bluuebunny/crossref_metadata_2025 huggingface dataset:
Relation of Coastal Faults and River Morphology to Sea Erosion in Dakshina Kannada, Karnataka
Authors: Ravindra B. M. , Krishna Rao B.
Published: November 2024

A set of longitudinal and transverse faults have been recognised in the coastal tract of Dakshina Kannada district. The coastal faulting and the uplift of Western Ghats are attributed to sea-floor spreading centred on the Mid-Indian Ridge in the Arabian sea. St. Mary dacite eruption during Late Cretaceous must have heralded sea floor spreading in this part of the West Coast. Variations in the coastline and discrepencies in lithology of coastal Dakshina Kannada are explained by lateral movements along transverse faults. The unusual coast-parallel bends of west flowing rivers appear to be guided by longitudinal coastal faults.

Severe sea erosion in Dakshina Kannada was initiated by the increase of pore water pressure in the coast-parallel river bends and blind tributaries, resulting from massive fluvial discharge during monsoon period. The storm waves may have reactivated preexisting longitudinal faults and triggered slumping of the foreshore sea bed in preferential areas of pore water pressure accumulation and with this, destructive sea erosion commenced and it continued till the stumped area in the foreshore bed was filled up by sands brought back by backwash currents.

It is suggested that severe sea erosion in Dakshina Kannada can be controlled effectively by devising suitable canals to release the surplus stream discharge from the coast-parallel river segments and associated blind streams.
Environmental Impact of Coal Utilization in India - A Geochemical Approach
Authors: Sahu K. C.
Published: November 2024

The basic geochemical principle of coal formation indicates that coal deposits are sinks of a vatiety of toxic heavy metals. Burning of a large amount of high ash coal in a thermal power plant produces a considerable amount of solid waste in the form of ash. Coal ash has been found to have enriched concentration of many of the toxic metals as adsorbed species which on contact with rain water easily leach-out of the matrix only to disperse into various compartments of the ecosystem around the thermal plant. It is suggested that while recognising the deleterious environmental impact of use of a large amount ef high ash coal in thermal plants, precautionary measures should be taken to prevent the entry of the toxic metals into the ecosystem. The ash should be utilized for various developmental purposes.
A Comparative Study of Clay Minerals for Pollution Control
Authors: Raymahashay B. C.
Published: November 2024

The structure of montmorillonite provides two exchange sites; one at the surface and the other between the silicate layers. This is confirmed by the dibasic nature of H-montmorillonite. As a consequence, montmorillonite is capable of removing larger amounts of cationic pollutants compared with kaolinite. Anion uptake is relatively feeble and similar for the two clays. A review of recent experiments suggests that clayey soils could act as barriers against dispersion of toxic metals, detergents and dyes.
Formation Parameters of the Lower Eocene Rocks in Qatar
Authors: El-Sayed A. A.
Published: November 2024

The study of some carbonate rock samples collected from four different locations in Qatar and attributed to the Rus Formation (Lower Eocene) reveals that these rocks are mainly heterogeneous in their petrophysical characteristics. This is indicated not only by study of pore space geometry but also by a skewed distribution of porosity, permeability and hydraulic conductivity data.

These parameters help in reservoir evaluation and description. Useful empirical relations have been derived by which both the storage capacity and the gas-permeability of the studied rocks can be estimated. Study of SEM-micrographs have shown the influence of post-depositional processes on both porosity and gas-permeability in varying degress.
Magnetic Polarity Stratigraphy and Vertebrate Palaeontology of the Upper Siwalik Subgroup of Jammu Hills, India
Authors: Ranga Rao A. , Agarwal R. P. , Sharma U. N. , Bhalla M. S. , Nanda A. C.
Published: November 2024

Magnetic polarity stratigraphy of Upper Siwalik Subgroup, Jammu Hills was worked out based on partially demagnetized data from 208 sites in three sections: Parmandal-Utterbeni, Nagrota-Jammu and Balli. One/two bentonitized tuff horizons occur close to the base of a long reversed polarity zone associated with Pinjor age fossils. Fisson track dates of 2.8±0.56 m.y. and 2.31±0.54 m.y. have been obtained on the zircon phenocrysts from these tuffs. These data permit correlation of our magnetic stratigraphy with the standard magnetic polarity time scale. The longest sampled section spans the interval from 4.92 to 0.22 m.y. This dating places the lower part of Upper Siwalik in the early Pliocene.

In the sampled parts of the sections, the magnetic polarity zonation establishes 16 magnetozones in Parmandal-Utterbeni, 13 in Nagrota and one in Balli. Individual magnetic transitions can be correlated over a lateral distance of 62 km and these provide time lines for correlation of lithology from one section to the other.

Estimated rates of sedimentation indicate rates varying from 0-45 m to 0.71 m/l000 years for Gilbert and Gauss epochs, while a decreased rate varying from 0.21 m to 0.37 m/l000 years is indicated during the Matuyama epoch.

