bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stratigraphic division and sedimentary facies of the Kathmandu Basin Group, central Nepal
Authors: Sakai Harutaka 
Published: April 2021

On the basis of core drillings for academic purpose and surface geological survey in the Kathmandu Basin, I propose separate stratigraphic schemes of the basin-fill sediments for the southern, central and northern part of the basin. In the south, the late Pliocene to Pleistocene Kathmandu Basin Group is divided into three formations: the Tarebhir, redefined Lukundol and Itaiti Formation in ascending order. The Tarebhir Formation is mainly composed of fluvial gravel and sand beds deposited by the Proto-Bagmati River. The Lukundol Formation is mainly comprised of carbonaceous muddy sediments showing their deposition in marginal shallow lake environments. The uppermost fluvial sandy beds of the Lukundol Formation are overlain by boulder beds of alluvial fan deposit, which was newly named as the ltaiti Formation. The continuous drill core and previous drill data obtained from the central part of the basin has allowed to lithologically divide the sediments into three: the Bagmati, Kalimati and Patan Formation from bottom to top, respectively. The Bagmati Formation is the northern continuation of the Tarebhir Formation, and overlain by the 200 to 400 m thick lacustrine Kalimati Formation. The basal part is characterized by lignite and bituminous pebbly mudstone beds, which is named as the Basal Lignite Member.
On the other hand, in the north and central parts, sand dominant lacustrine delta deposits called the Gokarna and Thimi formations are accumulated over the Kalimati Formation. In the central part of the valley, both Kalimati and Thimi formations are disconformably overlain by the mainly fluvial Patan Formation.
The Palaeo- Kathmandu Lake has existed since 2.8 Ma in the central part of the Kathmandu Valley, and it was existing till about 10 kyr B.P. after which it finally drained out. However, in the south, there are no open lacustrine deposits, and marginal lacustrine deposits of the Lukundol Formation were directly overlain by alluvial fan deposits spread over the northern slope of the Mahabharat Lekh.
Small-amplitude lake-level fluctuations recorded in aggrading deltaic deposits of the Upper Pleistocene Thimi and Gokarna formations, Kathmandu Valley, Nepal
Authors: Sakai Tetsuya , Gajurel Ananta Prasad , Tabata Hideo , Upreti Bishal Nath 
Published: April 2021

Small-amplitude lake-level fluctuations have been recognized from the aggrading delta-plain deposits in the lower parts of the Thimi and Gokarna formations, Kathmandu Valley, Nepal. The delta-plain deposits consist or gravelly sand beds of fluvial channel origin (coarse-sediment interval) and alternation of' fine to very line sand and sandy silt beds (line-sediment interval). Wave generated structures occur in the sand beds or the fine sediment intervals.
The vertical and lateral facies changes suggest that the deposition or a set of coarse- and fine-sediment intervals associated with prograding delta front deposits was controlled by a lake-level rise and fall sequence superimposed on a long-term lake­ level rise trend. The aggradation of fluvial sediments occurred during a lake-level rise period with sufficient sediment supply to fill a newly created accommodation space on the delta plain. The observation or wave-generated structures in an overlying fine-sediment interval suggests that the delta plain was subsequently inundated due to further lake-level rise, exceeding the sedimentation rate. Subsequent delta progradation occurred during a lake-level stabilized phase after a lake­ level fall. The small-amplitude lake-level changes are thought to be attribute able to seasonal wet and dry cycles, as inferred based on the presence of peculiar aggrading delta successions, implying that lake-level fluctuations may have occurred over short time scales, and on the results of a previous palaeopalynological study in which a moist palacoclimate was inferred in the lower part of the Gokarna Formation in particular.
Measurement of crystallinity and relative amount of clay minerals in the Kathmandu Basin sediments by decomposition of XRD patterns (profile fitting)
Authors: Kuwahara Yoshihiro , Fujii Rie , Sakai Harutaka , Masudome Yukiko 
Published: April 2021

