007 three eastern states of India. Sediment accumulates in the basin from the Ganges, Brahmaputra, and Meg- Received in revised form 9 May 2008 hna (GBM) river systems and is dispersed into the Bay of Bengal, forming the largest submarine fan in the Accepted 22 May 2008 world. The basin is located in the Himalayan foreland at the junction of the Indian, Eurasian, and Burmese plates. The basin is bounded by the Indian craton on the west and the Indo-Burmese fold belts on the east. It can be broadly divided into a stable shelf and a foredeep separated by a deep seismic hinge zone. Basin Keywords: sediments overlie Gondwanan basement and vary in thickness from a few kilometers on the stable shelf Ganges to more than 16 km in the foredeep. The basin was initiated at the breakup of Gondwanaland in the late Brahmaputra Meghna Mesozoic and evolved through the formation of the proto-GBM delta to the present delta starting around Fluvio-deltaic system 10.5 Ma.
    [Show full text]
  • 32. Himalayan Uplift, Sea Level, and the Record of Bengal Fan Sedimentation at the Odp Leg 116 Sites1
    Cochran, J. R., Stow, D.A.V., et al., 1990 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 116 32. HIMALAYAN UPLIFT, SEA LEVEL, AND THE RECORD OF BENGAL FAN SEDIMENTATION AT THE ODP LEG 116 SITES1 James R. Cochran2 ABSTRACT Three closely spaced sites located 800 km south of Sri Lanka on the distal Bengal Fan were drilled during ODP Leg 116. Two of these sites, 717 and 718, together penetrated over 1300 of the 2000 m of stratigraphic section present at that location and provide a complete record of sedimentation since the lower Miocene. The entire section consists of turbidites, primarily derived from the Ganges-Brahmaputra delta. The main controls on sedimentation appear to be the uplift and erosion history of the Himalayas, along with the position of sea level relative to the shelf edge. Although the base of the fan was not penetrated, a number of lines of evidence suggest that it was approached and that fan sedimentation began in the lower Miocene. This corresponds in time with the oldest known molasse sedimentation in India and Pakistan and probably represents the time of beginning of major uplift and erosion in the Himalayas. Sedimentation continued at a substantial rate from the lower Miocene to the upper Pliocene indicating continued erosion and thus presumably continuing uplift and significant relief in the Himalayas during that time. The unconformity in seismic sections corresponding to the beginning of intraplate deformation can be dated as occurring between 7.5 and 8.0 Ma. It does not correspond to any change in the nature of the sediments.
    [Show full text]
  • Miocene Sedimentation and Subsidence During Continent–Continent Collision, Bengal Basin, Bangladesh
    Sedimentary Geology 164 (2004) 131–146 www.elsevier.com/locate/sedgeo Miocene sedimentation and subsidence during continent–continent collision, Bengal basin, Bangladesh Ashraf Uddina,*, Neil Lundbergb a Department of Geology and Geography, 210 Petrie Hall, Auburn University, Auburn, AL 36849-5305, USA b Department of Geological Sciences, Florida State University, Tallahassee, FL 32306, USA Received 9 April 2003; received in revised form 1 September 2003; accepted 23 September 2003 Abstract The Bengal basin, a complex foreland basin south of the eastern Himalayas, exhibits dramatic variability in Neogene sediment thickness that reflects a complicated depositional and tectonic history. This basin originally formed as a trailing margin SE of the Indian continental crust, complicated by convergence with Asia to the north and oblique convergence with Burma to the east. Newly compiled isopach data and previously reported seismic data show evidence of thickening of basin fill toward the south, opposite of the pattern typically seen in foreland basins. This is presumably due to sedimentary loading of voluminous deltaic sediments near the continent–ocean boundary and basinward downfaulting analogous to that in the Gulf of Mexico. Isopach data show that there is considerable vertical relief along the base of the Miocene stratigraphic sequence, probably due to down-to-the-basin faulting caused by focused deltaic sedimentation and associated crustal flexure. In contrast, when viewed in east–west profile, basin shape is more typical of a foreland basin, with strata thickening eastward toward the Indo–Burman ranges, which reflects east–west convergence with Southeast Asia. Comparison of the lateral and vertical extent of the Bhuban and Boka Bil Formations with the Bouguer anomaly map of Bangladesh suggests that considerable subsidence of the Sylhet trough (in the northeastern part of the Bengal basin), which has the lowest gravity value of the region, had not taken place by the end of the Miocene.
    [Show full text]