ORIGINAL PAPER

Late Pleistocene-Holocene morphosedimentary architecture,Spiti River, arid higher Himalaya

Pradeep Srivastava • Yogesh Ray • Binita Phartiyal •

Anupam Sharma

Received: 16 May 2012 / Accepted: 6 February 2013 / Published online: 1 March 2013

� Springer-Verlag Berlin Heidelberg 2013

Abstract The Spiti River drains the rain shadow zone of

western Himalaya. In the present study, the fluvial sedi-

mentary record of Spiti valley was studied to understand its

responses to tectonics and climate. Geomorphic changes

along the river enable to divide the river into two segments:

(i) upper valley with a broad, braided channel where relict

sedimentary sequences rise 15–50 m high from the river-

bed and (ii) lower valley with a narrow, meandering

channel that incises into bedrock, and here, the fluvio-

lacustrine sediments reside on a bedrock bench located

above the riverbed. The transition between these geomor-

phic segments lies along the river between Seko-Nasung

and Lingti villages (within Tethyan Himalaya). Lithofacies

analyses of the sedimentary sequences show six different

lithofacies. These can be grouped into three facies associ-

ations, viz. (A) a glacial outwash; (B) sedimentation in a

channel and in an accreting bar under braided conditions;

and (C) formation of lake due to channel blockage by

landslide activities. Seventeen optically stimulated lumi-

nescence ages derived from ten sections bracketed the

phases of river valley aggradation between 14–8 and

50–30 ka. These aggradation phases witnessed mass

wasting, channel damming and lake formation events. Our

record, when compared with SW monsoon archives, sug-

gests that the aggradation occurred during intensified

monsoon phase of MIS 3/4 and that proceeded the Last

Glacial Maxima. Thus, the study reports monsoon modu-

lated valley aggradation in the NW arid Himalaya.

Keywords Arid NW Himalaya � Spiti River �Fluvial archive � OSL dating � Paleoclimate

Introduction

Erosion and sedimentation processes of rivers sculpt

landscapes and form terraces and alluvial fans that together

indicate the climate and tectonic activities in mountains

and its foreland. Interplay of tectonics and climate defines

the time scales and locations (hotspots) of sediment gen-

eration and deposition. Spatially heterogeneous distribution

of rainfall, erosion and mass removal potentially induces

non-uniformity in geomorphic development.

During the evolution of the southern mountain front, sed-

imentation and erosional processes in the Himalayan region

were dominated by the tectonics arising from south verging

regional scale thrusts like the Main Central Thrust (MCT),

Main Boundary Thrust (MBT) and Himalayan Frontal Thrust

(HFT) and by climatic conditions. The region between the

hanging wall of the MCT and the southern region of Indus

suture zone is located in the lee side of High Himalaya and

therefore is rather characterized by dry climate. This region is

also deformed by several normal faults. The Indus suture zone

itself is arid. This heterogeneity potentially induces variability

in landscape evolution across Himalaya. Rivers erode and

carry sediment from the High Himalaya to the foreland and

finally to the oceans and carrying signals of climate–tectonic

impacts on landscape development. Therefore, understanding

of fluvial systems in different climate and tectonic regime is

cardinal to the understanding of geomorphic evolution of

Himalaya vis-a-vis climate and tectonic changes.

P. Srivastava (&) � Y. Ray

Wadia Institute of Himalayan Geology, 33 GMS Road,

Dehradun 248001, India

e-mail: pradeep@wihg.res.in

B. Phartiyal � A. Sharma

Birbal Sahni Institute of Palaeobotany, 53-University Road,

Lucknow 226007, India

123

Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984

DOI 10.1007/s00531-013-0871-y

Several studies on the landscape development, erosion

and depositional processes, their time scales and forcing

factors such as tectonics and/or climate have been reported

(Thiede et al. 2004; Wobus et al. 2005; Srivastava et al.

2008; Ray and Srivastava 2010). However, Himalayan

region beyond the spatial limits of monsoon is not well

studied. Drier Himalaya has little vegetation and receives

average annual rainfall of 50 mm. During abnormal mon-

soon years, this rainfall episodically is up to 15 mm/day

and leads to heavy hill slope erosion, landslides and

damming of river channels (Korup et al. 2006). In Sutlej

and Spiti River valleys (western Himalaya), evidence of

land sliding and subsequent channel damming during Late

Pleistocene-Holocene intensified monsoon phase has been

reported (Bookhagen et al. 2005a; Phartiyal et al. 2009a,

2009b). Sutlej valley recorded a fivefold increase in sedi-

ment generation during phases of intensified monsoons

(Bookhagen et al. 2005a, b). These observations suggest

that arid and semi-arid regions of the Himalaya with sparse

vegetation, steep hill slopes and channel networks are

sensitive to climatic variability (Montgomery and Dietrich

1992; Tucker and Slingerland 1997).

Spiti River valley in the western Himalayan zone is

traversed by several active normal faults (e.g. Kaurick

Chango Fault; Bhargav et al. 1978; Bhargava and Bassi

1998). Therefore, climate is not the only factor that affects

the sedimentary deposit and landscape architecture of this

valley.

The present study reconstructed the geomorphic and

sedimentological evolution of the Spiti River valley via the

morphosedimentary record coupled with optically stimu-

lated luminescence (OSL) dating. Sedimentological anal-

ysis of provided lithofacies associations suggestive of mass

wasting, channel damming and formation of lakes helped

understand the phases of higher erosion and sediment

transport, and the role of neotectonic activities, in the

evolution fluvial landscape.

General geology

The Spiti valley is an area where Tethyan sediments from

Neoproterozoic to Cretaceous are exposed (Bhargava

and Bassi 1998; Sinha 1989 and references therein). The

Palaeozoic rocks are mostly splintery shale, sandstone,

limestone and metasediments (e.g. quartzites, marble,

slate). The Mesozoic rocks are dominantly limestone

(Kioto limestone-Jurassic), shale (Spiti shale-Triassic?)

and sandstone (Giumal sandstone-Cretaceous). At the

northern end of the Spiti valley, the Tso Morari Crystal-

lines of age *400 Ma comprises granitic gneiss, gneiss

and schist occur (Steck et al. 1998; Jain et al. 2003; Leech

et al. 2005).

Structurally, Spiti River valley is located SW of the

Karakoram Fault System (KFS), in a pull-apart basin lying

between NW–SE trending, right lateral, strike-slip Karak-

oram Fault System and high-angle faults near the southern

boundary of Tethyan Himalaya (Ni and Barazangi 1985;

Bhargava 1990; Mazari and Bagati 1991). The Tethyan

Himalaya falls between the MCT (in the south) and the

Zanskar thrust (Great Counter Thrust) in the north. The

NNE–SSW trending Kaurik-Chango fault and faults asso-

ciated with the Leo-Pargil Horst control active tectonics of

the region (Thiede et al. 2006; Hintersberger et al. 2010).

The Kaurik-Chango normal fault zone (KCnf) strikes

north-northeast, dips up to 808 west and comprises a

cataclastic zone along the western flank of the Leo Pargil

Dome (Bhargav et al. 1978). The faults cut the hanging and

footwall rocks of the Leo Pargil Dome and offset river

terraces of quaternary age (Thiede et al. 2006). Kinematic

data from this fault zone indicate dip-slip normal faulting

and an E-W extension. This was also supported by focal

mechanism data for Kinnaur earthquake of 1975 that

occurred along this fault indicated dominant normal dip-

slip displacement (Molnar and Chen 1983). Seismic

activity along this structure is visible in faulted lacustrine

and fluvial units dated to between 26 and 90 ka (Singh

et al. 1975; Mohindra and Bagati 1996; Baneerjee et al.

1997). Morphotectonic parameters such as basin asymme-

try and drainage anomalies also indicated that the KCnf has

been neotectonically active (Joshi et al. 2010).