The estimation of crystallinity and relative amount of clay minerals in the Kathmandu Basin sediments were made by using decomposition procedure of X-ray diffraction (XRD) patterns. Based on this study an attempt has been made to reconstruct the palaeoclimatic variation recorded in the clay minerals. The variations of the two illite crystallinity indices, Lanson index (LI) and modified Lanson index (MLI) of the drill-core sediments between 5 m and 49 m depth are linked to those of the relative amount of smectite to illitie minerals or to chlorite. The relative amount of kaolinite to illitic minerals or to chlorite roughly showed mirror image of the relative amount of smectite to illitie minerals or chlorite, respectively.
The variation of the hydrolysis condition inferred from these indices were congruous with the variation of δ18O from planktonic foraminifers of deep sea sediments in the Arabian Sea, confirming that the climatic variations during the last ~450 kyr in the Kathmandu Basin were closely related to global climate, without apparent local climatic changes. In addition, they depicted that it was dry during the cold climate and wet during the warm climate in the Kathmandu Basin.
Variability in palaeoclimatic periodicity over 2,500 kyr from magnetic susceptibility of Lake Baikal sediments
Authors: Horii Masae , Sakai Hideo , Takano Masao 
Published: April 2021

Magnetic susceptibility was measured on the sedimentary core, BDP-96-2 (100 m length), drilled at the Academician Ridge of Lake Baikal, central Siberia. The palaeomagnetic study has showed that the sediment core covers the past 2,500kyr. The magnetic susceptibility of BDP-96-2 showed high value during glacial periods and low value during interglacial periods, therefore, the susceptibility can be considered to be a good proxy for palaeoclimate around Lake Baikal region.
Spectral analysis to the susceptibility showed that principal periodicity well corresponded to the Earth's orbital cycles. Temporal changes in spectral power of principal periodicities showed a dominance of 100 kyr cycle since 1,200 kyr B.P. and an increase of 23 kyr cycle since 400 kyr B.P. The increase of 100 kyr cycle has been observed also in ODP records around 1200~700 kyr B.P. This variability in the periodicity is thought to be a reflection of change in the global climatic system related to the elevation of Himalayan Mountains. This study demonstrates that the signal of this global climatic change was also found in continental-interior region such as Lake Baikal. Whereas, the increase of 23 kyr precession cycle since 400 kyr B.P. is distinctive of Lake Baikal record. This suggests that local climatic system around Lake Baikal became highly sensitive to the solar insolation since 400 kyr B.P.
Geology, geochemistry, and radiochronology of the Kathmandu and Gosainkund Crystalline nappes, central Nepal Himalaya
Authors: Rai Santa Man 
Published: April 2021

A multidisciplinary study was carried out in the Lesser Himalaya (LH), the Kathmandu Crystalline Nappe (KCN) and the Gosainkund Crystalline Nappe (GCN) in central Nepal Himalaya. Two principal deformations are recorded in both the crystalline nappes and the Lesser Himalaya: ductile, syn-MCTor syn-MT metamorphic deformation marked by microstructures (stretching lineation, S-C structures, and isoclinal folding) and post-MCT/or post-MT metamorphic deformation recorded by a major EW-directed Likhu Khola anticline and by NNE-SSW-directed folds. The Upper Lesser Himalayan rocks close to the Main Central Thrust (MCT) record syn-MCT metamorphic conditions at 750 MPa and 566 °C. The rocks of the KCN record P-T condition from 900 to 720 MPa and 700 to 484 °C, while the GCN rocks were equilibrated at upper amphibolite- to granulite-facies conditions from 890 to 583 MPa and 754 to 588 °C. The P-T conditions and field observations exhibit well-preserved inverted metamorphism between the Upper Lesser Himalaya and the Gosainkund Crystalline Nappe.
The augen gneisses from the GCN yielding 486±9Ma U-Pb zircon age and the granites of similar age in the KCN bear similar petrographic and geochemical characteristics and suggest a similar magmatic origin although they belong to different tectonic units. The chemical analyses of the Proterozoic Ulleri augen gneiss of the LH and the granites of the KCN fall within the same compositional field, indicating a magmatic origin of these augen gneisses.
40Ar/39Ar datings on muscovite indicate cooling ages younging systematically from south to north: 22 to 14 Ma in the KCN, 16 to 5 Ma in the GCN, and 12 to 6 Ma in the LH. This systematic younging of muscovite ages does not have any correlation with the present elevation, lithology and tectonic unit and is interpreted as a result of the exhumation of the rock units on the Main Himalayan Thrust (MHT) ramp situated to the north of Kathmandu Valley. Both the KCN and the GCN record a late emplacement history, but the KCN was exhumed earlier than the GCN. The two crystalline nappes presently form a single tectonic block, and the combined uplift of the two nappes occurs on a ramp of a major decollement developed in the upper part of the Indian crust.
Quantifying displacement on the South Tibetan Detachment normal fault, Everest massif, and the timing of crustal thickening and uplift in the Himalaya and South Tibet
Authors: Searle M. P. , Simpson R. L. , Law R. D. , Waters D. J. , Parrish R. R. 
Published: April 2021