The ]ast folding event of Suruin-Mastgarh anticline is not older than 0.22 m.y. However, the decrease in the rate of sedimentation during post Gauss time could possibly be due to an earlier period of deformation.

A significant change in fauna near the Gauss-Matuyama boundary is observed by the appearance of Equus and cervids with antlers and by the absence of Hipparion. We correlate this boundary with the Tatrot-Pinjor faunal boundary, No change either in lithology or in the vertebrate fauna is observed at the Pliocene-Pleistocene boundary if it is to be placed at the top of the Olduvai Normal Subchron.
Secondary Geochemical Dispersion in the Lateritic Tracts Over Two Copper Sulphide Deposits in Orissa, India
Authors: Banerji P. K. , Mohanty A. K. , Mahakud S. P.
Published: November 2024

Host rocks are kyanite-quartzite at Kesarpur and uralitised garnet-diopside granulite (± scapolite) at Adash. Primary sulphides include chalcopyrite, pyrite and pyrrhotite with small but variable amounts of bornite. The ore bodies are lenticular and carry variable trace constituents of Ag. Au, Ni and Co. Supergene minerals occur only in thin stretches and include covellite, marcasite and violarite. No discrete zone of supergene enrichment is noted in the boreholes. Oxidised zones at the top are 15-45m. thick and analyse in Adash up to 2.27% Cu plus 0.4% Zn over 3-4 m width. Goethite, haematite, malachite, azurite and chrysocolla are the constituent minerals.

Feeble to strong anomalies are present in pedogenetic laterites over orc bodies. but spurious anomalies locally with 1 % Mn are common. Laterites in Adash are polycyclic and anomaly values are locally erratic. Over groundwater laterites of Kesarpur. very feeble secondary anomalies are confined to only 100 m from the ore zone.

Stream sediment signals are confined to first order seasonal drainge courses and are traceable for only 2-3 km from the source down stream. Such limited anomaly dispersion is due to differential block movements in this area.

Landforms developing under this dynamic system have not given rise to widespread and strong stream sediment dispersion patterns of chalcophile elements. Systematic search for small ore bodies in such tracts has, therefore, to be hased only on sampling the sediments of first order drainage courses.
A Study of Proterozoic Phosphorite from Chelima-Pachcherla Area, Kurnool District, Andhra Pradesh, India
Authors: Banerjee D. M. , Saigal Neeta
Published: November 2024

Stromatolitic and pelletal phosphorite deposits, belonging to Cumbum Subgroup of Nallamalai Group have recently been reported from Chelima-Pachcherla areas of Kurnool district in Andhra Pradesh. Most phosphorites of these areas are linked to the carbonate stromatolites like other Proterozoic phosphorite deposits of India. However, there are many variants which occur amidst quartzose rocks, assuming pel1etal forms, showing well marked neomorphic grain-growths and marked enrichment of elements like F, K2O, Ba, Co, Mn, V, Y and Pb. Based on mineralogy, petrology, and geochemistry of these phosphorites, a protected-isolated supratidal lagoon type of environment has been visualised for the precipitation and diagenetic alteration of the Cumbum phosphorite.
Tectonic Significance of Ultramafic and Associated Rocks Near Tal in the Bijawar Belt, Sidhi District, Madhya Pradesh
Authors: Roy Abhinaba , Bandyopadhyay B. K.
Published: November 2024

Serpentinised ultramafic bodies of peridotite-dunite composition occur as solid state intrusions in the Bijawar volcano-sedimentary sequence around Tal in Sidhi district, Madhya Pradesh. The associated basic volcanics and gabbros are predominantly tholeiitic in composition, although a slight enrichment in Na is recognised locally. However, apart from their juxtaposition, there is no petrological or chemical evidence to suggest that the uhramafic and gabbroic rocks were derived from a common magma. The ultramafics represent olivine-pyroxene cumulates, crystallised at depth and subsequently emplaced as crystalline mush (? diapiric intrusion) during the pre- to early-kinematic stage of basin development. This suggests the possible role of a mantle-derived magma to initiate basin depression. Near the cratonic margin of the basin, shelf sediments (orthoquartzite, carbonate-pelletal chert etc.) were deposited over the gneissic basement while the distal facies was mainly a turbidite. The rocks underwent polyphase deformation and low-grade greenschist facies metamorphism. The closing stage of Bijawar was marked by the emplacement of post-tectonic granite and occasional gabbroic diorite near the peripheral zones of the belt.
Triassic Microfauna of the Lilang Group with Special Reference to Scythian-Anisian Conodonts, Spiti Valley, Himachal Himalaya
Authors: Bhargava O. N. , Gadhoke S. K.
Published: November 2024

The Triassic microfauna from the type section of the Lilang Group recorded here includes conodonts (58 taxa), foraminifera (17 taxa), ostracoda (5 taxa) and radiolaria (one taxon).

