Indications of an extreme event deposits along the west coast of India: evidences from GPR investigations   总被引：1，自引：1，他引：0  

V. J. Loveson  A. R. Gujar  S. D. Iyer  P. Srivastava  G. M. Tirodkar  R. A. A. Luis 《Environmental Earth Sciences》2014,72(10):4155-4166

The ground-penetrating radar (GPR) was used to trace the subsurface details in the Palshet coastal zone (Maharashtra) as it exhibits an interesting array of geomorphological features. Furthermore, our main goal was to identify and locate features that might have formed during a reported extreme event and its effects on the flow of the nearby Sundri River. Two profiles (8 and 4 m depth) were collected across the beach and along the backshore, respectively. While the 8-m depth profile (west to east; across the beach) indicates a series of coastline regression in this area, the 4-m depth profile along the coastline (north to south) in the backshore zone reveals two significant incidents viz., (1) stages of development of the paleo-channels that indicate the migration of the Sundri River towards south and (2) huge sediment deposits up to 2.5-m thick in the backshore area. The erosional relict surface (~2.5 m depth) was traced along with various spells of sediments that perhaps occurred due to an extreme event. Sand samples were collected from two trial pits along the GPR profiles to understand the sedimentology and mineralogy in the backshore area. These data together with beach profiles and geomorphological maps suggest that the sands were deposited by an extreme event perhaps during the 1854 cyclonic storm. The sands were trapped in suitable geomorphological sites along the Palshet coast and these sand deposits of about 2.5 m thickness forced the River Sundri to shift its course towards the south. This new revelation facilitates a further study that could focus on the nearby coastal areas to document such extreme event deposits and their influence on the geomorphic set-up.  相似文献   

Provenance of the late Paleocene sandstones of the Jaisalmer Basin,Western India     

A. Patra  B. P. Singh  V. K. Srivastava 《Journal of the Geological Society of India》2014,83(6):657-664

Provenance of the late Paleocene sandstone of the Jaisalmer basin has been determined by petrographic and heavy minerals analysis supported by paleocurrent study. Petrography of the quartzose-arenite sandstone reveals an abundance of sub-angular to sub-rounded monocrystalline non-undulatory quartz and some amount of feldspar and rock fragments. The rock fragments are dominated by argillites (slate, phyllite) and limestone. The heavy minerals suite of these sandstones comprises of angular to sub-angular grains of magnetite, zircon, tourmaline, kyanite and staurolite. The paleocurrent analysis indicates bipolar paleocurrent pattern with the dominance of NW flow suggesting that the provenance was in the SE direction of the depositional basin. Q-F-L and Qm-F-Lt diagrams suggest for a provenance at the margin of the craton interior and transitional continental. It is envisaged that the basic igneous rocks of the Deccan basalt, low- to medium-grade metamorphic rocks of the Aravalli belt and Jurassic limestones present in the vicinity are the source rocks for the late Paleocene sandstones of the Jaisalmer basin.  相似文献   

Environmental impact on coastal wetlands since 4 ka in Cauvery Delta: Palynology and thecamoebian study     

Jyoti Srivastava  Anjum Farooqui 《Journal of the Geological Society of India》2014,84(4):459-466

Palaeoclimate and Palaeoecological study was carried out in ～2 m sediment core deposited since 4 ka in an estuarine environment along Uppanar River mouth, Cauvery Delta. Palynological and thecamoebian evidences indicate (1) a basal fluvial lacustrine depositional environment (～4–3 ka) characterized by sandy sediment, with low salinity and dominance of non-pollen forms like foraminiferal linings and thecamoebians with a low percentage of pollen and spores and (2) an estuarine environment (since 3 ka) characterized by clayey sediment with high salinity and a good percentage of mangrove and terrestrial pollen along with non-pollen forms. A shift in the depositional environment since ～3 ka indicates monsoonal and geomorphological changes in the coastal wetland. During this period dominance of Avicennia and Cheno/Ams indicate low freshwater runoff from land suggesting a weakened monsoon condition enhanced by anthropogenic activity.  相似文献   

Data analysis of continuous gravitational wave: Fourier transform – II     

D. C. Srivastava †  S. K. Sahay 《Monthly notices of the Royal Astronomical Society》2002,337(1):315-321

In this paper we obtain the Fourier Transform of a continuous gravitational wave. We have analysed the data set for (i) a 1-yr observation time and (ii) an arbitrary observation time, for an arbitrary location of detector and source, taking into account the effects arising due to the rotational as well as orbital motion of the Earth. As an application of the transform we considered spin-down and N -component signal analysis.  相似文献   

