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1.
H. M. Rajesh 《Journal of Earth System Science》2006,115(2):239-248
The proper usage of modal composition and geochemical classification of granitoids is discussed for assigning a proper nomenclature
for the Angadimogar pluton, Kerala, southwestern India. This discussion is mainly aimed at addressing questions concerning
the nomenclature of Angadimogar pluton (syenitevs. granite). Modal composition and whole-rock XRD data clearly show that the pluton exposed near Angadimogar is a quartz-syenite
and its geochemistry is typical of a ferroan, metaluminous, alkali (A-type) granitoid 相似文献
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Landslides - Assessment of the spatial probability of future landslide occurrences for disaster risk reduction is done through landslide susceptibility modelling. In this study, we investigated the... 相似文献
6.
The process of drilling, in general, always produces sound. Though sound is used as a diagnostic tool in mechanical industry, its application in predicting rock property is not much explored. In this study, an attempt has been made to estimate rock properties such as uniaxial compressive strength, Schmidt rebound number and Young's modulus using sound level produced during rotary drilling. For this purpose, a computer numerical controlled vertical milling centre was used for drilling holes with drill bit diameters ranging from 6 to 20 mm with a shank length of 40 mm. Fourteen different rock types were tested. The study was carried out to develop the empirical relations using multiple regression analysis between sound level produced during drilling and rock properties considering the effects of drill bit diameter, drill bit speed and drill bit penetration rate. The F-test was used to check the validity of the developed models. The measured rock property values and the values calculated from the developed regression model are fairly close, indicating that the developed models could be efficiently used with acceptable accuracy in prediction of rock properties. 相似文献
7.
Prakash Kumar Shrivastava Rajesh Asthana Sandip Kumar Roy 《Journal of the Geological Society of India》2011,78(2):117-123
Recession of the snout of Dakshin Gangotri glacier in the western part of Schirmacher Oasis, East Antarctica has been recorded
over two decades. However, the rate of retreat is not uniform and varies at different locations. The ice wall forming the
western flank of the glacier has shown an average retreat of 17.07 m between 2001 and 2009 while the snout had gone back by
6.94 m (average) during the same period. Before 2001, the snout had shown a complete recession of 3.13 m (average). The snout
occupies valley area receiving less amount of solar radiation as compared to the western wall, which is a vertical cliff receiving
maximum amount of solar radiation. The notable difference in the rate of recession in different parts of the Dakshin Gangotri
glacier overriding Schirmacher Oasis can be attributed to combined effect of natural factors, including meteorological parameters,
ice sheet dynamics and geomorphology of that area. 相似文献
8.
Rajesh Kumar S. K. Jain R. K. Misra M. Kachchwaha P. K. Khatri 《International Journal of Environmental Science and Technology》2012,9(1):79-84
An investigation was undertaken regarding the adsorption of different heavy metal ions from aqueous solutions using ??-diketone-functionalized styrene divinylbenzene resin under different experimental conditions such as initial concentration of metal ions, contact time, pH, and chelating capacity. The functionalization of resin was carried out by the condensation reaction of sodium salt of ??-diketones (pentane-1,3-dione) and chloromethylated styrene?Cdivinylbenzene resin in dichloromethane. Functionalized resin beads were characterized by Fourier transform infrared spectroscopy. The batch method was employed using different metal ions solution from 5 to 15?mg/L at different contact times. The adsorption kinetics was tested for the pseudo-first order, pseudo-second order reaction at different experimental conditions. The rate constant of adsorption kinetic models were also calculated and good correlation coefficient (R 2?>?0.9941) was obtained for pseudo-second order kinetic model. The maximum adsorption value obtain for lead (0.725728?mg/g), chromium (0.9199?mg/g), nickel (0.4974?mg/g), cobalt (0.6196?mg/g) and cadmium (0.6519?mg/g) at equilibrium condition, which shows that ??-diketone-functionalized styrene divinylbenzene resin is an effective adsorbent for toxic metal ions. 相似文献
9.
Rajesh K. Srivastava 《International Journal of Earth Sciences》2013,102(7):2043-2060
Major and trace element geochemistry of Proterozoic granitoids from the Dirang and Galensiniak Formations, of Lesser and Higher Himalayas, respectively, emplaced in and around Dirang and Tawang regions of the western Arunachal Himalaya, is discussed. In general, these granitoids are massive as well as foliated in nature and are characterized by granitic mineralogical compositions. Porphyritic and hypidiomorphic textures are common in massive type, whereas others show porphyroblastic and foliated textures. Augen structure is also observed in a number of samples. Geochemical and normative compositions together with petrographic features classify them as peraluminous granitoids. Major and trace element geochemistry of most of these granitoids shows granitic nature, while few samples also show monzonitic characteristics. Observed geochemical characters, such as their peraluminous and alkali-calcic/calcic-alkalic nature, crudely defined geochemical patterns, different multi-element and rare-earth element patterns, together with low Mg# (Mg number) of these granitoids suggest their derivation from lower crustal material rather than a mantle source. Multi-element and rare-earth element patterns corroborate their genesis from different crustal melts. It is difficult to explain variations observed in granitoid rocks by partial melting alone; definitely different other processes like migration of melts, magma mixing, assimilation and fractional crystallization also played important role in the genesis of these granitoids. These melts were likely generated at low temperature (730–760 °C) and low pressure (2–5 GPa). The chemical compositions suggest that most of these Paleoproterozoic granitoids are emplaced within the syn-collisional tectonic setting, while few granitoid samples also indicate their volcanic-arc nature. Probably, later group of granitoids are slightly younger to the syn-collisional type. 相似文献
10.
Rajesh Sharma Prabha Joshi P. D. Pant 《Journal of the Geological Society of India》2009,73(2):237-248
Talc deposits of Rema area in the Kumaun Inner Lesser Himalaya are hosted within high magnesium carbonates of the Proterozoic
Deoban Formation. These deposits occur as irregular patches or pockets mainly within magnesite bodies, along with impurities
of magnesite, dolomite and clinochlore. Textures represent different phases of reactions between magnesite and silica to produce
talc. Petrography, XRD and geochemistry reveal that the talc has primarily developed at the expense of magnesite and silica,
leaving dolomite largely un-reacted. Early fluid inclusions in magnesite and dolomite associated with talc are filled with
H2O+NaCl+KCl ± MgCl2 ± CaCl2 fluids, which represent basin fluid system during diagenesis of carbonates. Their varied degree of re-equilibration was although
not pervasive but points to increased burial, and hence requires careful interpretation. H2O-CO2 fluid with XCO2 between 0.06 and 0.12 was equilibrated with talc formation. The reaction dolomite+quartz → talc was not extensive because
T-XCO2 was not favourable, and talc was developed principally after magnesite+quartz. 相似文献