Except for one form in the Carnian Sanglung Formatiqn, the conodonts are exclusive to the Scythian-Anisian Mikin Formation. The foraminifers come mainly from the Mikin, Norian Hangrang and Rhaetian-Dogger Kioto Formations. In the former two, they are rare, while in the last one common. The ostracodes chiefly occur in the Mikin Formation. The radiolarians are common in the Carnian Chomule Formation and sporadic in the Mikin Formation.

Based on microfacies analysis, the Mikin, Chomule and Sanglung Formations are interpreted to represent clear basin margin, Hangrang back-reef to fores]ope and Kioto restricted platform to edge-sand and lagoon environments. The varying abundance of the microfauna in different formations is possibly environmentally controlled. The conodonts, and radiolaria preferred basin margin, and foraminifers restricted platform to edge-sand and lagoon environments.
Zoning in Plagioclase (Normal and Oscillatory) in the Feldspar Porphyries of Karsog Area, Lesser Himalaya, Himachal Pradesh, India
Authors: Gupta L. N. , Marwaha S.
Published: November 2024

Growth of plagioclase crystals accompanied by rapid cooling and contemporaneous crystallisation with falling temperature is considered to cause disequilibrium due to incomplete reaction between the growing crystal and the residual sodic melt. This causes the formation of normal zoning. Regular oscillatory zoning has been explained mainly due to the process of diffusion of An-molecules towards the crystal face of growing plagiolcase in a magma. Growth of zoned plagioclase was accompanied by fractional crystallisation and accumulation of magma of trondhjernitic composition. During this process, zoned plagioclases came in contact with one another and resulted in synneusis. Partial resorption resulted in truncated zones followed by crystallisation of a more calcic rim.
Structural Analysis of Shear Zones in Basement Granite and their Relationship with Folding, Shearing and Faulting in the Cover Sediments Near Hirapur, District Sagar, Central India
Authors: Roday Prakash P. , Chourasia L. P. , Chaudhari Shailendra
Published: November 2024

The morphology of ductile shear zones in the granitic basement of Bijawar rocks is described. The dextral shear zones are more ubiquitous than their sinistral counterparts and the obtuse angle between the two sets faces the direction of maximum shortening in rocks, the exact value of the angle presumably controlled by the mean stress. The maximum displacement vector of shear zones is generally subhorizontal. The negative dilatation in some shear zones has caused the overall defoi marion in them to be of the flattening type. The orientations of the principal stresses are calculated. The cleavage trajectories do not sometimes exactly bisect the acute angle between the conjugate zones, presumably due to rotation of principal strains with progressive shear or to the more accentuated development of one set of zones.

The sinusoidal and conjugate folds of monochnic or triclinic symmetry (D-1) in the Bijawar rocks are shown to be related genetically and from the point of view of orientation of principal compressive stresses to the ductile shear zone development in basement granite. The brittle-ductile shear zones in the basal carbonate unit associated at places with pressure solution or tectonic stylolitic structures whose formation was accompanied by about 14 to 24 per cent volume reduction formed at the same time.

There was a renewed activity during post-Vindhyan time along pre-existing shear zones in the older rocks but in the opposite sense under very Jow P-T conditions which produced ductile D-2 structures in Bijawar rocks, culminating in small or moderate scale strike-slip faults. The youngest movements along these faults were, however, with a vertical component under a subvertically oriented maximum principal compression. It appears that most shear zones have an minal period of strain softening, followed by rather sudden strain hardening or loss of material contmuity which causes either the termination of such zones or their passing into model ate scale wrench faults.
On the Occurrence of Upper Gondwana Plant Beds near Chintalapudi, West Godavari District, Andhra Pradesh
Authors: Lakshminarayana G. , Gururaja M. N. , Kutumba Rao N.
Published: November 2024

Variegated clay-clast-bearing sandstones and purple claystones containing upper Gondwana plant fossils viz. Cladophlebis cf. denticulata, Ptilophyllum sp., Pterophyllum sp., Elatocladus conferta and Elatocladus cf. plana are recorded for the first time near Chintalapudi from the upper part of the 'Chintalapudi Sandstone' hitherto believed to be of lower Gondwana age. The present study has established that the newly identified upper Gondwana rock units belong to the Kota Formation overlying the 'Chintalapudi Sandstone' (= Karnthi Formation) with an unconformable contact.
Planktonic Foraminifera from a Quaternary Deep Sea Core from the Southern Arabian Sea
Authors: Divakar Naidu P. , Rao P. S. , Pattan J. N.
Published: November 2024

An investigation on planktonic foraminifera and calcium carbonate content of a box core collected at a depth of 2556 m from the southern part of the Arabian sea indicates faunal changes depicting Quaternary climatic fluctuations. Based on the study the Last Glacial Maxima (LGM) boundary is placed at 65 cm and below LGM. Three warm and two cold episodes are identified.
Age of Manganiferous Laterite of Uttara Kannada District, Karnataka
Authors: Krishna Rao B. , Ahmed Mohamed Muzamil , Janardhana M. R.
Published: November 2024