Climate and sediment generation

The Spiti valley is located above the tree line

(3,000 m amsl), between 31 and 33�E and 77–79�S

(Fig. 1), with a few shrubs on the valley floor. This region

is in the monsoon rain shadow, behind the High Himalaya

(Fig. 2). The area receives average of 50 mm of annual

rainfall (excluding snow melt component) and\200 cm of

snowfall per annum. The extreme temperatures are -25 �C

(winters) and 15 �C (summers). Two precipitation regimes

operate, viz. the southwest (June to September) and the

winter monsoon from western disturbances (November to

February). During the past, flash floods in the Sutlej River

are reported, with instances of water level rising to 12 m

above the normal monsoon flow. During such abnormal

monsoon years, moist air bypassed orographic barriers and

reached arid regime (Bookhagen et al. 2005b). Such events

erode the slopes and fill the river valleys with sediments as

has been observed in other orogens (Trauth et al. 2003;

Bookhagen et al. 2005b).

Spiti River derives sediments from relict glacial mor-

aines and hill slope weathering via freezing and thawing

processes (Keiffer and Steinbauer 2012) that produce a

1968 Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984

123

huge amount of loose debris to form debris cones that

supply sediment to the main channel during anomalous

rainfalls (Fig. 3a). During intense snow and its subsequent

melting, pore pressure increase in the debris leads to debris

flow that form steep sedimentary cones (Fig. 3b). This is an

important source of sediment supply to the main channel.

Further only occasional debris flow events are not always

capable to dam the channel of the size like the Spiti River.

Geomorphology of the Spiti River

Spiti River is about 150 km long and originates from

Nogpo-Topko glacier, near Kunzum La (4,551 m) as the

Taktsi stream. This joins Pagnu and Kibji rivers, and the

system thereafter is called Spiti River. In its entire course,

the river descends up to *1,800 m, that is, an average slope

of 17 m/km. Longitudinal profile, slope gradient (Hack

profile) and steepness indices of the river show sharp knick

points when the channel crosses active normal faults, for

example, at Mane and Kaurik-Chango (Phartiyal and

Kothari 2011; Anoop et al. 2012). Initially, from Losar to

Mane, the river flows E-W, as a braided stream, in a

U-shape valley, takes a gentle right angle turn and thereafter

flows linearly in a SE direction in the axial plain of the Spiti

anticline and then joins the Sutlej river at Khab. The Spiti

River has a catchment of *6,300 km2, with Pin, Lingti,

Parachu as its major tributaries. Based on the channel

characteristics and disposition of the relict deposits, the

whole valley was divided into the upper and lower Spiti

valley (Fig. 1b). In the upper valley, between Losar and

Lingti, the river is braided and the valley walls are abutted

by relict fluvial and lake deposits, active fans, debris cones

and landslide sediments. The lower valley, between Lingti

and Khab, is characterized by a meandering and incised

channel (Fig. 4). This segment has incised gorges with

relict lacustrine and fluvial deposits residing on bedrock

which is 10–130 m above the river level. At places, the river

has incised into the bedrock with a sinuous course (Fig. 4).

The tributaries and other first- and second-order streams

join the main river at right angles suggestive of tectonic/

structural control. The general NW–SE course suddenly

Fig. 1 a The study area is

marked by blue rectangle, black

rectangle marks the region used

to prepare the swath profile as

shown in Fig. 2. b Lithotectonic

division of Himalaya, ITSZ,

Indus Tsangpo Suture Zone;

STD, South Tibetan

Detachment; MCT, Main

Central Thrust; MBT, Main

Boundary Thrust; and HFT,

Himalayan Frontal Thrust, red

rectangle marks the study area.

c Spiti River (in blue) valley

showing the distribution of

relict fluvial deposits in lower

and upper Spiti River valley.

d Braided pattern of the river.

Locations shown in pink are the

sites where sedimentary

sections are studied and dating

samples are collected and those

with red circle are the sites

where palaeolandslides are

located

Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984 1969

123

changes to almost N–S direction along the KCnf all the way

to junction with the Sutlej River at Khab. Apart from this

features like unpaired and tilted terraces, deep gorges and

knick points, basin asymmetry is also suggested as the

manifestation of neotectonic movement along the KCnf in

the area (Joshi et al. 2010; Phartiyal and Kothari 2011).

Methodology

The geomorphic study used Survey of India (SOI) topo-

graphic maps and field surveys. SOI Toposheets, altimeter

and hand-held global positioning systems were used to

determine the heights of terrace surfaces. Thickness of the

alluvial fill was measured using tapes and rods. Lithofacies

of fluvial fills, fans and palaeolake sequences were docu-

mented by a careful observation of grain size, colour,

degree of bioturbation, matrix percentage, physical struc-

tures, lateral geometry and bounding contacts of the indi-

vidual units. Gravel diameter and matrix percentage

estimation used field observation using 1-m2 grids, and

several outcrops were examined. The discussion here fol-

lows a type section. The morphological details were after

careful examination of SOI topographic maps, images from

Fig. 2 a Map showing the change in elevation from the frontal

Himalaya to the Spiti valley, black rectangle marks the area used to

prepare the Swath profile. b Swath profile (250 9 100 km) showing

black line as mean elevation derived from Shuttle Radar Topographic

Mission DEM (SRTM 2000), and blue line marks mean precipitation

derived from Tropical Rainfall Measurement Mission (TRMM)

rainfall data (Bookhagen, in review), shading denotes ±2r values

showing the maximum and least value along the transect. The

geomorphic and rainfall profile suggests that the influence of the SW

monsoon largely remains south of the Southern Himalayan Front,

keeping the Spiti River valley arid

Fig. 3 a Steep sedimentary

cones bordering the river

channel. b The fans often

collapse and slide down as

debris flows due to high

intensity rains, sometimes

blocking the river

1970 Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984

123

Google Earth and field observations. Sample collection for

dating was done in steel pipes, and generally sandy alluvial

units were sampled.

Optical dating was the preferred technique for the dating

of the various geomorphic units. The technique relies upon

the fact that process of erosion and transport, daylight

exposures of minerals constituting the sediments, resets

their latent luminescence to a near zero residual value. On

burial day, light exposure ceased and re-accumulation of

luminescence due to irradiation from the natural radiation

field (arising from the decay of natural radioactivity)

occurs. This continues unabated till excavation, and the

stored luminescence is proportional to the radiation expo-

sure and hence the burial age (Aitken 1998). There is

encouraging evidence of zeroing during fluvial transport of

quartz from the foothills of the NE Himalaya (Mukul et al.

2007; Srivastava and Misra 2008) which is facilitated by

dry conditions, lack of vegetation cover and enhanced UV

flux at higher altitudes.

A total of 21 samples were collected from sections along

the river (Fig. 1). Samples SP-2 to SP-14 were from the

upper valley and SP-14-21 were from the lower valley. The

details of the sections and stratigraphic positions of the

samples are given in Table 1.

Quartz fraction was extracted by treating the samples

sequentially with HCl, H2O2 followed by heavy liquid

separation using sodium polytungstate (density = 2.58 g/

cm3). These grains were then sieved to extract the

90–150 lm fractions and etched using 40 % HF for 80 min

followed by 12 N HCl treatment for 40 min, the alpha

irradiated skin, residual feldspars and insoluble fluorides.

Purity of quartz vis-a-vis feldspar contamination was tested

using infrared stimulated luminescence. Quartz grains were

mounted on stainless-steel discs using Silko-Spray silicone

oil, and 15–20 aliquots of 9 mm diameter were prepared

for luminescence analysis. Low luminescence sensitivity in

some samples necessitated the use of large aliquots.

Luminescence measurements were made in a Riso TL/

OSL-15 system with an array of blue LEDs for stimulation.

The signal was recorded through a combination of BG-

39 ? U-340 filter for 40 s at 125 �C. A 90Sr/90Y beta

source delivering a dose rate of 6.7 Gy/min was used for

irradiation. Palaeodose estimation was carried out using a

5-point single aliquot regeneration protocol of Murray and

Wintle (2000). Three regeneration dose points were used to

construct dose growth curves and two points to check the

recuperation effect and for sensitivity corrections (recycled

point), respectively. A preheat of 220 �C for 10 s for nat-

ural and regeneration doses was used. The dose growth

curves were selected having \10 % variation in recycling

ratio. The quartz examined shows a typical shine down

curve with a linear growth curve (Aitken 1998). The initial

part (2 s of a 100 s exposure) of a typical shine down curve

of quartz was used for analysis. The uranium (238U), tho-

rium (232Th) and potassium (K) concentrations were mea-

sured by X-ray fluorescence. The cosmic gamma

contribution was calculated following Prescott and Stephan

(1982), and water concentration was assumed to be

5 ± 2 % by weight.

