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Trace fossil evidences of an Early Miocene paleoseismic event and depositional regime change from the kutch(kachchh) Basin

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Journal of Palaeogeography 2024年第1期13卷 165-180页

作者： Ayush Srivastava sudipta dasgupta.k.ishanu chatterjee Mohuli Das Bombay Ichnos Research Group Department of Earth SciencesIndian Institute of Technology Bombay(lIT Bombay)PowaiMumbaiMaharashtra400076India

Unconsolidated siliciclastic sediments can undergo post-burial deformation, which leads to the formation of distinctive sedimentary structures, known as soft-sediment deformation structures(SSDS). The presence of a series of sand volcanoes confined to a particular lithostratigraphic horizon can represent a paleoseismic activity and, thereby, exemplifies the concept of “seismite”. The kutch Basin has been a tectonically active region since the initiation of eastern Gondwana rifting followed by a tectonic inversion during the Cenozoic due to the collision of the Indian and Eurasian plates. A stratum-bound series of sand volcanoes belonging to the khari Nadi Formation(kNF) is exposed along the banks of khari River. They separate the shallow marine deposits below and non-marine deposits above with their characteristic marine and paleosol trace fossil suites, respectively. Although a seismogenic origin has been much debated for the SSDS,the ichnofabric analysis of the sand-volcano-bearing stratum unequivocally points toward such an origin under a shallow seafloor condition. In addition to the sedimentary regime change from an open shallow-marine setting to a continental depositional environment concomitant with basinal uplift, the behavior of the burrowing crustaceans testifies to a syn-depositional development of a fault network associated with the fluidization, sand volcanism, and the resilience of the trace-producers in surviving those processes until the sedimentary regime change in the overlying strata. Although the ichno-sedimentological evidence apparently differs from the previous works that proposed a continuous base-level rise from the beginning of deposition of the khari Nadi Formation up to the middle part of the overlying Chhasra Formation, the paleoseismic activity,its ichnologic signature, and the depositional regime change refer to a higher-resolution(i.e., lower-order)sequence-stratigraphic change causing a short-duration regression within a longer-durat

关键词： Sand volcano Seismite Ichnology khari Nadi Formation kutch Basin kachchh Basin

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Lower-order transgressive-regressive cycles within a higher-order transgression at the basin margin: an aberrant intercalation of palaeosol and biostromal ichnofabrics from the early Miocene kutch Basin, India

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Journal of Palaeogeography 2024年第4期13卷 906-923页

作者： Ayush Srivastava sudipta dasgupta Seema Singh Bombay Ichnos Research Group Department of Earth SciencesIndian Institute of Technology Bombay (IIT Bombay) Department of Geology Panjab University

The Chhasra Formation (CF) of kutch Basin exemplifies a typical mixed siliciclastic-carbonate system with alternations of biostromal carbonate and fine-grained siliciclastic beds. The CF is subdivided into two members: the lower Claystone (CM) and the upper Siltstone(SM) member. Three CM outcrops (P1-P3) comprising buried palaeosols that formed under a specific environmental set-up involving imperfectly to poorly drained conditions, are exposed along the Berwali River. The biostromal carbonate beds, alternating with the palaeosols, contain invertebrate bioclasts(bivalves, gastropods, echinoids, etc.) and are characterized by a paucispecific firmground Thalassinoides ichnofabric. At section P1, below the contact between the underlying palaeosol and overlying carbonate, Thalassinoides transforms into firmground Gyrolithes inside the palaeosol forming a compound ichnotaxon. The palaeosol intervals of sections P1 and P2 consist of a Vondrichnus-Termitichnus-root trace ichnofabric defining the Termitichnus ichnofacies. At section P3, lenses of fully bioturbated siltstones with a monospecific firmground Thalassinoides ichnofabric can be observed within an overall silty palaeosol horizon, thereby, locally cross-cutting the pedogenic features. The ichnofabrics of section P3 indicate polyphase pedogenesis with three stages:(1) initial stage: pedogenesis in siltstone of undefined depositional affinity which was obscured by pedogenic processes,(2) transient stage: recurring marine incursions and colonization by crustaceans within the lens-shaped palaeotopographic depressions overprinting the palaeosol, and (3) final stage: subaerial exposure and another preserved phase of pedogenesis. The CM shows an apparent low-order T-R(transgressive-regressive) cyclicity within a 3rd-order TST (transgressive systems tract) that is supported by pedogenic intensity, ichnofabrics, and reciprocal sedimentation near the Miocene basin margin, though the cyclicity can be the result of both autoge

