eChapters

ABSTRACT

Coastal zones are credited for the important role they play in the economic, industrial and commercial activities of many countries. Starting from the early fifties of the last century, coastal zones have attracted greater attention from the earth scientists owing to the discovery of huge hydrocarbon deposits in the Persian Gulf, Africa and South America. In addition, coastal zones especially those bordering Precambrian Cratons house significant quantities of economically important placer minerals which are being explored and exploited vigorously. In the present paper, sedimentary basins located along the continental margins of Tamil Nadu state, their geology and hydrocarbon potential are discussed. In addition, an attempt has also been made to demonstrate the usefulness of remote sensing techniques in the exploration of this strategic mineral.

ABSTRACT

Lineaments are the surficial expression of sub-surface phenomena which are well discerned from low-orbital data, satellite data with its synoptic view and repetitive coverage and help to bring out more information on structural features hither to unknown by conventional geological surveys. Their study paved way to many new concepts on tectonism, mineralization, structural deformity etc. of an area both in regional and local perspective. In the present study, a small area was selected after careful observation, for their importance in mineral deposits. The lineaments are mostly structurally controlled and analysed for their relationship with the base metal deposits of the area. Moreover satellite parameters like spatial resolution, scale etc., and are observed for their changes in their orientation and relationship with the deposit of the study area, Jambughoda of Panchmahal District, Gujarat Satellite data of Landsat MSS and TM are used for the analysis. The results proved that the satellite parameters are important criteria and play a vital role in lineament analysis for mineral investigation.

ABSTRACT

Using a hand auger of 2 m length, upper, middle and lower core sediment samples of seventy nine in number have been collected from the Vaippar river, its tributaries and Vaippar beach in order to understand the role of Vaippar river and its tributaries in making up the Vaippar beach placer deposits. The heavies are found to be concentrated abundantly in fine and very fine size grades of all the samples collected from both the environments. The average heavy mineral concentration varies from 3.13 to 17.40 % in river bed while it is 6.19 – 64.82 % in the beach. In river bed, the pattern of concentration of heavies in upper, middle and lower core samples does not show any characteristic uniform pattern and inferred that it is controlled by the grain size of the parent rock, supply of sediments from the source, geomorphological features of the river and hydrological characters of running water. In the beach, the concentration of heavies are effected mainly due to the winnowing action of waves. However, a phenomenal increase in the heavy mineral concentration of beach samples might be due to the supply of sediments from other source besides the Vaippar river.

ABSTRACT

54 foraminiferal species belonging to 29 genera, 23 families, 17 superfamilies and 5 suborders have been identified from Nagaland. Of the total species 16 are planktic and 38 are benthic forms. The age for the Upper Disang Group of Nagaland is assigned as Late Eocene, based on the presence of Late Eocene markers i.e. Globigerinatheka semiinvoluta, Cribrohantkenina inflata, Hantkenina alabamensis and Turborotalia cerroazulensis. As per the present study the Disang succession in Nagaland can be grouped into five biofacies. The Uvigerina dominated biofacies consisting Uvigerina cocoaensis, U. continuosa, U. eocaena, U. glabrans, U. jacksonensis and U. cf. steyeri. In some samples even up to 100 % Uvigerina were present. The localized occurrence of thick “Uvigerinids” in high percentage with pyritized test in this section indicates anoxic conditions, suggestive of possible source rock for oil.

ABSTRACT

The Cretaceous formation of Ariyalur area is well known for its lithological and faunal variation. It contains rich assemblages of fossils as well as the occurrence of economic deposits of limestone, gypsum, phosphatic nodules and clays. Representative Uttatur clay samples have been collected and analysed for physical and chemical properties. The physical properties such as fired colour, plasticity, fusing temperature, slaging nature, shrinkage test, bulk density, liquid limit, and plastic limit and Atterberg number etc. of uttatur clays have been determined. The chemical properties of the clays show low in silica and alumina and high iron and lime which make them suitable for low duty refractories and stoneware works.

ABSTRACT

Sedimentological studies such as textural, heavy mineral and clay mineralogy have been carried out for Warkalli Formations at Varkala, situated in the southern part of Kerala, India. The X-ray diffraction study reveals that kaolinite is the only clay mineral present in all the samples with trace amounts of gibbsite and goethite. The higher amount of kaolinite and gibbsite indicates warm and humid paleoclimatic conditions. The textural analysis shows that the sediments are moderate to poorly sorted, nearly symmetrical to fine skewed and lepto to mesokurtic in nature. A plot of skewness against sorting shows fluvial trend. The major heavy minerals present in the samples are magnetite, ilmenite, rutile, sillimanite, anatase and zircon. It can be inferred from these studies that these sediments would have been deposited in a lagoon by fluvial action. During that time, the source region has experienced tropical humid climate with mean annual precipitation (MAP) above 200 cm and intensive chemical weathering. Heavy mineral assemblage indicates medium to high grade metamorphic source rocks.

