Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract For the first time, the presence of olivine-ringwoodite and plagioclase-maskelynite transformations is reported in Natun Balijan L4 chondrite determined by micro-Raman and infrared spectroscopic techniques with mineral phases characterised by electron microprobe analysis. Micro-Raman spectra reveal trace of ringwoodite, which is independently confirmed with the powder X-ray diffraction analysis. Full width at half maximum data of Raman spectrum reveals structural disordered olivine and pyroxene. The nature of infrared peaks at 639 and 724 cm−1 depicts the presence of maskelynite. Observed maskelynite Raman band at 509 and 581 cm−1 are used to estimate the shock stage of Natun Balijan L4 chondrite as at least S5. The impact metamorphism with a shock pressure of at least 40 GPa is estimated. PubDate: 2022-06-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract The underachievement of support systems in roof bolts layout design is one of the dominant causative factors of roof fall in underground mines. Various factors triggering the roof failure are the presence of laminated roof, the geological plane of weaknesses, the time lag in support installation, inefficient grouting/bonding of roof bolts, improper estimation of roof bolt length, the concentration of the induced stresses due to mining activities, etc. The roof fall concerns mining engineers as it seriously affects safety and productivity. Hence the stability of the openings has to be considered as a priority to suspend the movement of overlying layered strata by application of adequate support. Application of rock mass classification system helps in guiding suitable roof support design for apt stabilization of the mine openings. The study has been carried out to assess the befitting support design of various openings in underground chromite mine considering applicable rock mass classification systems namely Bieniawski’s Geomechanical System and Barton’s Q — system inclusive of numerical analysis. The values of rock load obtained by Bieniawski’s geomechanical system was on the higher side. Thus, in view of the safety and stability of engineering structures, Bieniawski’s geomechanical system was considered for the design of a support system. Rock load was determined for different dimensions of underground openings such as decline, cross-cut junctions, cross-cut roadways, ore drive, footwall drive, and haulage junctions, wherein width variation resulted in influencing rock load. Safety factor has also been analysed with respect to the width of the opening to demarcate stable and semi-stable zones. PubDate: 2022-06-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract During the last two decades, work carried out in the Eocene lignite sequences of Rajasthan and Gujarat has thrown considerable light on the terrestrial biotas during the drift of India and radically changed concepts regarding how the Indian plate was populated, the issues of cosmopolitanism and endemism, and the nature of the mixed sal-dominated forested community that supported a diverse mammalian fauna. While Madagascar and Australia, India’s erstwhile Gondwanan neighbours, supported highly endemic faunas, the biota of India shows strong affinities with Africa, Madagascar, Europe, and North America. PubDate: 2022-06-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Water is an essential resource for life. Effective management and sustainable development of this limited resource have become difficult not only in India but also in the world. Groundwater is a replenishable resource, but its availability is a heterogeneous distribution of complex hydrogeological terrain in both space and time. In this article, the groundwater reserves was estimated in a dense well network of basaltic terrain (area:360 km2) in central India for both regional and local scales. Groundwater level data were collected from four observation wells at a regional scale, which in general, were used to assess groundwater reserves, and also from a dense 58 well network at a local scale. These data were utilized for groundwater reserves at each well site in terms of static groundwater reserve (SGWR), dynamic groundwater reserve (DGWR), and monsoon groundwater reserve (MGWR). Their spatial and temporal variabilities were also compared with the help of Thiessen polygons. Results show that the SGWR and DGWR of the dense monitoring network range from 66.7 to 87.13 MCM, with an average of 75.77 MCM, and from 34.83–48.17 MCM, with an average of 41.95 MCM, respectively. Whereas, the MGWR varies from 36.81 to 55.08 MCM, with an average of 44.92 MCM. The comparison in the reserves of the regional scale is found to be higher than the dense well network data. This outcome could be useful for the implementation of groundwater development and sustainable management in this basaltic area in future. PubDate: 2022-06-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract The sandstones of the Bhuban Formation (Miocene) exposed in the Jampui hills of Tripura Fold Belt, India has been studied for provenance, tectonic setting and paleoclimate using the petrography, heavy mineral assemblage and clay mineral studies. The detrital mode of the sandstones indicate that the sediments consists predominantly of detrital quartz (avg. 92.19%), with subordinate proportions of feldspar (avg. 4.55%) and rock