Reconstruction of Late Quaternary climate and seismicity using fluvial landforms in Pindar River valley, Central Himalaya, Uttarakhand, India

Quaternary International xxx (2016) 1e17

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Reconstruction of Late Quaternary climate and seismicity using fluvial landforms in Pindar River valley, Central Himalaya, Uttarakhand, India Girish Ch. Kothyari a, *, Anil D. Shukla b, Navin Juyal b a b

Institute of Seismological Research, Raisan, Gandhinagar, Gujarat, India Physical Research Laboratory, Ahmedabad, Gujarat, India

a r t i c l e i n f o

a b s t r a c t

Article history: Available online xxx

Fluvial landforms in the Pindar River valley are investigated to understand the role of temporal variability in the Indian Summer Monsoon (ISM) and the spatial changes in crustal deformation. Employing the conventional geomorphological and sedimentological concepts, supported by optical dating, three major phases of valley-fill aggradation separated by phases on non-deposition are discerned. An oldest aggradation phase is dated to 33.5 ka during relatively strengthened ISM corresponding to the later part of pluvial Marine Isotopic Stage-3 (MIS-3). Following this, alluvial fan sedimentation impersistently continued during the declining phase of the ISM (until around 21 ka). A second major aggradation phase (17.5 kae13 ka) occurred during the post-LGM/lateglacial strengthening of the ISM in which contribution from tributary valleys overwhelmed the valley-fill sedimentation. A youngest aggradation phase dated to the middle to late-Holocene (8 kae3.6 ka), represents the transitional climate during which sporadic high sediment fluxes both from the upper catchment and tributary streams led to the development of fossil valleys (abandonment of old channels). The spatial variability in the incision/uplift rate, based on river strath terraces reveals that the terrain is undergoing differential crustal deformation. Two zones of relatively high crustal deformation are identified. These are located in the vicinity of the Main Central Thrust (MCT) and is attributed to the activity along the transverse fault and the in the inner Lesser Himalaya for which the thrust propagated fold associated with regional north-south compression is implicated. The study suggests that fluvial landforms (valley-fill and strath terraces) in the Pinder river valley are genetically related to the multimillennial scale changes in the ISM and spatial and temporal changes in the crustal deformation associated with regional compression. © 2016 Elsevier Ltd and INQUA. All rights reserved.

Keywords: Late Quaternary Fluvial terraces Crustal deformation Pindar River Optical dating Central Himalaya

1. Introduction Fluvial systems are one of the central Himalayas major geomorphic agents because of the monsoon dominated climate and the tectonic activity. The hill slope processes and bedrock incision magnitudes in the fluvial system are intimately associated with the spatial and temporal changes in the climatically and tectonically governed base level changes (Burbank et al., 1996; Alley et al., 2003). One of the consequences of the sensitive erosion and transport regime is that two broad categories of landforms of the main valleys can be classified as the aggradation landforms (valleyfill) and the degradation landforms (strath terraces) (Chaudhary

* Corresponding author. E-mail address: [email protected] (G.Ch. Kothyari).

et al., 2015). The aggradation landform in Himalaya receives sediment from two major sources notably paraglacial sediment released as the result of deglaciation (Church and Slaymaker, 1989; Schildgen et al., 2002) and slope wash/landslide generated colluvium, freshly generated under post glacial climate circumstances (Juyal et al., 2010; Chaudhary et al., 2015). It is observed that during periods of abnormal monsoon, the above sediment sources becomes active (Bookhagen et al., 2005) as a result the sediments temporary overwhelms the fluvial system's transport capability which eventually leads to the aggradation (Pratt-Sitaula et al., 2002; Chaudhary et al., 2015). Once the river becomes transport limited due to decrease in the discharge (weak monsoon in case of the Central Himalaya), the river began to incise its own sediment in order to attain the pre-aggradation base level (Juyal et al., 2010 and reference therein). According to Pratt-Sitaula et al. (2004), over

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Please cite this article in press as: Kothyari, G.C., et al., Reconstruction of Late Quaternary climate and seismicity using fluvial landforms in Pindar River valley, Central Himalaya, Uttarakhand, India, Quaternary International (2016), http://dx.doi.org/10.1016/j.quaint.2016.06.001

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timescales of
105 years, Himalayan Rivers oscillate between bedrock incision and valley alluviation owing to changes in monsoon intensity which in turn modulates the sediment flux. Further, due to extreme topographic variability in a rugged Himalayan terrain, the incision is likely to be discontinuous due to (i) the

climatically driven pulses of aggradation (Pratt-Sitaula et al., 2002) and the (ii) differential surface uplift (Hodgkinson, 2009). Climatic reconstruction based on the lacustrine, fluvial sequences and speleotheme records from the Himalayan region show considerable variability in the ISM during the late glacial stage

Fig. 1. (a) Generalized geological and structural map of the study area, (b) Topographic profile of the Pindar River valley. DPF (Dwali-Phurkiya fault), DKF, Dulam-Khati Fault, MCT (Main Central Thrust), AT (Askot Thrust), BjT (Baijnath Thrust), NT (Narayanbagad Thrust), and AF (Alaknanda Fault). (c) Longitudinal profile of the Pinder river (inset) is the segments in Pinder river that are undergoing high differential uplift (indicated by convex up profile).

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(Phartiyal et al., 2003; Juyal et al., 2004, 2009; Kotlia et al., 2010, 2012, 2014, 2016; Beukema et al., 2011; Walker et al., 2012; Duan et al., 2012; Sanwal et al., 2013; Joshi and Kotlia, 2015; Kathayat et al., 2016). However, catchment scale studies on fluvial response to monsoon variability are limited (Srivastava et al., 2008; Juyal et al., 2010; Ray and Srivastava, 2010; Shukla et al., 2010; Chaudhary et al., 2015). Further the surface uplift/erosion rate using in situ produced, cosmogenic radio-nuclide studies indicate that in the Alaknanda River catchment, the basin wide uplift/ erosion rate varies ~1.2 mm/year on the southern margin of Tibetan Plateau, ~2.7 mm/year in Higher Himalaya and <1 mm/year in the Lesser Himalaya (Vance et al., 2003). Such spatial variability in erosion/uplift over multi-millennial time scale may have implication towards influencing the fluvial landform and the rate of sediment delivery from precariously balanced valley slopes (Attal and Lave, 2006). Climatically the Indian Summer Monsoon is major source of precipitation which contribute ~80% of the total rainfall during the summer. The winter precipitation constitutes the remaining 20% which is contributed through the mid-Latitude westerlies. In the higher reaches (paraglacial zone) majority of the precipitation falls as snow (Juyal et al., 2010; Yadav, 2013; Yadav et al., 2014). Temperature varies from sub-zero in the paraglacial zone during winter to a maximum of ~40 degree centigrade in the lower reaches during the summer (Bali et al., 2013).

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The main goal of the study is to understand the role of a cyclic process (climate) and steady process (tectonic) in the phases of aggradation/incision in the Pindar River valley which is a major tributary of the Alaknanda River (Fig. 1a). The specific objectives are to generate detailed stratigraphic data on the alluvial sequences and morphotectonic evidences in order to understand (i) the role of cyclic (ISM) and steady (tectonic) processes in the evolution of fluvial landforms. 1.1. Study area The Pindar River originates from Pindari glacier at around 3820 m. At the outlet of its catchment with an area of ~1890 km2, it meets the Alaknanda River at Karnprayag (754 m) (Fig. 1a). The river traverses through three major lithological zones. The first zone is Tethyan Sedimentary Sequence (TSS) followed by the Higher Himalayan Crystalline (HHC) and the Lesser Himalayan metasediments (LHS) and are structurally differentiated by the South Tibetan Detachment System (STDS) and the Main Central Thrust (MCT) respectively (Fig. 1a). In addition to this, river cut through multiple subsidiary northwest-southeast trending thrusts such as the Askot Thrust (AT), Baijnath Thrust (BjT), Narayanbagar Thrust (NT), Berinag Thrust (BT), and the North Almora Thrust (NAT) (Fig. 1b). The TSS is composed of fossiliferous limestone, shale, slate and phyllites (Sinha, 1989). The HHC are dominated by the Pindari

Fig. 2. Detail geomorphological map of segment-3 showing development of fluvial and fluvially modified alluvial fan terraces at (a) Talora and Debal, (b) Trikot, (c) Tharali, (d) Bagoli, (e) Simli and (f) Gauchar localities.