ABSTRACT

We report here the occurrence of chrysoberyl bearing gem pegmatitesof Southern India. The Pan-African Chrysoberyl mineralization is associated with intrusive event of grey pegmatites within granulite facies parametamorphic aluminous khondalites. Lithological and structural controls of chrysoberyl mineralization are discussed. The chrysoberyl occurrences in southern India, southern Madagascar and Sri Lanka provide strong evidence for India-Sri Lanka-Madagascar juxtaposition in the East Gondwana assembly with the Achankovil Shear Zone of Southern India one side extending into Ranotsara Shear Zone in Southern Madagascar and other side into southern tip of Sri Lanka.

ABSTRACT

Mineral exploration is not only highly imaginative and creative but a very costly activity as well. The fast emerging Geomatics technology is a real boon in mineral exploration as it encompasses a whole spectrum of solutions and services which are of great help for exploration geologists. Geological maps which generally form the basic requirement for any kind of natural resources inventory operations currently witness tremendous changes and the same is mainly attributed to the integration of Geomatics technology. Usage of Geomatics has revolutionized the art of mineral exploration as geological maps can be easily integrated with other important details like geomorphology, structure and tectonic pattern, geophysical data etc. This kind of data integration facilitates for the better identification of mineralized zones. In addition, GIS with its powerful analyzing capability provides tools at several stages in the process of mapping for building up a database containing various types of data for quantifying and extracting features related to mineralization. The present paper narrates an overview of mineral exploration using Geomatics technology.

ABSTRACT

India is blessed with large reserves of strategic and economically important heavy minerals such as ilmenite, rutile, leucoxene, zircon, monazite, garnet and sillimanite. These deposits are mostly located in the coastal stretches of Peninsular India especially between the high tide line and 200-250m inland, with the exception of few inland deposits. Ilmenite is the largest constituent of the Indian beach sand deposits, followed by sillimanite and garnet. These minerals are one of the largest and higher grades in the World. The Indian Ilmenite resource base totals 348 million tones (Mt), along with 18 Mt of rutile, 21 Mt of zircon, 8 Mt of Monazite, 107 Mt of garnet and 107 Mt of sillimanite. Although Indian heavy mineral resources are one of the largest in the world, it is observed that the Production to Reserve Ratio (PRR) is a meager 0.0013; that is insignificant compared to other countries with similar resources.

ABSTRACT

Worldwide reinterpretation of evolutionary history of sedimentary basins had commenced with the introduction of sequence stratigraphic concepts by geoscientists of Exxon. The eustatic sea level controlled deposition in sedimentary basins together with synchronous excursions of many trace elemental and stable isotopic compositions of sedimentary strata have led to a proposition that geographically widely separated sedimentary strata could be classified and correlated with ease by application of sequence stratigraphy and chemostratigraphy, relatively younger branches. This paper reviews the key definitions of these stratigraphic methods, presents an overview on their applicability in petroleum exploration, reservoir characterization and stratigraphic correlation. Considering the man-hours required for interpretation of sequences and chemozones from large quantum of core samples being generated from exploration activities and the possibility of human-error and biased nature of interpretations, an automation scheme involving statistical discrimination is suggested. The statistical discrimination method has been tested to have 76-100 % distinction of depositional units of Recent – Cretaceous in age in terms of sequences, chemozones, lithostratigraphic units, petrographic types and sedimentary microenvironments with 100% reproducibility of predictions. Hence, creation of a large database with well constrained subpopulations and putting it to use for recognition of depositional units and correlation of strata and reservoir characterization is suggested which may reduce operational inconsistencies and improve exploration strategies.

