Conference Papers
Early Paleocene Planktic Foraminifers and Stratigraphy, Jaisalmer Basin, Rajasthan
SKU:
C-63307
Early Paleocene planktic foraminifera (Zones P1c to P4) from well sections (Sanu, Sam, Tanot, Ram-1, GTF-1) are reported from the Jaisalmer Basin. The Subzone P1c is characterized by the hemipelagic early Danian species Globoconusa daubjergensis, Eoglobigerina edita, Praemurica pseudoinconstans, P. inconstans, Parasubbotina pseudobulloides, Subbotina triloculinoides and Globanomalina compressa. Zone P2 is identified by the total range of Praemurica uncinata and Eoglobigerina spiralis and Zone P3 by the occurrence of Igorina pusilla in association of Morozovella angulata and M. conicotruncata. Larger benthic foraminiferal species, such as Assilina dandotica, are abundant in the interval identified as Zone P4 characterized by Globanomalina pseudomenardii, Morozovella velascoensis, Igorina albeari, I. tadjikistanensis, Subbotina velascoensis, S. triangularis, Acarinina soldadoensis, and Parasubbotina varianta. This indicates a lower P4 stratigraphic range for Assilina dandotica, which was assumed to appear in Zone P5 (= Standard benthic foraminiferal Zone 5). The Paleocene-Eocene boundary was identified based on Acarinina africana and A. sibaiyaensis marking the Zones P5 to E1 interval.
Effect of Temperature and Salinity on Stable Isotopic Composition of Shallow Water Benthic Foraminifera: A Laboratory Culture Study
SKU:
C-63288
Quantitative estimation of past climatic parameters from stable isotopic composition of foraminifera relies on estimating the precise relationship between stable isotopic composition of the species analyzed and the physico-chemical factors of the seawater. This relationship can be established either on species collected from surface sediments or in plankton tows. Another method to establish such relationships is by subjecting the foraminiferal species to known physico-chemical parameters in the laboratory. In the present work, shallow water benthic foraminiferal species, Rosalina sp. and Pararotalia nipponica were subjected to different combinations of seawater temperature (25?C to 35?C) and salinity (25 psu to 37 psu) in the laboratory to assess their stable oxygen isotopic composition and its applicability in determining seawater temperature and salinity. The stable isotopic ratio of the species shows no consistent relationship with salinity. The relationship between ?18O foraminifera and seawater temperature is more consistent for P. nipponica than for Rosalina sp. Salinity appears to have less control on ?18O foraminifera as compared to the seawater temperature, within the studied salinity and temperature range. The study shows that the changes in ?18O of P. nipponica can be used effectively to infer past seawater temperature changes.
Eocene Depositional Sequence and Cycles in Kutch
SKU:
C-105409
Two depositional sequences are recognized in the Eocene succession of Kutch. The Sequence-I in the lower part is of Ypressian age and 6 Myr duration. A hiatus of about 7 Myr is estimated between the Deccan trap and Sequence-I and a hiatus of equal magnitude exists between sequences I and II. The Sequence-II is of Bartonian (and possibly extending to late Lutetian) age and a major part of it formed during a small interval of planktic foraminiferal zone E12 (0.5 Myr). A hiatus of ~7 Myr is estimated between the two sequences. Five depositional cycles of low amplitude, low frequency and confined to inner shelf are inferred in Sequence-I. In contrast, eight depositional cycles are recognized in Sequence-II and cycles in the lower part are of high amplitude, reaching to middle shelf. The average cyclicity is of > 1 Myr duration in Sequence-I and < 0.1 Myr duration in Sequence-II.
