Utilization of high resolution satellite gravity over the Carlsberg Ridge     

S. Chatterjee  R. Bhattacharyya  T. J. Majumdar 《Marine Geophysical Researches》2007,28(4):309-317

The Carlsberg Ridge lies between the equator and the Owen fracture zone. It is the most prominent mid-ocean ridge segment of the western Indian Ocean, which contains a number of earthquake epicenters. Satellite altimetry can be used to infer subsurface geological structures analogous to gravity anomaly maps generated through ship-borne survey. In this study, free-air gravity and its 3D image have been generated over the Carlsberg Ridge using a very high resolution data base, as obtained from Geosat GM, ERS-1, Seasat and TOPEX/POSEIDON altimeter data. As observed in this study, the Carlsberg Ridge shows a slow spreading characteristic with a deep and wide graben (average width ∼15 km). The transform fault spacing confirms variable slow to intermediate characteristics with first and second order discontinuities. The isostatically compensated region of the Carlsberg Ridge could be demarcated with near zero contour values in the free-air gravity anomaly images over and along the Carlsberg Ridge axes and over most of the fracture zone patterns. Few profiles have been generated across the Carlsberg Ridge and the characteristics of slow/intermediate spreading ridge of various orders of discontinuity could be identified. It has also been observed in zero contour image as well as in the characteristics of valley patterns along the ridge from NW to SE that different spreading rates, from slow to intermediate, are occurring in different parts of the Carlsberg ridge. It maintains the morphology of a slow spreading ridge in the NW, where the wide and deep axial valley (∼1.5–3 km) also implies the pattern of a slow spreading ridge. However, a change in the morphology/depth of the axial valley from NW to SE indicates the nature of the Carlsberg Ridge as a slow to intermediate spreading ridge. For the prevailing security restrictions, lat./lon. coordinates have been omitted in few images.  相似文献   

The accessory mineral assemblage of the Bodmin Moor granite (Cornwall)     

M. Chatterjee 《Proceedings of the Geologists' Association. Geologists' Association》1929,40(2):147-IN10

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Spatio-temporal trends of rainfall across Indian river basins     

Bisht  Deepak Singh  Chatterjee  Chandranath  Raghuwanshi  Narendra Singh  Sridhar  Venkataramana 《Theoretical and Applied Climatology》2018,132(1-2):419-436

Theoretical and Applied Climatology - Daily gridded high-resolution rainfall data of India Meteorological Department at 0.25° spatial resolution (1901–2015) was analyzed to detect the...  相似文献   

Inhibition of mixed-layer deepening during winter in the northeastern Arabian Sea by the West India Coastal Current     

D. Shankar  R. Remya  P. N. Vinayachandran  Abhisek Chatterjee  Ambica Behera 《Climate Dynamics》2016,47(3-4):1049-1072

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Trace elements in the atmospheric aerosols at Delhi,North India     

L. T. Khemani  Medha S. Naik  G. A. Momin  R. Kumar  R. N. Chatterjee  G. Singh  Bh. V. Ramana Murty 《Journal of Atmospheric Chemistry》1985,2(3):273-285

The total suspended particulate (TSP) levels at Delhi (north India) were measured on 116 days between February and October 1980. The observations were stratified according to season and the values of cross-correlation of the TSP and its components were evaluated. High TSP (209 g m^-3) levels were found during the summer period associated with hot and dry weather in the region and low TSP (109 g m^-3) were found during the monsoon period. Most of the TSP mass was associated with natural soil elements, such as Fe, Al, Mn, Ca, and K. Only a fraction of the mass of the TSP was comprised of elements from anthropogenic sources, e.g., Pb, Ni, Cd, Sb, Cu, and Zn. The aerosols at Delhi were potentially basic in nature, unlike those in European countries which are acidic in nature and cause acid rainfall.  相似文献   

An empirical Redlich-Kwong-type equation of state for water to 1,000 °C and 200 Kbar     

