排序方式： 共有67条查询结果，搜索用时 15 毫秒
21.
Journal of Seismology - The North East (NE) of India is an earthquake (EQ) prone zone and has experienced considerable damages in the past due to high intensity EQs. With rapidly growing... 相似文献
22.
Durga Shanker Mitra Ratheesh Ramakrishnan Harshvardhan Dave Subhobroto Mazumder 《国际地球制图》2013,28(5):404-419
An attempt has been made to use synthetic aperture radar (SAR) data for detection and monitoring of offshore oil seeps in the eastern offshore areas of the Krishna–Godavari Basin, which has been supplemented and correlated with collateral free-air gravity and seismic data. Images of the study area obtained from ENVISAT ASAR image mode were processed and analysed in detail. A number of natural oil seepages were identified and distinguished from pollution and biogenic slicks. These were subsequently studied using different parameters to assign various degrees of confidence. The repetitiveness of the identified seepages was studied and a total of five areas of seep repetitions had been recognized in the study area. The seeps that are repeated in images of different dates are more likely to be of natural origin than others. Simulation and modelling of a particular oil slick arising has been attempted over the Krishna–Godavari offshore using MIKE 21 software. 相似文献
23.
M. Al Mamunul Haque C. S. Jahan Q. H. Mazumder S. M. S. Nawaz G. C. Mirdha P. Mamud M. I. Adham 《Journal of the Geological Society of India》2012,79(1):77-84
The Rajshahi city is the fourth largest metropolitan city in Bangladesh on the bank of the River Padma (Ganges). Here an upper
semi-impervious layer overlies aquifer — the source for large-scale groundwater development. The groundwater resource study
using Visual MODFLOW modeling shows that recharge occurs mainly due to infiltration of rainfall and urban return flow at low
rate, and water level fluctuates seasonally in response to recharge and discharge. Hydraulic connection between river and
aquifer which indicates inflow from high river water levels beyond its boundaries. The total groundwater abstraction in 2004
(15000 million liters) is lower than total input to aquifer reveals an ample potentiality for groundwater development with
increasing demand. But groundwater shortage (1000 million liter/year) especially in the vicinity of the River Padma in dry
season happens due to its increasing use and fall of river water level resulting in reduced inflows and hence decline in groundwater
level. The conjunctive use of surface water-groundwater and its economic use will help for sustainable groundwater supply
to avoid adverse impact. 相似文献
24.
The ca 2.74 Ga Mopoke Member,Kylena Formation: a marine incursion into the northern Fortescue Group?
D. T. Flannery M. J. Van Kranendonk R. Mazumder M. r. Walter 《Australian Journal of Earth Sciences》2013,60(8):1095-1108
The northern part of the Fortescue Group consists of interbedded flood basalts and sedimentary rocks that were deposited on the southern margin of the Pilbara Craton, Western Australia, during one or more periods of continental rifting between ca 2.78 and ca 2.63 Ga. Well-preserved sedimentary intervals within the group have yielded stable carbon and sulfur isotope data that have been used to infer changes in geobiological processes in the Neoarchean. However, the Fortescue Group is notable for being a predominantly subaerial succession, and it remains unclear whether data obtained from these intervals should be interpreted in the context of deposition in marine environments, possibly recording changes in the global ocean/atmosphere system, or in local and restricted lacustrine settings. Here, we describe the sedimentology, stratigraphy, stromatolites and stable carbon isotope geochemistry of the ca 2.74 Ga Mopoke Member, Kylena Formation, the oldest stromatolitic horizon in the Fortescue Group. This unit differs in terms of internal stratigraphic relationships, sedimentology, carbonate mineralogy and stable isotope geochemistry when compared with intervals of probable lacustrine origin in the overlying Tumbiana and Maddina formations. In contrast, we suggest that parts of the Mopoke Member may have been deposited under open marine conditions, or alternatively, in a lacustrine environment characterised by differing water chemistry and basement topography. Stromatolitic microfabrics of the Mopoke Member are dominated by spar, dolospar and vertically aligned calcitic crusts, rather than the micritic microfabrics described from other Fortescue Group stromatolites. Mud-draped ripples are common sedimentary features in the Mopoke Member, suggesting a tidal influence. Mopoke Member δ13Ccarb values are generally slightly positive, but also include some significantly depleted values, which may relate to the reoxidation of 13C-depleted organic matter. δ13Corg values average –36.7‰, consistent with Neoarchean marine units reported from elsewhere, but significantly less 13C-depleted than values reported from overlying lacustrine intervals in the Fortescue Group. We conclude that some features of Fortescue Group datasets relevant to the field of geobiology may be facies dependent, and that more work focusing on the overall depositional environments of the Fortescue Group is needed in order to appropriately interpret geobiological data reported from that group. 相似文献
25.
