Tidal rhythmites in offshore shale: A case study from the Palaeoproterozoic Chaibasa shale, eastern India and implications     

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   

Small-scale magnetic helicity losses from a mean-field dynamo     

Axel Brandenburg  Simon Candelaresi  Piyali Chatterjee 《Monthly notices of the Royal Astronomical Society》2009,398(3):1414-1422

Using mean-field models with a dynamical quenching formalism, we show that in finite domains magnetic helicity fluxes associated with small-scale magnetic fields are able to alleviate catastrophic quenching. We consider fluxes that result from advection by a mean flow, the turbulent mixing down the gradient of mean small-scale magnetic helicity density or the explicit removal which may be associated with the effects of coronal mass ejections in the Sun. In the absence of shear, all the small-scale magnetic helicity fluxes are found to be equally strong for both large- and small-scale fields. In the presence of shear, there is also an additional magnetic helicity flux associated with the mean field, but this flux does not alleviate catastrophic quenching. Outside the dynamo-active region, there are neither sources nor sinks of magnetic helicity, so in a steady state this flux must be constant. It is shown that unphysical behaviour emerges if the small-scale magnetic helicity flux is forced to vanish within the computational domain.  相似文献   

Dynamic groundwater resources of National Capital Territory,Delhi: assessment,development and management options   总被引：4，自引：2，他引：2  

Rana Chatterjee  B. K. Gupta  S. K. Mohiddin  P. N. Singh  Shashank Shekhar  Rajaram Purohit 《Environmental Earth Sciences》2009,59(3):669-686

Groundwater is one of the important source of water supply to meet the requirements of National Capital Territory (NCT) of Delhi, India which is a fast developing urban conglomeration. An assessment of dynamic groundwater resources of NCT Delhi has been attempted based on the methodology known as Ground Water Resources Estimation Methodology—1997. The methodology includes assessment of annual replenishable groundwater resources using water level fluctuation approach and empirical norms, estimation of the annual quantity of groundwater withdrawal and categorization of the assessment units based on the status of groundwater utilization and water level trend. Annual replenishable groundwater resources of NCT Delhi is about 297 million cubic meter (mcm) while the annual groundwater draft is about 480 mcm. This is because of over-exploitation of replenishable resources in seven out of nine districts of the Capital Territory. Based on the assessment of dynamic groundwater resources, a broad groundwater management plan has been proposed in this paper. This include augmentation of groundwater resources through rain water harvesting schemes to be implemented on a large scale, regulation on groundwater withdrawal in vulnerable areas, development of Yamuna flood plain aquifer and declaration of Delhi ridge as groundwater sanctuary.  相似文献   

Subaqueous early eruptive phase of the late Aptian Rajmahal volcanism,India: Evidence from volcaniclastic rocks,bentonite, black shales,and oolite   总被引：1，自引：0，他引：1  

Naresh C. Ghose  Nilanjan Chatterjee  Brian F. Windley 《地学前缘(英文版)》2017,8(4):809-822

The late Aptian(118-115 Ma) continental flood basalts of the Rajmahal Volcanic Province(RVP) are part of the Kerguelen Large Igneous Province,and constitute the uppermost part of the Gondwana Supergroup on the eastern Indian shield margin.The lower one-third of the Rajmahal volcanic succession contains thin layers of plant fossil-rich inter-trappean sedimentary rocks with pyroclasts,bentonite,grey and black shale/mudstone and oolite,whereas the upper two-thirds consist of sub-aerial fine-grained aphyric basalts with no inter-trappean material.At the eastern margin and the north-central sector of the RVP,the volcanics in the lower part include rhyolites and dacites overlain by enstatite-bearing basalts and enstatite-andesites.The pyroclastic rocks are largely felsic in composition,and comprise ignimbrite as well as coarse-grained tuff with lithic clasts,and tuff breccia with bombs,lapilli and ash that indicate explosive eruption of viscous rhyolitic magma.The rhyolites/dacites(68 wt.%) are separated from the andesites( 60 wt.%) by a gap in silica content indicating their formation through upper crustal anatexis with only heat supplied by the basaltic magma.On the other hand,partially melted siltstone xenoliths in enstatite-bearing basalts suggest that the enstatite-andesites originated through mixing of the upper crust with basaltic magma,crystallizing orthopyroxene at a pressure-temperature of ~3 kb/1150℃.In contrast,the northwestern sector of the RVP is devoid of felsic-intermediate rocks,and the volcaniclastic rocks are predominantly mafic(basaltic) in composition.Here,the presence of fine-grained tuffs,tuff breccia containing sideromelane shards and quenched texture,welded tuff breccia,peperite,shale/mudstone and oolite substantiates a subaqueous environment.Based on these observations,we conclude that the early phase of Rajmahal volcanism occurred under predominantly subaqueous conditions.The presence of grey and black shale/mudstone in the lower one-third of the succession across the entire Rajmahal basin provides unequivocal evidence of a shallow-marine continental shelf-type environment.Alignment of the Rajmahal eruptive centers with a major N—S mid-Neoproterozoic lineament and the presence of a gravity high on the RVP suggest a tectonic control for the eruption of melts associated with the Kerguelen plume that was active in a post-Gondwana rift between India and Australia-Antarctica.  相似文献   

