High Himalaya Research Articles

Provenance of the Langjiexue Group to the south of the Yarlung-Tsangpo Suture Zone in southeastern Tibet: Insights on the evolution of the Neo-Tethys Ocean in the Late Triassic

ABSTRACTThe Upper Triassic Langjiexue Group, which lies immediately south of the Yarlung-Tsangpo Suture Zone in the Shannan area of southeastern Tibet, represents an important part of the Tethyan Himalayan Sequence (THS). Its provenance and palaeogeography have been the subject of debate. We present new data on petrographic composition, whole-rock geochemistry, and detrital zircon U–Pb geochronology to constrain the provenance of the Langjiexue Group. The dominance of quartz grains and felsic volcanic lithic fragments suggests that the sandstones are litho-quartzose. The trace element geochemical signatures (V–Ni–Th*10, Co/Th–La/Sc, Eu/Eu*–Th/Sc) suggest derivation from felsic igneous sources. The detrital zircon age spectra display three major peaks: a Meso-to-Neoproterozoic peak (1200–900 Ma, 7–18%), a Neoproterozoic-to-Late Cambrian peak (750–500 Ma, 32–65%), and a Late Carboniferous-to-Late Triassic peak (300–200 Ma, 11–33%). The maximum depositional age of early Carnian (236–235 Ma) is obtained by calculating weighted average ages of the youngest zircons (≤250 Ma). The youngest age cluster (300–200 Ma) is incompatible with sources from neighbouring terranes, including the South Qiangtang terrane, Lhasa terrane, THS, and Higher Himalayan Crystalline. Correlations of the Permian–Triassic zircons with those of time-equivalent strata in northwest Australia, west Burma, and the Banda Arc unveil a potential connection to the Tasmanides along the convergent margin of eastern Australia. The New England Orogen (300–230 Ma) could have supplied the Langjiexue Group with magmatic materials via continent-scale drainage systems or a submarine fan complex. This scenario provides a new perspective into the transport of detritus from distal orogens to sedimentary basins thousands of kilometres away.

Traditional Beliefs and Practices of the Lepchas in Eastern India

India is a crucible comprising a multitude of tribes ranging from the high Himalayas, deserts, islands, plateau and coastal plains and has their own distinct culture, traditions and language. Through this study, we shall be gaining as insight into the old animist tribal beliefs of the Lepchas, who are an indigenous tribe residing in and around the Kanchenjunga basin. It is a well-known fact that as stronger and more established religions come in contact with animist tribal practices, these tribal religious beliefs wilt under pressure and eventually lose their identity. I shall through this paper try to shed some light on the state of this ancient animist religion commonly known as Monism or Bonism after the name of their priestesses Muns and their priest Boongthings. We shall see through their various tribal ceremonies as to how they are safeguarding their beliefs and take a glimpse the efforts that have been undertaken to cope alongside world famous beliefs in the 21st century.

Black Carbon and Ozone Variability at the Kathmandu Valley and at the Southern Himalayas: A Comparison between a “Hot Spot” and a Downwind High-Altitude Site

Several studies have reported the transport of short-lived climate forcers/pollutants (SLCF/P) from the highly polluted areas in southern Asia (e.g., the Indo-Gangetic Plain and the Himalayan foothills) to the Himalayas, with significant implications for the global and regional climate, crop yields, and human health. In this work, we perform a comparison of nearly three years (February 2013–October 2015) of simultaneous black carbon (BC) and surface ozone (O3) measurements at two sites in Nepal, viz., Paknajol (1380 m a.s.l.), in the Kathmandu Valley, and the WMO/GAW global station Nepal Climate Observatory-Pyramid (NCO-P, 5079 m a.s.l.), near the base camp of Mt. Everest. The two sites are only 150 km apart and are characterized by different situations: While the Kathmandu Valley is one of the regional urban “hot spots” for concerns related to air pollution, NCO-P is representative of the background conditions of the high Himalayas and the free troposphere. Therefore, the possible role played by emissions occurring in the planetary boundary layer (PBL) of the Kathmandu Valley in influencing the variability in SLCF/P at NCO-P was investigated. BC and O3 concentrations at NCO-P showed a linear correlation with the modeled PBL height over the Kathmandu urban area, providing evidence that the anthropogenic emissions occurring within the Kathmandu PBL could affect the variability in BC and O3 at NCO-P. Furthermore, when introducing an additional constraint into the analysis (viz., back-trajectories), we show that on days when air mass transport between the two measurement sites was observed (10% of the period), at least 22% and 16% of BC and O3 variability at NCO-P can be explained by concurrent variability in SLCF/P over the Kathmandu Valley.