Soil characterization based on land cover heterogeneity over a tropical landscape: an integrated approach using earth observation data-sets     

Diwakar Paudel  Jay Krishna Thakur  Sudhir Kumar Singh  Prashant K. Srivastava 《国际地球制图》2015,30(2):218-241

Soil is a vital part of the natural environment and is always responding to changes in environmental factors, along with the influences of anthropogenic factors and land use changes. The long-term change in soil properties will result in change in soil health and fertility, and hence the soil productivity. Hence, the main aim of this paper focuses on the analysis of land use/land cover (LULC) change pattern in spatial and temporal perspective and to present its impact on soil properties in the Merawu catchment over the period of 18?years. Post classification change detection was performed to quantify the decadal changes in historical LULC over the periods of 1991, 2001 and 2009. The pixel to pixel comparison method was used to detect the LULC of the area. The key LULC types were selected for investigation of soil properties. Soil samples were analysed in situ to measure the physicochemical soil properties. The results of this study show remarkable changes in LULC in the period of 18?years. The effect of land cover change on soil properties, soil compaction and soil strength was found to be significant at a level of <0.05.  相似文献   

Development of ground fissures: A case study from southern parts of Uttar Pradesh,India     

V. P. Gaur  S. K. Kar  Mridul Srivastava 《Journal of the Geological Society of India》2015,86(6):671-678

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Photometric and polarimetric studies of three W UMa-type binaries: FZ Ori,V407 Peg and LP UMa     

Vinod Prasad  J. C. Pandey  M. K. Patel  D. C. Srivastava 《Astrophysics and Space Science》2014,353(2):575-594

We present analyses of new optical photometric observations of three W UMa-type contact binaries FZ Ori, V407 Peg and LP UMa. Results from the first polarimetric observations of the FZ Ori and V407 Peg are also presented. The periods of FZ Ori, V407 Peg and LP UMa are derived to be 0.399986, 0.636884 and 0.309898 d, respectively. The O?C analyses indicate that the orbital periods of FZ Ori and LP UMa have increased with the rate of 2.28×10^?8 and 1.25×10^?6 d?yr^?1, respectively and which is explained by transfer of mass between the components. In addition to the secularly increasing rate of orbital period, it was found that the period of FZ Ori has varied in sinusoidal way with oscillation period of ～30.1 yr. The period of oscillations are most likely to be explained by the light-time effect due to the presence of a tertiary companion. Small asymmetries have been seen around the primary and secondary maxima of light curves of all three systems, which is probably due to the presence of cool/hot spots on the components. The light curves of all three systems are analysed by using Wilson-Devinney code (WD) and the fundamental parameters of these systems have been derived. The present analyses show that FZ Ori is a W-subtype, and V407 Peg and LP UMa are A-subtype of the W UMa-type contact binary systems. The polarimetric observations in B, V, R and I bands, yield average values of polarization to be 0.26±0.03, 0.22±0.02, 0.22±0.03 and 0.22±0.05 per cent for FZ Ori and 0.21±0.02, 0.29±0.03, 0.31±0.01 and 0.31±0.04 per cent for V407 Peg, respectively.  相似文献   

Magnetosonic waveguide model of solar wind flow tubes     

A. K. Srivastava  B. N. Dwivedi 《Journal of Astrophysics and Astronomy》2006,27(2-3):353-359

We consider solar wind flow tubes as a magnetosonic wave-guide. Assuming a symmetric expansion in edges of slab-modelled wave-guide, we study the propagation characteristics of magnetosonic wave in the solar wind flow tubes. We present the preliminary results and discuss their implications.  相似文献   

Three-colour photometry of GH pegasi     

R. K. Srivastava  T. D. Padalia 《Astrophysics and Space Science》1974,29(2):435-438

The geometrical elements of the system GH Pegasi and a slightly improved period of 2 _. ^d 556136 have been given.  相似文献   

Some anisotropic spatially-homogeneous cosmological models with electromagnetic field     

T. Singh  R. S. Srivastava 《Astrophysics and Space Science》1989,159(1):21-38

Considering Bianchi type-I metric, cosmological models of a perfect fluid with an electromagnetic field have been obtained, using a supplementary condition between the metric potentials. The four-current is either zero or space-like. The model has expanding and shearing but non-rotating fluid flow which is also geodetic. The requirement of positive conductivity imposes an additional restriction on the model. Various physical and mathematical properties of the model have been discussed.  相似文献