This study investigates the geothermal system of the Yumesamdong region in the eastern Himalayas through integrated geophysical, geological, and structural analyses. Apparent resistivity and vertical electrical profiling results reveal a prominent folded formation at approximately 50 meters depth, intersected by multiple steeply dipping, low-resistivity zones indicative of fluid-filled fractures. A dense cluster of these conductive features occurs between 40 to 60 meters, with several converging at the crest of the fold to form an extensive fracture conduit system facilitating the upward migration of geothermal fluids. Numerical factor analysis further aids in delineating the depth and extent of these fractures, supporting a conceptual model of dynamic mixing between shallow glacial meltwater and deep geothermal fluids. Although the geophysical and field-based observations support this model, the absence of isotopic and long-term hydrochemical data limits definitive validation. The findings indicate that meteoric water, circulating through tectonically controlled fractures, likely associated with the South Tibetan Detachment Zone, interacts with deep magmatic heat sources, producing elevated temperatures and distinctive geochemical markers, notably in sulfate and strontium concentrations. This work proposes a conceptual hydrogeological framework that connects surface recharge with deep thermal processes and underscores the geothermal potential of the structurally active eastern Himalayan region. The study provides a scientific foundation for sustainable geothermal energy exploration and resource management in similar high-altitude, tectonically dynamic environments.
Morphotaxonomical study on leaf impressions recovered from the Middle Siwalik sediments of a road cutting section in Sarkaghat area, Mandi District, Himachal Pradesh, India revealed presence of two new fossil leaves, Mappia siwalica n. sp. and Leea himachalensis n. sp. of the family Icacinaceae and Leeaceae respectively. The extant comparable taxa of these fossils reported here, are distributed chiefly in the tropical moist deciduous forests of South and North east and central India respectively which may suggest that a tropical forest under moist conditions was prevalent during the Upper Miocene times in this region in contrast to a mixed deciduous forest under the tropical humid climate having reduced precipitation at present. The fossil records of the genus Leea Royen ex. Linn. indicates that this is widely distributed from Late Cretaceous to Miocene. Its oldest record in India is from Late Cretaceous of central India which suggests that this genus is of Gondawanan origin.
This study presents the development of an updated and homogenized earthquake catalogue for the Reasi-Katra belt, a seismically active region within the northwestern Himalaya. Leveraging the robust General Orthogonal Regression (GOR1) technique, new empirical magnitude conversion relationships have been derived to support this effort. The selection of the Reasi-Katra belt is motivated by the presence of the active Reasi thrust, a notable increase in recent seismic activity, and previous geodetic studies (e.g., GPS measurements) that collectively underscore the region's tectonic sensitivity and the need for focused seismic assessment. The study has two principal objectives: (i) to develop regional empirical regression relationships between different magnitude scales and (ii) to construct a homogenized earthquake catalogue in the most recent and advanced magnitude scale, M-wg(Das Magnitude Scale). The dataset spans from 1555 to October 16, 2022, covering a geographical domain of 32 degrees-36 degrees N and 72 degrees-78 degrees E. The primary source of data is the International Seismological Centre (ISC) catalogue, supplemented by regional and historical records. The resulting M(wg )based homogenized catalogue is a significant advancement for this region, contributing improved accuracy and consistency over traditional magnitude scales such as Mw. Recent developments in seismological research support the superiority of the M(wg )in estimating seismic energy, particularly for intermediate and small-to-moderate earthquakes. Previous studies lackthe implementation of the GOR1 technique for homogenizing earthquake data in this region using the M(wg )hereby positioning the present work as the pioneering effort in this region. This catalogue compilation will serve as a critical input for future seismic hazard assessments and regional tectonic studies.
