Gya river, one of the main tributary of Indus, hosts several scattered palaeoflood deposits. The chronology, genesis and spatiotemporal relationships of these scattered deposits can throw light to the regional and global climatic fluctuations and their implications for the evolution of the valley. The valley structure of the Gya river consists of a broad middle reach alternating with narrow valleys and gorges in the upper and lower reaches which can be blocked by the slightest of sediment discharge damming the entire valley. The geomorphological, sedimentological and chronological study in this valley reveals multiple short-lived lake phases at 21-19.9 ka, 13 ka and 4.5 ka in the broader reach of the river during the transition periods when climate rapidly fluctuates between cold-dry and warmwet. The damming in the valley is the result of the glacial lake outbursts in the head waters of the Gya catchment blocking the narrow lower reaches of the main channel by massive sediment. These lakes that are formed by valley damming contains similar to 10(8) m(3) of water which subsequently breach out causing significant geomorphic changes on reach scale along the Gya river channel.

In this communication we reconstruct climate variability of Ladakh, Trans-Himalaya region, on sub-century timescale spanning the last four millennia (similar to 4130 to 260 cal yr 'before present' (BP)). To achieve this objective, we measured a suite of physical, biotic and inorganic proxies of a lacustrine sequence. In general, between similar to 4130 to similar to 2640 cal yr BP proxy records reveal climate variability following a typical pattern of the northern hemispheric climate and appear to be dominated by westerlies. Thereafter, the Indian Summer Monsoon (ISM) forcing appears to dominate regional climate. The former period appears to have experienced human presence as evidenced by an invasive species of diatom -Didymosphenia and charcoal, likely originating from human activities on trading routes with Central Asia, China and Tibet. After similar to 2640 cal yr BP, when ISM started governing the climate of the Ladakh-Karakoram region, it probably induced high-frequency climate variability leading to disasters related to landslides, debris flows, avalanches etc., eventually reducing the intra-boundary trade. A similar situation appears to be gripping the region again as meteorologically recorded precipitation data from Ladakh reveals arrival of high-frequency monsoonal variability in the region with recurrent flash floods (e.g., 2010, 2013).

A multi-proxy study using mineral magnetism, sediment texture, total organic content, palynofacies and diatoms was conducted in one of the highest proglacial lake situated at North Pulu (5098 m a.s.l.) of Ladakh sector of NW Himalaya – a high-altitude cold arid desert. This study presents climatic variations that occurred between 5412 and 419 cal. yr BP (14C AMS chronology). Directly recharged by meltwater from Khardung glacier, this proglacial lake provides a complete record of past climatic variability due to continuous sedimentation and this attribute makes it an exceptionally important geochronological archive for climatic studies. This first high-resolution palaeolimnology record from Karakoram Himalayas shows intermittent warm and cold periods in which the cold events are short but sudden events recorded at 5700, 4600, 4400, 4200, 3800, 3500, 3000, 1800–1700, 1200, 910, 840 and 770–710 cal. yr BP. Between 5412 and 4840 cal. yr BP, an oxic lake condition existed with freeze–thaw action, prominent weathering, more sediment generation and less organic productivity. The following period till 4410 cal. yr BP was cold and dry, a transition phase to the next warmer phase. Between 4410 and 2064 cal. yr BP, climate ameliorated to somewhat moderate warm climate and relatively high lake levels. Glacial melting due to a warm climate resulted in high TOC%, and well-preserved OM indicating reducing conditions in the lake system. From 2064 to 1711 cal. yr BP cold conditions and from 1272 to 1182 cal. yr BP warmer conditions are seen with large appearance in Amphora ovalis indicating increased nutrients input and moderate water levels. This was followed by warmer climatic conditions between 1182 and 958 cal. yr BP. LIA in the region is experienced between 958 and 644 cal. yr BP with anoxic condition. Between 644 and 419 cal. yr BP, climatic condition was again warmer comparatively. However, this warming was not so severe and only had a regional impact.