Most samples indicated inhomogeneous bleaching, and

therefore the mean of the least 30 % of the palaeodose

values (4–6 aliquots) was used for age calculations (Sri-

vastava et al. 2009; Ray and Srivastava 2010). This

approach helped to identify and discard ages from ali-

quots that contained a population of poorly bleached

quartz grains. Recently, a study indicated that that pos-

sibly due to high-energy sedimentary processes (deposi-

tion due to episodic flash floods, debris flow, etc.),

modern sediment (zero age) from Spiti River yielded an

OSL age of *2 ka. This implied that luminescence ages

from this area might be overestimated due to poor

bleaching (Anoop et al. 2012). Anoop et al. (2012) did

not present any information on the sedimentology and the

type of OSL analysis of this sample, and hence we were

unable to use this for our studies. We took care in col-

lecting the most suited samples for optical dating. The

samples were collected from thin sand lenses embedded

in gravel units or the lacustrine units. Sedimentation of

thin sandy lenses even in gravel units represents waning

phase of flood and does not represent a high-energy

sedimentation process as stated by Anoop et al. (2012),

and lakes in general represent a low-energy sedimentary

regime. We surmise that such samples would have a finite

time for bleaching.

Fig. 4 Meandering reach of the Spiti River from downstream Lingti

in lower Spiti valley. Note that the meandering channel has incised a

narrow gorge, with entrenched meanders. The river incises its

meanders thereby increasing sinuosity in response to episodic uplifts

Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984 1971

123

Results

Lithofacies

Parallel bedded gravel

This facies comprised moderately sorted, weakly imbricated,

parallel bedded gravel up to 10–40 m thick and is exposed

towards the headwaters of the river at Losar and Hansa. Indi-

vidual beds are internally fining upward with clast size ranging

from 2 to 10 cm with smaller clasts being more angular

(Fig. 5a). The matrix comprises coarse-grained sand, up to

5 % by volume. The unit includes thin lenses (10–25 cm) of

rippled fine sand. This facies towards the downstream trans-

forms into imbricated well-sorted gravel. The facies character

suggested that it is a deposit of a glacier outwash plain where

sedimentation took place under sheet flow during high flow

conditions (Gustavson and Boothroyd 1987).

Well-sorted imbricated gravels

This facies comprises 2- to 15-m-thick well-sorted clast-

supported gravels. Clasts range from 2 to 15 cm in size, are

well rounded and show imbrications. Internally, the

lithofacies units are divided into several fining upward

units (Fig. 5b). Laterally, the individual units are lensoidal,

showing development of cross-beds with erosional bases.

Often, lenses of cross-bedded fine sand separate deposi-

tional episodes. Alternating rippled fine sand and silt or

poorly sorted matrix-supported gravel units in general

overlie the facies. These arise from channelized flow

deposited in form of a braid bar. The association between

alternating rippled sand and silt suggests the development

of channel levee, while that with poorly sorted matrix-

supported gravel suggests channel disruption due to land-

slide activity (Srivastava et al. 2008; Ray and Srivastava

2010).

Table 1 Radioactive element concentrations, dose rates, palaeodose and ages of the samples collected from different sections and terrace

deposits along the Spiti River

Sample no. Laboratory no. Depth (m) U (PPM) Th (PPM) K (%) Palaeodose (Gy) Dose rate(Gy/ka)

Age (ka)

Mean Least Mean Least

Landslide zone (N 32� 020 13.300 E 78� 150 13.500)

SP-1 LD-217 2.0 5.0 1.68 28 ± 10 27 ± 6 2.6 ± 0.2 11 ± 4 11 ± 3

Seko-Nasung section (N 32� 090 55.800 E 78� 070 07.000)

SP-2 LD-218 12 0.6 1.5 1.33 18 ± 4 14 ± 2 1.7 ± 0.1 10 ± 3 8 ± 1

SP-3 LD-219 6 1.8 4.1 1.48 15 ± 3 15 ± 1 2.4 ± 0.2 6 ± 1 6 ± 1

SP-4 LD-220 26 0.8 6.3 1.58 34 ± 11 20 ± 3 2.3 ± 0.2 15 ± 5 13 ± 2

Hansa section (N 32� 260 4800 E 77� 500 1700)

SP-5 LD-221 12.5 1.0 6.5 1.97 40 ± 7 37 ± 3 2.7 ± 0.3 15 ± 3 14 ± 2

SP-6 LD-300 6 1.4 5.0 1.62 17 ± 3 17 ± 1 2.3 ± 0.2 8 ± 2 7 ± 1

SP-7 LD-301 0.7 2.3 5.7 1.73 24 ± 8 20 ± 4 2.7 ± 0.2 9 ± 3 7 ± 1

Kioto section (N 32� 260 14.500 E 77� 540 25.500)

KyTL Kioto 13 1.4 7.7 0.8 16 ± 2 16 ± 1 1.8 ± 0.1 10 ± 1 9 ± 1

SP-8 LD-302 24 1.2 3.5 1.81 26 ± 4 23 ± 1 2.4 ± 0.2 11 ± 2 10 ± 1

Pagmo-Hul section (N 32� 240 20.300 E 77� 560 11.100)

SP-11 LD-305 48 0.6 4.3 1.56 66 ± 9 57 ± 6 2.1 ± 0.2 32 ± 4 28 ± 3

Terraces at Kaza (N 32� 150 07.500 E 78� 020 11.7100)

SP-12 LD-231 2.6 5.5 1.78 27 ± 10 22 ± 3 2.8 ± 0.2 10 ± 3 8 ± 1

SP-13 LD-232 1.7 4.8 1.78 36 ± 2 25 ± 4 2.6 ± 0.2 14 ± 9 10 ± 2

SP-14 LD-233 3.1 8.1 2.4 38 ± 9 31 ± 6 3.7 ± 0.3 10 ± 2 9 ± 2

Lingti section (N 32� 060 30.900 E 78� 100 56.400)

SP-15 LD-234 32 0.3 2.6 0.86 23 ± 9 15 ± 2 1.3 ± 0.5 19 ± 8 12 ± 2

Sumdo section (N 32� 030 03.300 E 78� 360 21.400)

SP-20 LD-212 30 2.6 4.3 2.42 121 ± 22 102 ± 7 3.3 ± 0.3 37 ± 8 31 ± 4

Salkhal section (N 31� 530 27.000 E 78� 340 53.000)

SP-21 LD-213 58 2.8 5.4 2.73 127 ± 44 110 ± 15 3.7 ± 0.4 34 ± 12 30 ± 5

Hurling (N 32� 040 11.600 E 78� 350 50.800)

SP-22 LD-214 2.0 6.5 1.78 143 ± 10 140 ± 8 2.7 ± 0.2 53 ± 6 51 ± 5

Retti section (N 31� 570 18.200 E 78� 360 08.200)

SP-23 LD-215 1.6 5.8 1.57 128 ± 21 121 ± 7 2.4 ± 0.2 54 ± 10 51 ± 5

The average of the lowest 30 % palaeodoses was used in age estimation. Moisture content of 5 ± 5 % was assumed for all samples, and the cosmic ray Gammacontribution was calculated following Prescott and Stephan (1982)

1972 Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984

123

Poorly sorted matrix-supported angular gravel

Poorly sorted, matrix-supported angular gravels are

5–30 m thick. Clasts in this facies are disorganized and

range from few cm to 1.5 m except at few places where it

show the development of weak bedding. The individual

units are devoid of internal physical structure. Thin units

of fine sand often separate gravel units. Laterally, this

lithofacies runs for several tens of meters and forms debris

cones that are often vertically followed by parallel lami-

nated clays and imbricated well-sorted gravels. These were

a consequence of massive landslides or slope failure of

debris cones that eventually dammed the river channel.

Parallel laminated clay

This facies is recognized into two subfacies. Subfacies-a

comprise 0.5- to 1.0-m-thick units of 2- to 3-mm-thick

varved clay laminae with light and dark colours. Subfacies-

b show yellowish centimetre scale clayey laminations with

no colour alternation (Fig. 6a). These are interlayered with

rippled or laminated fine sand. At places, it also shows iron

reddening and moderate bioturbation.