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Formation of Vaikarta Group comprising gneisses, schist and Quartzite (Valdiya, 1999) whereas the LHS rocks are dominated by phyllite, dolomite, and Quartzite (Srivastava and Ahmad, 1979; Valdiya, 1980; Kothyari and Juyal, 2013; Kothyari, 2014). Based on the regional/local structures and lithology, the study area is divided into three segments. Segment-1 (5330 me2025 m) lies between Dwali-Phurkiya Fault (DPF) and MCT. This segment is dominated by HHC. The segment-2 (2025 me1380 m) is located between MCT and AT where the LHS sequences dominates, whereas the segment-3 (1380e754 m) which is located between AT and AF

is controlled by rocks of Baijanath klippen and LHS (Fig. 1b). In terms of geomorphic processes, segment-1 is influenced by the paraglacial processes. The wide “U” shaped valleys and associated glacio-fluvial sediment indicate that the terrain once occupied by the glaciers (Bali et al., 2013). In Segment-2, the Pindar River flows through narrow “V” shaped valleys with ancient and modern erosional (landslide deposits) events. In segment-3 Pindar River drain through relatively low relief terrain. The majority of the terraces (fluvial and fluvially modified alluvial fan) are located in this segment (Fig. 2).

Fig. 3. Showing the growth curve and shine-down curve of few selected samples.

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2. Method and material Geomorphological mapping of fluvial landforms along the Pindar River has been carried out as part of the present study, between Maliyadhor and Gauchar extending our previous work (Kothyari and Juyal, 2013: Tharali and Simli sites). The geomorphic mapping of the fluvial landforms is carried out using the Survey of India (SOI) topographic maps at the scales of 1:50,000, and ASTER 1.5 arc second (45 m pixel resolution) satellite data. The data is processed using Global Mapper-13 software and WGS 84 projection. The Digital Elevation Model (DEM) is generated with the help of ASTER data which is geo-referenced using the SOI topographic maps. The surface area of the fluvial landform is calculated using the 3D analyst tool of Global Mapper-13. The terraces have been

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differentiated with the help of MAGELLAN, Global Positioning System (GPS). The sediment successions of the terraces are documented in the field using the conventional sedimentological and stratigraphic techniques. The facies map of the fill terraces is reconstructed based on the detailed documentation of the sedimentary architectures and texture of spatially distributed fill terraces at seven locations (Fig. 1c). In order to ascertain the sediment provenance, lithoclast analyses were carried out on each section by random counts of lithoclasts in fixed 1  1 m grid overlay on the exposed sections. Fluvial terraces are particularly useful features as they provide information on rate of bedrock uplift/incision (Rockwell et al., 1984; Molnar and England, 1990). To derive the bedrock uplift rate, from the dated fluvial terraces it is assumed that the

Fig. 4. Radial plots showing the distribution of equivalent doses (De). Ages are computed using the De values that lies within the grey bar.

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geometry and elevation of the river remained constant during  and Avouac, 2001). Since the present day the down cutting (Lave V-shaped valley morphology postdate the valley-fill aggradation, it is reasonable to assume that the geometry of the valley was not changed significantly. Since the valley-fill deposits compared to the bedrock are easily incised due to the local base level changes (Schumm, 1993; Pazzaglia and Brandon, 2001; Gibling et al., 2011). The incision rate is calculated taking the total height of the valley-fill sequence from the present river bed (H1 in m) and subtracted by the height of the youngest valley-fill overlying the bedrock strath (H2 in m). This gives the DH and is expressed as DH/Time gives the incision rate in mm/yr (Pazzaglia et al., 1998). Basin morphometry indices and its derivatives have been used to ascertain the role of tectonic in modulating the fluvial landform. Towards this, the stream length gradient index (SL) which is sensitive to slightest perturbations in the channel slope (Hack, 1973; Seeber and Gornitz, 1983; Burbank and Anderson, 2001) has been used. The SL is defined as (DH/DL) x L, where, DH is the difference between two altitudes, DL is the change in length and L is the total channel length from the point of interest, where the index is being calculated, upstream to the highest point of the channel (Hack, 1973). Spatial variability in fluvial aggradations and bedrock incision is a function of channel width-to depth ratio. Conventionally the channel width variability influences the flow velocity (Finnegan et al., 2005). The relationship is expressed as a ¼ W/D, where, W is bank full width of river and D is depth of incised channel. In areas having high W/D ratio, river tend to shed its load due to reduction in the flow velocity and vice-versa. The steepness index in a longitudinal river profile provides a first order information towards the role of endogenic and exogenic process which can be used to asses the fluvial response to terrain instability/stability (Tyagi et al., 2009 and reference therein). In steady state condition, erosion is balanced by uplift, and the longitudinal profile of a river can be represented by a power law function (Flint, 1974). The steepness index is defined by S ¼ KsAƟ, where, S is the local channel slope, A is the stream drainage area, Ks is the steepness index and Ɵ is the concavity (Hack, 1973; Howard and Kerby, 1983; Howard, 1994; Whittaker et al., 2007; Whipple et al., 2013). For Ks calculation we used the DEM whereas the statistical analysis are carried in GIS plateform. The terraces have been characterized based on the criteria suggested by Bull (1991). This allowed us to identify three types of terrace the (i) cut-and-fill type (ii) fluvially modified alluvial fan and (b) the strath terraces. In addition to this, the study area also preserved the relict channels (fossil valleys). Majority of the terraces are preserved in segment-3 followed by segment-1, whereas segment-2 is devoid of any terraces. The stratigraphic details of the sections studied are given below.

measurements were made using an automated Risø TL-OSL reader (TL/OSL-DA-20; Bøtter-Jensen et al., 2010). The samples were stimulated using blue diode (470 ± 20 nm) and detection optics comprises EMI 9835QA photomultiplier tube coupled with a 7.5 mm Hoya U-340 filter (emission 330 ± 35 nm). Beta irradiations were carried out using an on-plate 90Sr/90Y beta source with a dose rate of 0.131 Gy/s. The equivalent doses (De) were measured using modified single aliquot regeneration protocol (double SAR; Banerjee et al., 1999; Murray and Wintle, 2000) with preheat of 240  C for 60 s and cut heat of 200  C. The preheat temperature was decided based on preheat plateau test (Murray and Wintle, 2000). The result showed a plateau of De in the preheat temperature range 180e280  C. The OSL were measured at 125  C for 40 s and prior to every OSL measurement, infrared stimulated luminescence (IRSL) were measured at 50  C for 100 s to remove any contribution from feldspar. Dose growth curve were constructed using five regeneration dose points including one points to estimate the recuperation and another point to estimate reliability of sensitivity correction (recycling ratio). A typical regeneration growth curve and OSL decay curves are shown in (Fig. 3). The recuperations were <1% of the natural signal and only those aliquots were considered for age estimation in which the recycling ratios was within 10% of the unity. In samples where the over-dispersion (OD) values was >40% minimum age model (MAM) is employed (Arnold et al., 2009) whereas in samples having <40% OD we used the weighted mean (Juyal et al., 2006). The distribution of equivalent doses of the samples dated is represented by radial plot (Fig. 4). Fig. 5 shows the probability density distribution of the ages obtained from the Pindar River valley suggesting major aggradation events occurred after the LGM and during the early Holocene. The annual dose rate is estimated by measuring the U, Th and K concentrations in high purity Germanium detector (HPGe). The samples are sealed in plastic boxes and kept for ~15 days to attain radioactive equilibrium. The errors of measurement (both systematic and statistical uncertainties) are <5% (Shukla et al., 2001). An average water content of 10 ± 5% (mass percentage) was used and cosmic ray contributions in dose rate were calculated using the method suggested by Prescott and Stephan (1982). Details of the radioactivity, De values, dose rate and ages obtained are given in Table 1. Barring few samples, all other ages correspond to the post Last Glacial Maximum (LGM) and the Holocene.

2.1. Optical chronology Samples for optical dating are collected from cleaned outcrops in opaque metal pipes from the intervening sand horizons of the terraces. At places multiple samples are collected from a vertical sediment succession in order to check the temporal variability in sedimentation. Ages are obtained on the quartz mineral which was extracted through sequential treatment with 1 N HCl and 30% H2O2 to remove carbonates and organic matter respectively. Samples were oven dried and sieved to obtain 90e150 mm grain size fractions. The grains were then etched with 40% HF for 80 min followed by 12 N HCL for 30 min with constant magnetic stirring to remove the outer alpha skin (~20 mm). Finally the pure Quartz was extracted using Frantz magnetic separator. Luminescence

Fig. 5. The Probability Density distribution curve of ages obtained on the alluvial sequence of Pindar valley. Gray horizontal bars indicates the major event of aggradation. (i) Later part of MIS-3, (ii) early part of MIS-2 till the early Holocene, and (iii) middle to late Holocene. Note that the major aggradation occur after the LGM and the early Holocene (represented by the large area under the curve).

