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Many problems in geology, especially structural geology, can only be solved by detailed mapping. Presently, mapping is still mainly carried out on paper using techniques from the 19th Century. However, tools are now available to carry out most mapping tasks on microcomputers in the field without any need of paper. This speeds up geological mapping and reduces the errors involved in the mapping process. Digital mapping also allows work in featureless areas and areas of great structural complexity that would not be possible using paper maps. We present two practical examples of the new technology of digital mapping using microcomputers, from Namibia and Greece. [ABSTRACT FROM AUTHOR]

The text summarizes the Proceedings of the Annual General Meeting of the Geological Society of India in 2022, which took place at the Wadia Institute of Himalayan Geology in Dehradun. The meeting focused on various aspects of geosciences, including research on the Himalayas, seismogenesis, climate-tectonic interactions, and natural resources. Discussions revolved around the Annual Report and Audited Statement of Accounts for the year ending March 2022, and awards were presented to geoscientists who made significant contributions to the field. The meeting aimed to address issues related to natural disasters in the region and find solutions for sustainable development. The text also includes replies from recipients of awards, who express gratitude for the recognition and discuss their areas of expertise and research contributions in geology, mineralogy, and geochemistry. Additionally, acknowledgments and awards are given to individuals for their papers on groundwater irrigation and contributions to Precambrian Geology. The text concludes with the announcement of elected council members for the Geological Society of India for the triennium 2022-2025. [Extracted from the article]

Earth Science research in India evolved over the years in tune with the trends in the global scenario from studying the geologic attributes and assessing the natural resources to addressing issues related to fundamental processes involving, for example, crustal evolution, geodynamics and other aspects of contemporary Earth Science problems. Apart from various Earth Science institutions the Department of Science and Technology (DST), Govt. of India, through the SERC (now SERB) has been sponsoring Earth Science research projects in the country, and thus playing a catalytic role by providing extra-mural funding. Although the DST started funding Earth Science projects since 1985, the extent of such support increased in the 1990s and thereafter with sponsoring of a number of specialized thematic Earth Science programmes. As a result of these initiatives a prodigious amount of data has been generated that are contained in the Project Completion Reports (PCR). An analysis of the database prepared from 440 PCRs for the period 1993-2015 indicated that the projects dealing mainly with 17 themes increased almost steadily in number from 1993 to 2012 with a slight decreasing trend till 2015. A similar trend is exhibited by the yearly total project funding and the average cost per project. These aspects and the relation between the number of projects under different themes, papers published, PhDs produced and scientific and technical personnel trained are discussed here. [ABSTRACT FROM AUTHOR]

The text is a summary of the GSA Connects 2023: Annual Convention of the Geological Society of America, held in Pittsburgh, USA. The convention brought together 4,463 Earth scientists from 45 countries, including professionals, early career professionals, and students. The event featured paper and poster presentations, technical sessions, invited talks, and exhibits showcasing instruments and capabilities in the field of Earth science. The convention focused on the theme of "Diverse Science for a Sustainable Future and Climate and Energy Transition." Additionally, the convention facilitated collaborations and partnerships between the Geological Society of America and other geological societies, including the Geological Society of India and the Geological Society of Nigeria. [Extracted from the article]

The paper pertains to the studies carried out on the eclogitic xenoliths of KL-2 kimberlite of Kalyandurg kimberlite cluster in south India. Petrographic studies revealed bi-mineralic and kyanite-bearing eclogitic xenoliths in KL-2 kimberlite. The bimineralic and kyanite-bearing eclogites of Kalyandurg KL-2 kimberlite pipe show variation in modal proportion of garnet, omphacite, clinopyroxene and kyanite. The paper reports discovery of native gold grains and Au-Pt alloy in the kyanite-bearing eclogite xenoliths of KL-2 kimberlite. The flaky gold grains occurring in the matrix of kyanite-bearing eclogite are homogeneous and two grains of Au-Pt alloy with Au and Pt in the proportion of 9.8:1.2 are also present. This is the first report of gold and gold-platinum alloy specs from eclogitic xenoliths of Indian kimberlites. [ABSTRACT FROM AUTHOR]

