Bahadur Singh Kotlia

Palaeoclimatic conditions in the upper Pleistocene and Holocene Bhimtal-Naukuchiatal lake basin in south-central Kumaun, North India

Abstract A 52 m thick upper Pleistocene and Holocene terrestrial succession in the Bhimtal-Naukuchiatal basin, south-central Kumaun Himalaya, India was studied using chronological, palaeontological, palynological and δ13C measurements. The section recorded evidence for climatic changes. At least two phases of arid climate and one phase of humid climate were recognised. Preliminary palaeomagnetic studies revealed a reversal of polarity, presumably correlatable with the Mono Lake excursion. Prior to this, no reversal event in the upper Pleistocene-Holocene terrestrial sediments of Indian subcontinent is known. A fossiliferous horizon, discovered in the lower part of the section, consisted of Sorex and Mus. This is the only report of a Late Pleistocene micromammalian assemblage in the Kumaun Himalaya.

Quaternary fluvio-lacustrine deposits of the Lamayuru Basin, Ladakh Himalaya: preliminary multidisciplinary investigations

Preliminary multidisciplinary investigations were carried out in a 105 m thick late Pleistocene terrestrial sequence in the Lamayuru basin, Ladakh Himalaya. Palaeomagnetic studies reveal a reversal of polarity at about 35 ka BP. This is the only report of this reversal event in the late Pleistocene terrestrial sequences of the Indian subcontinent. The valley fill sequence is the product of an interplay of lacustrine with fluvio-deltaic to colluvial processes. Four fossiliferous horizons have yielded ostracods and gastropods indicating shallow freshwater conditions. The Lamayuru lake was created by tectonically induced instabil- ity about 35-40 ka BP, an event that may be represented widely throughout the Himalaya.

Sedimentation pattern in a trans-Himalayan Quaternary lake at Lamayuru (Ladakh), India

Abstract Located on the Indo-Tsangpo Suture Zone, Lamayuru Lake in western Ladakh was created by neotectonic instability around 35–40 ka. The valley fill sequence, about 110 m thick, reveals an interplay of lacustrine to fluvio-deltaic to colluvial processes operating in response to changing climate and tectonic conditions. Based on integrated approach of sedimentology and palaeontological analysis, we propose a sedimentation model for Lamayuru Lake with reference to changing climatic conditions and neotectonics. The coarsening upward succession was divided into five lithofacies associations (Associations A–E). Each association, comprising one or more lithofacies, represents a specific depositional environment, and marks an independent episode of sedimentation. A dominantly muddy sequence of Facies Association A, a product of a lacustrine environment, is followed by coarsening upward cycles (Association B) composed of silt to sand that implies laterally shifting deltas. Thereafter, thick sand and gravel deposits constituting fining upward (FU) unit cycles (Associations C and D) represent deposition in a fluvial domain. The upper part of Association D, composed of matrix-supported gravel horizons, was deposited as debris flows and marks the termination of sedimentation in the valley. The clastic lithofacies (Facies Associations A to D) with plant fragments and charcoal presumably indicate warm–humid climatic conditions. In contrast, Association E, comprising marl lithofacies occurring at four different levels is biogenic and indicates arid to semi-arid climatic phases. Five main types of trace fossils (including rhizoliths) seem to be representatives of Scoyenia ichnofacies and animal burrows indicating a thin population of soft-bodied annelid and arthropod communities living under low energy condition. Nine fossiliferous horizons have yielded characteristic ostracods, charophytes and gastropods indicating shallow, low energy and cold-water ecological conditions. Coarsening up lake succession, extensive synsedimentary deformation, tilting of lake beds and the entrenchment of the Lamayuru drainage indicate basin evolution under an effective role of neotectonics in the area.

Crustal deformation revealed by GPS in Kumaun Himalaya, India

The foremost Global Positioning System (GPS) derived measurements in the Kumaun Himalaya indicate that most of the crustal motion of the Indian plate is accommodating towards the base as well as on the hanging wall of Main Central Thrust (MCT). Deformation pattern within the Kumaun Himalaya varies from south to north and indicates maximum deformation rate near MCT. Our study, based on the campaign mode GPS survey during 2003–2006, reveals that the area between north of North Almora Thrust (NAT) and at the base of Great Himalaya registers maximum strain rate, which is lowered towards the Trans Himadri Fault (THF). The GAMIT-GLOBK processed campaign data of the area show that currently, the Himalayan Frontal Fault (HFF) and Main Boundary Thrust (MBT) are locked with the Indian plate, and a 6.7 ± 2.5 mm/yr of horizontal shortening is taking place between the Lesser Himalaya and Peninsular India.