Palynological studies on the lateritoid manganese ore revealed the presence of angiosperm, bryophyta, pteridophyta, fungi and algae. Among these Polyporina sp., Polypodiaceaesporites haardti, Palmaepollenites communis, Sapotaceoidaepollenites africanus, Pediastrum simplex var.duodenarium, Pediastrum boryanum var. undulatum and Plumbaginacipitesneyvelii have been identified. They indicate that the lateritic weathering of the Precambrian manganiferous formation of the area took place during Neogene.
Geochemistry of the Continental Margin Sediments of the Central West Coast of India
Authors: Rao CH. M. , Murty P. S. N.
Published: November 2024

The modern sediments accumulating on the western continental margin of India between 17° and 13° latitude are composed predominantly of terrigenous material in the inner shelf with moderate organic carbon content (< 3%), carbonate sediments in the outer shelf with low organic carbon content (< 1%) and organic carbon rich (upto 12%) carbonate sediments in the slope region. The bulk and partition geochemistry of the surface sediments reflect the complex intermixture of several sedimentary components (lithogenic, authigenic and biogenic) and enable the identification of geochemical processes that are responsible for the incorporation of elements into the sediments. The elemental concentrations are found to be related to the distribution of three major components i.e, terrigenous debris (Si, Al,Ti, Fe, Mn, Cu), authigenic Calcium Carbonate (Sr, P) and organic carbon (P, Ni, Zn).
Silver Mineralisation in Early Proterozoic Rocks of Bharak Area, Near Baghera, District Bhilwara, Rajasthan
Authors: Goyal R. S.
Published: November 2024

Rich silver mineralisation (up to 0.78% on the surface and O. 58% in borehole) has been discovered in siliceous dolomitic marble at the interface with stratigraphically underlying calc-silicate rocks of Bharak area (Rajpura-Dariba Group of Late Archaean/ Early Proterozoic age). The surface geochemistry over the region bas helped in delineating a 600 m x 200 m zone on the surface having sil vel' content of more than 10 ppm and ranging up to 7800 ppm. The subsurface data obtained by drilling has shown the extension of the mineralised zone beyond the limits of the surface geochemical anomaly, and the extension is caused by the continuation of folded strata below surface. Ore microscopic study has indicated that the main silver ore mineral is cerargyrite (AgCI) with minor relicts of argentite Ag2S).

The variation diagram of Ag-Cu-Pb-Zn in the stratigraphic layering at the contact zone of siliceous dolomitic marble and the calc-silicate rocks, depicts significant patterns showing syn-sedimentary stratiform silver precipitation in a particular stratigraphic section, at the bottom of the siliceous dolostone. Two pulses of chemogenic silver precipitation within the bottom part of the siliceous dolomitic marble associated with CuPb- Zn are identified, while the effects of remobilisation and supergene enrichment are predicated by certain aberrant peaks of silver with variable relationship of associated metals such as Cu, Pb and Zn.
Late Pleistocene Fluvial Response to Tectonics in Jammu, Jammu and Kashmir
Authors: Ganjoo R. K.
Published: November 2024

The Quaternary tectonics in the sub-Himalayan zone is postulated on the basis of the LANDSAT imagery study of the structural features in the area. These studies are corroborated by geomorphic evidences as well. The deposition of Katra fill at the foot of Trikuta hill, the entrenchment by river Tawi and deep gorge at the exit of river Tawi from Udhampur dun indicate neotectonism. The event resulted in the integration of fluvial system. This is evident from the presence of rock components of Inner Himalaya in the late Pleistocene deposits.
Clay Mineral Distributions in Dated Miliolites of the Late Quaternary from Saurashtra and Kutch, Gujarat
Authors: Baskaran M. , Somayajulu B. L. K.
Published: November 2024

Forty-three dated miliolites (ages ranging from 30-235 kyr) of the late Quaternary period, from Saurashtra and Kutch regions of Gujarat State have been analysed for their detrital contents as well as for the four clay minerals, smectite, illite, kaolinite, and chlorite in the less than 2 micron fraction.

Between 235 kyr and 140 kyr BP. there was less detrital material available in the regions of miliolite formation. Landward and seaward sources, notably from southeast and northwest directions contributed equally efficiently to the clay component of the detritus resulting in illite smectite ratio of 1.0. This situation prevailed during 70-50 kyr BP as well as at around 12 kyr BP except that the total detritus in miliolites increased by a factor of about three, during the two recent periods. However, during 95-115 kyr BP, despite the high detrital content of 24%, the illite/smectite ratio dropped to 0.3 indicating the expected dominance of the local and southeastern sources which are enriched in smectite in their clay fractions.
Stratigraphy of the Gondwana Formations in the Chintalapudi Sub-Basin, Godavari Valley, Andhra Pradesh
Authors: Lakshminarayana G. , Murti K. S.
Published: November 2024

