Petrological and geochemical considerations to predict oil potential of Rajpardi and Vastan lignite deposits of Gujarat, western India

This paper entails the results of the investigations undertaken to assess the oil potential of two lignite deposits, Rajpardi and Vastan, from Gujarat, western India. They are ‘Low rank B’ type lignite. Petrographically, they are enriched in huminite and are low in liptinite and inertinite. Their elevated hydrogen content, in relation to carbon, has probably made them perhydrous in nature and oil prone. The reactivity of these coals during liquefaction has also been discussed in the light of petrofactor. Good correlation has been noticed between oil yield and conversion (r² = 0.999) in both the lignite deposits. The VRr (0.24–0.35% in both lignites), H/C atomic ratio (0.11–1.39 in Rajpardi and 1.09–1.88 in Vastan), reactive maceral content (91.6–99.8 vol % mmf in Rajpardi lignite and 75.5–99.7 vol % in Vastan lignite) and VM_daf (64.8–67.9 wt % in Rajpardi lignite and 42.1–80.0 wt % in Vastan lignite) of these lignites have a favourable range required for a coal to generate oil. Huminite is seen to play a vital role in conversion and maintains a good correlation with it. The calculations show that these lignites have a high conversion (> 95%) and oil yield (> 65%).     

A review of the seismicity and seismotectonics of Delhi and adjoining areas

Understanding of seismicity and seismotectonics of Delhi and adjoining areas is essential as these areas lie in the seismic zone IV and are geologically confined to the Delhi Fold Belt (DFB), juxtaposed to the Himalayan Frontal Thrust Fold Belt. Owing to the set-up, seismicity in this area is ascribed to the Himalayan Thrust System and activation of DFB Fault Systems. Considerably improved instrumental seismic monitoring in this area and data analysis had resolved three regions of pronounced seismicity that lie close to Sonepat, Rohtak and western part of the NCT Delhi, attributed to activation of various portions of the fault systems of the DFB. Based on seismic telemetry network data, the seismicity pattern analysis revealed that the Mahendragarh Dehradun Sub-Surface Fault (MDSSF) and Delhi Sargodha Ridge (DSR) are the two major zones of structural importance for the nucleation of seismicity in this region. These revelations were corroborated with the fault plane solution of the earthquakes. The dominant mechanism in nucleation of seismicity in DFB is the thrust with minor strike slip. The seismicity and seismotectonics of Delhi and adjoining areas endemic to activation of DFB is reviewed and presented in this paper.     

Influence of shear velocity on frictional characteristics of rock surface

Understanding the fundamental issues related with the effect of shear velocity on frictional characteristics at the interface of rock surfaces is an important issue. In this paper, strain-rate dependence on friction is investigated in relation to sliding behaviour under normal load. The phenomenon of stick-slip of granite and shaly sandstone with a tribometer at constant rate of strain under normal loads was observed.     

Atmospheric ultrafine aerosol number concentration and its correlation with vehicular flow at two sites in the western Himalayan region: Kullu-Manali,India

The concentration of ultrafine aerosol particles of aitken and nucleation mode having size in the range of 1–20 nm was monitored with water-based Condensation Particle Counter. The monitoring was carried out from midnight-to-midnight in every alternate day on a fortnightly basis to represent summer, monsoon and winter (autumn) seasons of 2008 at Mohal (1154 m amsl) and Kothi (2530 m amsl) in Kullu-Manali area of the northwestern Himalayan region of India. The results indicate that diurnal pattern has faint bimodal structure with two peaks, one in morning and the other in evening at both the sites but it is not as distinct as found in plains. There is rather a constant particle density pattern of large magnitude consistent with vehicular movement from morning till evening. The monthly 24 h average particle density gradually picks up from January, increases rapidly in summer months and then decreases in monsoon season at Mohal but at Kothi it keeps on rising from April to October with a slight more increase in September. The particle density is more in summer than in monsoon season at Mohal, a trend opposite to plains. It may be due to the development of warm thermal layer on valley floor while a cold layer develops along snowy hilltops in winter leading to convection of fine particle up the slopes of valley during daytime. At Kothi, the trend is same as it is in continental plains but opposite to Mohal. The relatively more value of particle density in September and October at both the sites may be due to month long International Kullu Dussehra fair in the valley. The vehicular survey conducted agrees well with entire study period averaged diurnal variations and monthly 24 h averaged value of fine particle density. The average value of ultrafine particle density at each hour of a day for entire study period is 20369 ± 1230 Ncm^− 3 and 14389 ± 1464 Ncm^− 3 at Mohal and Kothi sites, respectively. The comparison with earlier results shows a significant increase indicating impact of vehicular onslaught on pure air of this hilly region.     

The ice sheet dynamics around Dakshin Gangotri glacier,Schirmacher Oasis,East Antarctica vis-à-vis topography and meteorological parameters

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.     