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Table 1 Showing the radioactive elemental concentration, dose rate, paleodose and ages obtained. (* ages calculated using weighted mean). Sample

OSL Age of Institute of Seismological Research, Gandhinagar, Gujarat ISR code Wt (gm) U (ppm)

Khati

KH1 KH2 KH3 Maliyadhor KH4 Dewal Dw1a Dw1b Dw1c Talora Dwt2 Trikot TK1 Tharali TH1 TH2 TH3 Bagoli BO1 BO2 Simli SM

35.96 37.14 56.23 42.73 57.74 49.59 46.08 40.57 47.11 52.1 55.31 53.53 48.64 55.48 64.79

1.83 3.22 1.79 3.62 3.89 3.88 3.21 3.94 8.66 7.27 8.66 7.52 2.24 2.4 3.11

± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

0.1 0.1 0.08 0.18 0.19 0.19 0.16 0.19 0.4 0.36 0.43 0.37 0.11 0.12 0.15

Th (ppm)

7.76 12.1 8.57 16.5 18.5 15.15 11.45 13.43 26.6 33.3 29.8 32.9 9.21 11.03 12.04

± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

0.38 0.6 0.42 0.82 0.92 0.75 0.57 0.67 1.33 1.66 1.49 1.64 0.41 0.55 0.60

K (wt%)

1.39 2.34 1.15 2.57 1.85 2.08 1.58 1.6 3.44 3.78 3.52 3.76 1.94 2.76 2.01

± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

0.06 0.11 0.05 0.12 0.09 0.10 0.07 0.08 0.17 0.18 0.17 0.18 0.1 0.13 0.10

OD %

Age DR (Gy) model

53.74 41.87 66.6 77.01 39.07 37.57 38.98 30.87 34.51 42.6 55 36.18 32.16 70 44.39

MAM MAM MAM MAM WM WM WM WM WM MAM MAM MAM MAM MAM MAM

3. Result 3.1. Stratigraphy 3.1.1. Maliyadhor (Segment-1) Around 10 m thick terrace which appear as a degraded fan shaped body is preserved around Maliyadhor village (30.145140 Ne79.968214 ; elevation 2278 m), along the left flank of the Pindar River. The terrace alluvium comprises angular to sub angular, poorly organized lithoclasts of calc-silicate (40%), schist, (30%), gneisses, (10%) and granite (10%). The lithoclast are crudely laminated, matrix supported and are separated by impersistent coarse to medium sand lenses. The terrace morphology and lithoclast assemblages suggest that the sediments were deposited as alluvial fan from the tributary valley which was subsequently modified by the Pindar River (fluvially modified alluvial fan). A sand layer collected ~5 m above the present day river bed gave an MAM OSL age of 6.5 ± 0.8 ka.

3.1.2. Khati (Segment-1) Three terrace levels are preserved around Khati village (30.113151 Ne79.927855 E; elevation 2063 m) which is located proximal to Main Central Thrust (MCT) (Fig. 1a and 5a). The terraces are incised by a monsoon fed Sunderdhunga stream (Fig. 5a). The terrace T2 which is ~40 m thick and overlies granite basement, whereas, the younger terrace T1 overlies the schist bedrock which are differentiated by a NEeSW trending normal fault (Fig. 6b and 6c). The younger terrace T1 is around 35 m thick and dominated by sub-angular to sub-rounded gneisses lithoclasts, (60%), schist, (15%) granite (15%), and calc-silicate (10%) (Fig. 6d). The lithoclast assemblages of terrace T2 show dominance of sub-rounded to rounded gneisses lithoclast (50%), schist, (20%) granite (10%), and calc-silicate (10%) (Fig. 6e). The older terrace T2 is overlain by subangular to angular calc-silicate, granite, schist and gneisses lithoclast. The lithoclast assemblages and texture of the terraces suggests that sediments were contributed both from the trunk river (Pindar) and the local Sunderdhunga stream. The MAM OSL ages of Debris flow terraces T3 yielded an age of 15.15 ± 2.1 ka. However, the oldest terraces T2 gave an MAM OSL age of 16.7 ± 2.1 ka, whereas, the younger terraces T1 is dated to 13.6 ± 1.7 ka (Table 1).

2.2 3.6 2.1 4.2 3.8 3.8 2.9 3.2 6.3 6.7 7 7 2.9 3.8 3.3

± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

0.15 0.26 0.1 0.31 0.27 0.27 0.21 0.23 0.46 0.5 0.57 0.53 0.2 0.27 0.4

Palaeodose (GY)

Ages (ka)

MAM

WM

MAM

2.9 52 ± 0.8 6.2 90 ± 1.1 3.2 35 ± 0.4 2.8 30 ± 0.6 3.8 67 ± 0.8 5 79 ± 1.2 4.8 100 ± 1.3 8.2 83 ± 1.3 2.1 41 ± 0.8 2.6 48 ± 0.8 3.2 22 ± 0.5 5.8 87 ± 0.7 3.7 73 ± 1.1 1.4 8 ± 2.9 2.3 34 ± 0.3

13.6 16.7 15.15 6.5 9.9 13.12 16.10 24.97 3.3 3.8 4.5 8 13.4 3.6 6.8

29 62 32 28 38 50 48 82 21 26 32 58 37 14 23

± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

WM* ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

1.7 2.06 2.1 0.8 1.2 1.6 1.9 3 0.4 0.5 0.5 0.9 1.6 0.45 0.8

23 24 16.5 7 17.5 20.7 33.5 25.3 6.6 6.6 3.1 12 24.7 2 10

± ± ± ± ± ± ± ± ± ± ± ± ± ± ±

Final Age (ka) 1.6 13.6 ± 1.7 1.8 16.7 ± 2.06 1.2 15.15 ± 2.1 0.52 6.5 ± 0.8 1 0.3 17.5 ± 1.3* 1.5 20.7 ± 1.5* 2.4 33.5 ± 2.4* 1.8 25.3 ± 1.8* 0.82 6.6 ± 0.82* 0.5 3.8 ± 0.5 0.2 4.5 ± 0.5 0.8 8 ± 0.9 1.8 13.4 ± 1.6 0.8 3.6 ± 0.45 7.3 6.8 ± 0.8

3.1.3. Talora (Segment-3) Two levels of cut and fill terraces are preserved around Talora village (30.052790 Ne79.588147 E; elevation 1340 m) which lies in the vicinity of the south dipping Askot thrust (AT) (Fig. 2a). The terraces are dissected by the Kali Ganga a tributary of the Pindar River and overlie common beveled and 7e10 m deep incised bedrock (Fig. 7a and 7b). The older Terrace T1 which is ~10 m thick is located 17 m above the river bed. The matrix supported terrace is dominated by sub-angular to sub-rounded quartzite, dolomite, shale, schist, and granite lithoclasts. The surface of the terrace is covered with sub-recent landslide deposit. The younger terrace T2 is 15 m thick and is separated from terrace T1 by a 10 m vertical offset (Fig. 7b). The terrace alluvium is matrix supported, and dominated by sub-rounded to rounded quartzite (60%), dolomite (10%), shale (10%), mylonite granite (15%) and schist (5%) along with occasional lensoidal sand bodies (Fig. 7c). Sediment architecture and textural attributes suggests that the sediments were deposited by the Pindar River with subordinate contribution from the local source (alluvial fan). A sample collected from 10 m above the present day river bed gave an WM OSL age of 25.3 ± 1.8 ka (Table 1).