Tunnelling through the geologically active Lesser Himalayan region poses substantial engineering challenges, including instability caused by squeezing ground conditions, faulted and folded strata, high overburden, and groundwater ingress. Ensuring tunnel face stability and optimizing stand-up time necessitates careful selection of excavation techniques and construction sequences. This study evaluates various excavation approaches to improve face stability for a megatunnel, typically defined by diameters exceeding 10 m, using actual geological and geotechnical data from a representative site in the Lesser Himalaya. Finite Element Analysis (FEA) was employed to model and analyse vertical crown displacements at different excavation stages. A detailed parametric analysis was also carried out to assess the influence of water pressure on overall tunnel stability. Result indicate ring-cut excavation offers the most effective initial control, as it excavates the tunnel face sequentially in concentric rings from the periphery toward the centre, followed by the New Austrian Tunnelling Method (NATM), and eventually by mechanized excavation methods. For Tunnel Boring Machine (TBM) operations, precise prediction of machine parameters is critical to mitigate jamming risks. The presence of water was found to intensify face stability challenges and complicate pressure estimations. The findings contribute essential guidance for tunnel design and execution in the complex geology of the Lesser Himalayas.
This study examines the factors influencing the hydrogeochemical characteristics and stable isotope composition of groundwater in the study area. A systematic analysis of groundwater samples was carried out to evaluate both physical and chemical parameters, revealing the predominant ionic concentration order as Ca-2(+) > Na+ > Mg-2(+) > K+ > NH4+ > Li+ for cations and HCO3- > Cl- > SO42- > NO3- > F- > NO2- for anions. To interpret the hydrogeochemical processes governing groundwater composition, multiple analytical techniques were employed, including bivariate plots, Piper trilinear diagrams, and Principal Component Analysis (PCA). The Piper diagram highlights the dominance of the Ca-Mg-HCO3 water type, suggesting that chemical weathering of carbonate and silicate minerals significantly influences groundwater chemistry. The Chloro-Alkali Indices, which exhibit positive values, indicate reverse ion exchange reactions, where Na+ or K+ from groundwater are exchanged with Mg-2(+) or Ca-2(+) from the aquifer matrix. In contrast, samples with negative CAI values exhibit a direct ion exchange reaction. Saturation index calculations further suggest that groundwater hydrochemistry is primarily governed by geogenic factors, while PCA results reveal that contamination is influenced by geological weathering, ion exchange processes, and anthropogenic sources. Stable isotope analysis of delta D (ranging from -50.078 parts per thousand to -33.443 parts per thousand) and delta O-1(8) (ranging from -9.074 parts per thousand to -2.899 parts per thousand) indicates that groundwater recharge occurs predominantly after evaporation and precipitation, with evidence of paleo-water recharge in certain locations. Regarding agricultural suitability, the majority of groundwater samples fall within acceptable limits for irrigation purposes, affirming its usability for agricultural applications.
Modern society has been unsustainably extracting groundwater due to population growth, rapid urbanization, erratic monsoon, and climate change. Groundwater storage has undergone drastic changes in many parts of the world, necessitating a systematic approach to address long-term water requirements. Thus, delineating groundwater recharge zones and implementing artificial recharge programmes have become essential components of the sustainable development of groundwater resources. These days, geospatial technologies, including remote sensing and Geographic Information Systems (GIS), have emerged as versatile tools in conserving and managing groundwater resources, which have been successfully employed to identify suitable groundwater recharge zones. The study area primarily falls within the Himalayan terrain and partly covers the outer plains located in the Kathua region of the Union Territory of Jammu and Kashmir. This study presents the delineation of groundwater potential recharge zones using terrain