With the increase in the pace of development, the demand for tunnels has increased in recent years. Analysing the stability of a tunnel in a fractured rock mass is a very challenging and cumbersome activity. The tunnel stability depends on the strength of the rock, joints bolt strength, in-situ stresses, and their orientation. This paper focuses on constructing tunnels in fractured/jointed rock mass. Three different software namely Rocscience Phase2 (finite element based), FLAC3D (finite volume based) and PFC3D (distinct element based), were used to analyse the performance and stability under static and dynamic loading conditions. The geomaterial properties used for the analysis were taken from data obtained after laboratory testing and based on available literature. The effect of joint orientation and bolt length was analysed using Phase 2 assuming plain strain conditions. The effect of earthquake and performance of fully grouted, energy absorbing and deformation-controlled bolts under seismic loading conditions were compared using FLAC3D. While the 3D distinct element analysis of geometry was performed using PFC3D to evaluate the effect of joints and their orientation. The performance of the different types of bolts was also analysed numerically. The behaviour of bolts can be customised using the 'fish'function. The results indicate that analysis must incorporate the fusion of various numerical simulation techniques like finite element-, finite volume- and distinct element-based methods for more reliable results. [ABSTRACT FROM AUTHOR]

India witnessed a massive tsunami on 26th of December 2004, which adversely affected the East coast of India. This research focuses on the coastline between Nagoor to Poompuhar, Tamil Nadu which lies for a stretch of 35 km. Eight stations, namely, Poompuhar, Chinnangudi, Kuttyandiyur, Chandrapadi, Kottucherimedu, Karaikal Beach, Vadakku Vanjiyur North, and Nagoor Beach were chosen and a total of 73 samples were studied. The motive is to study the characteristics of pre and post tsunami sediment samples by analysing their grain size. The statistics of the sediments were done using G2Sd package of R programme, which showed lowering in the mean values of phi, percentage of increase in bimodality, change in skewness, and moderately well sorted sediments post tsunami indicating high-energy circumstances. The bivariate plots were plotted between different parameters to get more insight about depositional environments. Linear Discriminate Functions reveal the samples of pre-tsunami were deposited by aeolian process but most of the post-tsunami samples were deposited by beach process and 100% are from shallow marine conditions. The CM pattern and tractive current plots reveal the gradual suspension in pre tsunami whereas rolling in post tsunami. The characteristics of sediments of pre- and posttsunami in a more effective manner are presented in this paper. [ABSTRACT FROM AUTHOR]

The article discusses the discovery of India's first carbonatite at Amba Dongar, which had a significant impact on the field of petrology. The Amba Dongar carbonatite complex has been extensively studied for over 60 years and is considered one of the best-studied complexes in the world. It is known for its fluorite mineralization and the presence of rare earth elements, making India potentially rich in these resources. The document provides a list of references and publications related to the geology and mineral resources of the complex, including research papers and reports by renowned researchers in the field. [Extracted from the article]

Gangotri glacier located in the Uttarkashi District of the Garhwal Himalaya, is one of the longest valley glacier. It exhibits Lateral Moraines (LM), Recessional Moraines (RM), Kame Terraces (KT) and Outwash Plains (OWP) as important landforms. The sediments coded in these landforms, provide the information about sedimentary characteristics, and the evolutionary history of the Gangotri Glacier Region (GGR). The Gangotri is a well studied glacier, however the sedimentological characteristics and evolution of many landforms are yet to be understood. Therefore, present paper aimed to explain the sedimentological characteristics and the evolutionary history of the outwash plain deposits. The OWP deposits were studied by making a trench near Bhujbas and collecting the samples from it. The granulometric analysis explain that the mean grain size of the OWP sediments varies from 0.258 φ to 2.006 φ indicate coarse to medium sand. The skewness, varies from 0.138 φ to 0.427 φ indicate dominance of fine grained sediments. The kurtosis varying from 0.839 φ to 1.067 φ explain the dominance of finer sediments. The standard deviation varies from 1.210 φ to 1.633 φ thus indicating poor sorting of the OWP deposits and fluctuation in the energy of the depositional environment. Five sedimentary facies identified are gravel sandy facies, ripple laminated silty sand facies, sandy facies, poorly sorted sandy facies and silty sand facies. The study describes that the OWP deposits are stratified, consolidated to semi-consolidated, coarse to fine grained silt, sand and gravels with primary sedimentary structures, which are evolved by glacio-fluvial environment under fluctuating energy conditions during the late Holocene period. [ABSTRACT FROM AUTHOR]