关键词： Palaeosol Biostrome Ichnofabrics Chhasra Formation Transgressive–regressive cycles TST kutch (kachchh) Basin

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Atherosclerotic plaque classification in carotid ultrasound images using machine learning and explainable deep learning

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Intelligent Medicine 2024年第2期4卷 83-95页

作者： Soni Singh Pankaj k.Jain Neeraj Sharma Mausumi Pohit sudipta Roy School of Vocational Studies and Applied Sciences Gautam Buddha UniversityGreater NoidaUttar PradeshIndia Artificial Intelligence and Data Science Jio Institute Navi MumbaiMaharashtraIndia School of Biomedical Engineering Indian Institute of TechnologyVaranasiUttar PradeshIndia

Objective The incidence of cardiovascular diseases(CVD)is rising rapidly *** forms of CVD,such as stroke and heart attack,are more common among patients with certain *** development is a major factor underlying cardiovascular events,such as heart attack and stroke,and its early detection may prevent such *** imaging of carotid arteries is a useful method for diagnosis of atherosclerotic plaques;however,an automated method to classify atherosclerotic plaques for evaluation of early-stage CVD is ***,we propose an automated method for classification of high-risk atherosclerotic plaque ultrasound *** Five deep learning(DL)models(VGG16,ResNet-50,GoogLeNet,XceptionNet,and SqueezeNet)were used for automated classification and the results compared with those of a machine learning(ML)-based technique,involving extraction of 23 texture features from ultrasound images and classification using a Support Vector Machine *** enhance model interpretability,output gradient-weighted convolutional activation maps(GradCAMs)were generated and overlayed on original *** A series of indices,including accuracy,sensitivity,specificity,F1-score,Cohen-kappa index,and area under the curve values,were calculated to evaluate model *** output images allowed visualization of the most significant ultrasound image *** GoogLeNet model yielded the highest accuracy(98.20%).Conclusion ML models may be also suitable for applications requiring low computational ***,DL models could be more completely automated than ML models.

关键词： Explainable deep learning Carotid artery Classification VGG 16 ResNet-50 GoogLeNet XceptionNet SqueezeNet

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Computerized geochemical modeling of burial diagenesis of the Eocene turbidite reservoir elements：Urucutuca Formation,Espirito Santo Basin,southeastern Brazil passive margin

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Journal of Palaeogeography 2018年第4期7卷 363-377页

作者： Marcos Antonio klunk sudipta dasgupta Rommulo Vieira Conceicao Institute of Isotope Geology Federal University of Rio Grande do SulPorto AlegreBrazil Department of Earth Sciences Indian Institute of Technology (IIT) BombayMumbai India

The computerized geochemical modeling, a useful tool to understand the diagenetic processes influencing the quality of hydrocarbon reservoirs, is performed by using different modules of computer codes based on the thermodynamic and chemical kinetic principles and their associated parameters. As observed in the reservoir lithofacies deposited from the marine sediment-gravity flows, a case study of diagenesis is presented here from the Espírito Santo Basin in southeastern Brazil. The study uses the Geochemist＇s Workbench（GWB～（TM））, PHREEQC～（TM） and TOUGHREACT～（TM） computation packages. The comparison of performances of these packages demonstrates the convergence of results from the software-based geochemical modeling with the petrographic observation of dissolution, albitization, kaolinization, and the precipitation of calcite and dolomite. Moreover, with limited data points, e.g., the sedimentary petrographic data acquired from limited number of boreholes, the computer simulation establishes itself to be a powerful quantitative method estimating the degree and type of diagenetic alteration of turbidite reservoir bodies in contact with a source of saline-water influx associated with salt ***, using the limited petrographic data points, the geochemical computer-simulation method can even be utilized and extrapolated for areas where similar geological context is interpreted but no borehole data are available. Hence, porosity of turbidite reservoir lithofacies can be predicted in relation to the spatial distribution of dissolution, kaolinization, and albitization of feldspars and authigenic carbonate precipitation.