Heiner Halbach  Niranjan D. Chatterjee 《Contributions to Mineralogy and Petrology》1982,79(3):337-345

An empirically derived Redlich-Kwong type of equation of state (ERK) is proposed for H₂O, expressing a, the term related to the attraction between the molecules, as a pressure-independent function of temperature, and b, the covolume, as a temperature-independent function of pressure. The coefficients of a(T) and b(P) were derived by least squares non-linear regression, using P-V-T data given by Burnham et al. (1969b) and Rice and Walsh (1957) in conjunction with more precise recent data obtained by Tanishita et al. (1976), Hilbert (1979) and Schmidt (1979): $$a(T) = 1.616 x 10^8 - 4.989 x 10^4 T - 7.358 x 10^9 T^{ - 1} $$ and $$ = \frac{{1 + 3.4505x 10^{--- 4} P + 3.8980x 10^{--- 9} P^2 - 2.7756x 10^{--- 15} P^3 }}{{6.3944x 10^{--- 2} + 2.3776x 10^{--- 5} + 4.5717x 10^{--- 10} P^2 }}$$ , where T is expressed in Kelvin and P in bars. The ERK works very well at upper mantle conditions, at least up to 200 kbar and 1,000 °C. At subcritical conditions and those somewhat above the critical point, it still reproduces the molar Gibbs energy, \(\tilde G_{{\text{H}}_{\text{2}} {\text{O}}} \) , with a maximum deviation of 400 joules. Thus, for the purpose of calculation of geologically interesting heterogeneous equilibria, it predicts the thermodynamic properties of H₂O well enough. The values of molar volume, \(\tilde V_{{\text{H}}_{\text{2}} {\text{O}}} \) , and \(\tilde G_{{\text{H}}_{\text{2}} {\text{O}}} \) are tabulated in the appendix over a considerable P-T range. A FORTRAN program generating these functions as well as a FORTRAN subroutine for calculating the fugacity values, \(f_{{\text{H}}_{\text{2}} {\text{O}}} \) for incorporation into existing programs, are available upon request.  相似文献   

Thermodynamic calculation of peridotite phase relations in the system MgO-Al2O3-SiO2-Cr2O3, with some geological applications     

Niranjan D. Chatterjee  Ludger Terhart 《Contributions to Mineralogy and Petrology》1985,89(2-3):273-284

The system MgO-Al₂O₃-SiO₂(MAS) comprises 88–90% of the bulk composition of an average peridotite. The MAS ternary is thus a suitable starting point for exploring peridotite phase relations in multicomponent natural systems. The basic MAS phase relations may be treated in terms of the reactions (see list of symbols etc).

1. py (in Gt)=en (in Opx)+mats (in Opx),
2. en (in Opx)+sp (in Sp)=mats (in Opx)+fo (in Ol), and
3. py (in Gt)+fo (in Ol)=en (in Opx)+sp (in Sp).

Extensive reversed phase equilibria data on these three reactions by Danckwerth and Newton (1978), Perkins et al. (1981), and Gasparik and Newton (1984) employing identical experimental methods in the same laboratory have been used by us to deduce the following internally consistent thermodynamic data applying the technique of linear programming:ΔH ₂₉₈₍₁₎ ⁰ = 2536 J, ΔS ₂₉₈₍₁₎ ⁰ =? 6.064 J/K;ΔH ₂₉₈₍₂₎ ⁰ = 29435 J, ΔS ₂₉₈₍₂₎ ⁰ = 8.323 J/K; andΔH ₂₉₈₍₃₎ ⁰ =?26899 J, ΔS ₂₉₈₍₃₎ ⁰ =?14.388 J/K.These data are also found to be consistent with results of calorimetry. Figure 2 shows the calculated phase relations based on our thermodynamic data; they are consistent with the phase equilibria experiments. Successful extension of the MAS phase relations to multicomponent peridotites pivots on the extent to which the effects of the “non-ternary” (i.e. other than MAS) components can be quantitatively handled. Particularly hazardous in this context is Cr₂O₃, although it barely makes up 0.2 to 0.5 wt% of such rocks. This is because Cr⁺³ fractionates extremely strongly into Sp. This study focuses on the peridotite phase relations in the MgO-Al₂O₃-SiO₂-Cr₂O₃ (MASCr) quaternary. Thermodynamic calculations of the MASCr phase relations have been accomplished by using ΔH ₂₉₈ ⁰ and ΔS ₂₉₈ ⁰ values for the reactions (1) through (3) indicated above, in conjunction with data on thermodynamic mixing properties of