In Subfacies-a, light-coloured layers were deposited

under higher-energy conditions when glacial melt water

added sediment to a lake. During winter, when melt water

and input of associated suspended sediments are reduced,

and the lake surface freeze, dark laminae are formed.

Subfacies-a indicates deposition in a lake with strong

seasonality with temperatures reaching below freezing.

Subfacies-b lacks varves but contains rhythmites in the

form of silty and sandy layers, indicating longer summers

and short winters, with temperatures uniformly above

freezing point. The iron reddening and bioturbation sug-

gests shallowing of the lake with sub-aerial exposure of the

sediments. This is a warm and dry episode.

Cross-bedded sand

This 1.5- to 4.0-m-thick facies comprises fine to medium

sand showing planar and trough cross-laminations

(Fig. 6b). This facies usually overlies well-sorted imbri-

cated gravel and is overlain by alternating rippled fine sand

Fig. 5 Lithofacies a parallel bedded gravel, b well-sorted imbricated

gravels

Fig. 6 Lithofacies a parallel laminated clays, b cross-bedded sand

Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984 1973

123

and silt lithofacies. The individual units are divisible into

several fining upward depositional episodes that are lensoid

in lateral geometry. This facies is prevalent in the sections

at the confluence Parachu and Spiti rivers at Sumdo.

These are the deposits of channel bars. The confluence

played an important role in the formation of sandy channel

bars in an environment dominated by gravel transport. At

the confluence, the channel width and sediment load of the

main channel of Spiti increase and this in turn reduced

stream power of the channel. This condition promoted

sediment partitioning and development of sand-dominated

bars.

Parallel laminated sand

It is 0.25- to 4-m-thick parallel laminated grey-coloured

fine sand. The individual laminae are from mm to a cm

thick that are often interbedded with ripple-laminated fine

sand. It is found towards the top of well-sorted imbricated

gravel and cross-bedded sand and is sometimes interbedded

with matrix-supported angular gravel and parallel lami-

nated clays.

This facies forms a bar top when associated with well-

sorted imbricated gravel and cross-bedded sand, which was

deposited during receding flood conditions. It is associated

with matrix-supported gravel, indicating sedimentation

during the waning phase of landslide event, in small

channels and rills that are often developed on the surface of

a landslide cone. The facies when associated with parallel

laminated clays indicate shallowing phase of lacustrine

sedimentation.

Lithofacies associations

Based on genetic link, sedimentary facies can be grouped

into three lithofacies associations, viz. A, B and C.

Lithofacies association A is made up of thick units of

parallel bedded gravels, interbedded with thin lenses of

fine to medium sand. The sandy units may be parallel

laminated or cross-bedded. These are deposits of glacial

outwash. Lithofacies association B comprises well-sorted

imbricate gravels, followed by cross-bedded sand and

parallel laminated sand with few or no muddy units

associated with it. At places, the sequence is interbedded

with parallel bedded gravels. The thickness of this facies

association sometimes exceeds 40 m and extends several

kilometres laterally. Vertically, it is often consists of

several fining upward depositional episodes. This indi-

cates sedimentation in a channel on an accreting bar, and

lower amounts of mud indicate that the channel was

braided with high bed load. The banks were unstable, and

sediment from the hill slopes was being easily eroded and

transported to the channel.

Lithofacies association C is made up of matrix-sup-

ported angular gravels, followed by parallel laminated clay

and intermittent parallel laminated sand. This facies asso-

ciation overlies channel bound deposits and indicates for-

mation of a lake due to channel blockage by landslide

(Phartiyal et al. 2009a, b). A lateral litholog of *600 m

near Seko-Nasung (described later) indicated landslide-

borne sediment at the base followed vertically by a later-

ally lensoid unit of parallel laminated clays, capped by

channel deposits. Internally, the lacustrine deposits are

composed of several shallowing cycles with parallel lam-

inated sand marking a shallowing event.

Stratigraphy of the sequences and luminescence dating

Twelve representative sections, depending upon the max-

imum lithofacies representation and accessibility, were

chosen to understand the variation in sedimentation pattern

and morphostratigraphy along the river valley (Fig. 1), and

of these 10 sections were optically dated. The results of

luminescence dating are listed in Table 1. In the following,

we describe the landform, sedimentology, chronology and

seismites within these sections from the origin of the river

to its confluence with the river Sutlej.

Losar section (N 32� 260 2800 E 77� 460 26.500)

This *15-m-thick section, rises from the riverbed, is

located near the headwaters (Fig. 7a). The basal 13 m is

composed of lithofacies association A that is overlain by

2-m-thick unit of lithofacies association B. Moving *2 km

downstream of Losar, the basal unit pinches out and mer-

ges into lithofacies association A. This suggests that the

area was under the influence of paraglacial processes

depositing sediments via sheet flows followed by braided

channelized conditions.

Hansa section (N 32� 260 4800 E 77� 500 1700)

This section is located * 8 km downstream of Losar on

the left bank of the river (Fig. 7b) where a 24-m-thick

section rises from the riverbed (Fig. 7c). The stratigraphy

of basal 14-m-thick deposits, similar to that exposed at

Losar, comprises lithofacies association A. This is overlain

by *10 m of lithofacies association B. Seismites are seen

in the middle Hansa section. These are of simple mor-

phology constituting of convolute and pinch and swell

structures.

The sample collected from the top of the basal unit

yielded an age of 14 ± 2 ka (SP-5), and two samples from

the middle and top of the overlying units gave ages of

7 ± 1 ka (SP-6 and SP-7). This suggests that until 14 ka

1974 Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984

123

glacial outwash plain was extended till Hansa and

was subsequently taken over by fluvially dominated

environment.

Kioto section (N 32� 260 14.500 E 77� 540 25.500)

This section is located *4 km downstream of Hansa where

basal *9 m is composed of lithofacies association A

which is overlain by *20 m of lithofacies association C

(Fig. 8a). Several levels of seismic structures are also

noticed in the Kioto palaeolake section (Sangode and

Mazari 2007).

The lithofacies of the section indicates that a paraglacial

sheet flow was interrupted by a landslide that gave way to a

landslide-dammed lake sequence (Fig. 8b). Two samples

collected from the top of the basal unit (SP-8) and the

bottom of the lacustrine unit (KYTL) yielded ages of

10 ± 1 and 9 ± 1 ka, respectively.

Pagmo-Hul section (N 32� 240 20.300 E 77� 560 11.100)

The 50-m-thick section that lies on the right bank of the

river is mainly composed of lithofacies association B

(Fig. 9). The constituent gravels are mostly sub-rounded

except for top *5 m of imbricated well-rounded gravels.

This section is the result of braided channel conditions.

The angularity of the gravels indicates the clasts are

recycled from glacially deposited sediments and may rep-

resent a phase of high glacial discharge. This may indicate

that, moving downstream, glacial sheet flows were

channelised, indicating a transformation from paraglacial

regime to braided glacial stream environment. The sample

collected from the basal part of the section yielded an age

of 28 ± 3 ka (SP-11).

Kaza section (N 32� 150 07.500 E 78� 020 11.7100)

This section is located *2 km upstream Kaza town. The

section consists of terraces, viz. T1 located at 3.5 m and T2

at 11 m above the riverbed. A fan terrace FT3 overlies the

terrace T2 (Fig. 10). Thus, morphostratigraphically, T-2 is

the oldest, which is followed by the deposition of FT3 and

T1. Terraces T1 and T2 are parallel to the Spiti River and

are largely composed of several fining upward units of

lithofacies association B, whereas FT3 was deposited by a

tributary joining the Spiti from its right bank and is mod-

erately sorted, stratified sub-angular gravels with lenses of

cross-bedded fine sand.

Three samples collected from T2, FT3 and T1 yielded

ages of 10 ± 2 ka (SP-13), 9 ± 2 ka (SP-14) and 8 ± 1 ka

(SP-12), respectively.