fragments (avg. 3.25%). The provenance discrimination diagrams depict the derivation of the detritus from both plutonic and metamorphic source rocks having affinity to continental block provenance. The plots of QFR and semi quantitative weathering index of the clastics support a moderate degree of paleoweathering in the source area under humid climatic condition. The presence of zircon, tourmaline, rutile, kyanite, epidote, sillimanite and garnet in the Bhuban sandstones is ascribed to the provenance of plutonic and metamorphic rocks. Dominance of zircon in the heavy mineral assemblage and the ZTR index values (75.13% avg.) indicate towards moderate degree of maturity with long distance of transport. The study of the shale samples by XRD and SEM analyses shows the dominance of illite over kaolinite and montmorillonite. The presence of minor amount of montmorillonite may suggest the addition of tuff and volcanic ash in the sediments under alkaline environment. PubDate: 2022-06-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Gravity data at a grid spacing of 2.5 sq. km., acquired by Geological Survey of India (GSI), have been analysed to discern the subsurface disposition of northern extremity of the Aravalli Delhi Fold Belt (ADFB). Geologically, the area has sparse exposure of the Aravalli Delhi Fold Belt and is predominantly covered by alluvium of Quaternary age. Apart from Bouguer gravity anomaly (BGA) map, residual gravity map, regional gravity map, radially averaged power spectrum (RAPS) and 3D Euler deconvolution maps have been prepared for better insights of the subsurface. Two 2D subsurface gravity models describe possible upwarpment of crustal and mantle materials for gravity high in southwest part of the study area. The significant change in trend of gravity contour pattern from NE-SW to NW-SE near Rohtak and further north is closely parallel to the trends of ADFB and Delhi Sargodha Subsurface ridge respectively. This deflection of the ADFB may probably be caused by rotation related to collision of plates. Earthquake data from International Seismological Centre (ISC), since the year 2000, has been used in the study. The earthquake data shows cluster of shallow focus earthquakes (from 2 to 39 km) with low magnitudes (from ML 1.8 to 5) in the study area near Rohtak. The presence of subsurface disturbance north of Rohtak is well supported by cluster of 3D Euler solutions and distribution of seismicity in that region. The multimodal distribution of the earthquake hypocentres is correlating well with the 2D gravity model along the Bhiwani to Panipat section. PubDate: 2022-06-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract The ecological record of bryozoans from the continental shelf-slope region of the southwestern Bay of Bengal is very sparse, prompting this investigation. Forty-five sea-floor sediment samples were collected along eight transects during the cruise on R/V Sagar Paschimi from the offshore region between Chennai and Cuddalore in the southwestern Bay of Bengal. The distribution of bryozoans was assessed based on the fragments of bryozoan colonies from these samples, which were collected at depths ranging from 6–308m. The goal was to determine the relationship between environmental parameters measured from the study area and the abundances of various bryozoan species. Results revealed the presence of 29 species of recent bryozoans in 24 genera pertaining to eight morphotypes. It is evident from the present investigation that the major control on the spatial distribution of bryozoan colonies is the type of substrate available, as sample sites dominated by coarse sediments showed high species richness though other factors such as ocean dynamics and rate of sedimentation also seem to regulate their abundance. PubDate: 2022-06-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract The physical, mechanical and chemical processing of silica sand, the main ingredient of silicate glass, are routinely carried out in glass and ceramic industries worldwide to enhance the silica content and to reduce the concentration of ferromagnesian impurities. The processing of silica sand prior to glass synthesis generally involves washing with water, physical screening (size and magnetic separation) and chemical treatments. The silica sand mining, in parts of Prayagraj (earlier known as Allahabad) district, Uttar Pradesh, is continuing for more than six decades and yet meager peer-reviewed published scientific data is available hitherto. On the other hand, the continued rampant water cleaning of silica sand for more than six decades has led to the accumulation of toxic sludge in the vicinity and also causing ground water depletion in the area. In order to find an amicable balance amongst silica sand processing, ground water depletion and environmental degradation, an attempt has been made to use untreated/raw silica sand of Prayagraj district, mainly from the Shankargarh area, to synthesize soda-lime-silica (SLS) glass. Following this objective, thirty five silica sand samples are collected from different washeries and grouped into seven classes based on their magnetic susceptibility values (30.23 to −0.71 × 10−8 m3kg−1). Representative silica sand samples from these seven groups are mixed with sodium carbonate (Na2CO3) and calcium carbonate (CaCO3) in a ratio of 75:15:10 and melted at 1300°C under one atmospheric