Record of vegetation, climate change, human impact and retting of hemp in Garhwal Himalaya (India) during the past 4600 years

This study is focused on a 3.55-m-long sediment core retrieved from Badanital (i.e. the BT core) in 2008. Badanital (30°29′50″N, 78°55′26″E, 2083 m a.s.l.) is a small lake located in the upper catchment area of the Ganges in Garhwal Himalaya, northern India. The lake and the regional broad-leaved semi-evergreen forests are under the influence of the Indian Summer Monsoon (ISM) and westerly associated cyclones. Palynological investigation of the BT core revealed past vegetation changes reflecting both climate and human impact during the last 4600 years. Maximum spread of oaks occurred during c. AD 550–1100 and c. AD 1400–1630, that is, the intervals which partly overlap with the ‘Medieval Warm Period’ and the ‘Little Ice Age’, respectively. Three intervals of decreased oak pollen percentages are attributed to (1) continuously drier and cooler climatic conditions and fire activity (c. 2600–500 BC), (2) severe reduction in oak forests followed by secondary succession of alder woods (c. AD 1150–1270) and (3) pre-modern settlement activities since the British imperial occupation (after c. AD 1700). We argue that the high percentages (i.e. up to 28%) of Humulus/Cannabis type and Cannabis type pollen point to intense local retting of hemp c. 500 BC–AD 1050. Based on our age model, Cannabis fibre production at Badanital is contemporaneous with archaeological records of ancient hemp products from different parts of Eurasia suggesting possible linkages to early trade and knowledge exchange routes connecting India and the Himalaya with Central and East Asia and possibly Europe.

Rhagapodemus debruijni from the Pliocene of Kashmir Basin: First record ofRhagapodemus from India (Mammalia: Rodentia)

Rhagapodemus debruijni (Kotlia 1992), originally included in the taxonomically heterogeneous type material ofApodemus dominans debruijni is diagnosed and re-described. This species from about 2.4 Ma old sediments of Kashmir Basin, India, represents the evolutionary stage of Ruscinian, hence considerably older EuropeanRhagapodemus species and may have originated in parallel from a localApodemus source.KurzfassungRhagapodemus debruijni (Kotlia 1992), der ursprünglich Teil des taxonomisch uneinheitlichen Typenmaterials vonApodemus dominans debruijni war, wird mit einer Diagnose versehen und erneut beschrieben. Diese Art aus etwa 2.4 Mio. Jahre alten Sedimenten des Kaschmir-Beckens, Indien, zeigt das evolutive Niveau ruscinischer, also deutlich älterer europäischerRhagapodemus-Arten und könnte sich parallel aus einer eigenen lokalenApodemus-Population entwickelt haben.

Neotectonic and climatic impressions in the zone of Trans Himadri Fault (THF), Kumaun Tethys Himalaya, India: A case study from palaeolake deposits

Late Quaternary tectonic activity on a NW-SE trending fault within the Trans Himadri Fault (THF) zone in lower reaches of the Milam glacier (Indian Tethys Himalaya) resulted in development of a lake around 23 ka BP. The remnants of the ancient lake are preserved in form of a 25.6 m thick lacustrine profile, consisting of muds and sands. The palaeolake seems to have breached around 11 ka BP possibly due to revival of a further event of neotectonic activity. The geomorphic consequences of the tectonic movements in the fault zone are manifest in form of palaeo-landslide cones, unpaired terraces, fault facets, soaring waterfalls, deep gorges and slope failures etc. The soft sedimentary structures, e. g., micro-faulting and flame structures in the exposed profile also point to a possible reactivation of the THF in the Late Pleistocene. We present the first palynological results from otherwise a totally unexplored area in the eastern part of the Indian Tethys Himalaya. The preliminary results indicate that the area experienced cold desertic climatic conditions from ca. 22.9 to 15.7 ka BP covering a period of Last Glacial Maximum (LGM) and during which the sediment accumulation rate was also extremely slow. This phase was followed by deglaciation together with amelioration of climate between ca. 15.7 and 14.5 ka BP. A dry period from ca. 14.5 to 13.8 ka BP can be associated with the Older Dryas. The area underwent wetter/moist conditions from ca. 13.8 to 12.8 ka BP, followed by a century scale dry event (ca. 12.8 to 12.7 ka BP) which may be linked to the Younger Dryas episode.