ABSTRACT
Lithospheric convergence of India and Asia since collision has resulted in horizontal shortening, crustal thickening and regional metamorphism in the Himalaya and beneath southern Tibet. The boundary between the High Himalaya and the Tibetan plateau is a large scale, north-dipping, low-angle normal fault termed the South Tibetan Detachment (STD) which was active contemporaneously with the Main Central Thrust (MCT) bounding the southern margin of the High Himalaya. Previous studies have estimated minimum northward displacement along the STD of 35 km along the Everest profile. Here, we demonstrate approximately 200 km of southward displacement of footwall sillimanite + cordierite gneisses (minimum 90-108 km), formed at 600-630°C and pressures of 4.0-4.9 kbar ( 14-18 km depth), beneath the STD which acted as a passive roof fault during southward flow of the hot, viscous, ductile middle crust. U-Th-Pb dating of gneisses, sheared and cross-cutting leucogranites indicates that ductile shearing was active at 17-16 Ma, and later brittle motion at <16 Ma cuts all rocks in the footwall. High temperatures (>620°C) were maintained for -14 Ma along the top of the High Himalayan slab from 32-18 Ma, implying active crustal thickening and high topography in south Tibet during this time. The ending of metamorphism and melting in the Himalaya and ductile shearing along the STD coincides with the initiation of strike-slip faulting in SW Tibet and E-W extension in south Tibet.
Physical and geomechanical properties of the Siwalik sandstones, Amlekhganj-Suparitar area, central Nepal Himalaya
Authors: Tamrakar Naresh Kazi , Yokota Shuichiro , Shrestha Suresh Das 
Published: April 2021

The Siwalik Group, one of the world's largest fluvial deposits, distributed in the fore deep basin of the rising Himalayas, crops out well in Central Nepal. The group comprises of mudstones, sandstones and conglomerates ranging in age from middle-Miocene to early Pleistocene. Sandstones form the major lithology in the Siwalik Group and distributed pervasively. Forty-four samples of sandstones were tested for physical and geomechanical properties in order to create a database on Siwalik sandstones and to know the variability of these properties with respect to their stratigraphic levels. Dry density and saturated density of sandstones are 2.10-2.63 g/cm3 and 2.22-2.66 g/cm3, respectively. Porosity is found to vary between 1.93 and 15.2%.They bear weak to strong uniaxial compressive strength (1.29-51.6 MPa), very low to high point­ load strength (0.05-4.53 MPa, measured across bedding), high deformability (secant modulus =0.03-0.98 GPa and tangent modulus = 0.06-1.09)and low modulus ratio (17.8-86.6). The Schmidt hammer hardness in sandstones ranges from 12 to 52. Variation of these properties is independent of stratigraphic level. Dry density and porosity correlate well with uniaxial compressive strength, point-load strength and modulus ratio, and bear highly significant relationships. Hence, dry density and porosity can be used for predicting strength measures for the Siwalik sandstones.
Hydrogeologic and geomorphic settings of the Lower Subansiri Basin, Assam, India
Authors: Goswami U. , Patgiri A. D. , Sarma J. N. 
Published: April 2021