3.1.4. Debal (Segment-3) Terraces around Debal village (30.055938 Ne79.581154 E; elevation 1370 m) are located on the hanging wall of south dipping Askot thrust (Fig. 2a). The terrace alluvium overlies ~10e12 m incised bedrock. A total of four levels of terraces are identified which show cut and fill type morphology (Fig. 8a and 8b). The oldest terrace T4 is 16 m thick and is dominated by sub-angular to sub-rounded lithoclast of quartzite (40%), biotite schist (20%), granite mylonite (5%), dolomite (25%), phyllite (10%) with occasional sand lenses (Fig. 8c). The Terrace T3 is 20 m thick and is dominated by sub-angular to sub-rounded lithoclasts of quartzite (50%), biotite schist (20%), granite mylonite (10%), phyllite, (10%), dolomite (10%) (Fig. 8d). The matrix supported terrace T2 is 15 m thick contain sub-angular to sub-rounded lithoclasts of quartzite (50%), biotite schist (20%), granite mylonite (10%), phyllite, (10%) and dolomite (10%) (Fig. 8e). The younger terrace T1 overlies distinct beveled bedrock proximal to the present day river channel and is separated from terrace T2 by a 5 m vertical offset. The terrace show dominance of clast supported rounded to well-rounded lithoclast of quartzite (60%), biotite schist (20%), granite mylonite

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Fig. 6. (a) Terrace morphology of Khati area, (b) schematic cross section of terraces, (c) field photograph of Khati terraces, these terraces were offset by an NeS trending DulamKhati Fault (DKF), (d) note the lithoclast assemblage of terrace (T2), and (e) terrace (T1) are dominated by sub-round to angular lithoclast suggesting local (alluvial fan) and long distance transport (fluvial gravel).

(10%), dolomite 5%, and phyllite 5%and schist (5%) along with impersistent lensoidal sand bodies. There upper cut and fill morphology of the terraces indicate that sediments were largely contributed from the tributary streams (alluvial fans) in three major pulses which were subsequently modified by the Pindar River into three levels of fluvially modified alluvial fan terrace (T4 to T2). The lithoclast composition and texture of the youngest terrace T1 suggests long distance transport implying contribution from the trunk Pindar River. The terrace T4 yielded a WM OSL age of 33.5 ± 2.4 ka. The terrace T3 gave a WM OSL age of 20.7 ± 1.5 ka, whereas the terraces T2 gave a WM OSL age of 17.5 ± 1.3 ka (Table 1).

3.1.5. Trikot (Segment-3) The cut and fill type terrace at Trikot village (30.046646 Ne79.537385 E; elevation 1245 m) are located on the folded synclinal klippen, bounded by AT in the north and BjT towards south (Figs. 2b, 9a and 9b). A transverse stream has incised the terrace sediment which overlies the 6e7 m incised granite bedrock (Fig. 9c). The older terrace T2 is 21 m thick and overlies gently sloping beveled granite bedrock. The lithoclast assemblages are dominated by clast-supported, sub-rounded to well-rounded gravels of quartzite (60%), schist (10%), shale, (10%), granite (10%), and dolomite (10%). The alluvium of younger terrace T1 alluvium ~10 m thick and overlies ~5 m incised granite bedrock with sharp

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tributary steam from the northern slope meets the Pindar River (Fig. 10a). The morphology of the oldest terrace T3 which lies above 19 m from the Pindar River bed having sediment thickness of ~27 m suggests that the deposition occurred in a relict channel (fossil valley) that was subsequently beveled by the Pindar River giving rise to flat topped topography (Fig. 10b and c). The terraces is composed of angular to sub-rounded lithoclasts of granite (60%), schist (20%), quartzite (10%), shale (5%), and dolomite (5%) with occasionally developed sand lances resting over a granitic bedrock (Fig. 10c). Following this terrace T2 having a vertical thickness of ~20 m developed on the granite substratum (strath terrace) (Fig. 10b). The youngest terrace T1 is ~5 m thick and located proximal to the present day Pindar River channel. The terrace is dominated by matrix supported, sub-rounded to rounded clasts of granite (55%), schist (20%), quartzite (10%), shale (10%), and dolomite (5%) with send lanses (Fig. 10d). The oldest terrace preserved as part of a relict river channel. The river dissected the channel fill into a terrace before laterally migrating to its present course. During its lateral migration, it dissected the granite bedrock forming a strath terrace T2 (Fig. 10a and b). Finally the Pindar River occupied its present course during the aggradation of the youngest terrace T1 which has contribution from the tributary stream and the Pindar River. The fossil valley sediment is dated to 8 ± 0.9 ka whereas younger valley-fill was aggradated between 4.5 and 3.3 ± 0.4 ka respectively. 3.1.7. Bagoli (Segment-3) Around Bagoli village (30.193707 Ne79.309416 E; elevation 906 m) which is located in the proximity of Narayanbagar thrust (NT) (Figs. 2d and 11a), a terrace tread dominated by sub-rounded to rounded lithoclast of quartzite (50%), shale (10%), granite (20%), schist, (10%), dolomite (10%) overlies ~11 m thick phyllite bedrock (Fig. 11b and c). The terrace is overlain by ~20 m thick angular to sub-angular lithoclasts of phyllite, quartzite, and shale of LHS (source proximal landslide deposit) (Fig. 11a). The terraces T1 is dated to 13.4 ka whereas the overlying landslide deposit is dated to 3.6 ka.

Fig. 7. (a) Schematic cross section of Talora terraces, (b) field photograph of terraces located at Talora, (c) lithoclast assemblage of terrace.

erosional contact. The lithoclasts are dominated by sub-rounded to rounded quartzite (50%), schist 10%, shale (10%), dolomite (15%), and granite (15%) (Fig. 9c). Textural composition of the terraces suggests deposition from the Pindar River with subordinate contribution from the tributary valley. Cut and fill morphology suggests two events of terrace aggradation. A sample collected from 8 m above the present river bed gave a MAM OSL age of 6.6 ± 0.82 ka. 3.1.6. Tharali (Segment-3) Around Tharali town (30.074786 Ne79.498744 E; elevation 1235 m), terraces are located on a folded klippen bounded by the AT in the north and BjT towards the south (Fig. 2c). The Pindar River flow proximal to the plunging synclinal thrust sheets. Three levels of terraces can be observed on the right bank of the river where a

3.1.8. Simli (Segment-3) Around Simli town (30.229627 Ne79.260061 E; elevation 831 m), three levels of terraces are identified (Fig. 2e and 12a). Above Simili, the east-west draining Pindar River takes an abrupt southerly turn and then swings northwest ward (Fig. 2e). The terraces are aligned along north-south direction. Based on the morphology and sediment assemblages, the terraces can be differentiated into two categories. These are the (a) upper valley-fill modified into the oldest terrace T3 (b) lower bedrock strath terraces T2, and (c) younger fill terrace T1 (Fig. 12a and 12b). The older fill terraces T3 is approximately 14 m thick dominated by angular to sub-rounded lithoclasts which are by quartzite (30%), shale (20%) schist (20%), phyllite (20%) and granite (10%). The lower T2 terrace is ~11 m thick rocky terrace surface (strath). The younger T1 terraces is ~5 m thick and dominated by clast supported fabric of quartzite (40%), shale (15%) schist (15%), phyllite (25%) and granite (5%) (Fig. 12c). The oldest terrace T2 developed perpendicular to the northwest-southeast trending palaeocourse of the Pindar River implying that palaeocourse of the Pindar River was clogged due to high sediment flux that far exceeded the transport capacity (Fig. 12b) and is dated to 6.8 ka. Following this, decrease in sediment water ratio led to the development of the strath terrace T2. Finally the present day river course was attained during the development of the youngest terrace T1.

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Fig. 8. (a) Schematic cross section of terraces located at Debal, (b) field photograph of terraces, (c, d and e) lithoclast and textural assemblages of terraces. Except for terrace T4, all other terraces show contribution from local stream (alluvial fan).

Fig. 9. (a) Schematic cross section of terraces located at Trikot, (b) field photograph of terraces, (c) showing the lithoclast and textural assemblage of Trikot terraces overlying a 7 m incised bedrock.

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Fig. 10. (a) Schematic cross section of valley-fill terraces (fossil valley) located at Tharali, (b) field photograph of Tharali fossil valley (c and d) lithoclast and texture of terraces, the clast composition of T1 show dominance of local contribution.

3.2. Morphotectonics evidences The incision and steepening of valley slope adjacent to major thrusts is reflected by abnormal increase of steepness index. The observed Ks values ranges between 20 and 10,000 in AT zone, 200e30,000 in BjT zone, 5000e31,000 in NT zone, and 5000e23,000 in AF zone (Fig. 13a). The width-to depth ratio (a) of channel is very low at Talora (a ¼ 2), Debal (a ¼ 2), Trikot (a ¼ 4), Tharali (a ¼ 3), Bagoli (a-3), and Simli (a ¼ 2.5) respectively. Decrease of a indicates lowering of sediment transport capacity thus facilitated the deposition of valley-fill sediments and development of terraces.