Pangong Tso is a brackish water lake that lies along Pangong strand of the Karakoram strike-slip fault in arid Trans Himalayan region. The geomorphic mapping along the periphery of the lake suggested the presence of four palaeolake level strands located at 6, 4.8, 3.8 and 1.25 m above the present lake level. The gullied periphery expose relict deltaic sediments where sedimentological study enabled us to identify four deltaic lobes that make a classic Gilbert-type delta with well-developed top-set, fore-set and bottom-set. The top-set of the stratigraphically oldest delta lobe that corresponds to the highest lake level shows the presence of freshwater molluscs identified as Radix and a burnt sediment layer (hearth). The charcoal derived from this layer yielded C-14 date as 1.7 ka BP and six luminescence ages from different delta lobes suggested that delta evolution and lake level fall of similar to 6 m took place between similar to 2-1 ka. Review of palaeoclimate record available from NW Himalaya and Pangong Tso suggests that late Holocene aridity might be responsible for this rapid lake level fall. Sclerochronological analysis carried out on 54 subsamples from three Radix specimens suggested that the modern type of seasonal conditions may have prevailed at similar to 1.7 ka BP.

This paper highlights unique sites in Ladakh, India, investigated during our 2016 multidisciplinary pathfinding expedition to the region. We summarize our scientific findings and the site's potential to support science exploration, testing of new technologies and science protocols within the framework of astrobiology research. Ladakh has several accessible, diverse, pristine and extreme environments at very high altitudes (3000-5700 m above sea level). These sites include glacial passes, sand dunes, hot springs and saline lake shorelines with periglacial features. We report geological observations and environmental characteristics (of astrobiological significance) along with the development of regolith-landform maps for cold high passes. The effects of the diurnal water cycle on salt deliquescence were studied using the ExoMars Mission instrument mockup: HabitAbility: Brines, Irradiance and Temperature (HABIT). It recorded the existence of an interaction between the diurnal water cycle in the atmosphere and salts in the soil (which can serve as habitable liquid water reservoirs). Life detection assays were also tested to establish the best protocols for biomass measurements in brines, periglacial ice-mud and permafrost melt water environments in the Tso-Kar region. This campaign helped confirm the relevance of clays and brines as interest targets of research on Mars for biomarker preservation and life detection.

The Himalayan system is a complex and young fold mountain chain, rightly known as the water tower of Asia. Trans-Himalaya and the Tethyan Himalaya consist of a mountainous region about 1,000 km long and 225 km wide in the center, narrowing to ~32 km width at the eastern and western ends toward the northwestern side of the Himalayan chain in the Indian territory. The rivers of the Trans- and Tethyan Himalayan terrains follow the fault lines (Indus Suture Zone, Karakorum Fault, Spiti fault) and have a tectonic/structural control. These rivers as of today are unpolluted and still away from the anthropogenic and economic impact. They have enough potential which has not been utilized properly perhaps because of its strategic location. Vast exposures of the Quaternary sediments (lacustrine and fluvial) along the Indus (Ladakh, J&K) and Spiti rivers (Lahaul-Spiti, HP) are helpful in generating data on landscape evolution, paleoclimate, tectonics, and earth surface processes.

A bird’s humerus has been recovered from a microvertebrate subfossil accumulation bearing sand layer from a fluvial-lacustrine section exposed near the village Shachukul, Tangtse Valley, Ladakh. This is the first report of this kind of material from Trans-Himalaya. The specimen bone is identified as humerus bone of Coturnix coturnix(common quail), dated to 3400±40yr BP. The finding of such a high degree of preservation of bones with soft tissues indicates a sudden burial of the whole assemblage, including this bone might have caused by a flash-flood like event. This could be a roosting site for any carnivore mammal or a bird or a communal roosting site for any kind of a bird community. The ratio of skeletal and dental elements, preservation of scats/droppings with remains of bones and hair, the absence of long-distance fluvial transport features on the bones, supports an accumulation and burial of the scatological material at the site of origin.