关键词： Sandstone diagenesis Computerized diagenetic modeling Turbidite reservoir GWB PHREEQC TOUGHREACT

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Thermal history of a Late Mesoproterozoic paired metamorphic belt(?)during Rodinia assembly:New insight from medium-pressure granulites from the Aravalli-Delhi Mobile Belt, Northwestern India

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Geoscience Frontiers 2018年第2期9卷 335-354页

作者： Santanu kumar Bhowmik Somnath dasgupta sudipta Baruah Deepika kalita Department of Geology and Geophysics Indian Institute of Technology Kharagpur Department of Geography Faculty of Natural SciencesJamia Millia Islamia

In this study, we investigate the possible record of a Late Mesoproterozoic paired metamorphic belt in the Aravalli-Delhi Mobile Belt(ADMB), NW India using a suite of supracrustal and metaigneous granulites from the Pilwa-Chinwali granulite terrain at the north-western margin of the ADMB. Using metamorphic reaction textures, mineral chemistry, metamorphic reaction history, geothermobarometric computations and electron microprobe dating of monazite in 5 samples of pelitic granulite, leptynite gneiss, enderbite and charnockite, we have deduced a medium-pressure granulite facies metamorphism(P between 4.9 and 6.8 kbar, T> 760-815℃) along a heating-cooling, counterclockwise P-T path between 1.09 and 1.01 Ga. When collated with published metamorphic and chronological constraints and geological settings of the adjoining crustal domains of the ADMB, these findings provide new insights into the developments of two tectonic domains of contrasting thermal gradients at ca. 1.0 Ga, consistent with metamorphic transformations in tectonically thickened middle-lower crustal sections during continental collision to continental subduction and in the root zones of spatially adjacent island arc, as part of the Rodinia supercontinent assembly event.

关键词： ADMB Granulites CCW-P-T path Monazite chemical dating ca. 1.0 Ga metamorphism Paired metamorphic belt

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Accretion flow properties of XTE J1118+480 during its 2005 outburst

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Research in Astronomy and Astrophysics 2020年第11期20卷 222-230页

作者： Dipak Debnath Debjit chatterjee Arghajit Jana Sandip k.Chakrabarti kaushik chatterjee Indian Centre for Space Physics 43 ChalantikaGaria St.Rd.Kolkata700084India Physical Research Laboratory NavrangpuraAhmedabad 380009India

We study spectral and temporal properties of Galactic short orbital period transient black hole XTE J1118+480 during its 2005 outburst using archival data of RXTE PCA and HEXTE instruments in the combined energy range of 3−100 *** analysis with the physical two component advective flow(TCAF)model allows us to understand the accretion flow properties of the *** found that this outburst of XTE J1118+480 is an unconventional outburst as the source was only in the hard state(HS).Our spectral analysis suggests that during the entire outburst,the source was highly dominated by the low angular momentum sub-keplerian halo *** the source was active in radio throughout the outburst,we make an effort to estimate X-ray contribution of jets to total observed X-ray emissions from the spectral analysis with the TCAF *** total X-ray intensity shows a similar nature of evolution as that of radio and jet X-ray *** allowed us to define this‘outburst’also as a jet dominated‘outburst’.Total X-ray flux is also found to subside when jet activity *** detailed spectral analysis also indicated that although the source was only in the HS during the outburst,in the late declining phase the spectrum became slightly softer due to the slow rise in the keplerian disk rate.

关键词： X-Rays binaries-stars black holes-stars individual (XTE J1118+480)-accretion,accretion disks-ISM jets and outflows-radiation dynamics

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Effect of coefficient of restitution in Euler-Euler CFD simulation of fluidized-bed hydrodynamics

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Particuology 2014年第4期12卷 170-177页

作者： Chanchal Loha Himadri Chattopadhyay Pradip k.chatterjee Thermal Engineering Division CSIR-Central Mechanical Engineering Research InstituteDurgapur 713209India Department of Mechanical Engineering Jadavpur UniversityKolkata 700032India

Collision between particles plays an important role in determining the hydrodynamic characteristics of gas-solid flow in a fluidized bed. In the present work, earlier work （Loha, Chattopadhyay, ＆ chatterjee, 2013） was extended to study the effect of the elasticity of particle collision on the hydrodynamic behavior of a bubbling fluidized bed filled with 530-~m particles. The Eulerian-Eulerian two-fluid model was used to simulate the hydrodynamics of the bubbling fluidized bed, where the solid-phase properties were calculated by applying the kinetic theory of granular flow. To investigate the effect of the elasticity of particle collision, different values of the coefficient of restitution were applied in the simulation and their effects were studied in detail. Simulations were performed for two different solid-phase wall boundary conditions. No bubble formation was observed for perfectly elastic collision. The bubble formation started as soon as the coefficient of restitution was set below 1.0, and the space occupied by bubbles in the bed increased with a decrease in the coefficient of restitution. Simulation results were also compared with experimental data available in the literature, and good agreement was found for coefficients of restitution of 0.95 and 0.99.