Seko-Nasung section (N 32� 090 55.800 E 78� 070 07.000)

This section is located *12 km downstream of Kaza. The

section from the base is composed of 10- to 15-m-thick

gravel and parallel laminated clays representing lithofacies

association C followed by 10–12 m of well-sorted imbri-

cated gravel of lithofacies association A. Good lateral

exposure of this section provided an opportunity to

understand the geometries of individual lithofacies asso-

ciations. A lateral litholog of 600 m suggests that the basal

Fig. 7 Sedimentary

lithosection and chronology of

sections at a Losar, b Hansa.

c Field photograph showing

20-m-thick sequence rising

from the riverbed at Hansa

Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984 1975

123

matrix-supported debris resting on the riverbed is laterally

extensive and runs for more than 600 m. The lithofacies

forming a lacustrine sequence is lensoid with a maximum

thickness of *15 and 480 m of lateral extent. The

overlying fluvial gravels are also laterally extensive and are

vertically divisible into several fining upward, lensoid,

gravel bodies of lithofacies association A. Figure 11 shows

the lateral litholog of this section. Two levels of simple

Fig. 8 Kioto section

a sedimentary lithosection with

chronology, b photograph

showing the lensoid lacustrine

units and landslide cone at the

base

Fig. 9 a Lithosection and

chronology of Pagmo-Hul

section. b Photograph showing

cross-bedded angular gravels at

Hul

1976 Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984

123

convolute structures, pinch and swell structures are seen in

this section. The sequences at Seko-Nasung and Kioto also

suggest that landslides that blocked the Spiti River to be

more than 500 m in width.

A sample collected from near the base of the basal unit

yielded an age of 13 ± 2 ka (SP-4) and those collected

from the base and towards the top of the overlying fluvial

unit yielded ages of 8 ± 1 ka (SP-2) and 6 ± 1 ka (SP-3),

respectively. This indicates the blockage of channel and the

formation of a lake between 13 and 8 ka, and a fluvial

regime between 8 and 6 ka. The sequence was incised by

the river *6 ka.

Lingti Section (N 32� 060 30.900 E 78� 100 56.400)

This section occurs at a major geomorphic change as the

shape of the valley abruptly changes from a broad U-shape

to narrow V-shape, and this also shows a shift in terrace

configuration, that is, relict fluvial deposits rest on a bed-

rock bench. This section is located at the left bank of Spiti

River on Lingti-Lalung road. A 55-m-thick fluvial

sequence resides on *25 m of exposed bedrock bench

(Fig. 12a). From the base upwards, the sequence starts with

*4-m-thick debris of lithofacies association C which is

overlain by four cycles of fining upward units of imbricated

gravels of lithofacies association B (Fig. 12a). The section

includes strong deformation in the form of a folded fine

sand unit penetrated by flame structures (Fig. 12b–d). The

deformed units also show several faults of centimetre scale

and flame structures along with complex convolutes,

pseudonodules and pinch and swell structures.

This sequence formed by fluvial aggradation and has

preserved evidence of a strong seismic event. Such defor-

mation structures may also form due to landslide close to a

lake but the fact that the sequence does not show any

lacustrine or landslide-related sedimentary association

indicates that perhaps seismic activity was responsible for

this deformation feature. A sample from the deformed unit

*32 m below the surface yielded an age of 12 ± 2 ka

(SP-15). This indicates that the aggradation started prior to

12 ka and the seismic activity occurred at *12 ka.

Sumira Village section (N 32� 030 0000 E 78� 290 18.500)

This section contains an epigenetic gorge and palaeovalley

and it is located at the junction of a tributary. The palae-

ovalley, on the right bank of the Spiti River, is located at

9.5 m above the present river level. It is filled with several

depositional cycles of matrix-supported angular gravels.

The gorge is relatively narrow and is * 27 m deep as

measured from the top of the rocky ledge present at the

right margin of the palaeovalley (Fig. 13).

The older channel of the Spiti River aggraded, shifted its

course and incised to form the palaeovalley and epigenetic

gorge. In the Alaknanda valley, such epigenetic gorges

are mapped along the channel at several places (Pant 1975)

and similar phases of aggradation have been documented

(Srivastava et al. 2008). When a channel is laterally dis-

placed as a result of either river blockage or rapid aggra-

dation and incision occurs in bedrock rather than

unconsolidated fills to base level, fossil valleys and

Fig. 10 a Field photograph showing river terraces T2, T1 and the fan

terrace FT3 with the luminescence chronology. Note that morpho-

stratigraphically the terraces T2 and T1 represent phase of one valley

aggradation, whereas FT3 is a fan that sits on T2 and hence is younger

than this terrace. b Schematic cross-section along X–Y showing the

morphostratigraphy of the terraces and fan sequence

Fig. 11 Lateral litholog and

luminescence dates of Seko-

Nasung section. Note the

lensoid nature of the lacustrine

unit and that the aggradation in

the Spiti River took place up to

*6 ka

Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984 1977

123

epigenetic gorges are formed (Ouimet et al. 2008). There-

fore, the sedimentary fill preserved at Sumira, and the epi-

genetic incision represents a phase of rapid filling of the

valley. Unfortunately, we could not get any datable material

from the section.

Hurling section (N 32� 040 11.600 E 78� 350 50.800)

The basal * 5 m is unexposed, and the exposed part of the

sequence consists of * 35 m of poorly sorted matrix-

supported gravels and parallel laminated clays of lithofa-

cies association C. The topmost 1.5 m is made up of

matrix-supported sub-angular gravels.

The section is the result of a landslide-dammed lake on

the Spiti River. A sample below the 3 m from the top sur-

face of the sequence yielded an age of 51 ± 5 ka (SP-22).

Sumdo section (N 32� 030 03.300 E 78� 360 21.400)

There are two river terraces at Sumdo, namely T2 and T1

(Fig. 14a). The terraces consist of bedrock benches

with overlying alluvial cover. The upper terrace T2 lies

*130 m above the present river level with the top 30 m

being alluvial cover. The lower terrace T1 lies at *45 m

above the river bed with *35 m of alluvial cover. The

alluvial covers are composed of several cycles of fining

upward imbricated gravels of lithofacies association B

(Fig. 14b).

This section shows two phases of alluviation separated

bedrock incision. The river incised further from T1 to T0

following a second phase bedrock incision. The sample

dated from near the bottom of T1 yielded an age of

31 ± 4 ka (SP-20). The sample collected from T2 showed

luminescence saturation, but morphostratigraphically it is

older than 31 ka.

Salkhal section (N 31� 530 27.000 E 78� 340 53.000)

A *90-m-thick sedimentary sequence rests on 10 m of

exposed bedrock bench. The sequence starts with *40 m

of channel sediments of lithofacies association B, which is

divisible into several fining upward depositional episodes.

This is followed by *50 m of landslide-dammed lake

sediments of lithofacies association C (Fig. 15).

The section is the result of landslide damming of the

Spiti River after 30 ± 5 ka (SP-21). The uplift and bedrock

incision occurred later.

Fig. 12 a Lithosection and

luminescence chronology of the

section at Lingti. Note the

presence of a bedrock bench

below the alluvial sequence.

b Seismically deformed sandy

unit, c flame structure, and

d deformed laminae of the unit

are enlarged parts (b)

Fig. 13 Geomorphic configuration at Sumira. Note the presence of

the sediment filled palaeovalley and the epigenetic gorge

1978 Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984

123

Retti section (N 31� 570 18.200 E 78� 360 08.200)

This section contains two levels of river terraces, namely

T2 (upper) and T1 (lower). T2 and T1 are *150 and *66 m

above the riverbed, respectively. The 33 m of cover of T2

is composed at the base of 30 m of landslide-dammed

lacustrine sediments of lithofacies association C, while the

top 3 m is made up of imbricated gravels of lithofacies

Fig. 14 a Photograph showing

the terraces at Sumdo. Note the

presence of a bedrock bench

below the two levels of terraces.

b Schematic configuration of

the terraces, with lithosections

of the alluvial cover of the two

terraces with chronology

Fig. 15 a Lithosection of the

sedimentary sequence at

Salkhal. Note the presence of

bedrock below the alluvial

sequence, with luminescence

chronology. b Photograph

showing the section at Salkhal

Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984 1979

123

association B. T1 consists of a basal 3 m of channel sedi-

ments of lithofacies association B followed by 13 m of

lacustrine sediments representing lithofacies association C.

T2 preserves an episode of landslide damming. OSL date

from the top of the sequence indicates this landslide and

subsequent damming took place at 51 ± 5 ka (LD-215). A

similar event was also dated at Hurling at 51 ± 5 ka (LD-

215).