1. binary Sp (sp-pc) crystalline solution (Oka et al. 1984),
2. ternary Opx (en-mats-mcts) crystalline solution (this study), and
3. binary Gt (py-kn) crystalline solution (this study).

The results are shown in P-T projections (Figs. 3a and b) and isobaric-isothermal sections of MASCr in a projection through the component fo onto the SiO₂-Al₂O₃-Cr₂O₃ ternary (Figs. 4a and b). The most important results of this work may be summarized as follows:

1. With increasing incorporation of Cr⁺³ into Sp and Gt, the X _mats isopleths of the reactions (1) and (2) are shifted to higher temperatures (Fig. 3a); simultaneously, the spinel-peridotite to garnet-peridotite phase transition is moved to higher pressures (Fig. 3b).
2. At identical P and T, the X _mats values of Opx coexisting in equilibrium with Ol and Sp is strongly dependent upon the X _pc value in the latter phase (Figs. 4a and b). Accurate correction for the composition of Sp is, therefore, a necessary precondition for geothermometry of the spinelperidotites.
3. The discrepant temperatures reported by Sachtleben und Seck (1981, Fig. 5) from the spinel-peridotites of the Eifel area (systematically too high temperatures as a function of X _pc in Sp) are demonstrated to be the result of ignoring the nonideality in the chromian spinels.

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X-ray powder pattern and molar volume of synthetic 2M-paragonite: A refinement     

Niranjan D. Chatterjee 《Contributions to Mineralogy and Petrology》1974,43(1):25-28

Indexed powder X-ray data are given for synthetic 2 M-paragonite (Table 1); this set of data will supersede those published earlier (Chatterjee 1970). From refined cell dimensions of three synthetically prepared 2 M-paragonite, the molar volume is calculated as 3.1545±0.0012 cal/bar-gfw. Review of literature suggests that this is presently the best value for the molar volume of paragonite.  相似文献   

Microearthquake survey in the hot spring area in Parbati Valley (Himachal Pradesh, India)     

H.M. Chaudhury  S.N. Chatterjee 《Journal of Volcanology and Geothermal Research》1981,9(1):29-39

A number of hot springs occur in the Parbati Valley in Himachal Pradesh in India. Temperatures range from 21 to 96°C, the boiling point of water at that altitude. Geological conditions, temperature variations and chemical composition of spring water in the Parbati Valley hydrogeological unit indicate that the deep thermal fluids are of meteoric origin. The maximum temperature acquired by water during its circulation is estimated to come close to 200°C. In order to assess the possibility of extracting geothermal energy, a seismic survey was arranged to locate the hypocentres of microearthquakes associated with the thermal source. A total of eight microearthquake units was set up at an interstation spacing of about 10 km and two months recording were obtained. During this period an average of 2–3 events per day was recorded with S—P interval less than 5 seconds. The data have been analysed with the help of Hypo 71, a Fortran IV computer program designed to determine the hypocentral parameters of earthquakes from seismic data. The results indicate faulting but there is no apparent spatial relationship to surface manifestations of geothermal energy.  相似文献   

AGRO-CLIMATIC PERSPECTIVE ON IRRIGATION IN WEST BENGAL, INDIA: A DISTRICT LEVEL ANALYSIS     

Nandini Chatterjee  Ph.D. 《Singapore journal of tropical geography》1992,12(1):12-30

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