Estimating Water Resource in Wokha, Nagaland Using Geo-Informatics
SKU:
C-165858
Nagaland, a north eastern state of India has been suffering from water crisis since decades. Water scarcity has become chronic and perennial in many districts like Wokha. We have estimated the surface water resource and ground water potential zones in Wokha with the integrated use of Landsat OLI, LISS IV and Sentinel-1A SAR data. Thematic maps of LULC, slope, drainage density and fractional impervious surface are prepared. Published thematic maps of lithology, major faults and soil type are used.Our analysis shows that considering existing surface water resource and the population density of Wokha, the water crisis is more of economic nature than physical. Forested wetland and hydrologic wetlands are identified as potential new resource. Hydrologic wetlands are perennial water resources. These wetlands can act as an alternative water source. Further, our study shows that around 58% of the district have good ground water potential and they are well distributed throughout the terrain.
Evaluating Variability of Aerosol Concentration in Coal Mining Areas: A Case Study from Patratu Coal Mining Region, Jharkhand
SKU:
C-95904
The monitoring of aerosol concentration becomes a high environmental priority in mining and adjoining areas and it is one of the key parameters to assess the atmospheric pollution. Human activities, coal mine fire, overburden dumping, transportation and other mining operations or coal based industries are responsible for increasing pollution in mining regions. In the present study aerosol optical thickness (AOT) was determined using handheld MICROTOPS II sunphotometer at five different wavelengths (340, 500, 870, 936 and 1020 nm), along with temperature and precipitable water vapour (PWV) which are estimated from the measurements of solar intensity at 936nm and 1020nm during peak winter period. The pattern of measured aerosol concentration along with water vapour and temperature were spatially analyzed in GIS environment with reference to land use/land cover map of the region. The study revealed that the study area (381 sq. km) was dominated by wasteland (98.64 sq. km, 25.89%) and forest cover 136.50 sq. km (35.82%) as mapped during the year 2009. The area under coal mining is 16.87 sq. km (4.42%), built-up land is 33.88 sq. km (8.89%) and cropped area is about 62.29 sq. km (16.35%). The spatial distribution of AOT in the wavelength region 340-1020nm exhibits that the AOT values are higher for smaller wavelengths and lower for larger wavelengths indicating the dominance of fine particles in the atmosphere compared to larger sized particles. In this study, the AOT wavelength 340nm is therefore taken for further analysis due to its higher variation in the area as well as its harmful effect on human health. It was observed that AOT concentration was higher in the industrial area in the vicinity of thermal power plant, Sponge iron factory, mining area and coal based small industries located within the urban area, whereas lower in the forest and low population density areas within the agricultural lands.
Evidences of Partial Melting of Sulphides from Ajjanahalli Gold Deposit, Dharwar Supergroup, Karnataka
SKU:
C-165465
The Ajjanahalli gold deposit is a remobilized stratabound as well as stratiform type deposit where gold concentration is found within sulphidic BIF along several epigenetic quartz and quartz-carbonate veins. The sulphide minerals associated with the deposit are dominantly pyrite, pyrrhotite, arsenopyrite, sphalerite, chalcopyrite, Bi-sulphide, PGE minerals along with native phases of gold, bismuth and gold alloys such as auricupride, electrum and allopalladium. Almost all the sulphides occurring in the area have undergone deformation. There are two generations of sulphides, the primary sulphides along with sulfosalts occur as relicts and skeletal crystals, corresponding to the peak metamorphic assemblage of the area. The 2nd generation sulphides are observed as idioblastic crystals and porphyries around which the silicate and ductile sulphides have swirled. The remobilization and concentration of sulphides and gold in the Ajjanahalli gold deposit has been assisted by hydrothermal fluids as well as melting. Various studies have constrained the temperature of metamorphism at Ajjanahalli between 450 to 550?C. Studies have shown that pyrite and arsenopyrite can react to form pyrrhotite + melt at temperatures as low as 251?C. In the current study, an attempt has been made to study the evidences of sulphide melting from field, petrographic and ore microscopic studies as well as mineral chemistry. The recognition of features in sulphides which show indications of melting at the time of peak metamorphism provides a possible explanation for the erratic pattern of distribution of gold in the deposit.