Preliminary trace element analysis of arsenic in Nepalese groundwater may pinpoint its origin

Arsenic contamination of groundwater used as drinking water in South Asia poses a serious health threat to the inhabitants living on alluvial plains of the Himalayan foreland of countries like Bangladesh, India, Nepal and Myanmar. Although the geological and geochemical conditions favoring the release of the highly poisonous contaminant from the sediments hosting the groundwater are meanwhile quite well understood, there is still a significant debate about the origin of arsenic. The sediments forming a huge proportion of the Terai (lowlands of Nepal) aquifers are derived from two main sources, (i) sediments deposited by large rivers that erode the upper Himalayan crystalline rocks and (ii) weathered meta-sediments carried by smaller rivers originating in the Siwalik foothills adjacent to the Terai. In this article a so far underestimated source of As is discussed: the peraluminous leucogranites found ubiquitously in the Nepal Himalaya. The relationship between the trace elements analyzed in the groundwater in the Terai and trace elements found in such felsic rocks reflect the origin of the arsenic in the high Himalayas of Nepal. In addition to the high concentration of As, a striking feature is the presence of the lithophile trace elements like Li, B, P, Mn, Br, Sr and U in the groundwater. The mentioned elements point to a felsic initial source like metapelites or leucogranites—all rocks showing a high abundance of especially B, P and As as well as Cd and Pb.

Petrography of the Neogene Siwalik Group sandstones, Khutia Khola section, Nepal Himalaya: implications for provenance, paleoclimate and tectonic setting

The Neogene fluvial sediment (Siwalik Group) forming the southernmost foothill in the Himalaya is one of the best archives of climate history and uplift of the Himalaya. The petrographic composition of these fluvial sandstones provides information on source rocks, depositional climate of the Siwalik sediments and tectonic setting of the Himalaya. This study presents the petrographical results of the Siwalik sandstones from the Khutia Khola section, Nepal Himalaya. Petrographically, these sandstones are lithic arenites (30%) to sub-litharenites (70%). Provenance analyses show that sediments were mainly derived from recycled orogenic and transitional recycled areas in the recycled orogen block provenances. The climatic indexes suggest the semi-humid to humid climate during sedimentation of the Khutia Khola sandstones. The stratigraphic trend of the lithic components show that metamorphic lithic grains are increasing and sedimentary lithic grains are decreasing in up section, and the Lesser and Higher Himalayas are the mixed source of these Siwalik sandstones.

Erosional unroofing of Himalaya in far western Nepal: a detrital zircon U-Pb geochronology and petrography study

Since the collision between the Indian and Asian plates, several peripheral foreland basin were formed, and started to accumulate the sediments from the hinterland Himalayan orogeny. The sediments deposited at the northern tip of the Greater India have been uplifted, exhumed after the activation of several south propagating thrusts and finally transported to the foreland basin by southward flowing fluvial system. We present petrography and detrital zircon dating for the interpretation of possible provenance of the Neogene Siwalik foreland basin sediments in far western Nepal. The QFL ternary plot for provenance analysis show a 'recycled orogeny' field for the studied sandstone samples, indicating Tethys Himalaya, Higher Himalaya and Lesser Himalaya as the source of the foreland basin sediments. The detrital zircon U-Pb ages of the studied samples have shown that during the time of deposition there was dominant numbers of detritus supplied from the Tethys and upper Lesser Himalaya. Subsequently the amount of the Higher and Lower Lesser Himalaya increased during the time of deposition of the Middle Siwalik.