Geomorphic settings of an area provide valuable supplementary information regarding groundwater recharge, their occurrence and distribution. The geomorphic settings of the Lower Subansiri Basin can broadly be represented by three distinct geomorphic units viz., structural hills, piedmont zone and alluvial plain. While the elevation, slope, lithology, drainage pattern and various relevant morphometric parameters vary from one geomorphic unit to another, the conditions of recharge and discharge, occurrence and distribution of groundwater also differ in different units. The structural hills occupying only 4.5% of the area along the north-western boundary represent a high run-off zone characterised by steep slope and fairly dense parallel to sub-parallel drainage. The piedmont zone, built up by the coalescence of alluvial fan deposits, represents 7.7% of the area occurring in a long and narrow NE-SW trending steeply sloping belt along the foothills of Arunachal Pradesh. Owing to high permeability, this zone hardly retains any water and hence forms a high recharge zone with relatively deeper groundwater level. The alluvial plain, covering 87.8% of the basin area and characterised by a gentle slope, serves both as recharge and discharge areas where groundwater occurs relatively close to the ground surface.
Panel diagrams prepared for the Lower Subansiri Basin showing the thickness and extent of granular zones display that the unconsolidated alluvial sediments are primarily composed of sands of various grade and gravel with minor amounts of silt and clay. The sand-gravel isolith maps showing the cumulative thickness of the granular zones down to the depth of 40 m reveal that the subsurface formations in a major part of the alluvial plain of the Lower Subansiri Basin are entirely represented by granular zones. The granular zone in most parts of the area forms one single aquifer system where groundwater mostly occurs under unconfined to semi unconfined conditions. Due to the presence of thin clay and/or sandy clay lenses at shallow depths, however, the single aquifer system gets locally dissipated into multiple aquifer system where, barring the uppermost aquifer, groundwater mostly occur under semiconfined to confined conditions. The overall regional variation of depth to water level, from the piedmont zone in the north and north-west to the alluvial plain of the south and southeast, is controlled by the prevalent geomorphic settings of the area. The disposition of water table contours of the area indicates that the configuration of groundwater table closely controls to that of general topography of the area. The steeper hydraulic gradient observed to be present in the north and north-east indicates the possible control of the characteristically distinguished geomorphic setting, i.e., topography, relief and lithology.
Geological criteria for waste disposal site selection: a case study from Kanichadar, Dhangarhi, Far Western Nepal
Authors: Rimal Lila Nath , Jnawali Bharat M. , Manandhar Surya Prakash 
Published: April 2021

Proper management of municipal solid waste in an environmentally friendly way needs first-hand knowledge of site geology. A clay layer (i.e. geological barrier) of sufficient thickness and extension beneath the surface is a suitable condition for a sanitary landfill site. The clay layer acts as a natural barrier against the migrating pollutants originating from leachate into the ground. The leachate generated at the landfill site can pollute the groundwater in absence of such geologic barrier.
The Kanichadar area is underlain by about 3 m thick fine-grained soil. The topmost soil layer is 20-50 cm thick dark brown organic clay. There is a highly compact, dark brown and dry inorganic clayey silt layer of more than 1.5 m thickness below the organic clay layer. Soil samples collected from different Auger holes were subjected to laboratory analysis to determine their physical and chemical properties. The values thus obtained indicated that the soil belongs to 'CL' type, implying that the soil is inorganic clay of low to medium plasticity. However, the hydrometer analysis showed that the samples were of clayey silt.
The cation exchange capacity (CEC) values obtained from the depth of 0.5-2.30 m revealed that the soil had moderate to high barrier potential for attenuation of the migrating pollutants. Therefore, the area close to these auger holes was found to be suitable for sanitary landfill.
Natural hazards and environmental geological assessment of the Pokhara Valley, Western Nepal
Authors: Kaphle Krishna P. 
Published: April 2021

Pokhara Valley is an intramontane basin situated on the lap of southern foothills of Annapurna and Machhapuchhre Himal. The valley is surrounded by hills, which are mainly represented by low to medium grade metamorphic rocks. It is believed that the valley fill sediment s were derived from far north in the Himalaya, during three different catastrophic debris flow events along Seti River in Upper Pleistocene to Holocene Epoch. These sediments are rich in calcareous constituents and are susceptible to sinkhole and land subsidence hazards.
Karstification is widespread in the form of sinkholes, caverns and sub-soil pinnacles in the Pokhara Valley. Such sinkholes and pinnacles are frequently observed in Ghachok Formation. Soil erosion and landslides are other natural hazards that frequently occur in steep terrain. As a result of heavy rainfall in monsoon, a number of new landslides occur and many old and dormant landslides become active. These landslides are the sources of huge amount of loose sediments that cause loss of lives, damages of public properties, infrastructures, and siltation in Phewa and Begnas lakes. Haphazard mining of river gravel and sand has also created the problem of riverbank erosion and flooding in the rainy season. Several earthquake events greater than 4 Richter scale have occurred in the past within the Pokhara Valley and its close proximity. Of these the largest earthquake events were 7 Richter scale in 1939 and 6.5 Richter scale in 1954 by which the Pokhara Valley suffered considerable damages.
Unplanned urbanization, haphazard development of infrastructures and settlements, improper locations of industries, improper landuse, uncontrolled surface drain, haphazard disposal of municipal waste etc. are the root causes of environmental degradation in Pokhara Sub-Metropolitan.
All types of hazard prone areas are identified and categorized as low, medium and high hazard areas in Engineering and Environmental Geological map of the Pokhara Valley. The proposed recommendations are expected to be useful to the users in protecting environment and mitigating disaster.
Geology and structure of the Sundarijal-Melamchi area, central Nepal
Authors: Dhital Megh Raj , Sunuwar Subas Chandra , Shrestha Rajendra 
Published: April 2021