Exploration for Gold near Ajjanahalli, Chitradurga Greenstone Belt, Karnataka
SKU:
C-165468
Ajjanahalli Gold Field is a well-known BIF-hosted gold-bearing area of Karnataka. The gold prospects are hosted by the volcano-sedimentary sequence of Chitradurga Greenstone Belt in Western Dharwar Craton. The major lithologies are metabasalts, Banded Iron Formation (BIF) and argillite-greywacke of Hiriyur Formation of Chitradurga Group. Three phases of deformation have been noticed in the area. The bands are folded and repeated several times exhibiting both antiformal and synformal closures with fold axes plunging towards north. Multiple generations of quartz veins traverse all lithounits. Potentiality of gold mineralization in Ajjanahalli area has already been proved by earlier investigations in the Ajjanahalli Main Block and Western Block. Hutti Gold Mining Limited (HGML) had exploited the Ajjanahalli Main block and Western block during 1995- 2002 and recovered 963.4 kg of gold from 0.60 Mt of ore. Geological Survey of India (GSI), through systematic exploration under UNFC-G4, G3 and G2 stages is continuously augmenting the gold resource in Ajjanahalli Gold prospects. The work reframed the adjacent area of Ajjanahalli Main Block into several exploration blocks such as Ajjanahalli-A, B, C, D, E, F, G and H, Gungurpenta and Gungurpenta South. Gold Resource has been established by G3 stage of exploration in Ajjanahalli-A, B and G blocks by GSI. G3 stage of exploration is completed in block-F but no potential mineralization is established. G2 stage of exploration was carried out in blocks-C, D and E by GSI and Resource has been established. Mineral Exploration Corporation Limited (MECL) has completed G2 stage exploration in block-A. G4 stage of exploration was carried out in Gungurpenta, Gungurpenta South and Ajjanahalli-H Blocks. The total Resource in Ajjanahalli prospects is 7.34 Mt with 1.43 g/t average grade and 2.76m average width.
Freshwater Sources of Kerala ? Hydrometeorological Scenarios, Environmental Threats and Management Strategies
SKU:
C-165441
Kerala, the southwestern coastal state of India receives an annual average rainfall of about 3000 mm. However, providing uninterrupted freshwater supply to the community round the year is a major challenge to the water managers in the state because of several factors including high population density, increased human interventions in the river catchments, environmental effects due to climate change, etc. It has now become more and more evident that the nature and contributions of rainfall, especially its pattern, have been changing drastically over the years, aggravating the incidences of floods and landslides in the wet season and water scarcity in the summer months. Although such incidences were minimal in the pre-liberalization period (1956-1990), their recurrence and impacts are getting aggravated in the post-liberalization period - a period that witnessed severe environmental degradation due to rapid urbanization and economic development in the region. As per the records of the gauging stations, the number of no-flow/low flow days are found to be increasing even in the lowland reaches of the major rivers in the state. The adverse impact of unabated groundwater ion/pumping is on the rise in many parts of the state, as the activity is being carried out without due regard to the safe yield and natural recharge capability of the aquifer systems. The rapidly changing water scenario of the state in the pre-and post-liberalization periods needs a thorough investigation, especially in regard to the structure and functions of its near surface terrestrial environment called the Critical Zone. The Critical Zone, the zone extending from tree top to the aquifer bottom, of the state is under immense stress due to many of the aforesaid reasons. The stress in the Critical Zone will have a direct effect on the quality, quantity and availability of the freshwater resources in the surface and subsurface reservoirs, which needs to be addressed adequately for laying down strategies for the conservation and management of the freshwater sources.