Information about workshop "Western Ghats; Evolution and environmental issues" organised by research centre National Centre for Earth Science Studies (NCESS) on 1-2 January 2016 is presented. Topic included understanding knowledge gap between geoenvironmental issues, geological evolution and resource management of Western Ghat. Workshop featured three technical seasons including theme Western Ghats-A climate regulator, discussion over presented papers and forestry of Western Ghats.

Granitoids are well exposed in Jirang-Patharkhamah area (latitude N 25°57′− 25°41′ and longitude E 91°30′–91°38′). The area lies mostly in Ri-Bhoidistrict and is also extended to West Khasi Hills district of Meghalaya. The granitoids are medium grained and nonporphyritic. The colour is dominantly grey although some granitoids are pink in colour. The common minerals in order of abundance are quartz, plagioclase, K-feldspar, biotite and hornblende. Secondary minerals are sericite, chlorite, muscovite, secondary hornblende and secondary biotite. Among accessory minerals, sphene, zircon, apatite, calcite, zoisite, magnetite and monazite are significant. The intergrowth textures such as perthite, myrmekite in these rocks indicate that the rocks were affected by low temperature alteration. The representative samples ploy in the field of granite in various geochemical discrimination diagrams. The aim of the present paper is geochemical characterisation of the granitoids using major and trace elements (including REE). The whole rock geochemistry reveals that the granitoid is I-type, calc-alkaline, metaluminous to weakly peraluminous and an attempt is made to examine the nature of the magma based on biotite mineral chemistry. The biotite chemistry indicates that the granitoid is I-type and calc-alkaline. The paper also aims to estimate temperature of emplacement of granitoids based on two feldspar geothermometer and Ti-in biotite geothermometer. The temperature calculated from two feldspar thermometry is in the range 512–602°C and the average is 550°C. The temperature calculated by Ti-in biotite thermometer is in the range 623 to 656°C and the average is 645°C. Geothermometric results plays an important role in definition of petrogenetic history and regional tectonism. [ABSTRACT FROM AUTHOR]

This article is dedicated to the Silver Jubilee Year of Asian Seismological Commission (ASC) and provides details of its evolution from its nascent stage from a Chinese perspective. The review includes the seeding of the idea of ASC, its formation, the General Assemblies and the International Conference on Continental Earthquakes (ICCE) series in which ASC played an active role. The paper also highlights the profiles of the Commission as well as its role in the development of Asian seismology. [ABSTRACT FROM AUTHOR]

Nuclear power plants (NPP) play increasing role in power supply worldwide. To meet demands of the human society, the NPPs have to be built where the energy is required, including seismoactive regions. Therefore, the safety issues related to reliable assessment of earthquake hazard are crucial. The basic concept of seismic hazard assessment is that the seismic regime is stable, i.e. the prediction of future hazard is defined by the past observations. As a consequence, huge efforts are spent to get seismic history as long as possible. Palaeoearthquake studies can provide information on past earthquakes occurred 15,000–20,000 years before present. But for such time-intervals, the basic concept might be wrong, at least for certain regions. For example, for regions where earthquakes in the past were generated due to post-glacial processes — the geodynamic situation there today is different now. So, the time-arrow of geodynamic evolution has to be somehow incorporated in hazard assessment. In hazard assessment very rare occurrences are taken into account now: such as having 10−5 or 10−6 annual frequencies of occurrence (return period 100,000–1,000,000 years). This demands very accurate interpretation of the nature of past seismic event. In the paper, some examples are given when effects similar to earthquakes can be caused by other natural phenomena. [ABSTRACT FROM AUTHOR]