In the Sundarijal- Melamchi area, the following lithological units arc identified based on detailed field mapping: the Talamarang Formation (dark grey feldspathic schist and banded gneiss with garnet and kyanite), Gyalthum Formation (thin- to thick­ banded, light grey to grey, laminated quartzite with mica partings and bands of feldspathic schist. garnetiferous schist, and gneiss), Bolde Quartzite (grey to light grey, very thick-banded, massive quartzite with mica parting and schist bands containing sillimanite). Timbu Formation (light grey to dark grey, intensely deformed and folded quartzite, gneiss, and migmatite with abundant sillimanite), and Golphu Formation (grey to dark grey feldspathic schist and banded gneiss with large pegmatite veins) from bottom to top, respectively.
The Main Central Thrust (MCT) crosses the Indrawati River north of Majhitar and continues towards the Dhand Khola to SE and joins with the Mahabharat Thrust. It is moderately steep and dips essentially due NW. The footwall of the MCT is made up mainly of slate and phyllite and the grade of metamorphism is quite low in comparison with that of the hanging wall. The inverted metamorphism is conspicuous in the hanging wall of the MCT, where at first garnet schist is observed, which passes rapidly upwards to kyanite schist and then to sillimanite-bearing schist, gneiss, and migmatite.
Augen and banded gneisses invade the upper part of the northern limb and most of the southern limb of the Patibhanjyang Anticline. Apparently, the Sheopuri Injection Gneiss Zone is a continuation of the Kutumsang Gneiss Zone in the north, and the rocks were folded after the emplacement of the injection gneisses.
Miastenia gravis: fisiopatología y manejo perioperatorio
Authors: Hines Chaves Kevin Daniel , Gutiérrez Núñez Mariela , Tinoco Chavarría Valeria 
Published: April 2021

La miastenia gravis es una enfermedad autoinmue que afecta la únion neuromuscular, mediante el bloqueo funcional de la misma, al producirse anticuerpos contra receptores nicotínicos. Se presenta con síntomas de fatiga de diferentes grupos musculares, que puede llegar a afectar el habla, la deglución y la respiración. Esta patología se trata con medicamentos anticolinesterásicos, coticosteroides y/o timectomía. Los pacientes con miastenia gravis presentan mayor riesgo de complicaciones perioperatorias que la población general. Debido a esto se deben tener especiales cuidados en el perioperatorio. El fallo respiratorio es una complicación potencialmente mortal, por lo que se deben minimizar los riesgos de debilidad de los múaculos respiratorios.
Relación entre el Módulo de Elasticidad Global y Local en Elementos Estructurales de Populus Deltoides ‘Australiano 129/60’ y ‘Stoneville 67’ Cultivados en Argentina
Authors: Guillaumet Alfredo Aníbal , Manavella Roberto Daniel , Filippetti María Cecilia , Meyer Lía Caren 
Published: April 2021

En este trabajo se compara el valor del módulo de elasticidad local obtenido experimentalmente con el determinado a partir del módulo de elasticidad global de acuerdo a tres criterios reconocidos internacionalmente (UNE-EN 384 2016, INTI-CIRSOC 2016 y Danzler et al. 2008). El programa experimental se desarrolló de acuerdo a normas europeas sobre 396 elementos estructurales de madera aserrada de Populus deltoides, clones ‘Australiano 129/60’ y ‘Stoneville 67’, cultivados en el delta del río Paraná en Argentina. Se confirmó la alta correlación entre el módulo de elasticidad local y el módulo de elasticidad global. Se constató la incidencia que, en la relación entre ambos módulos, tiene la exigencia normativa de ubicar los mayores defectos en el tercio central al ensayar las piezas. La determinación a partir del módulo de elasticidad global presentó resultados menores a los experimentales con una aproximación superior al 95%.