关键词： Coefficient of restitution Fluidization Hydrodynamics Computational fluid dynamics Euler-Euler approach

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Euler-Euler CFD modeling of fluidized bed:Influence of specularity coefficient on hydrodynamic behavior

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Particuology 2013年第6期11卷 673-680页

作者： Chanchal Loha Himadri Chattopadhyay Pradip k.chatterjee Thermal Engineering Group CSIR-Central Mechanical Engineering Research Institute Department of Mechanical Engineering Jadavpur University

Euler-Euler two-fluid model is used to simulate the hydrodynamics of gas-solid flow in a bubbling flu- idized bed with Geldert B particles where the solid property is calculated by applying the kinetic theory of granular flow （kTGF）. Johnson and Jackson wall boundary condition is used for the particle phase, and different amount of slip between particle and wall is given by varying the specularity coefficient （φ） from 0 to 1. The simulated particle velocity, granular temperature and particle volume fraction are compared to investigate the effect of different wall boundary conditions on the hydrodynamic behavior, Some of the results are also compared with the available experimental data from the literature. It was found that the model predictions are sensitive to the specularity coefficient. The hydrodynamic behavior deviated sig- nificantly for φ = 0 and φ = 0.01 with maximum deviation found at φ = 0 i.e. free-slip condition. However, the overall bed height predicted by all the conditions is similar.

关键词： Fluidized bed Hydrodynamics Specularity coefficient CFD

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Enveloping Relief Surfaces of Landslide Terrain

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Journal of Mountain Science 2007年第3期4卷 203-208页

作者： A.k.Pachauri Abhirup chatterjee Reeta Gaur Department of Earth Sciences Indian Institute of Technology

Two relief surfaces that envelop the rock fall region in a part of Garhwal Himalayas around Chamoli have been identified. Relative relief and absolute relief have been analyzed and the enveloping surfaces recorded at two levels of relief in the landscape. All landslide activity lies within these surfaces. The lower enveloping surface （800 m） dips due south by 7-8 degrees, due to an elevation rise of lOO meters within 12 km from south to north, i.e., a gradient of 8 percent. The nature of the surface is smooth. The upper enveloping surface （〉 2500 m） is almost parallel to the lower one but its surface is undulatory due to landslides and denudation. The area has been a seismically active region and has undergone seismic activity up until recently, as evidenced by the Chamoli earthquake of 29th March 1999. The effects of earthquakes are seen at higher levels in the form of landslide imprints on the terrain.

关键词： Relief landslide terrain Himalayas

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Tree species composition and diversity in montane forests of Garhwal Himalaya in relation to environmental and soil properties

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Journal of Mountain Science 2020年第12期17卷 3097-3111页

作者： Dinesh Singh RAWAT P.TIWARI sudipta kumar DAS J.k.TIWARI Department of Botany&Microbiology HNB Garhwal UniversitySrinagar(Garhwal)-246174UttarakhandIndia Central National Herbarium Botanical Survey of IndiaHowrah-711103West BengalIndia

The montane forests of Garhwal Himalaya were investigated for tree species composition and diversity in relation to environmental and edaphic variables.A stratified random sampling approach was adopted to collect the field data from each forest.A total of 39 tree species belonging to 31 genera and 23 families were recorded from the sampling area(6 forest stands ×10 plots in each).Lauraceae with 5 species was the largest family while Quercus(4 species) emerged as the largest ***-area curve(asymptote) predicted more species than the observed number of *** analysis has shown that the two Abies pindrow dominant forest stands had the highest similarity in tree species *** tree stem density ranged from 540-1170 ha-1,basal area 23.01-55.94 m^2 ha-1,ShannonWiener diversity index 1.69-2.49,evenness index0.42-0.74,beta diversity 0.40-0.82 and similarity index 0.17-0.54 in the six studied ***-way indicator species analysis(TWINSPAN) identified four distinct tree communities in the study area with Daphniphyllum himalayense,Abies pindrow,Quercus oblongata,and Pinus roxburghii as indicator species of corresponding *** correspondence analysis(CCA) ascertained the TWINSPAN results and revealed the relation of tree species with environmental and edaphic *** phytosociological attributes of tree species varied from one forest stand to another;however,the tree species richness,density,and diversity peaked at intermediate elevation on the north *** reveal that tree composition and diversity in the montane forests of Garhwal Himalaya are influenced by both environmental(elevation and slope aspect)and soil variables(texture,water holding capacity,moisture content,available N,exchangeable P,and pH).This study will help in understanding the forest distribution across the western Himalaya,guiding the conservationists and policymakers in carrying out conservation-related management activities,designing the long-

关键词： Diversity Tree species Montane forests Soil properties Western Himalaya

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