Climatic records and linkage along an altitudinal gradient in the southern slope of Nepal Himalaya

To validate the climatic linkages under different topographic conditions, observational climate data at four automated weather stations (AWS) in different elevations, ranging from 130 m asl. to 5050 m asl., on the southern slope of the Nepal Himalayas was examined. the variation of means and distribution of daily, 5-days, 10-days, and monthly average/sum of temperature/ precipitation between the stations in the different elevation was observed. Despite these differences, the temperatures records are consistent in different altitudes, and highly correlated to each other while the precipitation data shows comparatively weaker correlation. The slopes (0.79-1.18) with (R2 >0.64) in the regression models for high Mountain to high Himalaya except in November and 0.56-1.14 (R2 >0.50) for mid-hill and high Mountain except January, December, June indicate the similar rate of fluctuation of temperature between the stations in the respective region. These strong linkages and the similar range of fluctuation of temperature in the different elevation indicate the possibilities of their use of lower elevation temperature data to represent the higher elevation sites for paleoclimatic calibration. However, the associations of precipitation between the stations at the different elevation are not as strong as the temperature due to heterogeneous topographical features and steep altitudinal contrast.

Geomorphic effectiveness of a long profile shape and the role of inherent geological controls in the Himalayan hinterland area of the Ganga River basin, India

Long profiles of rivers provide a platform to analyse interaction between geological and geomorphic processes operating at different time scales. Identification of an appropriate model for river long profile becomes important in order to establish a quantitative relationship between the profile shape, its geomorphic effectiveness, and inherent geological characteristics. This work highlights the variability in the long profile shape of the Ganga River and its major tributaries, its impact on stream power distribution pattern, and role of the geological controls on it. Long profile shapes are represented by the sum of two exponential functions through the curve fitting method. We have shown that coefficients of river long profile equations are governed by the geological characteristics of subbasins. These equations further define the spatial distribution pattern of stream power and help to understand stream power variability in different geological terrains. Spatial distribution of stream power in different geological terrains successfully explains spatial variability in geomorphic processes within the Himalayan hinterland area. In general, the stream power peaks of larger rivers lie in the Higher Himalaya, and rivers in the eastern hinterland area are characterised by the highest magnitude of stream power.

Stable isotopes of river water and groundwater along altitudinal gradients in the High Himalayas and the Eastern Nyainqentanghla Mountains

Study Region This study considers river water and groundwater in seeps and springs collected from the non-monsoon season in the valleys of the Dudh Koshi River in eastern Nepal and the Niyang River of eastern Tibet, both in the Himalaya Mountains.Study Focus Data from this study comprise water samples that provide a single season snapshot of δ18O and δD values that give additional information into the sources of moisture and the altitude lapse rates for the southern flank of the High Himalaya of Nepal and the Eastern Nyainqentanghla Mountains of the Tibetan Plateau.New Hydrological Insights The local water line for Nepal samples, δD=(7.8±0.3) · δ18O + (4.0‰±4.6‰), was moderately lower in slope than for Tibetan Plateau samples, δD=(8.7±0.1) · δ18O + (24.3‰±2.0‰); evaporation has a greater influence on the Nepal samples—consistent with warmer temperatures in Nepal versus Tibet within the same altitude range. Mean d-excess values for Tibet samples (13.1‰±2.0‰) implies that recycled continental moisture has more influence than marine moisture observed for the Nepal samples (7.4‰±4.4‰). Altitude lapse rates of δ18O and δD for Nepal samples (-2.8‰‰km−1 and −24.0‰km−1) do not significantly differ from Tibet samples (−3.1‰‰km−1 and −27.0‰km−1) and regional measurements; the lapse rates are reduced above 4500m and are not influenced by exceptionally high elevations in the Dudh Koshi River watershed.

