The Quaternary Glacial History of the Lahul Himalaya, Northern India
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JOURNAL OF QUATERNARY SCIENCE (1996) 11 (1) 25-42 CCC 0267-81 79/96/01 0025-1 8 0 1996 by John Wiley & Sons, Ltd The Quaternary glacial history of the Lahul Himalaya, northern India LEWIS A. OWEN, EDWARD DERBYSHIRE and SHAUN RICHARDSON Department of Geography, Royal Molloway, University of London, Egham, Surrey TW20 OEX, England DOUGIE I. BENN Department of Geography, University of Aberdeen, Aberdeen AB9 2UF, Scotland DAVID J. A. EVANS Department of Geography and Topographic Science, University of Glasgow, Glasgow G12 8QQ, Scotland WISHART A. MITCHELL School of Geological and Environmental Sciences, University of Luton, Luton LU1 3JU, England Owen, L.A, Benn, D.I., Derbyshire, E., Evans, D.J.A., Mitchell, W.A and Richardson, 5. 1996. The Quaternary glacial history of the Lahul Himalaya, northern India. fournal of Quaternary Science,Vol. 11. pp. 25-42. Received 7 October 1994 Accepted 8 February 1995 ABSTRACT: This paper presents the first glacial chronology for the Lahul Himalaya, Northern India. The oldest glaciation, the Chandra Glacial Stage, is represented by glacially eroded benches at altitudes greater than 4300 m above sea-level. This glaciation was probably of a broad valley type. The second glaciation, the Batal Glacial Stage, is represented by highly weathered and dis- sected lateral moraines, which are present along the Chandra valley and some of its tributaries. This was an extensive valley glaciation. The third major glaciation, the Kulti Glacial Stage, is rep- resented by well-preserved moraines in the main tributary valleys of the Chandra valley. This rep- ~ou~~~of~wt~~,,, resents a less extensive valley glaciation. Two minor glacial advances, the Sonapani I and 11, are represented by small sharp-crested moraines, which are within a few hundred metres or few kilo- metres of the present-day glaciers. The change in style and extent of glaciation is attributed to an increase in aridity throughout the Quaternary, due either to global climatic change or uplift of the Pir Panjal mountains to the south of Lahul, which restricted the northward penetration of the south Asian summer monsoon. KEYWORDS: Himalayas; stratigraphy; glacier reconstruction; palaeoclimate; neotectonics. Introduction within the high mountains of the Himalayas of northern India. Previous work has been concentrated in the Karakoram Mountains in Northern Pakistan (Derbyshire et a/., 1984; The Himalayas and Tibetan Plateau have attracted much Owen, 1989; Shroder et a/., 1993), Kashmir (Holmes and attention in recent years through the debate on the likely role Street-Perrott, 1989, Holmes, 1993), the central Himalaya in of late Cenozoic uplift of the central Asian mountains in driv- Nepal (Fort et a/., 1981; Burbank and Kang, 1991) and the ing regional and global climate change during late Tertiary Tibet Plateau (Zheng Benxing, 1989a; Li Jijun et a/., 1979). and Quaternary times (Ruddimann and Kutzbach, 1989; Prell In this study, evidence is examined for palaeoenvironmental and Kutzbach, 1992). In addition, the mountains of the west- change in the Lahul Himalaya, Himachal Pradesh, North India ern and central Himalayas and the Karakoram Mountains (Fig. 1). This is an important area in palaeoenvironmental comprise the greatest concentration of glaciers outside of the research because it marks the junction between the monsoon- polar regions. This makes the area particularly important in influenced southern flank of the Pir Panjal (Lesser Himalaya) understanding environmental change with reference to the and the Greater Himalaya, and should therefore contain geo- nature and timing of glacier fluctuations. Data associated with logical and geomorphological evidence for fluctuations in the this are extremely important to global climate modellers, who northern limit of the south Asian palaeomonsoon through need to consider albedo changes, weathering rates and time. Furthermore, the area has undergone significant change meltwater fluctuations associated with the growth and decay in topography owing to uplift of the Pir Panjal during the Pleis- of glaciers during the Quaternary in order to construct reliable tocene, which may well have a control on environmental con- models of climatic change. Accurate reconstructions of former ditions. Well-preserved glacial landforms and sediments in the glaciers are also important in resolving the contentious argu- northern part of this region and along the lower valleys pro- ment over the former extent of ice cover across the Tibetan vide evidence for at least three major glaciations. In this Plateau and the adjacent Himalayas throughout Quaternary paper, the styles and extent of glaciation are discussed, tenta- time (Zheng Benxing, 198913). tive