The Asian Seismological Commission (ASC) completed 25 years in August 2021 after fulfilling its primary aim of bringing together, Earth scientists from Asia and Oceania regions. Since its first formal meeting in Tangshan, China during August 1–3, 1996 under the umbrella of IASPEI Regional Assembly, ASC independently organized 11 General Assemblies across the Asian Continent from Armenia and Iran in western Asia to Australia in Oceania, once every two years, without a break. The Training Courses in Seismology preceding these Assemblies greatly helped in developing a strong work force that came very handy after the extreme event of 2004 Indian Ocean tsunami and underlined the importance of scientific cooperation within Asian and Pacific Ocean countries. The Global Seismic Hazard Assessment Program (GSHAP) in its closing report to the IDNDR/STC (1992–98) acknowledged the significant contributions of the first two ASC technical meetings held in Beijing (10/93, 10/94) and Hyderabad, India (3/96) in the outcome of their program in Eastern Asia (GHSAP Region 8). This paper describes the ASC events that occurred during its journey from birth to reaching the pinnacle of its glory at the end of the Silver Jubilee Year in 2021. This paper will also serve as a recorded history for posterity to build upon the efforts already made, by the coming generations in this field. [ABSTRACT FROM AUTHOR]

Escalated groundwater contamination around the world developed the idea of aquifer vulnerability, which has widely been employed globally to safeguard groundwater from contamination. Several extensive studies have been done to evaluate the degree of groundwater vulnerability using various techniques. However, a comprehensive assessment of existing literature in order to identify major research gaps associated with aquifer vulnerability is still required. The current study provides a critical overview of several groundwater risk assessment methodologies, including the GIS-based DRASTIC and modified DRASTIC methods, application of Artificial Intelligence (AI) and Machine Learning techniques, and integrated approach for both intrinsic and specific vulnerability assessment. The study discusses validation of DRASTIC model and its comparison with a few other methodologies as well. The paper also highlights the international approach (time dimension in groundwater vulnerability, integrated process based and isotopic studies, etc.) that needs to be practiced rigorously on a larger scale in India. A descriptive summary of the literature indicates that a multidisciplinary and integrated framework such as understanding contaminant type, uncertainties in vadose zone need to be implemented in a much more comprehensive way, especially in India. A conceptual framework that is both reasonably adaptable and scientifically sound must be created for specific vulnerability assessment. [ABSTRACT FROM AUTHOR]

Acid mine drainage and soil erosion are significant problems in the coal mining area. It affects the water quality and soil quality, henceforth affecting plant growth and most aquatic life. During the last two decades, coal mining areas were increased by 194 hectares in Makum coalfield (Assam), which led to an increase in acid mine drainage and soil loss. In this paper, the water chemistry of water samples was analyzed, and annual soil loss near the area of Makum coalfield was calculated to investigate the most affected region by Acid Mine Drainage (AMD) and soil erosion. The Watershed delineation, slope angle, elevation contour map, and drainage system of 57 km2 of the study area were developed by ArcGIS Pro. The Universal Soil Loss Equation was used to estimate the amount of annual soil loss. The USLE parameter was assessed using a Digital Elevation Model with a 30-meter X 30-meter resolution. The result indicates that the quality of drainage near the mines was highly acidic. Also, compared to the area near the riverside, the proximity of mines is more affected by soil erosion and needs improvement. [ABSTRACT FROM AUTHOR]

This paper reports the results of the geochemical study of the Jutogh metasedimentary rocks that occur as a tectonic window between the Lesser and the Higher Himalaya. The Jutogh Group of rocks are mostly mica-schists of different metamorphic grade. The weathering intensity parameters, such as chemical index of alteration (CIA), plagioclase index of alteration (PIA), and index of compositional variability (ICV), range from 81 to 65 (mean = 72), 97 to 68 (mean = 84), and 1.9 to 0.6 (mean = 1.2), respectively indicating low to moderate degrees of weathering. Transition element ratios [Ni/Co (6.98 to 2.88), and V/Ni (2.32 to 1.27)], and major and trace element geochemistry imply recycled, felsic to intermediate, Archean to post-Archean are the sources for Jutogh rocks. The tectonic discrimination diagram implies an active continental margin setting for the deposition of the Jutogh metasediments. The geochemical data from the Jutogh rocks, when combined with the S-type Paleoproterozoic granite magmatism, imply the existence of an active tectonic setting during the deposition of the Jutogh sediments at the northern margin of the Indian continent during Nuna assembly. [ABSTRACT FROM AUTHOR]