characteristics and geospatial technologies, and also proposes artificial recharge structures at various suitable sites. The delineation was performed using multiple influencing factors and weighted overlay index techniques in the GIS environment. Based on the influencing parameters of thematic layers, including geology, geomorphology, slope, soil texture, drainage density, lineament density, and land use/land cover, suitable weightages were assigned to each significant parameter, and an overlay analysis was performed to generate apotential recharge zonation map. The five potential recharge zones, categorized as excellent, good, moderate, poor, and very poor, with spatial coverage of 4%, 13%, 51%, 30%, and 2%, respectively, were delineated. Considering the delineated potential recharge zonation map, five sites for constructing check dams, 17 sites for gabion structures, and 26 sites for percolation tanks at different stream orders were proposed for augmenting groundwater. Prioritization was carried out for the implementation of artificial recharge programmes, and high priority was given to the Kandi and Siwalik geological units to enhance the groundwater availability and address the issue of water shortage in the study area. Finally, findings of the study establish that integration of geospatial technologies can provide a well-organized and effective platform for competently developing, planning, and managing groundwater resources. Abstract:
The Malani Igneous Suite (MIS) of the northwestern Indian Shield records one of the most voluminous episodes of Neoproterozoic anorogenic magmatism on the Indian craton. This study documents the petrographic and zirconmorphological characteristics of felsic rocks from the Riwasa and Khanak domains of the Tusham Ring Complex (TRC), an eastern outlier of the MIS. Detailed petrographic study reveals that the Riwasa rhyolite should be reclassified as porphyry microgranite with subsolvus nature. The Khanak granite is also classified as subsolvus porphyry microgranite. Zircon morphological studies indicate the nature of the melt to be alkaline, I-type affinity, and dominantly mantle-derived sources, with negligible supracrustal contamination. The calculated mean crystallization temperatures of Riwasa and Khanak porphyry microgranites are 799 +/- 50 degrees C and 780 +/- 50 degrees C. The mean alkaline indices of Riwasa and Khanak porphyry microgranites are 682 +/- 50 and 700 +/- 50. These findings reinforce the importance of zircon morphological studies in recognizing source characterization and the nature of melt.
Granite emplaced into Lansdowne klippe of Garwal Lesser Himalaya occur as small, isolated body that rests over the Krol Formation of the Garhwal nappe. Field investigation and petrography show that Lansdowne Granite (LG) and Lansdowne Granite Gneiss (LGGn) are medium to coarse-grained rocks, composed of plagioclase+K-feldspar+quartz+biotite+muscovites+tremolite+sphene+apatite and zircon, exhibiting porphyritic and perthitic texture. Dynamic recrystallization in quartz and feldspar phenocrysts caused grain size reduction and asymmetric strain softening. The geochemical composition shows an affinity to high-K calcic-alkali to shoshonite series. Its peraluminous characteristics reflect a syn-collisional to post-orogenic tectonic setting and S-type nature. The LG and LGGn are enriched in LREE and relatively depleted in HREE, with prominent negative Eu anomalies with high Th-U, Y, and Pb contents, and low Ba, Sr, Ti, and Nb contents. The Rb/Sr versus Rb/Ba ratios indicate an origin from clay-poor, plagioclase-rich greywacke
An ophiolitic melange exposed along the Shyok River in the NW part of the Shyok Suture Zone was studied to obtain micropaleontological and geochemical data from blocks of radiolarian chert and to enable a better understanding of age and nature of this m & eacute;lange. The m & eacute;lange includes blocks of ultramafic rocks, gabbro, basalts, pillow lavas and radiolarian cherts within both serpentinite and phyllite matrix. Micropaleontological investigation of cherts yielded Lower Cretaceous (lower Aptian) radiolarians. High SiO2/(SiO2 +Al2O3 +Fe2O3) ratios and the Fe-Al-Mn ternary plot indicate that these biogenic cherts were deposited far from any hydrothermal source. Major and trace element abundances and their relationships suggest an open ocean environment for the studied radiolarites.