correlations provided and theories for the changing styles Despite these important issues little research has been of glaciation are examined. undertaken on the nature of palaeoenvironmental change 26 JOURNAL OF QUATERNARY SCIENCE Figure 1 Location map of study area. Geomorphological setting lower limit of the snowline on the southern slopes of the Pir Panjal reaches as low as 1500 m (Sharma, 1986). Vegetation varies with altitude, ranging from forest charac- The geomorphological background to this region is discussed terised by Juniperus, Pinus, Betula, Salix, Populus, Picea and in detail in Owen et a/. (1995). The region comprises two Pyrus on the southern slopes of the Pir Panjal and in the lower mountain ranges, the Pir Panjal and the Great Himalaya, reaches of the valleys north or the Pir Panjal, to alpine veg- which trend NW-SE. The area is drained by the Chandra etation at altitudes of between 3550 and 4850 m. There is River, which flows south and then turns northwest near the little vegetation above 4850 m. Bara-Shugri Glacier, where it divides the Pir Panjal from the The geomorphological system is dominated by steep, high- Great Himalaya (Fig. 1). The climate varies from the mon- activity glaciers, which carry large amounts of supraglacial soonal influenced southern slopes of the Pir Panjal to semi- debris. The glacier margins indicate recent ice retreat, with arid valleys on the northern slopes of Pir Panjal and in the complex moraine systems down-valley of the present-day ter- Great Himalaya. minal zone (Owen etal., 1995). Mass movements, particularly The climate is dominated by a long winter season from mid- talus development and landsliding, have produced major November to March, with a spring season that lasts until the remodifications of landforms within the area and paraglacial end of May. Summer extends to the end of September, with processes are regarded as an extremely important landscape- October and early November being a short autumn season. forming process (Owen et a/., 1995). Little data are available on precipitation, but Mamgain (1975) suggested that most of the precipitation falls as snow in winter north of the Pir Panjal with little during the monsoon months Methods from June to September. On the southern slopes of the Pir Panjal there are heavy snow falls during the winter and Mapping intense heavy monsoon rains fall during July and August. Pre- cipitation, however, is strongly controlled by aspect and alti- Detailed base maps and aerial photographs are not available tude. The permanent snowline is above 4260 m, although the for this region. The best maps are at a scale of 1 : 250000 OUATERNARY GLACIAL HISTORY OF LAHUL HIMALAYA 27 Table 1 Tentative glacial chronology for the Lahul Himalaya compared with adjacent regions. Note that there is little or no dating control on these chronologies and dates that have been obtained are highly suspect because of reworking (cf. Owen eta/. 1992) and glaciotectonism (cf. Owen and Derbyshire, 1988; Owen, 1989) Glacial Lahul Middle Indus-Gilgit-Hunza Valleys Upper lndus Zanskar Swat Kohistan Tentative Non-glacial Dates Series Stage Stade This Study Derbyshire Shroder Zhang & Shi Cronin (1982) Osrnaston Porter (1970) Years et a/. eta/. (1 980) (pers comrn) (1984) (1993) Holocene Sonapani Pasu II Historical Historical -102 Sonapani I Pasu I Little Ice Age Little Ice Age Drang-drung -103 Batura Neoglacial Neoglacial Individual Neoglacial Neoglacial Moraines -104 Pleisto- Late Ghulkin II Darel-Shatial Kalam Glaciation cene glaciation Kulti Ghulkin I Moraine Hunza Late Stade Borit ]heel Dainyor Glaciation Tepuk Kalam Glaciation -105 Moraine Intermed. Stade Kalam Glaciation ? Early Stade M-L lG Valley Fill 111 Strong Erosion Thonde Glacial Alluviation Gabral Middle Late M2 Tills Yunz Satpura Till Glaciation Batal glaciation Stade Yunz Valley Fill II Glaciation ? Late Stade Early MI Tills Valley Fill Stade Kilima Glacial Gabral Glaciation E-M Upper Jalipur Bunthung Till Early Stade Inter G. Valley Fill 1 Shanoz Chandra Shanoz Lower lalip, Early Glaciation Laikot Glaciation -1 o6 glaciation Till (U502 Series) but they lack detail and are often unreliable. Glaciations For example, the largest glacier, the Bara Shugri, is not shown on these maps. Base maps were constructed for selected val- leys using reconnaissance survey techniques and a global pos- Three major glaciations (the Chandra Glacial, the Batal Gla- itioning system (GPS) (Figs 2-4). A variety of scales were used, cial and the Kulti Glacial) and two glacial advances (Sonapani ranging from 1 : 10000 to 1 :1000, in order to map moraines I and Sonapani 11) were identified on the basis of morphostra- and important landforms. tigraphy, weathering criteria, vegetation and soil develop- ment. Each will be discussed in turn from oldest to youngest. The chronology is listed