Rajat Acharya Bijoy Roy M.R. Sivaraman Ashish Dasgupta 《Journal of Atmospheric and Solar》2010,72(9-10):774-780
The variability of Total Electron Content (TEC) at Trivandrum, located within equatorial anomaly region at the dip equator, with respect to a reference level derived from the TEC measurements at Shimla, located outside the region has been studied during low solar activity period. Chapman function is assumed to hold good for regions outside the anomaly extent. It shows that the difference of total measured TEC at the equator from the derived reference is highly correlated with equatorial electrojet. The observations conform to the previous investigations and are interpreted in light of established relations. A stochastic relationship with electrojet is derived and validated. 相似文献
26.
Subhobroto Mazumder Kalyan Adhikari Durga Shanker Mitra Samiran Mahapatra Krishan Kumar Singh Pangtey 《Journal of the Geological Society of India》2016,88(1):87-97
TheAssamArakan fold thrust belt has highly deformed folded units of Tertiary sediments bounded by eastward dipping thrust slices with a convexity towards west. In the Tripura-Cachar region, this folded belt is characterized by the occurrence of wide synclines and narrow anticlines that hosts a number of hydrocarbon producing fields. In the Cachar area of Assam, most of these fields occur in the culmination of anticlinal structures. Other wells drilled in analogous structural settings are found to be dry. In this paper a neotectonic based geomorphic analysis is carried out to delineate a fault network and geomorphic highs in Cachar area as expressions of sub-surface structures which had subsequently been validated by available geophysical data. Of these geomorphic highs, those that are in the synclinal areas are believed to represent subtle sub-surface structural highs. Synclinal structures associated with NNE-SSW faults might be considered interesting for hydrocarbon exploration and are subsequently categorized following their degree of confidence for exploration of hydrocarbon. Additionally, a genetic model of the structures in the region is also proposed. 相似文献
27.
Ritabrata Biswas Nairwita Mazumder Subenoy Chakraborty 《Astrophysics and Space Science》2011,335(2):603-609
In this paper we deal with accretion of dark energy in the holographic dark energy model for a general non-rotating static
spherically symmetric black hole. The mass of the black hole increases or decreases depending on the nature of the holographic
dark energy (quintessence or phantom) as well as on some integration parameters. It is to be illustrated that the enhancement
or reduction of mass of a black hole is independent of the mass or size of the black hole itself. Rather it depends only upon
the radius of the event horizon of the universe. Finally, the generalized second law of thermodynamics has been studied on
the event horizon to be assured that the law holds even if when the black hole mass is decreasing though it is engrossing
some mass. 相似文献
28.
How does inflation depend upon the nature of fluids filling up the universe in brane world scenario?
Sudeshna Mukerji Ritabrata Biswas Nairwita Mazumder Subenoy Chakraborty 《Astrophysics and Space Science》2012,337(1):425-437
By constructing different parameters which are able to give us the information about our universe during inflation, (specially
at the start and the end of the inflationary universe) a brief idea of brane world inflation is given in this work. What will
be the size of the universe at the end of inflation, i.e., how many times will it grow than the original size is been speculated
and analysed thereafter. Different kinds of fluids are taken to be the matter inside the brane. It is observed that in the
case of highly positive pressure giving gas like polytropic, the size of the universe at the end of inflation is comparatively
smaller. Whereas for negative pressure creators (like Chaplygin gas) this size is much bigger. Except these two cases, inflation
has been studied for barotropic fluid and linear red shift parametrization ω(z)=ω
0+ω
1
z too. For them the size of the universe after inflation is much more high. We also have seen that this size does not depend
upon the potential energy at the end of the inflation. On the contrary, there is a high impact of the initial potential energy
upon the size of inflation. 相似文献
29.
L. MallikR. Mazumder B.S. MazumderM. Arima P. Chatterjee 《Marine and Petroleum Geology》2012,30(1):43-49
Tidal rhythmites have been documented from modern continental shelves and distal offshore settings. In significant contrast to their modern counterparts, sedimentological studies of ancient tidal rhythmites formed in distal offshore settings and quantification of tidal rhythms encoded therein are, however, scarce. This paper presents sedimentological analysis of vertically accreted tidal rhythmites from the Palaeoproterozoic Chaibasa shale facies in India, and quantification of their tidal rhythms. The facies characteristics of the Chaibasa Shale coupled with harmonic analysis of the laminae thicknesses of the sandstone inter-layers corroborate a distal shelf palaeogeography for the generation of the vertically accreted tidal rhythmites. The latter are the distal counterparts of laterally accreted, tidal “bundle” deposits, well preserved within the shallow marine Chaibasa sandstones. The number of lunar days in a synodic month (∼23) estimated from the Chaibasa shale facies is, however, considerably lower than that estimated from the Chaibasa sandstone facies (∼32) suggesting that the tidal record encoded from the Chaibasa shale facies is incomplete. 相似文献
30.
A total of 25 surface sediment samples, collected along a North-South transect (from 9.69° N to 55.01° S and from 80° E and 40° E) in the south western Indian Ocean, were used to study the coiling direction patterns in foraminifera planktonic species Neogloboquadrina pachyderma, Globigerinita glutinata and Globigerina bulloides. Comparison between the coiling direction and mean proloculus size (MPS) revealed that all these profiles along N-S transect were not in tandem and thus indicated non-existence of any relationship between the coiling direction and reproductive modes expressed in terms of mean proloculus size. 相似文献