Geochemistry of Gold-Hosting Granitoids from Jonnagiri Greenstone Belt, Eastern Dharwar Craton: Implications on Petrogenesis and Gold Mineralization
SKU:
C-165463
Jonnagiri gold deposit is a lone example of granitoid-hosted orogenic gold deposit in India. Gold mineralization is concentrated within silicified alteration zones along shear zones within the Pagadarayi granodiorite. Geochemical characteristics of unaltered Pagadarayi granodiorite show that, (i) these are granodiorite-tonalite suite of rocks, (ii) contain lower and variable amount of silica (63-72%), (iii) high Fe(Tot), (iv) varying alkali concentrations, (v) large variations in LILE and LREE, particularly K2O, Sr, Ba, Th, La, Ce. Further, in the Harker-type variation diagrams these granitoids show (i) decreasing agpaitic index (molecular Al2O3/Na2O + K2O) with increasing SiO2, (ii) characteristically low Sr/Sr* values, and (iii) no significant correlation of (Ce/Y)N. Hence, these rocks were possibly derived from partial melting of a mafic source with contribution from the LILE-enriched felsic crust. Harker-type variation diagrams plotted against SiO2 show decreasing trend for Fe2O3, MgO, CaO and TiO2 while Na2O increases with increasing silica content. These features are consistent with the initial stage fractional crystallization of plagioclase, pyroxene ? magnetite, followed by hornblende and biotite at a later stage. The higher Na2O, CaO, Sr and lower Cr, Ni, concentrations are similar to the continental arc magmas and therefore, these are grouped under the I-type granitoids which is in agreement with their crystallization from more oxidized melts in relation to major granitoid-hosted gold deposits elsewhere in the world.
Geological Mapping of Foundation Floor for Nuclear Building of Rajasthan Atomic Power Project, Rawatbhata, India
SKU:
C-95903
Foundation floor mapping is essential for important structures to provide permanent data set for geological interpretations. At Rawatbhata, Rajasthan, two units of 700 MW each Pressurized Heavy Water Reactor (PHWR) type Nuclear Reactors are being constructed adjacent to existing Rajasthan Atomic Power Project (RAPP) units 1 to 6. In order to evaluate the design basis foundation parameters engineering geological mapping on 1:100 scale was carried out for Nuclear Building-7 structures. 1 m x 1 m grids were prepared for mapping of the floors and walls. Based on the field observations and evidences, it was found that the floor area consists of fine to medium grained, compact quartzitic sandstones. The floor region was seen to contain certain iron stained and weathered zone. No evidence of faulting was observed on the surface of the floor areas. However, there were some isolated patches of soft, weathered/altered rock and small fractures in the rocks. Geotechnical assessment of the foundations of RB-7, RAB-7 and ECCS north and south pits was done on the basis of detailed engineering geological mapping, geological drill holes logging data, rock mass permeability values, geophysical profiling and laboratory test results. This permanent foundation record will assist in making better interpretation of post-construction foundation instrumentation data.