ABSTRACT

The carbonatites are genetically and geochemically distinct and contain several rare earth minerals that are unknown or are very rare in other types of rocks. A useful review of the REE’s in carbonatites is given by Cullers and Graf (1984), who point out that carbonatite contains the highest concentration of REE’s and highest LREE: HREE (La:Lu) ratio of any igneous rock. High REE abundances are considered as the diagnostic character of carbonatites to discriminate them against recrystallized limestone. Rare earth mineralization in carbonatities can be classified into three categories. The first is primary magmatic crystallization (bastnaesite). The second is hydrothermal mineralization and the third is supergene mineralization produced by weathering of carbonatitie bodies. The only economic Nb mineral in carbonatite is pyrochlore. Apatite deposits constitute the largest bulk mining in carbonatites and have higher phosphate content than marine phosphorites. Pyrochlore, cubic fergusonite, eschynite, Fe-Nb rutile, monazite apatite, bastnaesite and allanite are the rare earth minerals that are enriched in Tamil Nadu carbonatites. Such enrichment of above rare earths is typical of undersaturated alkaline complexes. The lanthanides are seen associated with these minerals, mainly the light lanthanides are predominant than heavier ones. Thus the carbonatite complexes provide the locus for several metal deposits that are presently of strategic importance, containing elements, which are otherwise largely dispersed in earth crust.

ABSTRACT

The multi-sensor airborne geophysical survey was carried out over Nalgonda district, Andhra Pradesh, during the field season 2002-03, with an objective to locate potential areas for mineral exploration. The area comprises older metamorphic rocks of Peninsular Gneissic Complex of Archaeanage represented by gneisses, granite, amphibolite and banded magnetite quartzite. Leucocratic intrusive granite, extending over a length of about 40 km around Suryapet in NNW-SSE direction exhibits intense fracturing. Two sets of vertical to sub-vertical fractures have been noted in granite. Yellow stains observed in granite near fracture planes reveal the presence of secondary radioactive mineral encrustation. The ground magnetic and spectrometric observations indicated that the uranium mineralization is confined to these fractures in granite. Petrographic, ore-microscopic and scanning electron microscopic studies revealed evidences of metamict alteration surrounding monazite/apatite inclusions within biotite, and magnetite grains in granite. These studies also indicated evidences of discrete grains of uraninite / coffenite / pitchblende (containing Thand Ce). Chemical analysis of the rock samples (by NAA) collected from anomalous zone reveal high uranium concentration of the order of 1200 ppm, marked by high values of total Rare Earth Element concentration (800 ppm).

The leucogranites are characterized by high LREE and a negative Eu anomaly suggesting plagioclase fractionation. An ultramafic enclave near village Kutubsahipur shows highest concentration of both uranium (1240 ppm) and REE (890 ppm) analyzed by BARC and NAA Lab, GSI.

ABSTRACT

Serious infections caused by bacteria that have become resistant to commonly used antibiotics have become a major global healthcare problem in the 21^st century. Antibiotic resistance, initially a problem of the hospital setting associated with an increased number of hospitals acquired infections usually in critically ill and immuno-suppressed patients, has now extended into the community causing severe infections difficult to diagnose and treat. In hospitals, most common resistant bacteria include methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci and gram-negative rods including Enterobacteriaceae and Pseudomonas aeruginosa. Vancomycin intermediate and resistant S. aureus, represent a new treatment challenge. In the community, penicillin and macrolide-resistant pneumococci developed several decades ago and are now present all over the world. More recently, communityacquired methicillin-resistant S. aureus has become a problem in several countries causing skin infections but also severe diseases. The molecular mechanisms by which bacteria have become resistant to antibiotics are diverse and complex. Bacteria have developed resistance to all different classes of antibiotics discovered to date. The most frequent type of resistance is acquired and transmitted horizontally via the conjugation of a plasmid. In recent times new mechanisms of resistance have resulted in the simultaneous development of resistance to several antibiotic classes creating very dangerous multidrug-resistant (MDR) bacterial strains, some also known as ‘‘superbugs’’. In many cases the use of antibiotics is unnecessary or questionable. The indiscriminate and inappropriate use of antibiotics in outpatient clinics, hospitalized patients and in the food industry is the single largest factor leading to

ABSTRACT

Frankia is a gram-positive, microaerophilic, actinomycete that enters into symbiotic associations with a number of woody dicotyledonous plants called actinorhizal plants. Frankia can fix atmospheric nitrogen through such associations. The actinorhizal-Frankia association is beneficial for the environment, since it increases the fertility of soils. Extensive studies on the biochemical and molecular aspects helped in the classification of Frankia. PCR-RFLP studies of the 16S rRNA and the nif regions of Frankia revealed considerable information regarding the diversity of Frankia strains, isolated from different parts of the world. The completion of three whole genomes of Frankia has bolstered the study of the molecular organization of the genome. Comparative genomics study of the three complete genomes revealed that, the strains reflected the biogeographical history of the host plants they infected. Striking similarity in the codon usage patterns highlights the fact that they may have evolved as a unit. In the present review we highlighted the taxonomy of Frankia and the host plants, the Frankia-actinorhizal association, regulation of infectivity, biochemical and molecular characterization, phylogeny and genomics of Frankia and stressed the need for metabolomic study of the Frankia-actinorhizal association.