Pookode, the freshwater lake in the Western Ghats, is a well-known tourist place in southern India, and human interference has turned the otherwise serene environment into a polluted one. This paper discusses the geochemical and textural characteristics of the Pookode lake and by determining the sedimentation rate, an attempt is made to predict the useful life of the lake. The predominance of mud fraction and high organic matter content in sediments favour the accumulation of heavy metals as indicated by the different indices. The sedimentation rate was determined using 137Cs dating method and the maximum lifespan of the lake maintaining its hydrological and ecological functions is estimated as ∼700 years. [ABSTRACT FROM AUTHOR]

One of the most significant challenges of construction of underground large size structures is to determine the effect of the geological discontinuities. Fault is a natural discontinuity which allows significant displacement of the rock mass along the fault plane and increases the plastic zones around the underground structure. For instance, an underground hydropower plant comprising more than two underground caverns and large distance between the underground cavern incurs the higher cost because of connecting tunnels or transfer of electricity from powerhouse cavern to transformer cavern. However, presence of the fault would result in the increase of the plastic zone and shear displacement along the fault. Thus, with regards to the effect of the fault on the stability of the two parallel caverns, in this paper different numerical models were simulated to study the effect of the fault on plastic zone around the cavern group and pillar between the caverns, and shear displacement along the fault plane under different scenarios such as fault location, fault dip angle, fault friction angle and in-situ stress conditions. The results are produced graphically and discussed. These results offer advance guidelines in construction of the two parallel large size caverns. [ABSTRACT FROM AUTHOR]

The East coast bauxite deposits of Odisha are well known in the mineral map of India. Some such deposits exposed at Nunapaimali, Sasubohumali and Baphlimali overlying khondalite of the Precambrian Eastern Ghats belt have been studied in respect of petrology, mineralogy and microstructure with a view to find out their genetic evolution. Bore hole samples from two former deposits and mine profile samples from Baphlimali revealed a good profile differentiation, in terms of three horizontal zones of variable thickness, which in descending order are: 1 to 29m laterite zone, 2 to 28m bauxite zone, 9 to 36m saprolite zone, comprising of lithomarge and partially lateritised khondalite [PLK] developed over host khondalite. Petrographic and mineralogical difference between these three zones, brought out through optical microscopy and XRD studies, further confirms the differentiation. Genetic evolution of bauxite is interpreted from the study of a large number of samples and results are collated from the photomicrographs appended in the paper. The authigenic bauxitisation was brought about by gradual dissociation of Al-silicate to Al-hydroxide minerals through different weathering cycles as indicated from their microstructural manifestations and mineral assemblages. Primary gibbsite is formed in the initial stage of weathering directly from Al-silicate minerals. Advanced stage of prolonged weathering converts the Al-silicate to kaolinite and then to secondary gibbsite. Grain size enlargement and recrystallisation showing mosaic habit, grain boundary migration and grain orientation are the outcome of digenesis. The weathering/lateritisation process continues, resulting in colloidal precipitation of gibbsite from pore water of lateritic residuum and is in progress even in recent period The Fe-oxide phases, represented by goethite and hematite are youngest in the paragenesis, and formed due to solution, precipitation and dehydration. Iron is mostly contributed by almandine garnet present in the host khohdalite. During chemical leaching, Fe gets released from garnet and occur either as FeOOH along its fractures or fill the weak planes/inter-granular space as secondary goethite. The goethite dehydrates to hematite during digenesis. Goethitisation and limonitisation particularly in the laterite zone are the results of supergene alteration. [ABSTRACT FROM AUTHOR]

It is very much fundamental to identify the susceptibility of river bank materials to erosion for implementing management strategies. The present paper intends to find out the susceptibility of river bank materials to erosion and it also focuses on vulnerability assessment based on susceptibility of river bank materials to erosion. A vulnerability assessment model based on susceptibility of river bank material to erosion has been used in this study. To satisfy the objectives of this study, a stretch of river Ganga-Bhagirathi in Jangipur sub-division under the district of Murshidabad has been selected. The results of the study show that aggregate stability of the soil in study area is less than 10% and the percentage of aggregated clay (less than 8%) and organic matter (less than 0.5%) in the soil are also very less. The areas categorized as high susceptibility to erosion are highly vulnerable than the rest. [ABSTRACT FROM AUTHOR]