On the early morning of 28th April, 2021, a large earthquake of magnitude M-W similar to 6.1, origin time 07 h 51 min 25.0 s wof IST(Indian Standard Time), jolted the Dhekiajuli sub-division, Sonitpur district, Assam, India. This event, occurred in the central part of the Brahmaputra river basin, not only shook the basin, but was also widely felt in the entire Northeast India region (NER). The epicenter is within the Kopili fault zone at 26.781 degrees N, 92.457 degrees E, with a focal depth of 40 km as per Global rdCentroid Moment Tensor (GCMT) solution. This earthquake is the largest event in NER after the 3rd January 2016, M-W similar to 6.7 Tamenglong (Manipur) earthquake (Gahalaut et al. 2016). As per the media reports and macroseismic survey, this earthquake can be assigned a maximum intensity of VIII in the meizoseismal area. The damage distribution shows an asymmetric and heterogeneous pattern. The isoseismal map pertinent to this event shows an E-Wtrend intensity distribution with an elongation towards the WSWdirection along the Brahmaputra basin. This earthquake caused significant damage to poorly built buildings and old framed structures up to 150 km from the epicenter zone. We summarize the damage reports of macroseismic field surveys, media reports and graphically represent the damage in the form of isoseismal map for the earthquake. The seismic intensity decreased sharply with distance from the epicenter. The egg-shaped isoseismal pattern might have been controlled by local geological conditions, focal mechanism and different seismic moment-rate releases along the propagating rupture. As the epicentral region is located in the foredeep of the great Himalayan thrust belt region, as well as along with fast-growing urbanization on the alluvial plain of the Brahmaputra basin, as such the risk of severe seismic hazard is of high concern, and warrants further scientific and policy involvement.
The coesite bearing Tso Morari eclogites are one of the only Ultra High Pressure (UHP) complexes identified in the Indian Himalayas representing the leading edge of the subducted Indian continental plate to mantle depths before being exhumed back. Raman microspectrometric analyses in mapping mode on silica inclusions within garnets were carried out to identify and record coesite-quartz transformation. Quartz inclusions in garnets are sub-rounded to elliptical and occur as single crystals as well as polycrystalline aggregates. Coesite with & aacute;-quartz (peak 464 cm ) is recognized optically and-1 confirmed through Raman spectroscopy (peak at 521 cm ). Partial to complete transformation of coesite to & aacute;-quartz are-1 recorded through Raman analyses in mapping mode; 95 volume% to as low as 1volume% respectively. Combination of petrographic, mineral chemistry, Raman mapping data along with prior experimental work clearly point to near complete transformation of & aacute;-quartz to coesite between temperatures 700-800 degrees C at 2.8 GPa pressures. Retrograde reactions of coesite to & aacute;-quartz can be envisaged between 600-700 degrees C. Experimental as well as studies carried out on natural samples clearly point to factors such as pressure vessel effect along with fast exhumation rates being instrumental in partial preservation of coesite in these eclogite samples.
The multi-branch pinnate borehole gas extraction technology has the potential to address the inefficiency of traditional gas extraction methods in thick coal seam with high gas-containing. The study focuses on the 2308 working face of GJH mine and develops a continuous equation to quantitatively describe the gas drainage process of multi-branched pinnate borehole in coal seams. Utilizing numerical simulation methods, the effect of multi-branched pinnate borehole parameters on gas drainage effectiveness were systematically studied. The results indicate that the angle between the branches and the main borehole, branch length, branch hole spacing, and the number of branches are critical factors affect extraction effectiveness, and these factors are mutually influence for each other.The acute angle between the minor branches and the main borehole can rapidly decrease coal seam pressure in a short period. As a result, the length of the branches increases. The spacing between branch openings and the number of branches are considered as secondary factors. Increasing the spacing between branch openings can improve cumulative gas production per unit length of drilling, but it may lead to a reduction in drainage range. Alarger branching angle can extend the drainage range, but at this point, branch spacing and quantity become the primary influencing factors. Decreasing branch spacing can improve drainage efficiency, although it may lead to an excessive number of branches; The research can offer valuable insights for the engineering of multi-lateral pinnate drilling in high-gas-content thick coal seams under similar geological conditions
Tripura state in northeast NE India falls in the high-risk zone Vin the seismic zoning map of India. In this study, we select the city Udaipur, Tripura, for seismic hazard analysis. Characterization of soil is much essential for seismic hazard risk studies in any developing urban city like Udaipur. We conducted Multichannel Analysis of Surface Waves (MASW) experiments at 15 selected locations in the city area to estimate shear wave velocity (V-s) of the subsurface soil / weathered layer. The dispersion data of the recorded Rayleigh waves (R-wave) were inverted using a Genetic Algorithm (GA) to obtain shear wave velocity profiles of the investigated sites. In addition, Standard Penetration Test (SPT-N) using, bore logs at these sites, and its proximity, were obtained from the government drilling agencies. These data are used to develop correlation equations by nonlinear regression. The results are then compared with the established correlations for soil characteristics. The V-s30 ranges from 130-400 m/s in most of the sites except at Bhubeneswari Temple (site no 2) and Kaluadhepa SB School (site no 6), where V-s30 reaches up to 445 m/s and 425 m/s respectively. A V-s30 map for the city area is s30 prepared and average dynamic characterization is examined, which reveals susceptibility of site-effects and liquefactions in some parts of the study area. These results are much useful for seismic hazard risk analysis and for seismic design and engineering considerations for urban development in the study area.