ABSTRACT

The continuing depletion of the stratospheric ozone layer mainly due to release of man-made atmospheric pollutants such as chlorofluorocarbons (CFCs) have resulted in the increase of solar ultraviolet-B radiation (UV-B; 280-315 nm) reaching to the Earth’s surface. UV-B is a small (less than 1% of total energy) but highly active component of the solar spectrum that can penetrate to biologically significant depths in lakes, ponds, rivers and oceans. It has been demonstrated that UV-B can cause wide ranging effects including mutagenesis, destruction of proteins/enzymes, inhibition of a number of vital metabolic processes and formation of thymine dimers in DNA leading to death of a number of organisms. A number of microbes including strict photoautotrophs always grow in lighted habitats and thereby always sense and face the stress of solar UV-B radiation. Similarly, humans are also exposed to varying levels of UV-B radiation depending upon the altitudes and latitudes of the location. A wide ranging effect of UV-B such as cataracts, skin cancer, immunosupression etc. has been reported in human. Damaging effects of increased UV-B radiation has also been shown in a number of microbes. These effects include inhibition of growth and survival, decrease in photosynthetic pigments, loss of PS II and RuBISCO activity, inactivation of nitrogenase enzyme and inhibitory effects on several other metabolic processes. Among photosynthetic pigments, phycobiliproteins seem to be the primary target of action since phycobilisomes are completely disintegrated after UV-B exposure. In this contribution an attempt has been made to put in perspective the main effects of UV-B radiation on microbes and human health.

ABSTRACT

Heavy metal contaminated soils are biologically inactive and extremely poor in soil fertility status. These metals are highly resistant and cannot be easily degraded by either chemical reactions or amendments. Microorganisms are biological softwares capable of degrading the metals efficiently. Among microorganisms, mycorrhizas are known to circumvent metal toxicities through a series of processes that assist in immobilization in biological systems which converts toxic metals into less or nontoxic forms. There are five mechanisms such as biosorption, solubilization, hyphal transport, detoxification and dilution are involved in promoting tolerance of host plants to heavy metal toxicities. These processes are strategies that can be exploited to phytoremediate the contaminated soils. The phytoremediation strategies encompass tolerance of mycorrhizal fungi, phytostabilization (preventing entry of heavy metals into plants), phytoextraction (luxuriant uptake and transport to shoots) and intercropping or crop rotation with mycorrhizal dependent hyperaccumulators or non-hyperaccumulators. Despite mycorrhizas are natural, the indigenous population is not sufficient enough to induce tolerance of host plants to abiotic and biotic stress conditions. This necessitates adopting recommended agronomic practices to promote mycorrhizal colonization in natural agro-ecosystem or to derive full benefits from phytoremediation strategies. Thus mycorrhizas are important naturally occurring microorganisms capable of withstanding highly contaminated metal sites and offer protection against phytotoxicities caused by heavy metals.

ABSTRACT

Plasmids are circular, double-stranded DNA molecules which replicate autonomously from the chromosome of the host organism. Plasmids are found in many bacterial species and often confer upon the host cell phenotypic characteristics such as resistance to antibiotics, resistance to heavy metals, ability to produce particular protiens, conjugative (mating) ability and ability to degrade xenobiotc compounds. One of these degradative plasmids may encode a complete catabolic pathway (such as toluene to pyruvate, formate and acetaldehyde) or partial degradative steps, such as octane to octanol. In this later case, the remainder of the pathway may be encoded by chromosomal genes, by genes of other plasmid present in the host, or by other microorganisms. Many degradative plasmids possess a broad host range, especially among the gram-negative bacterial species.

