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41.
An anisotropic, homogeneous Bianchi type-I cosmological micro model is obtained in Barber's modified theory of general relativity.
Some properties of the model are discussed. Further, it is found that this theory leads to Einstein theory as the coupling
parameterλ → 0 in micro level (i.e., quantum level) in general.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
42.
Pramod Kumar B. Panigrahi G. B. Joshi 《Journal of the Geological Society of India》2016,87(4):424-428
Sandstone–type uranium deposit hosted by reduced feldspathic sandstone sequence of lower part of Cretaceous Mahadek Formation occurs at Lostoin area of Mahadek basin and is confined within a prominent palaeochannel of NNE-SSW trend with flow towards SSW. The channel-fill comprises of about 10 m to 55 m grey to dark grey coloured, reduced, coarse to medium grained feldspathic sandstone along with abundant carbonaceous matter (5 to 15% by visual estimation) and is overlain by 5 m to 80 m of oxidized sub-feldspathic sandstone. Correlatable medium grade (~ 0.1% U3O8) uranium mineralization is intercepted in the boreholes aligned along the palaeochannel. Uraniferous solutions generated from the fertile provenance of south Khasi batholith flow through the channel and precipitated uranium at suitable reduction traps. Gentle slope of 2° to 3° of the basement channel facilitated prolonged interaction of uraniferous solution with reductants causing ore grade concentration. It has been envisaged that the control of palaeochannel and palaeobasement topography of the ore body would continue towards the SSW beyond Wahblei river. 相似文献
43.
The Malanjkhand copper ( + molybdenum) deposit, India: mineralization from a low-temperature ore-fluid of granitoid affiliation 总被引:2,自引:0,他引:2
Copper and subordinate molybdenum mineralization at Malanjkhand occurs within a fracture-controlled quartz-reef enclosed
in a pink granitoid body surrounded by grey-granitoids constituting the regional matrix. Sulfide-bearing stringers, pegmatites
with only quartz + microcline and sulfide disseminations, all within the pink-granitoid, represent other minor modes of occurrences.
Despite this diversity in mode of occurrence, the mineralogy of ores is quite consistent and conform to a common paragenetic
sequence comprising an early `ferrous' stage of precipitation of magnetite (I) and pyrite (I) and, the main-stage chalcopyrite
mineralization with minor sphalerite, pyrite (II), magnetite (II), molybdenite and hematite. Both stages witnessed continuous
precipitation of quartz ± microcline ± (chlorite, biotite and epidote). The enclosing pink-granitoid and the regional grey-granitoids
display alteration features such as saussuritization of plagioclase, breakdown of hornblende and chloritization of biotite
on a regional scale, indicating interaction with a pervasive fluid. Quartz and microcline precipitation mostly restricted
within the pink granitoid, postdates this alteration. Four types of primary inclusions were encountered in quartz from ore samples: (1) type-I – aqueous-biphase(L + V) inclusions, the commonest variety in all ore types; (2) type-II – aqueous-carbonic(Laq + Lcarb ± Vcarb); (3) type-III – pure-carbonic(Lcarb ± Vcarb) – type-II and III being restricted to stringer and pegmatitic ores, and (4) rare polyphase (Laq + Vaq + calcite/gypsum) inclusions. Quartz in granitoids contain primary type-I inclusions only. Type-I inclusions from ore samples furnish a temperature range (after a rough pressure
correction to the T
H
-maxima of 140–180 °C) of 150–275 °C and a moderately low salinity of 4–12 wt.% NaCl equivalent. This is inferred to represent
the signature of the major component (F2) of the ore fluid. A few type-I inclusions of higher T
M
(up to 380 °C) and low salinity and density represent the other (F1) identifiable component of the ore fluid present in low
proportion. The T
H
-maxima and the total range in salinity of type-I inclusions in quartz from granitoids are strikingly similar to those from the ore samples. Composition of syn-ore chlorites furnished a temperature range of 185–327
°C, which conforms to the fluid inclusion microthermometric data. Pressure estimates using standard fluid inclusion geobarometric
methods, vary from 550 to 1790 bar in the stringer ores. Observed temperature-salinity/density relationships are best explained
by a two-stage evolution model of the ore fluid: the first stage witnessed mixing of the two components, F1 and F2 in unequal
proportion, bringing about mineralization. The second stage of evolution was marked by the separation of a carbonic component
on continued sulfide precipitation and attendant increase in salinity of the fluid. The F1 component emerged as a distinct,
heated and (CO2 + S)-charged entity due to steam-heating and contamination of the early-ingressed F2 fluid at the fracture zone. The pervasive
fluid phase in the surrounding granitoids contributed the F2 component.
Received: (10 August 1994), 15 August 1995 / Accepted: 12 January 1996 相似文献
44.
Mruganka K. Panigrahi Brendan R. Bream Kula C. Misra Rajesh K. Naik 《Mineralium Deposita》2006,40(6-7):766-768
45.
Cyclone-generated surface waves are simulated using state-of-art SWAN (Simulating WAves Nearshore) model coupled with hydrodynamic
model inputs. A severe cyclonic storm passed over the Arabian Sea during 4–9th November 1982 is selected from UNISYS track
records. The cyclone lasted for nearly 6 days and subsided with a land fall at Gujarat coast, west coast of India. In this
study, cyclonic wind fields are generated using a well-established relationship suggested by Jelesnianski and Taylor (1973). The associated water level variations due to storm surge and surge generated currents are simulated using POM (Princeton
Ocean Model). The outputs are one-way coupled with the wave model SWAN for simulating wave parameters off Gujarat, north-east
basin of Arabian Sea. An extensive literature review is carried out on the progress and methodology adopted for storm wave
modelling and analysis. The results presented in this paper reveal the severity of the storm event and would be highly useful
for assessing the extreme wave event/climate especially for the south coast of Gujarat. 相似文献
46.
Hydrogeochemical characteristics of acid mine drainage and water pollution at Makum Coalfield,India 总被引:1,自引:0,他引:1
Acid mine drainage (AMD) is one of the severe environmental problems that coal mines are facing. Generation of AMD in the northeastern part of India due to the coal mining activities has long been reported. However detailed geochemical characterization of AMD and its impact on water quality of various creeks, river and groundwater in the area has never been reported. Coal and coal measure rocks in the study area show finely disseminated pyrite crystals. Secondary solid phases, resulted due to oxidation of pyrite, occur on the surface of coal, and are mainly consisting of hydrated sulphate complexes of Fe and Mg (copiapite group of minerals). The direct mine discharges are highly acidic (up to pH 2.3) to alkaline (up to pH 7.6) in nature with high concentration of SO42−. Acidic discharges are highly enriched with Fe, Al, Mn, Ni, Pb and Cd, while Cr, Cu, Zn and Co are below their maximum permissible limit in most mine discharges. Creeks that carrying the direct mine discharges are highly contaminated; whereas major rivers are not much impacted by AMD. Ground water close to the collieries and AMD affected creeks are highly contaminated by Mn, Fe and Pb. Through geochemical modeling, it is inferred that jarosite is stable at pH less than 2.5, schwertmannite at pH less than 4.5, ferrihydrite above 5.8 and goethite is stable over wide range of pH, from highly acidic to alkaline condition. 相似文献