The present paper discusses the evolution of the coal bearing sequences of Tharad Formation of Cambay Basin (Gujarat) based on coal petrological and organic geochemical signatures. Cambay Basin is a craton margin rift basin of Late Cretaceous age which is narrow and elongated. This north-south trending graben hosts huge sub-surface lignite/coal deposits of Early to Middle Eocene age. These coals have been petrographically and geochemically characterized to understand the type of flora, coal facies, depositional environment and coalification. Thickening of seams with depth is towards central part. Vitrinite rich Cambay Basin coals contain a considerable amount of liptinite indicating their derivation from the forest type of vegetation that grew under humid tropical climate while its high resin content indicates growth of conifers and gum-producing plants. High collodetrinite relates to soft woody tissues from herbaceous/bushy plant sources. Abundance of bioclasts in the western flank of the Sanchore low occur in stack indicating poor transportation and abrupt drop in bathymetry under tidal flat environment. The palynofloral assemblages indicate tidal deposition. Gas chromatography-mass spectroscopy (GC-MS) studies indicate low amount of oleanane suggesting a terrestrial source. The microlithotypes suggest limnic and telmatic mixed environment with typical forest floral input with intermittently changing water table conditions. The maceral composition of the coals indicates terrestrial origin having high tree-density. Marine influence caused influx of calcium rich water promoting decomposition of organic matter due to high bacterial activity and high pH values with depth. The ground water flow index (GWI) values indicate ombrotrophic hydrological condition while the vegetation index (VI) values support herbaceous plants. The swamp, therefore, suffered oxic and anoxic condition alternatingly with influence of reed marshes favouring the growth of anaerobic bacteria in high bathymetric region. The depth of burial of coal seams in Sanchore is extrapolated to be 1350–1800m with a temperature range of 40–80°C. [ABSTRACT FROM AUTHOR]

The Jara dome in the western part of the Kachchh basin is the distal-most exposure of the Callovian to Aptian age sediments of the Kachchh stratigraphy. These outcrops are represented by three formations, namely, the Jumara, Jhuran, and Bhuj formations. The central part of this dome is represented by the entire succession of the Jumara Formation (Member-I to IV). This paper aims to document ichnofabric changes in the distal part of the basin during a basinal-scale transgression. The Jumara succession at the Jara dome is represented by finer sediments compared with the other coeval sediments across the basin. Ichnofabric analysis of the Jumara Formation at the Jara dome implies 21 ichnospecies from 12 ichnogenera with the reconstruction of ichnofabric constituent analysis for all four members. Member-I implies low diversity-low density trace fossils with a simple tiering profile. Member II is two thick bands of marls rich with high diversity and density occurrence of Zoophycos. Ichnofabric analysis suggests slow sedimentation in the shelf environment below the Storm wave base under dysoxic conditions. Ichnofabric analysis of overlying Member III suggests deposition below the fairweather wave base with well-oxygenated, shifting substrate-type environments. Ichnological analysis of Member IV (Dhosa oolite Member) suggests that a transgression event was inferred at Jumara Dome. Thus, the ichnofabric analysis of the Jumara Formation suggests an increase in ichnodiversity steadily from member-I to III and then a decline. A comparison of the Jara dome ichnology data with other coeval sediments of the Kachchh basin suggests high diversity in the Jara dome area. [ABSTRACT FROM AUTHOR]

Despite being essentially a bryozoan limestone, the youngest member of the Bagh Formation (Turonian) is traditionally known as 'the Coralline Limestone'. Origin of this misnomer has been traced to a research paper by Fraser, in which a reference to this limestone was made. A footnote was appended to that research paper stating that this limestone contained fragments of corals. Presumably relying on this footnote, Carter designated this limestone as the Coralline Limestone. Authentic information regarding the Bagh Formation was later documented by Blanford as well as by Bose. Though both of them observed that this limestone is made up of bryozoan skeletal remains, they retained the invalid lithostratigraphic designation 'Coralline Limestone', which is still being followed. It is proposed here to formally designate this member as the Sitapuri Bryozoan Limestone. It is the youngest member of the Bagh Formation. Thin sections exhibit mainly bryozoan fragments; along with echinoid spines and plates, algae, molluscan shell fragments, etc. Both sparitic and micritic cement are present. It is ideally developed in the Man River Valley. Apropos, so-called Lower Coralline Limestone consists of sparse lenticular intercalations of bryozoan limestone developed at the bottom of Deola-Chirakhan Marl, and thus does not constitute a discrete lithostratigraphic member. [ABSTRACT FROM AUTHOR]