There are different mechanisms which may be involved in the evolution of aromatic pathways in general and in the process of adaptation of microorganisms to xenobiotic substrates in particular. Gene transfer, the occurrence of plasmids in bacteria in the natural environment is an important pool of genetic information residing on plasmid vehicles may flow among indigenous microorganisms. Since many examples of self-transmissible plasmids that carry genes for degradation of aromatic or other xenobiotic compounds are known, and their role in spreading these genes to other microorganisms is well characterized. Early, studies of TOL, NAH, and SAL plasmids revealed strong homologies among these plasmids in regions both inside and outside the catabolic gene clusters. Plasmids, pJP4, pAC25, and PSS50, catabolic plasmids carrying genes for chloroaromatic degradation, have strongly homologous plasmid backbone that determine replication and transfer function. Furthermore, the chlorobenzoate plasmid p51 was also shown to be homologous to pJP4 outside regions of the catabolic genes. These observations suggest that a few common self-transmissible ancestor replicons (includes origin of replication and replication gene) may have been involved in acquisition and spread of different catabolic genes. DNA

ABSTRACT

An understanding of the metabolism of heavy metals facilitates biotechnological use of these functions just recently, although heavy metals comprise the major part of the elements in the periodic table. Due to their ability to form complex compounds, some heavy metals are essential trace elements. In any case, essential or not, most heavy metals are toxic at higher concentration. Heavy metal pollution from last few decades has led to an increased environmental concern. Heavy metal like cadmium is a non-essential toxic heavy metal and is also being increased in soil during last few years posing a serious threat to environment and human health worldwide. Therefore, remediation strategies of the contaminated sites are great concerns and can be achieved by a number of different physico-chemical and biological means.

ABSTRACT

Industrial and agricultural activities and the disposal of waste products have resulted in the contamination of many terrestrial environments. Industrial effluents often contain considerable amount of potentially toxic compounds such as Cd, As, Pb and Hg. Due to their small size, which provides a large contact area that can interact with the surrounding environment, microorganisms are the first biota showing the impact of toxic compounds. Microorganisms being in intimate contact with the soil environment are considered to be the best indicators of soil pollution. In general, they are very sensitive to low concentrations of contaminants and provide a rapid response to soil perturbation. Rhizobium spp. are ubiquitous gram-negative soil bacteria that have a profound scientific and agronomic significance due to their ability to establish nitrogen-fixing symbiosis with legumes, which is of major importance to the maintenance of soil fertility and to feed livestock and populations in many developing countries. Therefore, the present work aimed to evaluate the impact of heavy metals on Rhizobium populations isolated from different locations contaminated with heavy metals. In order to reach this goal some physicochemical parameters that influence metal bioavailability were determined, as well as their concentrations in soil. Cadmium tolerance of Rhizobium isolates was screened in artificial media and the highest cadmium concentration allowing growth was defined as the maximum resistance level (MRL). The heavy metal tolerance variability found among Rhizobium isolates, suggests that beyond basic metabolic machinery also exist variations that allow isolates to display distinct tolerance responses to Cd stress. To better understand Rhizobium cadmium tolerance, wall-bound and intracellular Cd was determined. Sensitive and moderately tolerant isolates showed low intracellular Cd amounts when compared to extremely tolerant isolates, which were able to withstand intracellular Cd concentrations 40 times higher. Lipopolysaccharides (LPS) bind cations unspecifically, so they constitute the initial defence mechanism to heavy metals since they sequestrate cations and therefore prevent their entry into the cell. LPS quantity varied significantly between isolates. LPS increases were observed in most sensitive, moderately tolerant and tolerant isolates, evidencing an attempt of cells to adjust to cadmium entry. These results may be of great importance for understanding how Rhizobium persists in contaminated soils. They also provide important data to the development of bioremediation processes and to the improvement of soil productivity.

ABSTRACT

The world ocean with a coastline of approximately 3,50,000 km is the largest ecosystem on earth. Marine organisms are the major, sustaining components of ecosystem processes and are responsible for biogeochemical reactions that drive our climate changes. Despite this, many marine organisms are poorly described and little is known of broad spatial and temporal scale trends in their abundance and distribution. With new molecular and analytical techniques we can advance our knowledge of marine biodiversity at the species level to understand how marine biodiversity supports ecosystem structure, dynamics and resilience. We can then interpret environmental, ecological and evolutionary processes controlling and structuring marine ecosystem biodiversity. In biotechnology applications marine microbes represent a potential source for numerous commercially important biomolecules and their bioremediation capabilities are also remarkable. They also play a crucial role in decomposition of organic matter and cycling of nutrients. Microbes also serve as food for some bottom-living organisms. Understanding and preserving biodiversity was one of the most important global challenges for the past 20 years and will continue to be an important scientific issue into the new millennium. Our knowledge of marine microbial diversity has, however, been severely limited by relying on microorganisms that have been cultured which are less than 1%.