In segment 1 the westward flowing lower orders streams shows prominent NeS offset (parallel to the Pindar River) in the vicinity of DPF, implying left lateral displacement. There is an abrupt change in valley morphology from wide “U” to narrow “V” shaped valley in the vicinity of the DPF. In segment-1 the SL value ranges between 1500 and 4000, whereas the Ks ranges between 6000 and 800 thus indicate structural control on valley morphology. Further downstream of Dwali (near Maliyadhor village) the valley become narrow and the river cut into the bedrock forming a waterfall on the hanging wall of the MCT. Triangular fault facets and cones can be observed which suggests normal sense of fault movement and is morphologically expressed by a vertical offset of ~48 m in the

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westerly deflection of Pindar River (parallel to AT) near Debal village (Fig. 2a). Additionally, the deeply entrenched monsoon fed tributary streams in the folded and sheared phyllite and schist bedrocks of Berinag formation further support the suggestion that the AT is a tectonically active structure.

4. Discussion 4.1. Paleoenvironment

Fig. 11. (a) Schematic cross section of Bagoli terraces, (b and c) lithoclast and textural composition of terraces at Bagoli show long distance transport of the sediments (Pindar River).

underlying granite and schist bedrock of Khati terrace (Fig. 6a and b). We attribute the normal sense of faulting to the localized extension on the foot wall of the MCT. In the upstream of Khati village, (above MCT) the width-to depth ratio (a) ranges between 15 and 30 implying over steepened river gradient hence high stream power and is morphologically expressed by the absence of fill sequence. However around Khati village, the low a (~3) is manifested in low channel gradient which led to the aggradation of valley-fill sediment. Similarly structural control on Pindar River morphology is observed in segment-3 which is dominated by folded Baijnath klippen of HHC and metasedimentary rocks of Lesser Himalaya. The geomorphic expression of AT is reflected by an abrupt south-

The morphology and sediment architecture of the Pindar River valley-fill aggradation suggests that the alluvial fans were the major contributor from the juvenile tributary valleys with subordinate contribution from the paraglacial zone and hill slopes. . One of the reasons could be the smaller glacier area (~95 km2) compared to the Alaknanda (~1204 km2) and Bhagirathi (~755 km2) river valleys (Raina and Srivastava, 2008). Thus we speculate that paraglacial sediment production (in the recent times and during the late Quaternary) was comparatively low, hence even during the post glacial strengthened ISM relatively lower contribution came from the upper reaches. Optical chronology indicates that the aggradation occurred during distinct time intervals indicating different climatic conditions. The oldest preserved record of alluvial fan sedimentation in the Pindar River valley can be bracketed between 33.5 ka and 21 ka (Table 1). Climatically, this phase encompasses the later part of pluvial Marine Isotopic Stage-3 (MIS-3) and the relatively drier mid MIS-2 (Glennie and Singhvi, 2002; Fleitmann et al., 2003; Fleitmann and Matter, 2009; Preusser, 2009; Atkinson et al., 2011; Parton et al., 2013). It would imply that the alluvial fan sedimentation was triggered both during the enhanced ISM as also during the transitional phase. The above inference is in agreement with the glacial record in the Pindar valley suggesting that ~25 ka valley glaciers descended down to an altitude of ~3200 m (Bali et al., 2013) thus suggesting decrease in the ISM strength under relatively drier condition. The second major aggradation phase occurred during the post-LGM/lateglacial strengthening of the ISM with fluctuations (Church and Slaymaker, 1989; Schildgen et al., 2002; Juyal et al., 2009) and dated between 17.5 ka and 13 ka

Fig. 12. (a) Schematic cross section of valley-fill terraces (fossil valley) located at Simli, (b) field photograph of fossil valley, (c) lithoclast and textural assemblage of valley-fill.

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Fig. 13. (a) Solid blue line is the longitudinal river profile, steepness (Ks) index values are shown by dotted red line. (b) Topographic cross section profile of the study area showing different tectonic units, also shown are the focused incision rates along with the ages. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

(Table 1; Fig. 5). During this period no significant glacier advance is observed in the Pindar valley (Bali et al., 2013). Lithology and sediment texture (Fig. 6d and e) suggest contribution from the (local) Sunderdhunga tributary stream and the long distance contribution from the paraglacial zone. The third phase of valley-fill aggradation is dated between 8 ka and 3.6 ka, a period known for the fluctuating ISM (Bond et al., 2001; Berkelhammer et al., 2012). Summarizing the sedimentological and chronometric data presented above, the oldest valley-fill sequence corresponding to the first phase of aggradation (33.5 ka) occurred during relatively strengthened ISM. Following this, alluvial fan sedimentation impersistently continued during the declining phase of the ISM (until around 21 ka) (Table 1). The second aggradation phase (17.5e13 ka) occurred during the post glacial strengthening of the ISM (Sirocko et al., 1993). During which the sediments were contributed both from the tributary valleys and the area vacated by the valley glacier in the upper reaches (praglacial zone). However, the youngest phase which led to the clogging of the old channel course (fossil valleys) at Tharali and Simli (Figs. 10 and 12) represents the transitional climatic declining ISM (Fleitmann et al., 2003; Roberts et al., 2011; Liu and Feng, 2012). The chronologically constrained discrete aggradation events in the Pindar River valley are in accordance with the overall pattern of monsoon variability reconstructed using the fluvial sequences and the lake records from the monsoon dominated Himalayan region. For examples, the Ray and Srivastava (2010) observed a major event of fluvial aggradation in the Alaknanda valley between 49e25 ka and 18e11 ka (WM OSL ages) which they ascribed to the

deglaciation, when sediment supply in the valley was significantly increased, which is in conformity with our first major aggradation event in the Pindar valley. Similarly, the second aggradation corresponding to the post glacial strengthened ISM (17.5 kae13 ka) correspond well with the valley-fill aggradation in the Alaknanda valley (Juyal et al., 2010; Ray and Srivastava, 2010). Further, the relict lake record in the upper reaches of Dhauli Ganga indicates overall strengthened ISM with fluctuations between 17 ka and around 12 ka. Dominance of alluvial fan sedimentation along with the debris flows (landslide) dated between 8 ka and 3.6 ka (early to mid-Holocene) suggests decreasing strength of the ISM. Observations similar to this were obtained from the fluvial sequences of Satluj (Bookhagen et al., 2005, 2006) and the Alaknanda valleys (Juyal et al., 2010). Finally the present day river morphology was achieved after ~3 ka. Fig. 14 is the compilation (Fig. 14a) the ages obtained in the Pindar valley (present study) and from the adjoining Alaknanda valley (Juyal et al., 2010). A broad concordance with the events of aggradation can be observed in these two valleys. Further, comparison with Total Organic Carbon (TOC) of core KL 136 (Schulz et al., 1998) collected from the monsoon upwelling area of the northern Arabian Sea and is used as a proxy for monsoon variability (Fig. 14b), the effective moisture data from stacked lake records of central Asia (Herzschuh, 2006) suggests a coupling between (Fig. 14c), temporal changes in insolation (Berger and Loutre, 1991) (Fig. 14d) and monsoon variability. A close correspondence between periods of strengthened ISM and fluvial aggradation in the study area is observed (Fig. 14a).

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Fig. 14. (a) Optical chronology of fluvial terraces plotted along with the existing chronology obtained from the adjoining Alaknanda valley (Juyal et al., 2010; Ray and Srivastava, 2010) (b) Total organic carbon concentration a proxy for ISM variability (Schulz et al., 1998). (c) Temporal changes in the effective moisture from stacked lake records (Herzschuh, 2006). (d) Changes in insolation (June insolation 30 N) (Berger and Loutre, 1991). Note that two major events of aggradation (marked by grey vertical bars) corresponds to post glacial strengthening of ISM (18e12 ka) and early to mid-Holocene (9e3 ka).

However, unlike in the adjoining Alaknanda, the valley-wide fluvial aggradation in response to early Holocene intensification of ISM (12 and 8 ka) (Juyal et al., 2010) was not observed in the Pindar River valley. Could it be due to (i) the erosion or concealment of the fluvial deposit due to relatively steep valley morphology, (ii) limited sediment availability in the paraglacial zone, or (iii) does it support the suggestion that intensified ISM not necessarily associated with the phases of aggradation in Himalaya (Srivastava et al., 2008; Scherler et al., 2015)? Answer to this question probably awaits more intensified studies in the region.