The morphometric analysis of a river reveals any change in the tectonic/climatic regimes experienced by the region. These morphometric parameters can be utilized to assess the geodynamics of both tectonically active regions and relatively stable regions. In this study, we compare two such contrasting regions, the Himalaya and the central Indian forebulge, to understand how tectonic forces shape the landscapes differently in these two regions. The Himalayas are continuously uplifting due to the northward movement of the Indian plate, and as a result the Indian plate has flexured due to loading of the Himalayas and given rise to the central Indian forebulge. This central Indian forebulge undergoes slow uplift and migration as the Himalayan Mountain front advances. Therefore, the rivers flowing through the Himalayan region experience high rates of uplift, whereas the forebulge rivers experience a very slow uplift rate. In this study, we measure and compare the basin morphometric parameters, such as the normalized steepness index (Ksn), precipitation-weighed normalized steepness index (KsnQ), concavity, hypsometric integral (HI), and basin gradient, with the existing erosion rates. We find that the rivers in the Himalayas show a higher steepness index, local relief, and erosion rates, suggesting a dominance of active tectonics. Conversely, the forebulge rivers show a low steepness index, erosion rates, and moderate HI values, suggesting an equilibrium between erosion and uplift. Comparisons reveal that the primary control on the evolution ofrivers in both regions is tectonics, with climate playing a secondary role.
The Trans-Himalaya represents the South Tibetan Thickened Crust. This thickened crust is the product of the collision between the Indian and Eurasian plates. The trans-Himalaya ranges from the Hindukush mountain to the Tibetan plateau. It comprised of Karakorum batholith, metamorphosed rocks, migmatite, and mylonites. The main emphasis of our review is to reveal the role of the fluid in the evolution of theAsian continent crust. This review emphasizes the fluid flux and its evaluation history (exhumation, metamorphism, and magmatic process). The Trans-Himalayan rocks are comprised of carbonic, carbonic-aqueous, and aqueous-rich fluids. The aqueous-rich carbonic fluids, having 70-45% water, were initially entrapped in the Karakoram terrane. This aqueous phase was drained out from the aqueous-carbonic inclusions during the deformation and partial melting. Henceforth, the monophase pure carbonic (CO2) fluid was predominantly present in the Trans-Himalayan rocks. The carbonic fluid derived from prograde decarbonization of the marl carbonate-rich rocks during metamorphism is associated with the subduction-collision tectonics. Abstract: The Karakorum rocks were unearthed from the deepest part of the crust (i.e., 1020 MPa at 670 degrees C) as well as speedily exhumed along the isothermal cooling path at 4.5 degrees C/km rate from 34 Km to 11 Km (i.e., 1020 MPa to 330 MPa) by losing 105 degrees C (670 to 565 degrees C) temperature following crustal thickening of the Asian continent (or South Tibetan Crust) between 18 and 15 Ma. The metamorphic rocks are syn-tectonically placed along with leucogranites along the Karakorum. This further implies that the Karakorum fault acted as a conduit for fluids. Thus, it can be suggested that the CO2 throughout metamorphism might have been tracked from a deep-seated reservoir through the Karakorum fault.