The Chintalapudi sub-basin, in the southeastern part of the Pranhita-Godavari Valley, was hitherto believed to contain mainly the Kamthi Formation of the Lower Gondwana Group. Recent geological mapping has brought to light the existence of the upper Gondwana sequence consisting of Kota and Gangapur Formations and also the occurrence of new areas of Talchir and Barakar Formations. Revised stratigraphic succession shows, in ascending order, Talchir, Barakar, Kamthi (Lower Gondwana). Kota and Gangapur Formations (Upper Gondwana). The Gondwana sediments are disposed in a NW-SE trending' graben affected by longitudinal and transverse faults. The Barakar Formation is identified over an area of 130sq km in Ayyanapalem-Sattupalli-Pakalagudem area, Khammam district, Andhra Pradesh. Stratigraphic drilling near Sattupalli has established the presence of coal seams with in a depth of 325 m in this newly identified Barakar Formation. The preliminary study of coal seams indicates that the coal is of Class III to Class IV type. The present study has established a new coal belt around Sattupalli in Chintalapudi Subbasins and this find is expected to augment the coal resources of the Godavari Valley considerably.
Geothermal Model of the North-Eastern Region of India: Its Possibilities and Limitations
Authors: Cermak V. , Kubik J. , Saikia M. M. , Sitaram M. V. D.
Published: November 2024

The empirical relationship between observed Pn (Sub-Moho) seismic velocities and the surface heat flow (including also the assessed crust-upper mantle temperatures) was used to improve the understanding of the regional geothermal activity of the North-Eastern Region of India. Vertical seismic velocity profile was further converted into radiogenic heat production and the knowledge of the crustal heat sources helped in both, to estimate deep temperature distribution within the crust and to evaluate the Moho heat flow. The most probable existing temperature at the crust-upper mantle boundary is between 800 and 900°C and the flow of heat from below the crust attains about 50% of observed surface heat flow, i.e, about 30mW. m-2.
Facies Analysis and Depositional Environment of Pokaran Saline Rann, District Jaisalmer, Rajasthan, India
Authors: Rai Vikram
Published: November 2024

Pokaran Rann occupies an area of 12.0 sq. km in Jaisalmer District of Rajasthan, resting over the basement rocks of Marwar Supergroup. Five distinct litho-facies are recognized in a basin developed along E-W-trending linear stretch of palaeo-course after calcification. The base of the sequence consists of inter-laminated clay /gypsite unit. This unit grades into carbonate-rich clay showing pede-calcic pedogenesis. After a break in sedimentation, highly bio-turbated clays were deposited probably during a prominent humid phase. This was followed by present day semi-arid climatic conditions which resulted in the formation of silt to silty-clay deposits.
Upper Barakar Lebensspuren from Hazaribagh, India
Authors: De Chirananda
Published: November 2024

A five metre thick silty-sandstone unit, below the topmost coal seam of the Barakar Formation, has been given a status of 'Burrrow Zone' owing to the presence of trace fossils in large numbers and variety. Six geometric forms have been described. The first two represent horizontal intrastratal burrow system (branching and nonbranching), and were produced by fresh water crickets. The fecal pellets (type 3) and the associated vertical tubular burrows (type 6) are correlated with one or both of beetles and crustaceans. Selective search for food from organic matter-rich sediments led to the formation of these fecal pellets. Type 4 and 5 structures represent trail marks of horsehair worms on the sediment-water interface.

Late Barakar basin experienced a very low energy condition of deposition which accelerated the luxuriant growth of plants and organic activities in all possible interfaces. Sudden change over to high energy condition prior to the start of Barren Measure sedimentation ceased all biogenic activities. This resulted in the formation of a burrow zone below the Barren Measure Formation.
Geoenvironmental Appraisal of the Proposed Site for Vidyadharnagar Township, Jaipur, Rajasthan
Authors: Das Sarma D. C.
Published: November 2024

The Amanisha river has shifted from west to east over the area and has left behind an array of abandoned channels and gullies under blown sand cover. This imparts considerable restraints on the urbanisation of the area. The potential environmental hazards include accentuated gully erosion, aggradation of the river leading to flash flood, underseepage in abandoned channels, sand mobilisation etc. The areas under potential hazards have been demarcated.
Petrogenesis of Metabasites from the Schist Belts of the Dharwar Craton: Implications to Archaean Mafic Magmatism
Authors: Rajamani V.
Published: November 2024

The supracrustal belts of the Dharwar Supergroup in the Dharwar Craton include variably metamorphosed komatiitic and tholeiitic volcanics. Komatiites in general occur only in minor amounts. Available geochemical data of these rocks from the Holenarasipur ? Kudremukh, Bababudan and the Kolar schist belts were quantitatively modelled to infer that (1) Komatiitic magmas originated from deeper mantle sources at depths > 100 km., (2) tholeiitic magmas formed at depths < 50 km from sources different from those of komatiites and with much higher Fe/Mg ratios compared to normal mantle, (3) the two magma types are not genetically related either to one common parental magma or to one common source, (4) Dharwar magmatism could be related to rift related volcanism perhaps associated with one or more mantle plumes. High quality geochemical, including isotopic, data on a large number of samples is required to test this model of Dharwar magmatism.
Gravity Surveys for Lignite in Parts of Soutb Arcot and Tiruchchirappalli Districts, Tamil Nadu
Authors: Vajdyanathan N. C. , Appa Rao M. , Balakrishna Rao N. , Subrahmanyam S.
Published: November 2024