Seasonal Migration and Livelihood Resilience in the Face of Climate Change in Nepal

Migration for work remains a livelihood strategy in subsistence farming communities globally, especially in view of unprecedented environmental change. Farmers in the high Himalaya migrate during the winter, when farming activities are reduced. This study examined the drivers of seasonal migration in the context of climate change and migration's role in food security and livelihood resilience in the district of Humla, Nepal. Focus group discussions and a household socioeconomic survey were conducted. The results suggest that rather than climate change impacts, structural poverty is the root cause of migration, such that men from poor households with small landholdings and high food insecurity, mainly belonging to low-caste groups, migrate for work during the winter. Focus group participants also presented a clear perception of climate variability and change and their negative impacts on crop production. In this context, the poorest households find cultivating their own land risky. Moreover, the traditional practice of sharecropping, which helped them reduce food shortages, has also become less profitable. Therefore, more households are likely to participate in seasonal migration in the context of climate change, and those already migrating are likely to do so for longer time periods. Currently, such migrants take up low-paying unskilled wage work, mainly in towns and cities in Uttarakhand, India, which enable them to make only modest savings, hardly enough to repay the debt their family has incurred during food shortages. Even in the future, these farmers are likely to be limited to the same migration pattern, because they lack the social ties, education, and financial capital needed to fulfill the administrative and monetary requirements for more economically promising long-term overseas migration. Thus, it is unlikely that migration will make a significant contribution to building livelihood resilience in the context of climate change in remote Himalayan farming communities.

The value of ecosystem services in the high altitude Spiti Valley, Indian Trans-Himalaya

The high mountain ranges of South and Central Asia are increasingly being exposed to large-scale development projects. These areas are home to traditional pastoralist communities and internationally important biodiversity including the endangered snow leopard Panthera uncia. Development projects rely on economic cost-benefit analysis, but the ecosystem services in the high Himalayas are poorly understood and are rarely accounted for. As a first step to fill this gap, we identified the main ecosystem services used by local people in the Trans-Himalayan Spiti Valley (7591 km2), a region important for conservation of snow leopards and high mountain biodiversity, and undertook an economic valuation. Stakeholders identified a range of services, though these were dominated by provisioning services identified by 90% of respondents. Only 5.4% of the respondents recognised regulatory services and 4.8% recognised cultural services. The mean economic value of provisioning services was estimated at US$ 3622 ± 149 HH−1 yr−1, which was 3.8 times higher than the average annual household income. Our results underscore the need to account for ecosystem services in the cost-benefit analyses of large-scale development projects in addition to assessments of their environmental and social impact.

"No former travellers having attained such a height on the Earth's surface": Instruments, inscriptions, and bodies in the Himalaya, 1800-1830.

East India Company surveyors began gaining access to the high Himalaya in the 1810s, at a time when the mountains were taking on increasing political significance as the northern borderlands of British India. Though never as idiosyncratic as surveyors insisted, these were spaces in which instruments, fieldbook inscriptions, and bodies were all highly prone to failure. The ways surveyors managed these failures (both rhetorically and in practice) demonstrate the social performances required to establish credible knowledge in a world in which the senses were scrambled. The resulting tensions reveal an ongoing disconnect in understanding between those displaced not only from London, but also from Calcutta, something insufficiently emphasized in previous histories of colonial science. By focusing on the early nineteenth century, often overlooked in favor of the later period, this article shows the extent to which the scientific, imaginative, and political constitution of the Himalaya was haphazard and contested.

Size and spatial distribution of landslides induced by the 2015 Gorkha earthquake in the Bhote Koshi river watershed

The Mw 7.8 Gorkha earthquake in Nepal on April 25, 2015, produced thousands of landslides in the Himalayan mountain range. After the earthquake, two field investigations along Araniko Highway were conducted. Then, using remote sensing technology and geographic information system (GIS) technology, 1481 landslides were identified along the Bhote Koshi river. Correlations between the spatial distribution of landslides with slope gradient and lithology were analyzed. The power-law relationship of the size distribution of earthquake-induced landslides was examined in both the Higher Himalaya and Lesser Himalaya. Possible reasons for the variability of the power exponent were explored by examining differences in the geological situations of these areas. Multi-threshold cellular automata were introduced to model the complexity of system components. Most of the landslides occurred at slope gradients of 30°–40°, and the landslide density was positively correlated with slope gradient. Landslides in hard rock areas were more common than in soft rock areas. The cumulative number-area distribution of landslides induced by the Gorkha earthquake exhibited a negative power-law relationship, but the power exponents were different: 1.13 in the Higher Himalaya, 1.36 and Lesser Himalaya. Furthermore, the geological conditions were more complex and varied in the Lesser Himalaya than in the Higher Himalaya, and the cellular automata simulation results indicated that, as the complexity of system components increased, the power exponent increased. Therefore, the variability of the power exponent of landslide size distribution should ascribe to the complexity of geological situations in the Bhote Koshi river watershed.