In mountainous regions, rockfall stands out as a prevalent natural process where rock fragments detach and move downhill through actions such as sliding, toppling, and falling. These incidents usually impact the surrounding infrastructure, such as roads, bridges, buildings, trains, and other essential facilities. The rockfall hazards are intensified by recurrent freezing and thawing cycles, heavy precipitation, and seismic activity. In the present research, a vulnerable road-cut slope with rockfall potential, located along a National Highway (NH-7) near Shivpuri in the Tehri Garhwal district of Uttarakhand, India has been studied. A kinematic analysis was carried out to determine the potential failure mode in the slope (Planar/Wedge/Toppling). The studied slope was found to have potential for a wedge mode of failure. The slope mass rating (SMR) rock mass classification has been used for slope stability assessment. The studied slope has been found to be under the completely unstable category of stability grade with SMR value 13. The trajectory path of rockfall has been traced using rockfall simulation. The various parameters, including run-out distance, total kinetic energy, translational velocity, and maximum bounce height, were evaluated by rockfall simulation followed by design and comparison of two mitigation strategies, i.e., rock traps or ditches and rockfall catching nets or rockfall barriers. The rockfall simulation result shows that the maximum bounce height, run-out distance, translational velocity, and total kinetic energy of the falling block are 3.1 m, 39.7 m, 16.6 m/s and 137.3 kJ, respectively. All the falling blocks have the potential to reach the road level and accumulate, thus posing a significant risk to vehicular traffic in the future. Therefore, proper mitigation measures are required to minimize the risk. For this, the effectiveness of a ditch, designed by utilizing the ditch design chart for rock fall catchment, has been analysed. Furthermore, the potential barrier capacity for the studied site was calculated as 130 KJ for 914 Kg of falling block and we checked its net barrier against rockfall events. Notably, the rockfall net barrier demonstrated superior efficiency, considering space constraints andmitigating associated risks.
The present study is first of its kind on water quality of Rudraprayag and Uttarkashi districts of Garhwal Himalaya, Uttarakhand. 95 samples were collected in the months of March-May (pre-monsoon) and November-January (post-monsoon) seasons from Rudraprayag (27 samples) and Uttarkashi (68 samples) districts. These samples were analyzed for physiochemical properties like total dissolved solids (TDS), Electrical conductivity (EC) and heavy metal. Heavy Metal Pollution Index (HPI) and Water Quality Index (WQI) analysis were also carried out. It is observed that few Uttarkashi samples show high values of the HPI (114.6) whereas, Rudraprayag show high value of 100 thus, having high water pollution. PCA and factor analysis further strengthen the presence of heavy metals in the area. Due to the geogenic and anthropogenic activities, Groundwater interaction with the source rock is also visible at many places The pollution level of ground water around Baseiri area is unsuitable for drinking purposes. Proper treatment and flushing of the handpumps for around 10 minutes are recommended before use and and usage of those should be stopped whose calculated values indicate higher concentrations of heavy metals in the groundwater. Finally, it is recommended to authorities that necessary steps should be taken to control the contamination of supply of groundwater which is the major source of drinking water and other uses in the region.
A new zircon and apatite fission-track (ZFT &AFT) thermochronological study has been carried out along the Karakoram Fault (KF) zone in the Nubra Valley, SE Karakoram, India. The ZFT ages range from 8.7 +/- 0.7 to 11.3 +/- 0.6 Ma, and the AFT ages range from 3.8 +/- 0.5 to 6.9 +/- 1.1 Ma, respectively. The calculated exhumation rates using ZFT ages vary from similar to 0.54 +/- 0.04 to 0.66 +/- 0.04 mm yr(-1) since similar to 9.9 Ma and for AFT ages from similar to 0.58 +/- 0.1 to 0.68 +/- 0.11 mm yr (-1) since similar to 4.8 Ma. The exhumation rates from the Nubra Valley are more than double those observed in the southern Ladakh Batholith (LB) and are similar to the Karakoram Transpression Zone (KTZ) and Karakoram Terrane (KT) to the north of the KF zone. The consistent decreasing pattern of AFT ages from the LB towards the KT indicates that local tectonic influences play a negligible role and the role of regional tectonics in this zone's exhumation history. No systematic ZFT age pattern was found from south to north. There is evidence of the southward thrusting of the KT over the northern LB during the middle Miocene in the Nubra region. We suggest that the south-directed thrusting of the KT at similar to 12 Ma along the Shyok Suture Zone (SSZ)/Main Karakoram Thrust (MKT) results from intense crustal shortening in the KT during the Miocene. We propose that during the early Miocene, the delamination-induced high topographic uplift triggered the initial phase of exhumation of the KT, the evidence of which exists in the form of the presence of mantle-derived He-3/He-4 isotope ratios in geothermal springs along the KF from the Nubra Valley and Miocene K-rich lamprophyres from the central Karakoram. The exhumation in the last phase was facilitated by the underthrusting of the Indian Plate beneath the KT.