4.2. Tectonics As discussed above, Pindar River flows across the major thrusts. On a regional scale, crustal shortening/uplift can be assumed to be constant for different segments in the Himalaya (Vance et al., 2003). However, at a local scale abnormal uplift in the proximity of major and minor structures can modify the river profile (Pazzaglia and Brandon, 2001). The incision rate is estimated using the equation suggested by Pazzaglia et al. (1998) (discussed in methodology) and the data is presented in Table 2.

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Table 2 Bedrock incision rates estimated at selected locations along the Pindar River. Sample

Height of terraces (m)

Strath height (DH)

Terraces type

Terrace age (ka)

Incision rate (mm/yr)

Average incision (mm/yr)

Major structure

Khati

2031 2050 2064 2299 1337 1378 1435 1342 1255 1206 1222 1247 912 965 834

8 48 e e 15 e e 7 7 24 e e 8 e 5

Fluvially modified Alluvial fan (Strath) Fluvially modified Alluvial fan (Strath) Fluvially modified Alluvial fan Alluvial Fan Fluvially modified Alluvial fan (Strath) Fluvially modified Alluvial fan Fluvially modified Alluvial fan Fluvially modified Alluvial fan (Strath) Strath terraces Alluvial fan Strath terraces and fossil valleys Fluvially modified Alluvial fan Fluvially modified Alluvial fan Cut-and-fill terraces (Strath) Debris flow (Landslide) Strath terraces and fossil valleys

13 16 15 7 18 21 33 25 6.6 8 4 3 13 4 7

0.61 3

1.9

MCT

0.6

AT

2.03

BjT

0.78

NT

Maliyadhor Dewal

Talora Trikot Tharali

Bagoli Simli

The incision/uplift rates estimated from the terraces at Khati in MCT zone (segment-1) is ranges between 0.61 mm/yr (minimum) and 3 mm/yr (maximum) (average 1.9 mm/yr). In segment-3 terraces of Debal and Talora located in the vicinity of AT, the values ranges between 0.83 mm/yr and 0.28 mm/yr (proximal to AT) (average 0.6 mm/yr). The relatively high incision rate of 1.06 mm/yr and 3 mm/yr are obtained at Trikot and Tharali which is located proximal to the BjT. This is again followed by a relatively low incision/uplift rate of 0.61 mm/yr and 0.72 mm/yr around Bagoli and Simli respectively which lies proximal to NT (Table 2). The average high incision rate/uplift rates are located at two distinct structural domains such as, the MCT (1.9 mm/yr) and the

e 0.83 e e 0.28 1.06 3 e e 0.61 e 0.72

BjT (2.03 mm/yr) respectively. MCT is known for experiencing high crustal deformation (Seeber and Gornitz, 1983) due to which high compressive force causing the segmental reactivation of the transverse faults that are known to generate relatively high magnitude earthquakes in the region (Kayal et al., 2003; Mukhopadhyay, 2011). However around BjT, the higher incision/ uplift is ascribed to the activity along the BjT in the south and AT in the north and is schematically represented in Fig. 15. As the trusting progress between BjT and AT, the rocks belonging to Baijnath klippen (granite) are compressed and folded (Fig. 15a). A mechanism similar to the fold growth caused due to the propagation of thrusts in which the maximum crustal shortening is

Fig. 15. (a) Schematic cross section between the BjT and AT showing the deformation of Baijnath klippen forming a broad anticline. (b) The high incision rate in this area is attributed to the continued deformation leading to the formation of a growing anticline.

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accommodated at the crest (Fig. 15b). Presently the Pindar River is incising through the hinge of the anticline hence the continued fold growth is reflected in higher incision rate in the inner lesser Himalaya. Our estimates accords well with the recent GPS studies from the region (Jade et al., 2014). Further comparable incision rates are obtained from the Higher and the Lesser Himalaya, which we ascribe to a combination of enhanced crustal deformation coupled with periods of strengthen of ISM (Fig. 13b). 5. Conclusions Based on the geomorphology, sedimentology and optical chronology of eight sites from three segments of the Pindar River valley in the Central Himalayas, the following broad inferences on Late Quaternary climatic and tectonic control on mountain river incision and sediment routing can be drawn. 1. The aggradation in the Pindar valley occur under three climatic domains such as the earlier part of Marine Isotopic Stage (MIS3), early to mid MIS-2, and post glacial to early Holocene. The later was the most extensive phase of aggradation in the study area suggesting fluvial dynamics during the late Quaternary period was intimately associated with the ISM variability. 2. The valley fill aggradation was dominated by the contribution from tributary streams during the insolation driven post glacial strengthen Indian summer monsoon (ISM), implying that local streams in areas having relatively small glaciers, are significant contributor to fluvial sediment budget in Himalaya. 3. The study suggests that maximum crustal deformation as expected was observed in the proximity of MCT and is attributed to the activity along the transverse faults. However, the terrain lying between the AT and BjT (in the Lesser Himalaya) is also experiencing higher crustal deformation implying that in areas where thrust propagated growing anticline exists are prone to tectonic instability. 4. Finally, the study indicates that fluvial landforms in the Pindar River valley are genetically related with the temporal changes in the ISM and special variability in the crustal deformation. Acknowledgements We are thankful to Dr. B. K. Rastogi, Director General, Institute of Seismological Research, Gandhinagar for his support and encouragements. GCK acknowledges SERB division, Department of Science and Technology for financial support in the form of Fast Track Young scientist grant SR/FTP/ES-184/2010 (G). Appendix A. Supplementary data Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.quaint.2016.06.001. References Alley, R.B., Marotzke, J., Nordhaus, W.D., Overpeck, J.T., Peteet, D.M., Pielke, R.A., J. R, Pierrehumbert, R.T., Rhines, P.B., Stocker, T.F., Talley, L.D., Wallace, J.M., 2003. Abrupt climate change. Science 299, 2005e2010. Arnold, L.J., Roberts, R.G., Galbraith, R.F., DeLong, S.B., 2009. A revised burial dose estimation procedure for optical dating of young and modern-age sediments. Quaternary Geochronology 4, 306e325. Atkinson, O.A.C., Thomas, D.S.G., Goudie, A.S., Bailey, R.M., 2011. Late Quaternary chronology of major dune ridge development in the northeast Rub' al-Khali, United Arab Emirates. Quaternary Research 76 (1), 93e105. Attal, M., Lave, J., 2006. Changes of bedload characteristics along the Marsyandi River (central Nepal): implications for understanding hillslope sediment supply, sediment load evolution along fluvial networks, and denudation in active orogenic belts. In: Willett, S.D., Hovius, N., Brandon, M.T., Fisher, D.M. (Eds.),