Discussions

Style of valley aggradation in an arid region

of Himalaya

The sedimentary architecture of cliff sections preserved

along *150 km stretch of Spiti River, from the headwaters

to its confluence with the Sutlej River, was examined. In

the headwaters of the Spiti valley, lithofacies composition

of sequences from Losar to Hul indicates paraglacial pro-

cesses in the form of sheet flow deposition followed by

episodes of landslide and channel damming. Luminescence

dating at Hul, Hansa and Kioto suggests that paraglacial

sedimentation started *28 ka (basal age at Hul sequence)

and continued up to 14 ka (basal age at Hansa, Fig. 7b).

Upper part of landslide sediment at Kioto was dated to

10 ka and the lake sediments 9 and 7 ka at Hansa (Figs. 7b,

8). This implies that valley aggradation started due to

increased sediment supply from glacial outwash between

28 and 14 ka, with channel damming and formation of a

lake between 14 and 7 ka. Further downstream, at Kaza,

sedimentation dominated by channel processes took place

between 10 and 8 ka with tributary channels carrying high

sediment loads forming fans. The progradation of tributary

fans into the main channels implies that the hydraulic

competence of the main channel, as compared to the

present day, was low. Similarly, landsliding and lake for-

mation at Seko-Nasung took place between 13 and 7 ka,

and the sequence at Lingti was also deposited around the

same time (12 ka, Fig. 12). Sequences at Hurling, Sumdo,

Salkhal and Retti all rest on bedrock benches and were

deposited from [30 to \50 ka, all of which involved

landslide-dammed lacustrine aggradation. Thus, extensive

mass wasting and channel damming facilitated aggradation

in the entire valley during 14–6 ka in the upper valley and

at [50–30 ka in the lower valley.

Rivers in the Himalaya aggrade and incise in response to

(1) climate-related factors such as discharge, sediment

load, vegetation cover and (2) tectonic perturbations such

as local uplift and the subsequent formation of intermon-

tane basins. However, the response time of a river to global

climatic changes and the style of aggradation depend upon

climatic and orographic domains through which it drains

(Blum and Tornqvist, 2000). Spiti River lies in rain the

shadow zone of Himalaya with *50 mm rainfall annually

and temperatures remaining below freezing during most

part of year. During abnormal monsoon years, when the

valley receives unusually high rainfall (*1,000 mm; see

Bookhagen et al. 2005a, b), massive landslides block the

main channel and form landslide-dammed lakes. Such

episodes produce a sedimentary profile, exhibiting a

channel deposit at the base followed by landslide-borne

gravels and fine-grained lacustrine sediments (Phartiyal

et al. 2009a, b). Trans-Himalayan rivers, such as river Spiti,

have lower discharge, higher sediment to water ratio and

lower stream power than their counterparts in wetter

Himalaya, allowing landslide-dammed lakes to last longer

and their sedimentary sequences to be preserved. It has

been reported that similar landslide-dammed lake sustained

for several thousand years in moderately humid Baspa

valley also (Bookhagen et al. 2006).

Glacial, landslide and fluvial processes are the geo-

morphic agents that sculpt mountains. A review of palae-

ogeomorphic changes in the trans-Himalayan region

indicates a higher frequency of landslides and landslide-

dammed lakes soon after the last glacial phase (Sundriyal

et al. 2007; Dortch et al. 2009). Dortch and others using

cosmogenic radionuclide dated several palaeolandslides in

the NW Himalaya (see Dortch et al. 2009, 2011) including

Lahul and Spiti valley and inferred that these events

occurred between 15 and 5 ka. This age range of 15–5 ka

landslides occurrences correlated well with period of post-

LGM increased monsoon (see Prell and Kutzbach 1987;

Bookhagen et al. 2006).

In the present work, a sand lens from a massive land-

slide downstream of Lingti is also dated to 11 ± 3 ka (SP-

1; Table 1) and belongs to the same time frame. Figure 16

shows published chronology of landslide and synchronous

aggradation in the Spiti River valley (Dortch et al. 2009).

Similar inferences drawn from chronological records of

landslides in the Italian Dolomites (Soldati et al. 2004) and

from the Argentine Andes (Trauth et al. 2003) suggest

increased landslide and channel damming in response to

high rainfall. Chronological data for glacial stratigraphy in

monsoon-affected regions of Himalaya show that glaciers

expanded to their maximum extent during Marine Isotope

Stage III (MIS III). In the western Himalaya, cosmogenic

radionuclide dating of moraines in the Lahul valley

(adjacent to and west of Spiti) suggests glacial advance (the

Batal Glacial Stage) at 15.5–12 ka and again at 11.4–10 ka

(Kulti glacial stage; Owen et al. 2001). Chronologies of

moraines of Pin and Thangi valleys indicated maximum

glaciation at *18 ka (Scherler et al. 2010). The chronol-

ogy of landslide-driven aggradation of Spiti River, pre-

sented here, indicates (i) extensive mass wasting during the

intensified monsoon after last glacial phases of MIS-II and

1980 Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984

123

MIS-III and (ii) the basal part of the sequence from Losar

to Hul suggests advance of glaciers in the valley head at

28–14 ka. Thus, the aggradation history of the Spiti valley

suggests that valley filling by mass wasting occurred during

an intensified monsoon and the incision took place during

middle Holocene when sediment to water ratio decreased.

Sediment in such river systems is largely supplied from the

hill slope failures, tributary fans and moraines, throughout

the valley. During drier conditions, in rivers of wetter

Himalaya, for example, Alaknanda, only upper and middle

part of the catchment become arid–semiarid and the lower

part where aggradation occurs remains wet and vegetated.

Thus, during the transition from a dry to wetter climate,

sediment is largely supplied from the upper–middle parts

of the valley and deposited in its lower reaches. Therefore,

most aggradation in Alaknanda occurred in form of chan-

nel-borne aggradation (Ray and Srivastava 2010). This

glacial–paraglacial hypothesis enables landform connec-

tivity in a glacially sourced river and suggests that lower

part of the valley alleviates and derives sediments from the

deglaciated part of the upper valley mostly during warmer

interludes (Church and Slaymaker 1989).

Geomorphic evolution of the Spiti River valley

since the last glacial phase

The geomorphic evolution of the Spiti River valley is

determined by three factors, viz. (1) glacial action, (2) mass

wasting and (3) tectonics in trans-Himalayan. The present

study suggests a three-stage evolution of Spiti valley dur-

ing the past 50 ka.

Stage I (28–14 ka): During the last glacial phase of

weak monsoon, glaciers expanded in the Spiti valley

(suggested by glacial outwash gravel up to Kioto), and

river discharge was controlled by glacial melting. This

resulted in a braided river system, and the sediment

transport and deposition were controlled by paraglacial

processes. The slopes were barren and frigid, leading to

marked physical weathering and debris cone formation.

Stage II (14–8 ka): In this phase of monsoon intensifi-

cation, the Spiti River valley experienced periods of high

rainfall. Debris cones cascaded into the main channel as

debris flows and unstable hill slopes generated massive

landslides causing damming and formation of numerous

small lakes throughout the length of the river (Bookhagen

et al. 2006). These lakes lasted typically for 3–5 ka. Wetter

conditions after 8 ka increased vegetation and stabilized

both the slopes and debris fans. Such a condition reduced

sediment load in the channel and increased stream power.

This in turn resulted in increased sediment removal and

valley incision. Incision of lake sediments took place

*6 ka as is evident from the Seko-Nasung section. Such

conditions prevailed along the valley in the region

upstream of Hurling. Downstream from Hurling, Sumdo,

Salkhal and Retti, the sequences suggest similar palaeo-

geomorphic and climatic conditions during [30–*50 ka.

This corresponds to an older episode of warming and

intensified monsoon that preceded the MIS III/IV. Rainfall

at the termination of glacial phases and initiation of wet

conditions is normally episodic when monsoon front

competes with the cold fronts and a local build-up of rain

systems takes place (Li and Fu 2004). Such phases generate

Fig. 16 Chronology of

landslides and aggradation in

the Spiti River valley, showing

a role for increased SW

Monsoon (Modified after

Dortch et al. 2009). Phase I

occurred at 50–30 ka and Phase

II at 15–6 ka during warm

phases

Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984 1981

123

landslides and slope failures. We envisage such a climatic

set-up in Spiti valley during 14–8 ka.