Owing to a rapid rate of depletion of conventional energy resources and to keep pace with the ever increasing energy demand, scientists all over the world are looking for some alternate source. Coal bed methane (CBM) is one of them. With the discovery of coalbed gas from an oil and gas producing basin- the San Juan basin in Colorado and New Mexico by AMOCO in early 1980's, the attention of world-wide hydrocarbon industry shifted to evaluation of CBM potential of Tertiary basins. The Tertiary Cambay basin in Gujarat is a known onland hydrocarbon province of India and has been producing oil since 1958. During drilling for petroleum, thick Eocene coal seams are encountered at varied depths in Mehsana area and further north. In 2004, few coalbed methane (CBM) blocks were awarded in northern Cambay basin and contagious Barmer Basin. The present paper entails the results of investigation carried out for CBM in the deep-seated coals of Sanchore and Tharad area in north Cambay basin. The methane content of the desorbed gases varies from 20–68%. The stable carbon isotope study (δ13C) shows that the desorbed gas is dominantly biogenic but the compositional analysis of desorbed gas reveals significant fractions of ethane (C2) and butane (C3) indicating the gases to be of mixed origin. Further, presence of high CO2 content is observed which varies from 20–45% of the total volume of desorbed gas. The estimated mean CBM resource of the study area is ∼ 46 billion cubic meters. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive account on the evolution of the Tertiary Himalaya coals of India and their various attributes. The coal bearing sequences in Himalaya have formed in two different geotectonic settings, first under foreland basin (Oligocene coals of Assam, Nagaland and Arunachal Pradesh of northeastern India) and second under Platform basin (Eocene coals of Meghalaya of north-eastern India) conditions. The Jammu coals of northwest India developed in the late Paleocene in the western Himalayan foreland basin. A sea transgression inundated the Jammu area which gave rise to forest swamp and Jammu coals eventually formed under tropical humid climatic conditions in the tropical climatic belt of northern hemisphere. In northeastern India, the Oligocene coals have shown more maturity than the Eocene coals and have relatively high carbon content and they also have developed caking characters in many coalfields. This may be because the Eocene coal developed in the tropical climatic belt when the northern part of the northeast India was still in the southern hemisphere and the Oligocene coal evolved when the northern part of the northeast India was in the northern hemisphere and the collision during the Oligocene in this part improved the maturity of Oligocene coal due to Himalayan orogeny. The Himalayan coals are exceedingly rich in vitrinite with variable quantities of liptinite and inertinite macerals. Dominance of typical Tertiary angiospermic floral assemblage in the Himalayan coals is well indicated by the occurrence of single, double and triple celled telutospores. [ABSTRACT FROM AUTHOR]

In this paper the first results of anisotropy of magnetic susceptibility (AMS) studies carried out on 10 schist samples taken from different depths of a borehole in the vicinity of Singhbhum Shear Zone (SSZ) are presented. A cube of 8 cm3 volume was extracted from each borehole sample and its AMS was measured; the shallowest sample is from 112 m depth, while the deepest is from 850 m depth. In the depth vs. mean magnetic susceptibility (Km) plot, a sharp decrease in the Km values is noted in samples from 547 m and 588 m depths. Microstructural investigation of the different samples reveals presence of thick quartz veins in samples from the above mentioned depths vis-à-vis other samples. Petrographic studies also reveal presence of the mineral "allanite" in sample from 547 m depth, which contained a thick quartz vein. It is thus suggested that studies involving AMS investigation of borehole samples from the top 1 km depth of the region hold promise in mineral exploration studies. [ABSTRACT FROM AUTHOR]