Environmental impact on groundwater of Maheshwaram Watershed,Ranga Reddy district,Andhra Pradesh

Maheshwaram watershed is situated in Ranga Reddy district of at a distance of about 30 km south of Hyderabad. The watershed has an area of 53 km² and has hard rock aquifers with semi-arid climate. The study area has been expanding at a fast pace and now has the distinction of being one of the fastest growing urban centers, facing the problem of groundwater depletion and quality deterioration due to the absence of perennial source of surface water and also due to over exploitation. Human activities involving industrial and agricultural development and the inadequate management of land and water resources have, directly or indirectly resulted in the degradation of environment viz. water and soil.     

Multiple Regressive Pattern Recognition Technique: An Adapted Approach for Improved Georesource Estimation

Multiple Regressive Pattern Recognition Technique (MRPRT) is an adapted approach for improved geologic resource estimation. We developed and tested this approach for the Platinum (Pt) bearing region near Goodnews Bay, Alaska, which presents an example of a complex depositional environment. We applied geospatial and pattern recognition methods to assess the spatial distribution of offshore Pt in the Goodnews Bay area from point data collected by various agencies. We used the coefficient of correlation (r) and the Nash–Sutcliffe efficiency (E) to quantitatively assess the degree of accuracy of the estimated Pt distribution. We split the study area, based on trend analysis, into two regions: inside the Bay and outside the Bay. We could not obtain appreciable estimates from the geospatial and pattern recognition methods. Using MRPRT, we were able to improve r from 0.57 to 0.93 and the E from 28.31 to 92.91 inside the Bay. We achieved improvement in r from 0.55 to 0.61 and E from 28.46 to 34.52 outside the Bay. The reasons for a non-significant improvement outside the Bay have been discussed. The results indicate that the proposed MRPRT has wide application potential in georesource estimation where input data is often scarce.     

Nitrogen sources for new production in the NE Arabian Sea

New productivity measurements using the ¹⁵N tracer technique were conducted in the north-eastern (NE) Arabian Sea during six expeditions from 2003 to 2007, mostly in winter. Our results indicate that the NE Arabian Sea has a potential for higher new productivity during blooms. Nitrate uptake by plankton is the highest during late winter. New productivity and f-ratios in the NE Arabian Sea are mainly controlled by hydrodynamic and meteorological parameters such as wind strength, sea surface temperature (SST), mixed layer depth (MLD) and mixed layer nitrate. Deepening of the mixed layer supplies nitrate from below, which supports the observed nitrogen uptake. Higher f-ratios during blooms indicate the strong coupling between surface layers and sub-surface layers. Deepening of mixed layer below 100 m (from its inter-monsoon value between 30 and 40 m) transferred often more than 100 mmol N–NO₃ m^? 2 into the surface layers from below. The observed winter blooms in the region are supported by such input and are sustained for more than a month. Higher new productivity has been found in late winter, whereas transport of nitrate is maximum in early winter. In general, new production varies progressively during winter. Diurnal cycling of the mixed layer could be the reason for the under utilization of entrained nitrate during early winter. New productivity values and wind strength show significant differences during Feb–Mar 03 and Feb–Mar 04. These differences indicate that the winter cooling and parameters related the biological productivity also vary inter-annually. However, the difference between the new productivity values between Feb–Mar 03 and Feb–Mar 04 is much lower than the difference between Jan 03 and Feb–Mar 03. The results suggest that amplitude of seasonal variation is higher than the inter-annual variation in the region. During spring, Fickian diffusive fluxes of nitrate into the surface layer range from 0.51 to 1.38 mmol N–NO₃ m^? 2 day^? 1, and can account for 67% and 78% of the observed nitrogen uptake in the coastal and open ocean regions, respectively. We document the intra-seasonal and inter-annual variations in new productivity during winter and identify sources of nitrate which support the observed productivity during spring.     

Field and textural relationship in pelitic schists and gneisses from the area around Mangpu, Darjeeling district, West Bengal

The metasedimentary rocks of the area around Mangpu constitute a portion of the hinge zone of the northern limb of the major synform of Lower Darjeeling Himalaya. The rocks display evidences of multiple deformation and at least three major phases of deformation have been recognized. The time relations between the phases of deformation (D₁, D₂, D₃) and metamorphic crystallization reveal a single major prograde metamorphic event that initiated with the D₁ deformation and finally outlasted it. The earlier phase of this metamorphism is essentially regional syn-tectonic lowgrade (greenschist facies) which may be designated (M₁, early). This was followed by regional static metamorphism (M₁, late) in the post-tectonic phase between D₁ and D₂ deformations (upper green schist and amphibolite facies). This M1 metamorphism is superposed by later retrogressive metamorphism (M₂) during the D₂ and D₃ deformations (lower greenschist facies). Within the study area four isograds have been delineated by the first appearance of index minerals in the pelitic schists and gneiss which display Barrovian type of metamorphism.