Stage III (\7 ka): The upper part of the valley to Seko-

Nasung is wide, where the channel is braided and the relict

fluvial deposit rises from the present day riverbed. How-

ever, from Lingti downstream, the channel is narrow,

meandering, and all the sedimentary sequences are located

above the channel on bedrock benches. This implies that

this valley responded to tectonic deformation along a

normal fault where the valley upstream of Lingti is a

downthrown block. Based on the youngest aggradation

date derived from Seko-Nasung, we place this fault activity

\6 ka and infer a fault just upstream Lingti at Mane.

Recent studies on sedimentary profile from a palaeolake at

Mane suggest four episodes of tectonic activity along this

fault and that the lake was formed in response to early

Holocene warming and increased rainfall (Anoop et al.

2012).

The transitions between geomorphic segments in lower

and upper valley occur between Seko-Nasung and Lingti

villages. Changes in channel planform from braided to

meandering, incised river bed and the occurrence of

uplifted terraces, in the meandering stretch, from down-

stream of Lingti indicate the presence of a fault. We also

report seismites near Lingti optically dated to *7 ka.

Thus, the study indicates that this fault was reactivated at

*7 ka. Structural observations in the vicinity (Lingti val-

ley) by Neumayer et al. (2004) suggest the presence of

bookshelf-type extensional faults or steeply dipping con-

jugate brittle normal faults. This is in accordance with

instrumentally monitored seismicity in this region (see

Molnar and Chen 1983). Such faults are associated with

faulting of lake sequences and soft sediments deformation

in Lingti valley and adjoining area (Neumayer et al. 2004)

as described previously (Mohindra and Bagati 1996;

Baneerjee et al. 1997; Dubey and Bhakuni 2004; Singh and

Jain 2007). It is suggested that such brittle deformation can

occur in the hanging wall extension of KCnf. Several other

such faults have been well documented from the trans-

Himalayan region (Thiede et al. 2006; Hintersberger et al.

2010). These faults indicate E–W-oriented crustal exten-

sion, contemporaneous to N–S shortening in the Himalaya.

This, however, needs further confirmation.

In summary, the present study indicates that during

Early-Mid Holocene, Spiti River valley experienced

deglaciation, increased precipitation and seismic activity

along the KCnf. This necessitates an explanation as to

whether active land sliding was facilitated just by increased

rainfall or glacial retreat and subsequent debuttressing of

slopes and/or seismic shaking along KCnf acted as addi-

tional forces.

In the Alpine SE France, rock slope failures concentrated

within the area that was ice-covered during LGM. This

suggested glacial debuttressing to be a controlling factor

(Cossart et al. 2008). In our view, glacial debuttressing and

enhanced precipitation after the LGM might have triggered

the landslides. The role of KCnf may at present be able to be

discounted because the locations of the major landslides in

the area do not follow the fault trend.

Conclusions

Following conclusions can be drawn from this study:

1. The Spiti River valley can be divided into two

segments: (i) upper valley with broad, braided channel

where relict sedimentary sequences rise from the

riverbed; (ii) lower valley that is narrow, meandering,

incised into the bedrock, and here, the relict fluvio-

lacustrine deposits sit on the bedrock bench located

above the riverbed. The transition of these geomorphic

changes lies between Seko-Nasung and Lingti at

Mane.

2. Sedimentary sequences have three lithofacies associ-

ations: (A) representing glacial outwash; (B) indicative

of sedimentation in an accreting bar under braided

conditions; and (C) representing formation of lakes

due to channel blockage by landsliding. The valley is

usually arid, so any period of mass wasting-related

channel damming and lake formation is likely during

intensified monsoon phases (Bookhagen et al. 2005a,

b; Phartiyal et al. 2009a, b)

3. Luminescence dating indicated two phases of intensi-

fied monsoon during at 14–8 and 50–30 ka.

4. Between Seko-Nasung and Lingti at Mane, a fault is

inferred, which developed broad and braided upper

valley and narrow and meandering lower valley.

Luminescence dating suggests that this fault was

active *7 ka.

Acknowledgments We thank the Directors of the Wadia Institute of

Himalayan Geology, Dehradun, and the Birbal Sahni Institute of

Palaeobotany, Lucknow, for encouragement. Prof. A.K. Singhvi and

Prof. R.J. Wasson are acknowledged for pre-submission reviews on

the manuscript. Bodo Bookhagen and two anonymous reviewers

helped improve the manuscript. Drs. Rasmus Theide, Barun

Mukherji, S. Mukherjee topic editors, is thanked for his efforts in

bringing up this contribution.

References

Aitken MJ (1998) An Introduction to optical dating. Academic Press,

London

Anoop A, Prasad S, Basavaiah N, Brauer A, Shahzad F, Deenadaya-

lan K (2012) Tectonic versus climate influence on landscape

evolution: a case study from the upper Spiti valley, NW

Himalaya. Geomorphology 145–146:32–44

1982 Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984

123

Baneerjee D, Singhvi AK, Bagati TN, Mohindra R (1997) Luminescence

chronology of seismites in Sumdo (Spiti valley) near Kaurik-

Chango Fault, northwestern Himalaya. Curr Sci 73:276–281

Bhargav ON, Ameta SS, Gaur RK, Kumar S, Agrawal AN, Jalote PM,

Sadhu ML (1978) The Kinnaur (H.P. India) earthquake of 19

January 1975: summary of geoseismological observations. Bull

Indian Geol Assoc 11:39–53

Bhargava ON (1990) Holocene tectonics south of the Indus Suture,

Lahaul-Ladakh Himalaya, India: a consequence of Indian Plate

motion. Tectonophysics 174:315–320

Bhargava ON, Bassi UK (1998) Geology of Spiti-Kinnaur, Himachal

Himalaya. Geol Sur of India Memoirs 124:1–210

Blum MD, Tornqvist T (2000) Fluvial responses to climate and sea-

level change: a review and look forward. Sedimentology 47(1):

2–48

Bookhagen B (in review) High resolution spatiotemporal distribution

of rainfall seasonality and extreme events based on a 12-year

TRMM time series, in review

Bookhagen B, Thiede R, Strecker MR (2005a) Abnormal Monsoon

years and their control on erosion and sediment flux in the high,

arid northwestern Himalaya. Earth Planet Sci Lett 231:131–146

Bookhagen B, Thiede R, Strecker MR (2005b) Late Quaternary

intensified monsoon phases control landscape evolution in the

Northwest Himalaya. Geology 33:149–152

Bookhagen B, Fleitmann D, Nishizumi K, Strecker MR, Thiede RC

(2006) Holocene monsoonal dynamics and fluvial terrace

formation in the northwest Himalaya, India. Geology 34:601–

604

Church M, Slaymaker O (1989) Disequilibrium of Holocene sediment

yield in glaciated British Columbia. Nature 337:452–454

Cossart E, Braucher R, Fort M, Bourles DL, Carcaillet J (2008) Slope

instability in relation to glacial debuttressing in alpine areas

(Upper Durance catchment, southeastern France): evidence from

field data and 10Be cosmic ray exposure ages. Geomorphology

95:3–26

Dortch JM, Owen LA, Haneberg WC, Caffee MW, Dietsch C, Kamp

U (2009) Nature and timing of large landslides in the Himalaya

and Transhimalaya of northern India. Quat Sci Rev 28:1037–

1054

Dubey AK, Bhakuni SS (2004) Development of extension faults on

the oblique thrust ramp hanging wall: example from the Tethys

Himalaya. J Asian Earth Sci 23:427–434

Gustavson TC, Boothroyd JC (1987) A depositional model for

outwash, sediment sources, and hydrologic characteristics,

Malaspina Glacier, Alaska: a modern analog of the southeastern

margin of the Laurentide Ice Sheet. Geol Soc Am Bull 99:

187–200

Hintersberger E, Thiede RC, Strecker MR, Hacker BR (2010) East-

west extension in the NW Indian Himalaya. Geol Soc Am Bull

122:1499–1515

Jain AK, Singh S, Manickavasagam RM, Joshi M, Verma PK (2003)