Tectonics, Climate, and Landscape Evolution, vol. 398, pp. 143e171. GSA Special Papers. Bali, R., Nawaz, A.S., Agarwal, K.K., Rastogi, S.K., Krishna, K., 2013. Chronology of late Quaternary glaciation in the Pindar valley, Alaknanda basin, Central Himalaya (India). Journal of Asian Earth Sciences. http://dx.doi.org/10.1016/ j.jseaes.2013.01.011. Banerjee, D., Singhvi, A.K., Pande, K., Gogte, V.D., Chandra, B.P., 1999. Towards a direct dating of fault gouges using luminescence dating techniques e methodological aspects. Current Science 77, 256e269. Berger, A., Loutre, M.F., 1991. Insolation values for the climate of the last 10 million years. Quaternary Sciences Review 10, 297e317. Berkelhammer, M., Sinha, A., Stott, L., Cheng, H., Pausta, F.S.R., Yoshimura, K., 2012. An Abrupt Shift in the Indian Monsoon 4000 Years Ago. American Geophysical Union. http://dx.doi.org/10.1029/2012GM001207. Beukema, S.P., Krishnamurthy, R.V., Juyal, N., Basavaiah, N., Singhvi, A.K., 2011. Monsoon variability and chemical weathering during the late Pleistocene in the Goriganga basin, higher central Himalaya, India. Quaternary Research 75, 597e604. Bond, G., Kromer, B., Beer, J., Muscheler, R., Evans, M.N., Showers, W., Hoffman, S., Lotti-Bond, R., Hajdas, I., Bonani, G., 2001. Persistent solar influence on North Atlantic climate during the Holocene. Science 294, 2130e2136. Bookhagen, B., Fleitmann, D., Nishiizumi, K., Strecker, M.R., Thiede, R.C., 2006. Holocene monsoonal dynamics and fluvial terrace formation in the northwest Himalaya, India. Geology 34, 601e604. Bookhagen, B., Thiede, R.C., Strecker, M.R., 2005. Abnormal monsoon years and their control on erosion and sediment flux in the high, arid northwest Himalaya. Earth and Planetary Science Letters 231, 131e146. Bøtter-Jensen, L., Thomsen, K.J., Jain, M., 2010. Review of optically stimulated luminescence (OSL) instrumental developments for retrospective dosimetry. Radiation Measurements 45 (3e6), 253e257. Bull, W., 1991. Geomorphic Response to Climatic Changes. Oxford University Press, 326 pp. Burbank, D.W., Anderson, R.S., 2001. Tectonic Geomorphology. Blackwell Science. Burbank, D.W., Leland, J., Fielding, E., Anderson, R.S., Brozovic, N., Ried, M.R., Duncan, C., 1996. Bedrock incision, rock uplift and threshold hillslopes in the northwestern Himalayas. Nature 379, 505e510. Chaudhary, S., Shukla, U.K., Sundriyal, Y.P., Srivastava, P., Jalal, P., 2015. Formation of paleovalleys in the Central Himalaya during valley aggradation. Quaternary International. http://dx.doi.org/10.1016/j.quaint.2014.12.064. Church, M., Slaymaker, O., 1989. Disequilibrium of Holocene sediment yield in glaciated British Columbia. Nature 337, 452e454. Duan, W., Kotlia, B.S., Tan, M., 2012. Mineral composition and structure of the stalagmite laminae from Chulerasim cave, Indian Himalaya, and the significance for palaeoclimatic reconstruction. Quaternary International. http://dx.doi.org/ 10.1016/j.quaint.2012.03.042. Finnegan, N.J., Roe, G., Montgomery, D.R., Hallet, B., 2005. Controls on the channel width of rivers: implications for modeling fluvial incision of bedrock. Geological Society of America 33 (3), 229e232. Fleitmann, D., Burns, S.J., Mudelsee, M., Neff, U., Kramers, J., Mangini, A., Matter, A., 2003. Holocene forcing of the Indian monsoon recorded in a stalagmite from southern Oman. Science 300, 1737e1739. Fleitmann, D., Matter, A., 2009. The speleothem record of climate variability in Southern Arabia. Comptes Rendus Geoscience 341, 633e642. Flint, J.J., 1974. Stream gradient as a function of order, magnitude, and discharge. Water Resources Research 10, 969e973. Gibling, M., Sinha, R., Roy, N., 2011. Response of the Ganges River of India to monsoonal changes since the Last Glacial Maximum. In: AGU Fall Meeting Abstracts 1, 08. Glennie, K., Singhvi, A., 2002. Event stratigraphy, paleoenvironment and chronology of SE Arabian deserts. Quaternary Science Reviews 21, 853e869. Hack, J.T., 1973. Stream profile analysis and stream-gradient index. U.S. Geological Survey Journal of Research 1, 421e429. Herzschuh, U., 2006. Paleo-moisture evolution in monsoonal central Asia during the last 50,000 years. Quaternary Science Reviews 25, 163e178. Hodgkinson, J.H., 2009. Geological Control of Physiography in Southeast Queensland: a Multi-scale Analysis Using GIS. Bikbeck University of London, p. 254. Howard, A.D., Kerby, G., 1983. Channel Changes in Badlands, 94. Geological Society of America Bulletin, pp. 739e752. Howard, A., 1994. A detachment-limited model of drainage basin evolution. Water Resources Research 30 (7), 2261e2285. Jade, S., Mukul, M., Gaur, V.K., Kumar, K., Shrungeshwar, T.S., Satyal, G.S., Dumka, R.K., Jagannathan, S., Ananda, M.B., Kumar, P.D., Banerjee, S., 2014. Contemporary deformation in the KashmireHimachal, Garhwal and Kumaon Himalaya: significant insights from 1995e2008 GPS time series. Journal of Geodesy. http://dx.doi.org/10.1007/s00190-014-0702-3. Joshi, L.M., Kotlia, B.S., 2015. Neotectonically triggered instability around the palaeolake regime in Central Kumaun Himalaya, India. Quaternary International. http://dx.doi.org/10.1016/j.quaint.2014.10.033. Juyal, N., Chamyal, L.S., Bhandari, S., Bhushan, R., Singhvi, A.K., 2006. Continental record of the southwest monsoon during the last 130 ka: evidence from the southern margin of the Thar desert, India. Quaternary Science Reviews 25, 2632e2650. Juyal, N., Pant, R.K., Basavaiah, N., Bhushan, R., Jain, M., Saini, N.K., Yadava, M.G., Singhvi, A.K., 2009. Reconstruction of Last Glacial to early Holocene monsoon

Please cite this article in press as: Kothyari, G.C., et al., Reconstruction of Late Quaternary climate and seismicity using fluvial landforms in Pindar River valley, Central Himalaya, Uttarakhand, India, Quaternary International (2016), http://dx.doi.org/10.1016/j.quaint.2016.06.001

G.Ch. Kothyari et al. / Quaternary International xxx (2016) 1e17 variability from relict lake sediments of the Higher Central Himalaya, Uttrakhand, India. Journal of Asian Earth Sciences 34, 437e449. Juyal, N., Pant, R.K., Basavaiah, N., Yadava, M.G., Saini, N.K., Singhvi, A.K., 2004. Climate and seismicity in the Higher Central Himalaya during the last 20 ka: evidences from Garbayang basin, Uttranchal, India. Palaeogeography, Palaeoclimatology, Palaeoecology 213, 315e330. Juyal, N., Sundriyal, Y.P., Rana, N., Chaudhary, S., Singhvi, A.K., 2010. Late Quaternary fluvial aggradation and incision in the monsoon dominated Alaknanda valley, Central Himalaya, Uttarakhand, India. Journal of Quaternary Science 25 (9999), 1e13. Kathayat, G., Cheng, H., Sinha, A., Spotl, C., Edwards, R.L., Zhang, H., Li, X., Yi, L., Ning, Y., Lui, E.L., Breitenbach, S.F.M., 2016. Indian monsoon variability on millennial-orbital timescales. Nature Scientific Report. http://dx.doi.org/ 10.1038/srep24374. Kayal, J.R., Ram, S., Singh, O.P., Chakraborty, P.K., Karunakar, G., 2003. Aftershocks of the March 1999 Chamoli earthquake and seismotectonic structure of the Garhwal Himalaya. Bulletin of the Seismological Society of America 93, 1854e1861. Kothyari, G.C., 2014. Morphometric analysis of tectonically active Pindar and Saryu River basins: central Kumaun Himalaya. Zeitschrift für Geomorphologie. http:// dx.doi.org/10.1127/zfg/2014/0162. Kothyari, G.C., Juyal, N., 2013. Implications of fossil valleys and associated epigenetic gorges in parts of Central Himalaya. Current Science 105, 383e388. Kotlia, B.S., Ahmad, S.M., Zhao, J.X., Raza, W., Collerson, K.D., Joshi, L.M., Sanwal, J., 2012. Climatic fluctuations during the LIA and post-LIA in the Kumaun Lesser Himalaya, India: evidence from a 400 y old stalagmite record. Quaternary International. http://dx.doi.org/10.1016/j.quaint.2012.01.025. Kotlia, B.S., Sanwal, J., Phartiyal, B., Joshi, L.M., Trivedi, A., Sharma, C., 2010. Late Quaternary climatic changes in the eastern Kumaun Himalaya,India, as deduced from multi-proxy studies. Quaternary International 213, 44e55. Kotlia, B.S., Singh, A.K., Joshi, L.M., Dhaila, B.S., 2014. Precipitation variability in the Indian Central Himalaya during last ca. 4,000 years inferred from a speleothem record: impact of Indian Summer Monsoon (ISM) and Westerlies. Quaternary International. http://dx.doi.org/10.1016/j.quaint.2014.10.066. Kotlia, B.S., Singh, A.K., Zhao, J.X., Duan, W., Tan, M., Sharma, A.K., Raza, W., 2016. Stalagmite based high resolution precipitation variability for past four centuries in the Indian Central Himalaya: Chulerasim cave re-visited and data re-interpretation. Quaternary International. http://dx.doi.org/10.1016/j.quaint.2016. 04.007. , J., Avouac, J.P., 2001. Fluvial incision and tectonic uplift across the Himalayas of Lave central Nepal. Journal of Geophysical Research 106, 26561e26591. Liu, F., Feng, Z., 2012. A dramatic climatic transition at ~4000 cal. yr BP and its cultural responses in Chinese cultural domains. Holocene. http://dx.doi.org/ 10.1177/0959683612441839. Molnar, P., England, P., 1990. Late Cenozoic uplift of mountain ranges and global climate change: chicken or egg? Nature 346, 29e34. Mukhopadhyay, B., 2011. Clusters of size earthquake along Main Central Thrust (MCT) in Himalaya. International Journal of Geoscience 2, 318e325. Murray, A.S., Wintle, A.G., 2000. Luminescence dating of quartz using an improved single aliquot regenerative-dose protocol. Radiation Measurement 32, 57e73. Parton, A., Farrant, A.R., Leng, M.J., Schwenninger, M.J., Rose, J.I., Uerpmann, H.,P., Parker, A.G., 2013. An early MIS 3 pluvial phase in Southeast Arabia: climatic and archaeological implications. Quaternary International 300, 62e64. Pazzaglia, F.J., Brandon, M.T., 2001. A fluvial record of rock uplift and shortening across the Cascadia forearc high. American Journal of Science 301, 385e431. Pazzaglia, F.J., Gardner, T.W., Merritts, D.J., 1998. Bedrock fluvial incision and longitudinal profile development over geologic time scales determined by fluvial terraces. In: Tinkler, K.J., Wohl, E.E. (Eds.), Rivers over Rock: Fluvial Processes in Bedrock Channels. American Geophyisical Union, Washington DC, pp. 207e235. Phartiyal, B., Appel, E., Blaha, U., Hoffmann, V., Kotlia, B., 2003. Palaeoclimatic significance of magnetic properties from Late Quaternary lacustrine sediments at Pithoragarh, Kumaun Lesser Himalaya, India. Quaternary International 108, 51e62. Pratt-Sitaula, B., Burbank, D.W., Heimsath, A., Ojha, T., 2002. Impulsive alleviation during early Holocene strengthened monsoon, central Nepal Himalaya. Geology 30, 911e914. Pratt-Sitaula, B., Burbank, D.W., Heimsath, A., Ojha, T., 2004. Landscape disequilibrium on 1000-10,000 year scales Marsyandi River, Nepal, central Himalaya. Geomorphology 58, 223e241. Prescott, J.R., Stephan, L.G., 1982. Contribution of cosmic radiation to environmental dose. PACT 6, 17e25. Preusser, F., 2009. Chronology of the impact of Quaternary climate change on continental environments in the Arabian Peninsula. Comptes Rendus, Geoscience 341, 621e632.