Recent Wetting and Glacier Expansion in the Northwest Himalaya and Karakoram

Hydroclimatic variability driven by global warming in the climatically vulnerable cold semi-arid to arid northwest (NW) Himalaya is poorly constrained due to paucity of continuous weather records and annually resolved proxies. Applying a network of annually resolved tree-ring-width chronologies from semi-arid region of Kishtwar, Jammu and Kashmir, India, we reconstructed April-May standardized precipitation index extending back to A.D. 1439 (576 years). The reconstructed series is featured by the most conspicuous long-term droughts during the 15th to early 17th centuries followed by a general wetting, with 1984–2014 being the wettest interval in the past 576 years. The data, consistent with other independently developed tree-ring-based hydrological records from cold semi-arid to arid NW Himalaya and Karakoram, point to an increased regional wetting in the recent decades. Such an increased wetting might have led to the anomalous behaviour of glaciers in the NW Himalaya and Karakoram in contrast to the general receding trends in the central and eastern Himalaya.

Structural Overview and Morphotectonic Evolution of a Strike-Slip Fault in the Zone of North Almora Thrust, Central Kumaun Himalaya, India

The aim of the present research is to provide the base line details of the NNW-SSE trending Raintoli fault (RF) which is running parallel to the North Almora Thrust (NAT) along the Saryu valley from Seraghat-Naichun to Seri in the central sector of the Uttarakhand Himalaya, India. The RF is characterized as dextral strike slip fault and behaves as a ductile shear zone within the zone of NAT. The dextral sense of shear movement of RF is delineated by the fabric of the shear zone rocks including microscopically observed indicators such as sigma and delta porphyroclasts, quartz c-axis, and the field structural data. Additionally, in the quaternary period the dextral strike slip fault is reactivated with oblique slip component as characterized by various geomorphic indicators, for example, triangular facets, abandoned river channels, unpaired fluvial terraces, and V-shaped valleys with recurrent seismicity. Further, the morphometric parameters including Valley Floor Width to Valley Height ( ), asymmetry factor (AF), and gradient index (GI) further prove active nature of RF as suggested by low values of hypsometric integration, V-shaped valley, higher gradient index, and tilting of Saryu basin.

Stalagmite Inferred High Resolution Climatic Changes throughPleistocene-Holocene Transition in Northwest Indian Himalaya

Investigated for d18O and d13C isotopes, mineralogy and growth rate, a 20 cm long and 230Th-dated calcite stalagmite from Kalakot (Jammu and Kashmir Himalaya), has recorded high resolution precipitation variability during the Pleistocene-Holocene transition. At present, the study area is influenced by both the Indian Summer Monsoon (ISM) and Westerlies. The StalAge model indicates that the stalagmite grew between 16.3 ka to 9.5 ka BP under the ideal isotopic equilibrium conditions as revealed by the Hendy test results. The d18O and d13C values range from -5.41 to -8.82% and -7.09 to -10.84% respectively. Although the U/Th chronology is poor due to low Uranium content in the samples resulting in relatively large errors, the first stalagmite inferred precipitation variability reconstructed from NW Indian Himalaya makes this study significant. The near footprints of three global events, e.g., Older Dryas (OD), Allerod period and Younger Drays (YD) can be noticed at ~14.3-13.9, 13.9-12.7 and 12.7-12.2 ka BP. The precipitation strength was weaker during the OD and YD, but was stronger during the Allerod interstadial. By the termination of YD interval, the climate seems fluctuating in the NW Himalaya. There seems variation in commencement, duration and termination of the above mentioned events in different parts of the globe due to latitude location and response time.