Geological Setup for Gold Prospects and Deposits in India
SKU:
C-165460
Gold metallogeny having distinct temporal distribution has a direct relationship with changes in the global tectonic processes. In India too gold metallogeny is episodic from Mesoarchaean to Neoproterozoic peaking in the Neoarchaean and Paleoproterozoic periods. Indian Phanerozoic also show discrete feeble mineralisation which is not of any economic interest. The most productive gold deposits are restricted to Neoarchaean granite-greenstone terranes of Dharwar Craton. Gold deposits/ prospects occur in the eastern as well as western blocks of the Craton, but most productive deposits are in the Eastern Dharwar Craton. Current gold production in the country is mainly from three Neoarchaean deposits in the Hutti-Maski greenstone belt. A small size Mesoarchaean deposit has been located in Singhbhum Craton also. The gold deposits are generally lode type or vein/reef type restricted to shear zones. Secondary shear zones or splays are the loci for mineralisation of commercial interest. Deformed and metamorphosed host rocks exhibit extensive wall rock alteration along the mineralised zones. The deposits are of epigenetic Au or Au-W types with sulphides.During Palaeo and Mesoproterozoic times, gold mineralization occurred in the Fold Belts/Supracrustal belts of the Singhbhum, Bastar and Bundelkhand cratons, namely Aravalli belt, Mahakoshal belt, Singhbhum belt, Kotri belt, Sonakhan belt, Sakoli and Raigarh belts. The mineralization is of Au-Cu and Cu-Au types with basemetals (Cu & Zn) as a dominant component as compared to the gold-only type during Archaean period. Despite the existence of a number of drilled gold and copper-gold resources spread over the three cratons mentioned above, only one mine is being operated at Lawa in Singhbhum Fold Belt which produces a small quantity of about 13kg of gold per annum (as reported in IBM?s Mineral Year Book).VMS type Cu-Au-U metallogenesis reported from Singhbhum Shear Zone, contributing gold as a by-product of copper mining. VMS type Cu-Au prospects abound in Rajasthan. Neoproterozoic (830-850 Ma) Khetri copper deposits exhibit IOCG type Cu-Au mineralisation where gold is recovered as a by-product. Porphyry style Cu-Au-Mo mineralisation is associated in Malanjkhand granite producing gold as a by-product. Mesoproterozoic Cu-Au-Zn prospects are common in the Sakoli Fold Belt. Gold is also found within the Chhotanagpur Gneissic terrain.Palaeoplacer deposits in Quartz Pebble Conglomerate (QPC) are present in Neoarchaean Iron Ore Group (IOG) of Singhbhum Craton and in Bababudan Group of Dharwar craton. Paleoplacer U-Au occurrences are found at the Neoarchaean-Paleoproterozoic boundary exposed at the basal part of Dhanjori basin in Singhbhum Fold Belt. U-Au bearing palaeoplacers, sampled so far, have shown anomalous to interesting gold valuesGold is also reported from the Tertiary laterite covering parts of the Southern Granulite Terrain and Neoarchean greenstone belts in Goa State. Present day placer gold is being recovered locally from eluvial, alluvial and colluvial zones in different parts of the country.
Geomicrobiology of Arsenic (As) Contaminated Groundwater of West Bengal Reveals Microbial Role in Sediment Bound Arsenic Mobilization
SKU:
C-165856
Geogenic arsenic (As) in groundwater of the Bengal basin has led to ?the worst mass poisoning in human history? with >170 million people exposed to toxic levels of As. Understanding the mechanism(s) underlying As release into groundwater from host minerals is a critical issue for developing any sustainable drinking water supply strategy. Release of As results from complex interplay between hydro-geo-microbiological processes. The present study aims at analyze microbial community structure, dynamics, and metabolic role using groundwater sampled from two As hotspots of West Bengal (Barasat and Swarupnagar). Metagenomic DNA based 16S rRNA gene (V4 region targeted) sequencing showed dominance of Gammaproteobacteria and Alphaproteobacteria. Incubation of groundwater microbiome with aquifer sediment showed a marked shift in community composition with an abundance of Rhizobium, Paenibacillus, Acinetobacter, and Staphylococcus reportedly known for anaerobic hydrocarbon utilization, iron reduction, As biotransformation, and fermentation abilities. Change in physicochemical properties indicated microbe-mediated geochemical transformations. Thus, the study highlighted the role of groundwater microbial community members in facilitating the mobilization of sediment-bound As.