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Raina, V.K., Srivastava, D., 2008. Glacial Atlas of India. Geological Society of India, 315pp. Ray, Y., Srivastava, P., 2010. Widespread aggradation in the mountainous catchment of the Alaknandae Ganga River System: timescales and implications to Hinterland foreland relationships. Quaternary Science Reviews 29, 2238e2260. lu, C., Perez, R., Sadori, L., 2011. The midRoberts, N., Brayshaw, D., Kuzucuog Holocene climatic transition in the Mediterranean: causes and consequences. Holocene. http://dx.doi.org/10.1177/0959683610388058. Rockwell, T.K., Keller, E.A., Clark, M.N., Johnson, D.L., 1984. Chronology and rates of faulting of Ventura River terraces, California. Geological Society of America Bulletin 95, 1466e1476. Sanwal, J., Kotlia, B.S., Rajendran, C., Ahmad, S.M., Rajendran, K., Sandiford, M., 2013. Climatic variability in Central Indian Himalaya during the last ~1800 years: evidence from a high resolution speleothem records. Quaternary International. http://dx.doi.org/10.1016/j.quaint.2013.03.029. Scherler, D., Bookhagen, B., Wulf, H., Preusser, F., Strecker, M.R., 2015. Increased late Pleistocene erosion rates during fluvial aggradation in the Garhwal Himalaya, northern India. Earth and Planetary Science Letters. http://dx.doi.org/10.1016/ j.epsl.2015.06.034. Schildgen, T., Dethier, D.P., Bierman, P., Caffee, M., 2002. 26Al and 10Be dating of Late Pleistocene and Holocene fill terraces: a record of fluvial deposition and incision, Colorado Front Range. Earth Surface Processes and Landforms 27, 773e787. Schulz, H., Von Rad, U., Erlenkeuser, H., 1998. Correlation between Arabian Sea and Greenland climate oscillations of the past 110,000 years. Nature 393 (6680), 54e57. Schumm, S.A., 1993. River response to base level change: implications for sequence stratigraphy. Journal of Geology 101, 279e294. Seeber, L., Gornitz, V., 1983. River profiles along the Himalayan arc as indicators of active tectonics. Tectonophysics 92, 335e367. Shukla, U.K., Bora, D.S., Singh, C.K., 2010. Palaeoclimatic response to Quaternary gravels: a case study from Kumaun Himalaya. India Quaternary International 213, 33e43. Shukla, U.K., Singh, I.B., Sharma, M., Sharma, S., 2001. A model of alluvial megafan sedimentation: Ganga megafan. Sedimentary Geology 144, 243e262. Sinha, A.K., 1989. Geology of Higher Central Himalayas. Wiley, Chichester. Sirocko, F., Sarnthein, M., Erlenkeuser, H., Lange, H., Arnold, M., Duplessy, J.C., 1993. Century-scale events in monsoonal climate over the past 24,000 years. Nature 364, 322e324. Srivastava, P., Tripathi, J.K., Islam, R., Jaiswal, M.K., 2008. Fashion and phases of Late Pleistocene aggradation and incision in Alaknanda River, western Himalaya, India. Quaternary Research 70, 68e80. Srivastava, R.N., Ahmad, A., 1979. Geology and structure of Alaknanda valley, Garhwal Himalaya. Himalayan Geology 9, 225e254. Tyagi, A.K., Chaudhary, S., Rana, N., Sati, S.P., Juyal, N., 2009. Identifying areas of differential uplift using steepness index in the Alaknanda basin, Garhwal Himalaya, Uttrakhand. Current Science 97, 1473e1477. Valdiya, K.S., 1980. Geology of the Kumaun Lesser Himalaya. Wadia Institute of Himalayan Geology, Dehradun, p. 291. Valdiya, K.S., 1999. Reactivation of faults and active folds and geomorphic rejuvenation in eastern Kumaun Himalaya: wider implications. Indian Journal Geology 71, 53e63. Vance, D., Bickle, M., Ivy-Ochs, S., Kubik, P.W., 2003. Erosion and exhumation in the Himalaya from cosmogenic isotope inventories of river sediments. Earth and Planetary Science Letters 206, 273e288. Walker, M.J.C., Berkelhammer, M., Bjorck, S., Cwynar, L.C., Fisher, D.A., Long, A.J., Lowe, J.J., Newnham, R.M., Rasmussen, S.O., Weiss, H., 2012. Formal division of the Holocene Series/ Epoch: a discussion paper by a Working Group of INTIMATE (Integration of ice-core, marine and terrestrial records) and the Subcommission on Quaternary Stratigraphy (International Commission on Stratigraphy). Journal of Quaternary Science. http://dx.doi.org/10.1002/jqs.2565. ISSN 0267-8179. Whipple, K.X., Di-Biase, R.A., Crosby, B.T., 2013. Bedrock Rivers. Treatise on Geomorphology 9, 550e570. Whittaker, A.C., Cowie, P.A., Attal, M., Tucker, G., Roberts, G.P., 2007. Bedrock channel adjustment to tectonic forcing: implications for predicting river incision rate. Geology 35, 103e106. Yadav, R.M., Misra, K.G., Kotlia, B.S., Upreti, N., 2014. Premonsoon precipitation variability in Kumaon Himalaya, India over a perspective of ~300 years. Quaternary International 325, 213e219. Yadav, R.R., 2013. Relationship between winter precipitation over the western Himalaya and central northeast India summer monsoon rainfall: a long-term perspective. Quaternary International 304, 176e182.

Please cite this article in press as: Kothyari, G.C., et al., Reconstruction of Late Quaternary climate and seismicity using fluvial landforms in Pindar River valley, Central Himalaya, Uttarakhand, India, Quaternary International (2016), http://dx.doi.org/10.1016/j.quaint.2016.06.001