Leucogranites in Lhozag, southern Tibet: Implications for the tectonic evolution of the eastern Himalaya

Petrogenesis of the Himalayan leucogranite is strongly influenced by conditions which are associated with the tectonic evolution of Himalayan orogen. In this article, we present petrological, geochronological and geochemical results of the Lhozag leucogranites that crop out alongside the South Tibetan Detachment System (STDS) in the east of Himalaya. Zircon U-Pb dating revealed three episodes of leucogranitic magmatism in Lhozag at 17.8±0.1Ma, 15.1±0.1Ma, and 12.0±0.1Ma, respectively. The Lhozag leucogranites show relatively low εNd(t), low zircon εHf(t) and high initial 87Sr/86Sr ratios, which are similar to the High Himalayan Crystalline Series (HHCS), indicating that they were derived from the HHCS. The characteristics of relatively high Na2O and Rb contents, high Rb/Sr ratios and low CaO, MgO, TFe2O3, TiO2, and Sr contents indicate that both the ca. 18Ma Lhozag tourmaline leucogranites and the ca. 15Ma Lhozag two-mica granites were derived from fluid-absent muscovite-dehydration melting of metasediments. The opposite geochemistry characteristics of the ca. 12Ma Khula Kangri two-mica granites imply that these granites are derived from fluid-present melting of metasediments. Four Khula Kangri two-mica granite samples with relatively lower TiO2, TFe2O3, MgO, and CaO contents, higher Rb concentrations and Rb/Sr ratios could be evolved from the Khula Kangri two-mica granites with relatively lower Rb/Sr ratios. The melting behaviors of the Lhozag leucogranites varied from fluid-absent melting to fluid-present melting, implying that there were P-T-XH2O variations in the deep crust. The tectonic evolution would give rise to variation of P-T-XH2O variation, and subsequent transformation of melting behavior. Our new results display the transformation of melting behavior of the Lhozag leucogranites, which implies the tectonic evolution from earlier N–S extension to later E–W extension in the eastern Himalaya at ca. 12Ma.

Current strain accumulation in the hinterland of the northwest Himalaya constrained by landscape analyses, basin-wide denudation rates, and low temperature thermochronology

Rupture associated with the 25 April 2015 Mw 7.8 Gorkha (Nepal) earthquake highlighted our incomplete understanding of the structural architecture and seismic cycle processes that lead to Himalayan mountain building in Central Nepal. In this paper we investigate the style and kinematics of active mountain building in the Himalayan hinterland of Northwest India, approximately 400km to the west of the hypocenter of the Nepal earthquake, via a combination of landscape metrics and long- (Ma) and short-term (ka) erosion rate estimates (from low temperature thermochronometry and basin-wide denudation rate estimates from 10Be concentrations). We focus our analysis on the area straddling the PT2, the physiographic transition between the Lesser and High Himalaya that has yielded important insights into the nature of hinterland deformation across much of the Himalaya. Our results from Northwest India reveal a distinctive PT2 that separates a Lesser Himalaya region with moderate relief (∼1000m) and relatively slow erosion (<1mm/yr) from a High Himalaya with extreme relief (∼2500m), steep channels, and erosion rates that approach or exceed 1mm/yr. The close spatial similarity in relative rates of long- and short-term erosion suggests that the gradient in rock uplift rates inferred from the landscape metrics across the PT2 has persisted in the same relative position since at least the past 1.5Ma. We interpret these observations to suggest that strain accumulation in this hinterland region throughout at least the past 1.5Ma has been accomplished both by crustal thickening via duplexing and overthrusting along transient emergent faults. Despite the >400km distance between them, similar spatiotemporal patterns of erosion and deformation observed in Northwest India and Central Nepal suggest both regions experience similar styles of active strain accumulation and both are susceptible to large seismic events.