Geomorphic Characterization of the Banni Plain, Kachchh, Using Orbital Imaging Radar (RISAT 1C) and Optical Remote Sensing Data
SKU:
C-105419
The present study employs multisensor remote sensing approach for delineating the morphological intricacies of the Banni plain, a hyper arid saline terrain, generally referred to as 'flat'. The Banni plain is a part of the Great Rann basin and is the culmination of shallow marine sedimentation during the Holocene. Owing to the variable submergence characteristics, the Banni plain displays geomorphological characteristics that are unique and distinctly different from the rest of the terrain of the Great Rann. The RISAT SAR data of the Banni plain used in the present study was acquired in the month of August, 2012, i.e. during the monsoon season when large parts of the Banni plain are normally submerged, waterlogged or saturated with rain water. The inundation is found to be a key factor, in the backscatter of radar waves in the available SAR data which is exploited in the present study to interpret landscape characteristics of the Banni plain. Backscatter from non-inundated sites is relatively high and for areas with water table at the surface is intermediate and inundated areas, it is low. Geomorphological interpretation is done by combining SAR data, LANDSAT ETM + images and Google earth data. The present study concludes that structurally controlled variations in the elevations in different parts of the Banni plain is the prime factor influencing the submergence pattern which in turn controls the moisture distribution and soil type. Since Banni Plain is characterized by very gentle slope and scanty vegetation, we also infer that the variations in the backscattering in the SAR data of the Banni plain are a reflection of the variation of moisture content in soils.
Geomorphology of North-Western India (Marusthali to Narmada Valley Ending Up with Vindhyan Scarplands) with Special Reference to Surface Waters
SKU:
C-62870
Resource potential in space and time is dependent upon the hydro-geomorphic dynamics that include topography, precipitation and lithology. Regional geo-climatic conditions control the distribution and availability of water resources and their development requires a scientific evaluation of potential and terrain appropriate structures. In this context, the northwestern region of the Indian subcontinent has diverse geomorphologic characteristics ensuring a wide disparity in the distribution of surface water resource. The rivers are seasonal and the flow is dependent on the rainfall which varies from less than 100 mm in the arid land to more than 1000 mm in the eastern hilly areas. Based on the variations in these parameters, the area is divided into five hydro-geomorphic units 1) Dunal Plains of Thar, 2) Semi-arid to Arid Alluvial Plains, 3) The Eastern Hill Ranges, 4) The Plateau and Pediments (buried/exposed) and 5) Coastal Plains. The major issues in harnessing the surface water include seepage/evaporation losses in the plains and excessive runoff due to steep slopes and hard rock lithology in the hilly areas. Unavailability of water in the downstream due to damming of rivers, changing land use and obliteration of drains in the catchment of ponds are some human induced major issues in this region. Ample groundwater resource and advent of tube wells led to neglect of the existing water harvesting structures as well as surface water bodies, but now, the ground water is fast depleting. There is good surface water potential at least in parts of the region, but its rejuvenation needs impetus. The water availability and security can be improved adopting a basin perspective provided the resource is managed in a holistic and integrated manner at this level.
Geomorphology of the North Eastern Region of India with Special Reference to Surface Water Resources
SKU:
C-62879
The North Eastern Region represents a unique geophysical and ecological setup vis-a-vis the eastern Himalayas dominated by extremely dynamic earth processes, intensely potent monsoon rainfall regime, hyperactive seismicity and a fabulously rich biological and cultural diversity. The region is richly endowed with a vast water resource potential accounting for about one-third of the country's total water wealth although its utilization has so far been grossly limited. The Brahmaputra, a transboundary river originating in Tibet (China) and one of the world's largest and most complex alluvial river systems, drains a major part of the region. The Barak is another dominant river system flowing in the southern part of the region that eventually flows across the border to Bangladesh. The floodplains of these rivers are dotted with a large number of wetlands (locally known as Beels) that have considerable ecological, hydrological as well as economic significance. However, most of these wetlands are in degraded or derelict condition due to accelerated sedimentation, eutrophication, encroachment and various other anthropogenic factors. The study discusses different aspects of fluvial geomorphology in relation to the geologic and geotectonic frameworks of the region. An integrated basin planning and management approach seems to be the most appropriate paradigm for utilizing the vast water wealth of the region and mitigating its associated hazards. The geologic/geomorphic ideas and techniques are increasingly known to have great relevance in the management and conservation of rivers and other water bodies like wetlands, especially in the context of North East India.