The Ariyalur Group of Upper Cretaceous rocks in the Cauvery Basin includes several distinct formations. The sequence begins with the Lower Sillakudi Sandstone Formation, which is unconformably overlain by the Kallankurichi Limestone Formation. This is succeeded by the Kallamedu, Ottakoil, and Sendurai calcareous sandstone formations. The Kallankurichi Limestone Formation comprises four distinct limestone beds: Lower Ferruginous Gryphaea Limestone Bed, LowerArenaceous Limestone Bed, Middle Yellow Gryphaea Limestone Bed and UpperArenaceous Limestone Bed. These limestone beds lie unconformably between the Cretaceous Sillakudi Sandstone Formation and Sub-Recent Calcrete deposits, particularly in TANCEM Mine No. 1. Geochemical analysis of these beds reveals high concentrations of major oxides, including CaO, SiO2, Al2O3, and Fe2O3 (>1%), as well as minor and trace elements like V, Cr, Zn, Rb, Sr, Zr, and Ba ( >10 ppm). Additionally, the limestone beds are enriched in light rare earth elements (LREEs) such as La, Ce, Pr, Nd, Sm, Eu, and Gd ( > 0.5 ppm) while being depleted in heavy rare earth elements (HREEs), including Tb, Dy, Ho, Er, Tm, Yb, and Lu (< 2 ppm). The geochemical profile also displays a negative europium (Eu) anomaly and a positive cerium (Ce) anomaly. The high CaO content is attributed to the preservation of Cretaceous marine invertebrates, deposited during the global Maastrichtian marine transgression of the Indo-Pacific Sea in the Upper Cretaceous period. Tectonic interpretations based on geochemical parameters suggest that these deposits formed in a passive continental margin setting. Furthermore, paleooxygenation studies indicate an oxic depositional environment for these limestone beds, as inferred from their geochemical signatures.
A cloudburst event took place at around 01:00hrs (IST) on 10(th) September 2022, which led to the flash floods at Khotila village, Dharchula near India-Nepal border. The heavy incessant rainfall at the mid-night of 10(th) September, 2022 increased the water level alarmingly in the Lasko khola river, originating from Nepal in the Lasko Khotila valley, a tributary of the Kali River. The flash flood caused 6 fatalities, 11 reported missing, 72 houses severely damaged and more than 62 families stranded at several places in the India-Nepal border areas. Other impacts of this catastrophe are roads washed away, land-degraded, landslides occurred, and small bridges destroyed. The local administration estimated economic losses of similar to Rs 30 Lakhs in Dharchula of Uttarakhand state in India and similar to Rs. 5 crores in Darchula of Nepal. The immediate rescue and evacuation practices were carried out by the State Disaster Response Force (SDRF) and National Disaster Response Force (NDRF). Affected villagers were evacuated and put up in the makeshift shelters built at the Dharchula stadium. Previous reports show that the majority of cloudburst incidences had occurred between 1000 to 2500 m above sea level in the Indian Himalayan region. However, it has been observed in recent times that these events have occurred between 700 to 3000 m above sea level. It has also been observed that the frequencies and intensities of cloudburst events show an increasing trend since the year 2018 to 2023, which is a serious concern to climatologists and policy makers for building disaster-resilient and climate-adaptable future.