pressure for a run duration of 90 minutes. Transparent to translucent SLS glasses of various hues and variable refractive indices (1.504–1.547) are formed. The glasses, thus analyzed by the electron probe micro analyzer (EPMA), comprise SiO2 (80.56–85.79 wt%), Na2O (9.70–12.69 wt%), CaO (4.80–6.51 wt%), Al2O3 (0.51–1.46 wt%), FeOT (0.15–0.95 wt%) and TiO2 (0.12–0.29 wt%), similar to the commercial SLS glasses manufactured worldwide. The present study suggests that the raw silica sand from Shankargarh area can be used to synthesize coloured SLS glasses even without washing with water and as a consequence the water resources and geo-environment of the area shall remain protected from further degradation. PubDate: 2022-06-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Ammonium (NH4+) accumulation and variability in Antarctic ice cores possess signals of various biological, anthropogenic, and atmospheric processes. However, the use of NH4+ variability in Antarctic ice cores for paleoclimate reconstructions is not well established. Addressing this, we have utilized, published NH4+ ice core records from the Dronning Maud Land (DML), Antarctica to assess the sources of NH4+, its transport, major forcing factors, and their mechanism in controlling the variability of ammonium signals in coastal ice cores. The first principle component (PC1) derived from PC analysis of NH4+ data comprises ∼43% of total variability and also depicts a significant spatial correlation with the NSIDC Sea ice concentration (SIC) variability in the Weddell Sea region of the Southern Ocean. In addition, the PC1 shows strong 2–9 year periodicities related to El Niño Southern Oscillation along with two major decadal to centennial periodicities of ∼40 and 100 years. The control of sea ice fluctuations and related oceanic processes (ENSO) provide evidence of the marine sources and influence of ocean-related processes as a major controlling factor for the NH4+ variability in DML ice cores. The cumulative accumulation of the NH4+ produced from enhanced biological decomposition, and unutilized ammonium during nitrification under high SIC conditions are possible mechanisms for the increased supply. The correlation of ERA5 surface air temperatures with Nino3.4 suggests that during El Niño conditions, the air temperatures significantly dropped in the Weddell Sea sector, fostering the high SIC conditions. The findings of this study regarding the role of the SIC in the ammonium variability in Antarctic ice cores would help us better interpret the paleo NH4+ records and their applications to deduce the paleoclimate conditions in coastal Antarctic regions. PubDate: 2022-06-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Field, petrography, and crystal size distributions (CSD) of different lithological variants from Sirsilla granitic pluton (SGP), southern India, is described here to understand operative magmatic processes. The SGP contains many mafic microgranular enclaves (MMEs) and syn-plutonic dykes. The contact relationship between MMEs and the host granite is often diffusive or gradational and rarely sharp, implying disaggregation and under-cooling of MMEs. Petrographic features like resorption textures, quartz ocelli, and the poikilitic nature of the large K-feldspar grains enclosed within plagioclase indicate interaction and magma mixing/mingling processes in an open magma chamber. Bladed biotite and acicular apatite grains in MMEs are due to rapid crystallization during the magma mingling process. The CSD curves generated for plagioclase provide an inverse relationship between population density and crystal size. Multiple crystal populations, i.e., a gently sloping line for the core samples and a steeply sloping line for margin samples, are interpreted to be caused by the mafic — felsic magma mixing and mingling processes. PubDate: 2022-06-01
Please help us test our new pre-print finding feature by giving the pre-print link a rating. A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract This review study has focused on existing sedimentological information of Late Jurassic transgressive deposits of Tendaguru Formation (110 m thick), Mandawa basin, Tanzania exposed around Tendaguru hill and Kanthkot Formation (150 m thick), Kachchh basin, India exposed near Wagad hill. Based on comparison between the two coeval deposits shows variable transgressive characteristics. Studies have revealed that during transgression there existed a storm-dominated sedimentary facies in Kanthkot Formation and tidally influenced facies type in Tendaguru Formation. Both represent similar cyclic sedimentation patterns and high-energy transgressive deposits into different depositional regimes. Lithofacies review reveals that Kachchh basin (Wagad region) was an open marine and relatively deeper and steeper shelf environment in late Jurassic time. However, Mandawa basin (Tendaguru region) was a restricted marginal marine with an estuarine setting. Faunal affinities in both formations indicate a shallow marine environment of deposition with variable depth. The close similarity of transgressive episodes and upward stacking pattern of facies successions in both basins indicates overall shallowing of the sea that correlates with the global trend of relative sea-level fall during late Jurassic time. PubDate: 2022-06-01
Hybrid journal (It can contain Open Access articles)
[2469 journals]
