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Soumyajit MUKHERJEE 《《地质学报》英文版》2014,88(6):1729-1741
Abstract: Biotite and muscovite inclusions inside mica host minerals from the Sutlej section of the Higher Himalayan Crystalline were studied under an optical microscope. These inclusions formed possibly by local recrystallization of mica grains during regional prograde metamorphism, with some affected by top-to-SW shear leading to parallelogram shapes. Recrystallization may have been assisted by solution transfer along the cleavage planes of the host grains. The relative competency of deformed phyllosilicate inclusions with the same or different composition to the host depends on the size and orientation of (001) cleavage planes of the inclusions relative to the host. Shearing of mica inclusions led to their parallelogram geometries within the contained mica inclusions. Some of the sheared inclusions deflect cleavage planes in the host minerals and define flanking microstructures. Trapezoid-shaped inclusions are a new finding that deserves more attention for their genesis. These structurally anisotropic inclusions did not originate from sub-grains, secondary infillings or retrogression. These inclusions are also not related to pseudomorphism, isomorphism, folding of the bulk rock etc. Some of the inclusions formed by recrystallization of the host mineral during top-to-SW ductile shear. 相似文献
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Tidal variations in the Sundarbans Estuarine System, India 总被引：1，自引：0，他引：1
MEENAKSHI CHATTERJEE D SHANKAR G K SEN P SANYAL D SUNDAR G S MICHAEL ABHISEK CHATTERJEE P AMOL DEBABRATA MUKHERJEE K SUPRIT A MUKHERJEE V VIJITH SIDDHARTHA CHATTERJEE ANWESHA BASU MADHUMITA DAS SARANYA CHAKRABORTI ARAVIND KALLA SURJA KANTA MISRA SOUMYA MUKHOPADHYAY GOPAL MANDAL KANKAN SARKAR 《Journal of Earth System Science》2013,122(4):899-933
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ANUBHOOTI SAXENA HIMANSHU K SACHAN PULOK K MUKHERJEE DILIP K MUKHOPADHYA 《Journal of Earth System Science》2012,121(1):29-44
The Malari Leucogranite in the Garhwal Himalaya is cut across by a continental-scale normal fault system called the South
Tibetan Detachment (STD). A mineralogical, geochemical and fluid inclusion study of samples from the fault zone of the Malari
Granite was performed to reveal the imprints of fluid–rock interaction. Fluid inclusion assemblages observed in the alteration
zone indicate the presence of NaCl-dominated aqueous fluids with varied salinity of 6–16 wt.% of NaCl equivalent. Mineralogical
changes include the alteration of feldspar to muscovite and muscovite to chlorite. This alteration took place at temperatures
of 275°–335°C and pressures between 1.9 and 4.2 kbars as revealed by the application of chlorite thermometry, fluid isochores,
and presence of K-feldspar+muscovite+chlorite+quartz mineral assemblage. Geochemical mass-balance estimates predict 32% volume
loss during alteration. An estimated fluid/rock ratio of 82 is based on loss of silica during alteration, and reveals presence
of a moderately low amount of fluid at the time of faulting. 相似文献
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R. K. VERMA R. MAJUMDAR DEBABRATA GHOSH ASHISH GHOSH N. C. GUPTA 《Geophysical Prospecting》1976,24(1):19-30
Results of a gravity survey conducted over Raniganj coalfield, one of the Gondwana basins of Damodar Valley in north-eastern part of India, are presented. The gravity field was separated into regional and residual components. The residual Bouguer anomaly map shows that the coalfield is characterized by a gravity low of about—32 mGal associated with Gondwana sediments. The deepest part of basin is found to be located near Asansole (23° 40’N, 86° 55’E), where the maximum thickness of sediments is estimated to be about 1.3 miles (2.08 km). The faults along the northern as well as the southern boundaries are found to be normal. The Gondwana sediments appear to continue eastward beneath alluvium and laterite of Bengal basin as far as 87° 25’E. 相似文献
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P. SENGUPTA S. DASGUPTA P. K. BHATTACHARYA M. MUKHERJEE 《Journal of Metamorphic Geology》1990,8(2):191-197
Using the experimental data on Fe–Mg exchange between orthopyroxene and biotite of Fonarev & Konilov (1986), an orthopyroxene–biotite geothermometer is developed. The thermometer is corrected for mixing of Ti and Al in octahedral sites in biotite and also for non-ideal mixing of Fe and Mg in orthopyroxene. The thermometer is applied to several amphibolite–granulite transition facies and granulite facies rocks and also to mantle xenoliths. It yields consistent results in rocks of widely varying bulk composition, and highly magnesian mantle xenoliths. This thermometer removes the difficulty of estimating temperature in garnet-free rocks in high-grade terrains and also provides independent estimates of temperature in garnet-bearing assemblages. 相似文献
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SOUMYAJIT MUKHERJEE 《Journal of Earth System Science》2017,126(1):1
Shear heating by reverse faulting on a sharp straight fault plane is modelled. Increase in temperature (T i ) of faulted hangingwall and footwall blocks by frictional/shear heating for planar rough reverse faults is proportional to the coefficient of friction (μ), density and thickness of the hangingwall block (ρ). T i increases as movement progresses with time. Thermal conductivity (K i ) and thermal diffusivity (\(k_{\mathrm {i}}^{\prime }\)) of faulted blocks govern T i but they do not bear simple relation. T i is significant only near the fault plane. If the lithology is dry and faulting brings adjacent hangingwall and footwall blocks of the same lithology in contact, those blocks undergo the same rate of increase in shear heating per unit area per unit time. 相似文献
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Six bathymetric transect profiles were drawn from the nautical charts of 1942, 1962 and 1992 to show that the nearshore seabed
remained unstable during the recent 50 years in the middle channel of the eastern entrance to the Qiongzhou Strait, South
China Sea. Our results demonstrate that the multi-year averaged seabed aggradational rate was 25 cm/a and erosion rate was
12.5 cm/a. Lateral migration rate of the sea bedform identified from the historical contours was about 100 m/a in the SE direction.
Bedform measurements were made using GPY Shallow Seismic Profiler in 1994 in the study area. The records revealed four types
of distinctive bedforms that were composed of fine and medium sands. The average spacing of large and small-scale sand dunes
is 416 m and 144 m and the average height remains 8.8 mand 4.9 m. The spatial and temporal equilibrium-range spectra of numerical
bedform records were applied to estimate short term celerity of bedform movement. Results indicate that large and small dunes
migrated at an average celerity of 0.02 cm/hr eastward and 0.09 cm/hr westward in the calm sea weather, while their celerity
can reach 53 cm/hr eastward during typhoon season and is only 0.008 cm/hr westward when NNE winds prevail. The results also
show that the larger the temporal and spatial scale is, the smaller the bedform movement celerity appears. On the other hand,
the smaller-scale bedform celerity of the present study is much greater than that of flume, empirical and theoretical data,
but close to the wind tunnel and field-measured data of similar grain size. 相似文献