Geotechnical Attributes of Active Sediments and its Prospective in Hazards Susceptibility and Mitigation Measures: A Study on Soils from Leh Valley, Ladakh Himalaya, India

In the present study, attempts have been made to evaluate the geotechnical characteristics of Quaternary sediments from high altitude Ladakh Himalaya to demarcate the active sediment (soil) for its bearing on natural hazards susceptibility and mitigation measures. The experimental works have been carried out on collected sediments (soils) from different locations and depths during year 2014 for determination of grain size sensitive parameters and geotechnical attributes as per American Society for Testing and Materials standard and empirical relationships. The results reveal that the majority of uniformly graded sediments (soils) of size 0.02–2.0 mm exhibit wide range of shear, cohesions (c) and angle of internal frictions may be due to difference in their bulk and dry densities, void ratios, liquid limit, plastic limit and liquid index. Thus, the sediments of Leh Valley can be classified in normal sediment (soil) unit and normally active sediment (soil) unit. The normally active unit exhibits lower shear strengths and cohesions in comparison to normal unit due to higher liquid and plastic limits of sediment subjected to temperature sensitive freezing and thawing actions. The active sediment (soil) unit has been found more prone to slope instabilities, differential settlements and mass flow hazards, hence requires special care during developments and mitigation measures.

Evaluating the contribution of avalanching to the mass balance of Himalayan glaciers

ABSTRACT Avalanching is a prominent source of accumulation on glaciers that have high and steep valley-walls surrounding their accumulation zones. These glaciers are typically characterised by an extensive supraglacial debris cover and a low accumulation area ratio. Despite an abundance of such glaciers in the rugged landscapes of the High Himalaya, attempts to quantify the net avalanche contribution to mass balance and its long-term variation are almost missing. We first discuss diagnostic criteria to identify strongly avalanche-fed glaciers. Second, we develop an approximate method to quantify the magnitude of the avalanche accumulation exploiting its expected control on the dynamics of these glaciers. The procedure is based on a simplified flowline model description of the glacier concerned and utilises the known glaciological mass-balance, velocity and surface-elevation profiles of the glacier. We apply the method to three Himalayan glaciers and show that the data on the recent dynamics of these glaciers are consistent with a dominant contribution of avalanches to the total accumulation. As a control experiment, we also simulate another Himalayan glacier where no significant avalanche contribution is expected, and reproduce the recent changes in that glacier without any additional avalanche contribution.

Timing of fluvial terrace formation and concomitant travertine deposition in the upper Sutlej River (Tirthapuri, southwestern Tibet) and paleoclimatic implications

Travertines are carbonates precipitated from hydrothermal springs and are relatively common on the Tibetan plateau and occur along tectonically active faults. The Karakoram fault system is an active strike-slip fault that extends from the Pamir into southwestern Tibet, where it controls the course of the upper Sutlej River and the occurrence of several hydrothermal springs, including the Tirthapuri hot springs. Multiple fluvial terraces that are partly capped by travertine are preserved in the Tirthapuri area. Four main fluvial terrace levels (labelled as T1 to T4 with increasing height above river) were identified and several meter-thick travertine platforms occur on the current river level as well as the T2 and T3 terraces. Sedimentological and petrographic observations suggest that the travertine platforms were deposited on active floodplains of the paleo- and modern Sutlej River, and preserved from fluvial erosion because travertine precipitation was immediately followed by vertical river-bed incision and thus terrace abandonment. Results of 230Th/U in combination with luminescence dating show that the deposition of travertine platform and river incision that led to the formation of T3 terrace (∼93 m above the Sutlej) took place at ca. 127.5 ka. The development of terrace T2 and overlying travertine platform (∼28 m above the Sutlej) occurred between ca. 10.0 and 8.8 ka. Fluvial incision has arrived at the modern level at least ca. 0.2 ka ago. Both the travertine deposition and major river incision are likely triggered by the intensified Indian summer monsoon and are linked to phases of maximum monsoon strength. During strong monsoon phases, a large quantity of moisture is transported into southwestern Tibet, activating hot springs and thus travertine precipitation, facilitating fluvial incision and stripping off sediments from the regional hill-slopes. At least over the last glacial cycle we suggest that the Tirthapuri travertine and associated fluvial incision are sensitive indicators of (peak) monsoonal activity and can thus provide valuable insights into past climate change and climate-driven landscape evolution on the southwestern Tibetan Plateau. Comparison of our findings with published data further suggests that monsoon-controlled fluvial aggradation and incision during the early Holocene is synchronous in southwestern Tibet and the adjacent sector of the Himalayan orogen (north-western Sub-to High Himalaya).