Lignite occurs within the Cuddalore sandstones of the Tertiary Group. The Bouguer gravity map has demarcated the basin with the axis extending from north to south passing close to Andirnatam, with steep gradients towards east and south. The residual gravity map has revealed three broad negative zones, comprising several gravity closures with magnitudes varying from -0.2 to as much as -1.7 milligals. Only a fraction of the anomaly could have been caused by the lignite body. It is likely that these zones indicate possible local depressions forming troughs or sub-basins where lignite deposits are likely to be confined. The boundaries of the lignite-bearing zones are fairly well marked. Drilling in two zones has proved the presence of lignite seams of 3 to 14 metres thickness at depths varying from 67 to 135 metres. The surveys have proved that the gravity method could advantageously be employed for delineating zones favourable for lignite deposits in similar environs.
Geochemistry of Trondhjemites from Sigegudda, Hassan District, Karnataka
Authors: Rama Rao P. , Naqvi S. M. , Govil P. K. , Balaram V.
Published: November 2024

The Sigegudda trondhjemites contain moderate Zr, high Ni and Cr and therefore appear to have formed by partial melting and/or fractional crystallization of Ni- and Cr-rich rocks like amphibolites. Lack of fractionation of Y, Zr and TiO2 and comparatively lower LREE/HREE ratio in these rocks perhaps indicate that garnet was not present in the magma source. The trondhjcmites were probably emplaced during the stabilization of the western Dharwar craton around 3.0 b.y. ago.
Central Indian Shear Zone: A Major Pre-Cambrian Crustal Boundary
Authors: Jain S. C. , Yedekar D. B. , Nair K. K. K.
Published: November 2024

The paper records the occurrence of mylonites along a major ductile shear zone in Nagpur-Bhandara- Balaghat-Bilaspur-Korba region of Central India, now named as Central Indian Shear/Suture zone (C.I.S.). The main shear zone extends from SSE of Nagpur to south of Korba over a distance of 500 km with a sinuous E-W trend and subvertical to steep northerly dips. Its northern branch extending in ENE direction from Amarkantak to north of Nagai has been named as the Tan Shear. The CIS separates the high-grade Sausar metasediments with a zone of granulites to its north from the dominant low-grade volcanogenic sequences to its south.

Bouguer gravity trends over Central India suggest that the CIS probably extends eastwards into the Singhbhum shear zone of Bihar-Orissa and westwards, into the Delhi-Aravalli shear zone in Rajasthan.
Geomorphic History and Lithostratigraphy of a part of Eastern Gangetic Plain, Uttar Pradesh
Authors: Joshi D. D. , Bhartiya S. P.
Published: November 2024

The Quaternary deposits of the area are classified into three lithounits, viz., Varanasi Older Alluvium, Chhoti Sarju Older Flood Plain Deposits and Chhoti Sarju Recent Flood Plain Deposits. The facies organisation of the Varanasi Older Alluvium (+300 m thick), indicates a braided to meandering river environment for the lower sandy facies and meandering river to local lacustrine conditions for the upper silt clay facies. Presence of a regionally persistent shell-bearing silty-clay horizon (at a depth of about 1 m to 2 m below ground level) indicates commencement of lacustrine conditions towards the waning phase of sedimentation of Varanasi Older Alluvium. The Chhoti Sarju Older Flood Plain Deposits rest over the eroded surface of Varanasi Older Alluvium. This deposit is about 10 m thick with fining upwards sandy facies deposited in a meandering river regime. The Chhoti Sarju Recent Flood Plain Deposits are confined within a very narrow zone (approx. 250 m wide) in the bed portion and flood plain of the river. In this regime, the sedimentation is still going on in the form of point bars, channel bars and side bars. At places, lacustrine conditions (oxbow lakes) are also present.

The Quaternary history of the area indicates at least two prominent episodes of base-level (sea-level) rise during the Late Pleistocene-Holocene period.
Compositional Variations in Mackinawites from the Chandmari Mine of Khetri Copper Belt, Rajasthan
Authors: Mukherjee Ananda Deb , Sen Partha Pratim
Published: November 2024

The occurrence and optical properties of mackinawites of different chemical, compositions from the Chandmari mine are described. The fact that mackinawites are clearly capable of accommodating a wide range of cations in their structures has been explained.
A Note on the Yttrium Mineral Potential of Granitic Soils in Parts of Andhra Pradesh, India
Authors: Singh Yamuna , Rai S. D. , Lakshminarayana Y. , Sankaran R. N.
Published: November 2024