HIMPROBE programme: integrated studies on geology, petrol-

ogy, geochronology and geophysics of the Trans Himalaya and

the Karakoram. Mem Geol Soc India 53:1–56

Joshi M, Kothyari GC, Ahluvalia AD, Pant PD (2010) Neotectonic

evidences of rejuvenation in Kaurik-Chango fault zone, North-

western Himalaya. J Geog Info Sys 2:176–183

Keiffer DS, Steinbauer C (2012) Geotechnical remediation strategies

for the Ancient Monastery of Dangkhar, Spiti Valley, Himachal

Pradesh, India. Research and restoration report project- annual

report 2011, Institute of Applied Geosciences, Graz University

of Technology. Graz, Austria. http://savedangkhar.tugraz.at/

pdfs/2011/01_geotechnical%20remediation_hp.pdf

Korup O, Strom AL, Weidinger JT (2006) Fluvial response to large

rock-slope failures: examples from the Himalayas, the Tien shan,

and the southern Alps in new Zealand. Geomorphology 78:3–21

Leech ML, Singh S, Jain AK, Klamperer SL, Manickavasagam RM

(2005) The onset of India-Asia continent collision: early, steep

subduction by the timing of UHP metamorphism in the western

Himalaya. Earth Planet Sci Lett 234:83–97

Li W, Fu R (2004) Transition of the large-scale atmospheric and land

surface conditions from the dry to the wet season over Amazonia

as diagnosed by the ECMWF re-analysis. J Clim 17:2637–

2651

Mazari RK, Bagati TN (1991) Post-collision graben development in

the Spiti valley, Himachal Pradesh. J Himal Geol 2:111–117

Mohindra R, Bagati TN (1996) Seismically induced soft-sediment

deformation structures (seismites) around Sumdo in the lower

Spiti valley (Tethys Himalaya). Sed Geol 101:69–83

Molnar P, Chen WP (1983) Focal depths and fault plane solutions of

earthquakes under the Tibetan Plateau. J Geophy Res 88:1180–

1196

Montgomery DR, Dietrich WE (1992) Channel initiation and the

problem of landscape scale. Science 255:826–830

Mukul M, Jaiswal MK, Singhvi AK (2007) Timing of recent out-of-

sequence deformation in the frontal Himalayan wedge: insights

from Darjiling sub-Himalaya, India. Geology 35:999–1002

Murray AS, Wintle AG (2000) Luminescence dating of quartz using

an improved single aliquot regenerative-dose protocol. Radiat

Meas 32:57–73

Neumayer J, Wiesmayr G, Janda C, Grasemann B, Draganits E (2004)

Eohimalayan fold and thrust belt in the NW-Himalaya (Lingti-

Pin Valleys): shortening and depth of detachment calculation.

Austria J Earth Sci 95(96):28–36

Ni J, Barazangi M (1985) Active tectonics of western Tethyan

Himalaya above the underthrusting Indian plate: the upper Sutlej

river basin as a pull apart structure. Tectonophysics 112:277–295

Ouimet WB, Whipple KX, Crosby JP, Jhonson JP, Schildgen TF

(2008) Epigenetic gorges in fluvial landscapes. Earth Surf

Process Landf 33:1993–2009

Owen LA, Gualtieri L, Finkel RC, Caffee MW, Benn DI, Sharma MC

(2001) Cosmogenic radionuclide dating of glacial landforms in

the Lahul Himalaya, Northern India: defining the timing of late

Quaternary glaciation. J Quat Sci 16:555–563

Phartiyal B, Kothari G (2011) Impact of neotectonics on drainage

network evolution reconstructed from morphometric indices:

case study from NW Indian Himalaya. Zeitschrift fur Geomor-

phologie 56:121–140

Phartiyal B, Sharma A, Srivastava P, Ray Y (2009a) Chronology of

relict lake deposits in the Spiti River, NW trans Himalaya:

implications to Late Pleistocene-Holocene climate-tectonic per-

turbations. Geomorphology 108:264–272

Phartiyal B, Srivastava P, Sharma A (2009b) Tectono-Climatic

signatures during late Quaternary Period from Spiti valley, NW

Himalaya, India. Himal Geol 30:164–174

Prell WL, Kutzbach JE (1987) Monsoon variability over the past

150,000 years. J Geophys Res 92:8411–8425

Prescott JR, Stephan LG (1982) Contribution of cosmic radiation to

environmental dose. PACT 6:17–25

Ray Y, Srivastava P (2010) Widespread aggradation in the moun-

tainous catchment of the Alaknanda-Ganga River system:

timescales and implications to Hinterland-foreland relationships.

Quatern Sci Rev 29:2238–2260

Sangode SJ, Mazari RK (2007) Mineral magnetic response to climate

variability in the high altitude Kioto palaeolake, Spiti valley,

Northwestern Himalaya. Himal Geol 28:1–9

Scherler D, Bookhagen B, Strecker MR, Blanckenburg VF, Rood D

(2010) Timing and extent of late Quaternary glaciation in the

western Himalaya constrained by 10Be moraine dating in

Garhwal, India. Quatern Sci Rev 29:815–831

Singh S, Jain AK (2007) Liquefaction and fluidization of lacustrine

deposits from Lahaul-Spiti and Ladakh Himalaya: geological

Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984 1983

123

evidences of palaeoseismicity along active fault zone. Sed Geol

196:47–57

Singh S, Sinha P, Jain AK, Singh VN, Srivastava LS (1975)

Preliminary report on the January 19, 1975, Kinnaur earthquake

in Himachal Pradesh. Earthq Eng Stud 75:1–32

Sinha AK (1989) Geology of higher central Himalaya. Wiley,

New York

Soldati M, Corsini A, Pasuto A (2004) Landslides and climate change

in the Italian Dolomites since the Late glacial. Catena 55:141–

161

Srivastava P, Misra DK (2008) Morpho-sedimentary records of active

tectonics at the Kameng river exit, NE Himalaya. Geomorphol-

ogy 96:187–198

Srivastava P, Tripathi JK, Islam R, Jaiswal MK (2008) Fashion and

phases of Late Pleistocene aggradation and incision in Alak-

nanda River, western Himalaya, India. Quat Res 70:68–80

Srivastava P, Bhakuni SS, Luirei K, Misra DK (2009) Fluvial records

from the Brahmaputra River exit, NE Himalaya: climate-tectonic

interplay during Late Pleistocene-Holocene. J Quat Sci 24:175–

188

SRTM (2000) Shuttle radar topography mission (SRTM). USGS,

reprocessing by the GLCF, 2004. 3 arc second SRTM elevation.

The Global Land Cover Facility, College Park, Maryland

(Version 1.0)

Steck A, Epard JL, Vannay JC, Hunziker J, Girard M, Morard A,

Robry M (1998) Geological Transect across the Tso-Morari and

Spiti areas: the nappe structures of the Tethyan Himalaya.

Eclogae Geol Helv 91:103–121

Sundriyal YP, Tripathi JK, Sati SP, Rawat GS, Srivastava P (2007)

Landslide-dammed lakes in the Alaknanda basin, Lesser Hima-

laya: causes and implications. Curr Sci 93:568–574

Thiede R, Bookhagen B, Arrowsmith J, Sobel E, Strecker MR (2004)

Climatic control on rapid exhumation along the Southern

Himalayan front. Earth Planet Sci Lett 222:791–806

Thiede RC, Arrowsmith JR, Bookhagen B, Mc Williams M, Sobel

ER, Strecker MR (2006) Dome formation and extension in the

Tethyan Himalaya, Leo Pargil, Northwest India. Bull Geol Soc

Am 118:635–650

Trauth MH, Bookhagen B, Marwan N, Strecker MR (2003) Multiple

landslide clusters record Quaternary climate changes in the

northwestern Argentine Andes. Palaeogeog Palaeoclimat Palae-

oeco 194:109–121

Tucker GE, Slingerland R (1997) Drainage basin response to climate

change. Water Resour Res 33:2031–2047

Wobus C, Heimsath A, Whipple K, Hodges K (2005) Active out-of-

sequence thrust faulting in the central Nepalese Himalaya.

Nature 434:1008–1011

1984 Int J Earth Sci (Geol Rundsch) (2013) 102:1967–1984

123