Concept in Determining the Height of Mount Everest (Sagarmatha)

In this paper we describe the concepts in determining the height of the Mt. Everest and elucidate the method of height measured relative to sea level. The current height determination procedure is limited by the accuracy of the calculation of height of the sea, (less than +/- 2m) or its mathematical approximation the geoid. Although Nepal has been recognizing 8848m as the official height of the Everest, many climbing team and scientific explorations from different countries in different time have been conducted and achieved different numerical values of height of the Everest. The challenging issue is defining the elusive sea level with or without nearby shoreline. Through some recognized media it has been made public that the Government of Nepal have plan to ascertain the height of Mt. Everest and if it is so this would be the first attempt by Nepal government to determine the height on its own. Survey Department under the Ministry of Land Reform and Management is the authoritative organization to translate Government’s decision into action. Depending on the nature of the work; in order to accomplish the measurement, the complete task is divided into five parts such as Precise leveling survey, Determination gravimetric geoid, Trigonometrical leveling, Global Positioning System (GPS) Survey and Data processing. Survey Department, lacks in enough resources and infrastructures for completing this project in the complex environment of the most rugged High Himalayas therefore some other potential International Scientific organization can be expected to join hands in the process of height determination.

Petrography and provenance of Upper Cretaceous – Palaeogene sandstones in the foreland basin system of Central Nepal

ABSTRACTSedimentary deposits of the Cretaceous to Miocene Tansen Group of Lesser Himalayan association in central Nepal record passive-margin sedimentation of the Indian Continent with direct deposition onto eroded Precambrian rocks (Sisne Formation onto Kaligandaki Supergroup rocks), succeeded by the appearance of orogenic detritus as the Indian continent collided with Asia on a N-dipping subduction zone. Rock samples from two field traverses were examined petrographically and through detrital zircon U–Pb dating, one traverse being across the Tansen Group and another across the Higher and Tethyan Himalaya (TH). The Tansen Group depositional ages are well known through fossil assemblages. We examined samples from three units of the Tansen Group (Amile, Bhainskati, and Dumri Formations). The Sedimentary petrographic data and Qt F L and Qm F Lt plots indicate their ‘Quartzose recycled’ nature and classify Tansen sedimentary rocks as ‘recycled orogenic’, suggesting Indian cratonic and Lower Lesser Himalayan (LLH) sediments as the likely source of sediments for the Amile Formation (Am), the TH and the Upper Lesser Himalaya (ULH) as the source for the Bhainskati Formation (Bk), and both the Tethyan and Higher Himalaya (HH) as the major sources for the Dumri Formation (Dm). The Cretaceous–Palaeocene pre-collisional Am is dominated by a broad detrital zircon U–Pb ~1830 Ma age peak with neither Palaeozoic nor Neoproterozoic zircons grains, but hosts a significant proportion (23%) of syndepositional Cretaceous zircons (121–105 Ma) would be contributions from the LLH volcanosedimentary arc, Gangdese batholith (including the Xigaze forearc). The other formations of the Tansen Group are more similar to Tethyan units than to Higher Himalaya Crystalline (HHC). From the analysed samples, there is a lack of distinctive evidence or HH detritus in the Tansen basin. Furthermore, the presence of ~23±1 Ma zircons from the HH unit suggests that they could not have been exposed until the earliest Miocene time.