Metamorphe Mineralreaktionen in vesuvianführenden Paragenesen     

Prof. Dr. Otto Braitsch  Dr. Niranjan Deb Chatterjee 《Contributions to Mineralogy and Petrology》1963,9(4):353-373

Zusammenfassung In Fortsetzung einer früheren Arbeit (Chatterjee, 1962) werden weitere Beispiele vesuvianführender Paragenesen aus der Grünschieferfazies Bowie aus der Albit-Epidot-Hornfelsfazies beschrieben. Hieraus ergibt sich, daß die Paragenesen Vesuvian + Epidot, Vesuvian + Tremolit und Vesuvian + Chlorit für die niedrig-temperierten Mineralfazies kennzeichnend sind, und zwar unabhängig vom wirksamen Gesamtdruck. Die Bildungsmöglichkeiten des Vesuvians und seine Umbildungen bei stärkerer Metamorphose werden anhand von stöchiometrischen Reaktionsgleichungen behandelt. Die Reaktionen Bind schematisch in ACF-Diagrammen dargestellt, und die Gleichgewichtstemperaturen sind qualitativ in Abhängigkeit von der Zusammensetzung der Gasphase mit Hilfe einer vonGreenwood (1962) aufgestellten thermodynamischen Beziehung abgeleitet.

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In continuation of a former paper (Chatterjee, 1962), further data pertaining to vesuvianite-bearing mineral parageneses from the greenschist fades of the western Alps, albite-epidote-hornfels facies of eastern Harz Mountains as well as from the hornblende hornfels facies of the Oslo region are reported. It is shown that the coexistence of vesuvianite-epidote, vesuvianite-tremolite and vesuvianite-chlorite is characteristic of the lower temperature mineral facies, irrespective of the different total pressures acting during the metamorphism. Metamorphic reactions have been derived to explain the formation of vesuvianite, successive changes of the critical parageneses as well as its final disappearence within the system CaO-(Mg, Fe²⁺)O-(Al, Fe³⁺)₂O₃-SiO₂-H₂O ± CO₂. The phase transformations are illustrated on ACF diagrams as a function of temperature and mole fraction CO₂ of the gaseous phase (in an isobaric section).

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Vesuvianite-epidote paragenesis as a product of greenschist facies of regional metamorphism in the Western Alps     

Dr. Niranjan Deb Chatterjee 《Contributions to Mineralogy and Petrology》1962,8(6):432-439

Occurences of stable vesuvianite-epidote paragenesis within greenschist facies of metamorphism are described. It is suggested that this paragenesis gives way to grossularite-diopside (plus vesuvianiteor epidote) assemblage in the almandine-amphibolite facies. This interpretation conforms best to the results of petrographic observations and also satisfies the topological requirements of the CaO-(Mg, Fe²⁺, Mn)O-(Al, Fe³⁺)₂O₃-SiO₂H₂O-CO₂ system, to which these assemblages belong. Contrary to the ideas in vogue, it is suggested that vesuvianite can very well originate within the greenschist facies, whereas the appearence of grossularite and diopside (consequent on which vesuvianite and epidote becomesmutually incompatible) ushers the almandine-amphibolite facies in.  相似文献   

Authigenic tourmaline in the Precambrian metasediments around Jamua,District Bhagalpur,Bihar, India     