A general review account of the late-Quatenary moisture history of monsoonal Central Asia inferred from the published literature 1.2 is given . All studies show high effective moisture form the area dominated by the India Monsoon during the early Holocene , suggesting Holocene optimal climate conditions . In contrast , areas which are dominated by the South-East Asian monsoon and the Westerlies, optimal condition prevailed their during the mind-Holocene. These apparent in the Holocene. Strengthened insolation during the early Holocene , possibly caused an enhanced low-level convergence over the Tibetan Plateau which results in the intensification of the summer monsoon, Tibetan Plateau experienced strong air uplift which caused intensified precipitation and air divergence in the upper troposphere. This divergence over the plteau led an intensified descent of air masses and consequently increased aridity in the area adjacenmt to the north. The majority of the palaeoclimatic records suggest reduced effective moisture since the late Holocene in the region.

Records from the Tangtse Valley in the Trans-Himalaya reveal depositional history since 48ka, with fluvial aggradation followed by incision, lacustrine sediment fill, and later incision. Varied sedimentary architecture with fluvial episodes intervened by lacustrine pulses, flood events, colluvial and glacial activity are preserved. The valley is located west of the Pangong Tso/Bangong Co, one of the largest lakes in Tibet which has served as a spillway, flooding and damming the entire Tangtse Valley, resulting in the formation of a lake. Today Pangong Tso consists of five basins separated by shallow sills and is fed by snow melt. Documentation based on 14C and OSL chronologies of the sediment sections throughout the valley reveals evidence of a sixth basin of Pangong Tso toward west, occupying the present day Tangtse Valley between 9.6–5.1ka. This event coincides with periods of high lake levels in Tibet, China as well as intensified monsoon periods over the Indian subcontinent. A fluvial regime around 48ka and 30–21ka with comparatively arid conditions and dry phases interspersed by flooding is documented. The valley has been incised to depths of 40–50m in the upper part and to 130m in the lower part. The incision rate ranges from 0.3 to 1.2mmyr−1 in the upper part and reaches as high as 10.8mmyr−1 in the lower valley. Much of the incision took place between 22 and 9.6ka although repeated sediment fill-incision cycles in the valley from 30–22ka, 22–9.6ka, 9.6–5.1ka, 5.1ka, and even to present time were observed.

Lake records are one of the best archive to provide high resolution climatic data of terrestrial regime. Khardung La (5602 m), one of the highest pass of the world, separates the Indus valley and Shyok valley in Ladakh. This region is a cold desert at high altitude and is mostly get rains by the Western Disturbances. The Indian Summer Monsoon (ISM) penetrates the Himalayan barrier and provide rains in this region only during periods of high monsoon due to the northward shift of the ITCZ [1].The Khardung glacier that occupies the summit of this range presently has records of its extent till Ganglas village (near Leh) during ~90,000 yrs BP [2]. The two streams originating from the water divide are – Khardung rong (28km) to the north joins the Shyok river and Sangto tokpo (26 km) towards the south meets the river Indus. Both these streams host small glacial lakes (<0.5 sq km area) North Pulu (NP) and South Pulu (SP) on the either sides of Khardung La pass, are mostly frozen during the year round except for few months during summer. The 14C AMS chronology of sediment (1.3 m pit ; core of 80 cm) from NP lake bracketing the lake record from 4700 to 360 yrs BP and 1.32 m sediment core from SP bracketing it to 3800 to 320 yrs BP provides Mid-late Holocene lacustrine archives from this region. A multiproxy studies involving textural, sedimentological, mineral magnetic, geochemical and biotic proxies (palynofacies and diatoms) were carried out on NP and SP sediment cores. High magnetic susceptibility and clay content along with diversified diatom and other freshwater algae and land derived organic matter are indicative of fresh water supply leading to high lake level from ~4700 yr BP onwards. The multiproxy data provides evidence of much higher and stable lake level during ~3700 yr BP and ~3000 yr BP onwards in NP and SP due to high water supply in these lake. It is in contrast to the records of weak ISM conditions and low lake level in rest of the part of Indian peninsula during the period. Present study thus suggests strong western disturbance activity during ~4800-3000 yr BP leading to high lake level in this region. There are indications of a bigger lake basin at NP in the past as seen from the palaeo-strand. This data will throws light on the type of precipitation (Westerly or ISM) that was dominant in the area from 5000 yrs BP onwards in the Trans Himalaya.