Survey in parts of Karimnagar district, Andhra Pradesh, has brought to light the occurrence of colluvial placer deposits with appreciable concentration of REE and Y minerals in Dharmawaram-Yerabali area. The heavy minerals in the soil are thorite, zircon, xenotime, monazite, rutile, ilmenite, brookite, and magnetite. Panned concentrates (n=18) analysed 0.19 to 0.40% Y2O3 Dilute sulphuric acid leaching of the mineral concentrates solubilised 50% Y2O3.
On the Occurrence of Sargur Type Banded Iron-Formation in Banded Gneissic Complex of South Rajasthan
Authors: Sahoo K. C. , Mathur A. K.
Published: November 2024

The occurrence of BIF from a part of Banded Gneissic Complex of Rajasthan is reported. Older than 3.0 Ga granites, their field-setting and petrochemical characters are comparable to the BIF of older supracrustals of south India (Sargur Group).
A New Fluorite Deposit in the Palamau District, Bibar and the Associated Iron-Fluorine-Tungsten Skarns and Hornfelses
Authors: Soni S. , Mukherjee A. B. , Sengupta D. K.
Published: November 2024

Fluorite ore has been located at the Gore and Nawadih magnetite mines, about 20 km SW of Daltonganj. Palamau district, Bihar. The fluorite-bearing parageneses include amphibole-magnetite-quartz schists. mica schists and magnetite-quartz rocks-all occurring as discontinuous bands within the Chotanagpur granite gneiss. The amphiboles include hornblende, cummingtonite and anthophyllite. Scheelite occurs as an accessory mineral with fluorite', Pegmatitic granite and tonalitic gneiss occur as tongue-like intrusives within the schists. A calcite-clinohumite-periciase (brucite)-spinel-magnetite-sphalerite paragenesis is also reported from an adjoining area at Teliaband, 14 km east from the Gore-Nawadih mines. Thermal metamorphism of the hornblende hornfels facies accompanying a high temperature Fe-F-W pneumatolysis has apparently produced the fluorite-magnetite ore.
Origin of Miniature Pits in the Quartz-Arenites of the Badami Group (Younger Proterozoic), Umatar, Belgaum District, Karnataka
Authors: Ganesh A. , Sathyanarayan S.
Published: November 2024

A 50 metre thick horizontal to gently inclined sequence of granule conglomerate and Quartz arenite of the Badami Group (younger Proterozoic, ~1.6 Ga-1.0 Ga) is exposed at Umatar, Belgaum district, Karnataka. During the course of field mapping the presence of numerous miniature pits were noticed along the southern fringes of the outcrop, i.e., on the farther updip edge of the seaward slope inclined due north. Such structures have been commonly interpreted as products of weathering processes. But the morphology and anatomy of the miniature pits at Umatar points to their origin initially by wave splash action, later primary tilling by subsequently deposited sand, lithification and later modification by weathering leading to the removal of loose incoherent sand, filling the pits; finally, colesion, frost action and undercutting of the pits. The marginal updip concentration or the pits strongly supports their primary-origin.
Salinity in the Ground Water of the Purna Basin-Its Genesis
Authors: Muthuraman K. , Tiwari M. P. , Mukhopadhyay P. K.
Published: November 2024

Major element chemistry of the saline and the non-saline waters occurring between Popat-Khed and north of Akola indicate that the saline/fresh water contact is quite sharp and the saline waters are significantly restricted to the sandy aquifers inter-layered by clay beds, creating quasi-confined condition.

The ratios of major anions and cations of the saline waters are not comparable to those of sea-water. The plots of the major cations versus chloride are quite scattered and do not indicate any trend similar to their evaporite curves.

In view of the high 'Na/(Ca+Mg)' ratio, negative indices of base exchange and high SiO2-content of these waters, it is contended that these saline waters are nothing but diagenetically altered meteoric water having a long residence time.
Pegmatites: A Potential Source for Siting High Yielding Wells
Authors: Karanth K. R. , Jagannathan V. , Prakash V. S. , Saivasan V.
Published: November 2024

Exploratory wells drilled in pegmatites in Karnataka, Kerala and Tamil Nadu have recorded high yields. The median specific capacity value is 80 1/min-m. A commonly observed phenomenon is that discharge of a borewell increases immediately after striking pegmatites. The detailed, long duration pump tests conducted also indicate their sustained high performance.
Intrabasinal Differential Subsidence and its Influence on Coal Thickness Configuration, Barakar Formation, Sohagpur Coalfield, Madhya Pradesh
Authors: Chakrabarti Utpal
Published: November 2024

Spatial and temporal variations in small scale subsidence pattern in a part of Sohagpur Coalfield have been identified and mapped using the method of graphic correlation. Subsidence was differential at the initial stage which later gave way to a tectonically stable condition of deposition. Lateral variations in thickness and continuity of mineable coal seams, however, cannot be satisfactorily explained in terms of relative rates of subsidence only. Geometric properties of the coal seams instead reveal a dominant control of depositional environment on seam morphology.
Geochemistry of the Sarnu-Dandali Carbonatites, District Barmer, Rajasthan, India
Authors: Chandrasekaran V. , Srivastava R. K.
Published: November 2024