S.R. Chatterjee  D.K. Sen Gupta  T.C. Bagchi 《Sedimentary Geology》1975,13(2):153-156

The presence of detrital and perfectly oriented tourmaline grains with authigenic overgrowth is recorded for the first time from the dark-coloured quartzite pebbles in a conglomeratic horizon in the Precambrian metasediments around Jamua. The grain morphology indicates not only a sedimentary provenance but also the passage of more than one cycle of sedimentation. Optically, Li-rubellite is found to predominate over other varieties of tourmaline.It is concluded that psammites and psammo-pelites containing the authigenic tourmaline have an undoubted sedimentary parentage and that these metasediments are younger than the Kolhans from which they are possibly derived.  相似文献   

A comparative study of the petrochemistry of the tholeiitic rocks of India     

A. C. Chatterjee 《Bulletin of Volcanology》1971,35(4):1037-1050

A comparative study of the petro-chemistry of the tholeiitic rocks (Cuddapah, Gwalior, Rajmahal and the Deccan traps) is made employing various crystallization parameters such as the differentiation index (D. I.) and the solidification index (S. I.). The D. I. values of the upper Deccan traps are much higher than those of the lower traps, rocks of intermediate composition being rare. The S. I. values of the Deccan traps allow them to be classified into three categories i.e., (1) the lower trap with higher S. I. values, (2) the differentiated upper division traps, (3) the unusual rock types of Western India. Murata’s alkali-silica diagram, based on all the available analyses of the traps (Pre-Cambrian to Eocene), indicates that, following the chemical definition, it is not possible to group the entire upper Deccan trap flows under the tholeiites. All the Precambrian traps are not tholeiitic either. There is a clear relationship between optical and petro-chemical characters. Attention is drawn to the difficulties in the application of Barth’s «f-norm » to trace the cooling history of the rocks crystallizing at a later stage.  相似文献   

Experiments on the phase transition calcite+wollastonite+ +epidote=grossular-andraditess+CO2+H2O     

Dr. Niranjan D. Chatterjee 《Contributions to Mineralogy and Petrology》1967,14(2):114-122

The reaction 2 epidote+2 calcite+3 wollastonite3 grossular-andradite_ss+ 2 CO₂+1 H₂O has been explored by hydrothermal experiments at a total fluid pressure of 1000 bars. For a grossular-andradite_ss of andradite ₂₅ composition, the isobaric univariant curve passes through the points 458°C: X_CO2=0.00; 521°C: X_CO2=0.026; 523°C: X_CO2=0.052; 526°C: 0.088; 528°C: X_CO2=0.104. This curve intersects the isobaric univariant curve of the reaction calcite+quartz+[H₂O] wollastonite+CO₂+[H₂O] at the isobaric invariant point around 528°C and X_CO2=0.12. At higher values of X_CO2, this reaction is replaced by another one, namely: 2 epidote+5 calcite+3 quartz3 grossular-andradite_ss+5 CO₂+ 1 H₂O. It is demonstrated that both the reactions do actually take place during the metamorphism of calcareous rocks. The petrologic significance of contrasted sequence of reactions within this system observed by various workers is also discussed.  相似文献   

Delineation of surface waterlogged areas in parts of bihar using IRS-1C LISS-III data     

Chandranath Chatterjee  Rakesh Kumar  Pankaj Mani 《Journal of the Indian Society of Remote Sensing》2003,31(1):57-65

Pre-monsoon and post-monsoon surface waterlogged areas were delineated using satellite remote sensing data for Muzaffarpur, Vaishali and Saran districts of North Bihar. Digital data of IRS-1C LISS-III sensor acquired on December 7, 1998 and April 6, 1999 were analyzed using digital image processing software-ERDAS Imagine 8.3.1. The surface waterlogged areas were delineated using modeling technique which is the most advanced and accurate method. Using the modeling technique, a pixel is classified as water if the digital number (DN) value of its Near Infra Red (NIR) band is less than the DN value of the Red band and the Green band, and the Normalized Difference Water Index (NDWI) is greater than or equal to 0.32. The pre-monsoon surface waterlogged areas are found to be 14.02, 23.61 and 9.61 km² while the post-monsoon surface waterlogged areas are found to be 231.83, 118.19 and 176.06 km² for Muzaffarpur, Vaishali and Saran districts, respectively. Also, land use/land cover maps were prepared.  相似文献