The Sarnu-Dandali carbonatites of Western Rajasthan are some of the few occurrences of a typical carbonatit-nephelinite magmatic association known from India. They occur as dykes and dykelets of sovitic-alvikite and ferrocarbonatite showing distinct variation in their chemistry. The sovitic-alvikites have high contents of BaO (up to 3.42%) and SrO (up to 1 %). Fractionation trend is marked by decreasing concentration of SrO from sovitic-alvikite (1.00%) to ferrocarbonatite (0.06%). Trace element contents reveal pronounced preference of Ce and other rare earth elements for sovitic-alvikites. Their oxygen and carbon isotope values are that of typical primary igneous carbonatites. The chemical and isotopic data reveal that the Sarnu-Dandali carbonatites are magmatic, fractionated and have originated from a mantle-derived nephelinitic magma.
Volcanological Aspects of Jungel Metavolcanic Suite, Bijawar Greenstone Belt, Central India: Suspect Ancient Island-Arc Volcanism
Authors: Kumar Vinod
Published: November 2024

Spectacular array of volcanic structures shown by Jungel metavolcanics include pillow structures, pahoehoe flows and toes, groove lava and shark tooth projections. Some of these features are indicative of small volume phreato-magmatic eruptions under shallow water conditions. The style of igneous activity is inferred to be moderately explosive, fragmental and spasmodic, supported by substantial. amount of volatiles. Based on volcanological, geochemical and tectonic evidences it is suggested that the present volcanic rocks were erupted in island-arc environment and that the southern margin of the Bundelkhand protocontinent formed a zone of subduction.
Volcanic eruption of the Barren Island Volcano, Andaman Sea
Authors: Haldar D. , Laskar T. , Bandyopadhyay P. C. , Sarkar N. K. , Biswas J. K.
Published: November 2024

Geotectonically the Barren and Narcondum islands lie on the Neogene Inner volcanic are, which proceeds from the recent volcanoes of Central Burma in the North to the Miocene to Recent volcanoes of Indonesia in the SE and are believed to have evolved as a result of eastward subduction of the Indian Ocean lithosphere below the SE Asian plate. The Barren island volcano is characterised by resurgent volcanism; so far, three distinct volcanic episodes have been recorded. An initially submarine volcanism, possibly taking place in late to Post-Pleistocene time formed a giant volcanic cone representing the ancestral Barren island. This ancient volcanic cone was at times, blown out and a thick pile of pyroclastics got deposited over the surface of the relict cauldron. Historical records reveal that the volcano became active again in 1789 when the existing cone with a crater and three subsidiary vents were developed. The present eruption initially starting from the NE subsidiary vent, subsequently merged with the main crater. The intensity of volcanic eruption gradually gathered momentum and continued unabated with thundering explosions till the end of September, 1991. Since November it is lying dormant. There is no major disastrous effect.

The lava of the first phase was olivine basalt and that of the second pbase a high-alumina olivine basalt.
The Central Crystalline Precambrian Peraluminous Granites of the Western Part of Bhutan Himalaya
Authors: Sarvothaman H.
Published: November 2024

The quartzo-feldspathic protoliths associated with the Central Crystalline gneisses of the western Bhutan-eastern Sikkim Himalayan segment are of peraluminous adamellite, granite (s.s.) and trondhjemite compositions. Peraluminous granite melt of first event is generated coeval to the kyanite or sillimanite grade metamorphism and it has syntectonically intruded a metapelite-quartzite sequence. These granites, along with the mctasedimentaries. have undergone partial melting under amphibolite facies conditions resulting in the generation of the peraluminous granite melt of second generation. which has syn- to late-tectonically intruded the pelitic sehist-quartzite-peraluminous gneiss assemblage. Approximately 20 Ma old post-tectonic peraluminous granites (s.s.) of the third event have intruded the Central Crystalline. The Central Crystalline adamellite-granite-trondhjemite suite is of 'non-minimum' melt compositions in contrast to the 'minimum melts' of the =20 Ma old leucogranites (such as the Manaslu granite of Nepal), which show unifonn granite (s.s.) compositions.
Sedimentological Evidence for a Palaeobeach off Mangalore, West Coast of India
Authors: Shankar R. , Karbassi A. R.
Published: November 2024

Sedimentological and SEM studies have been carried out on surface and sub-surface samples of outer shelf sands off Mangalore, west coast of India. The outer shelf sediments can be described as coarse sands, moderately sorted, nearly symmetrical to positively skewed and mesokurtic. Multi group discriminant analysis of the data shows that the sands were deposited in a beach environment during Pleistocene when the sea level was lower than at present. SEM studies reveal mechanically formed features like  'v' pits and curved grooves, which also corroborate the beach environment of deposition. The' v' pits and grooves have been smoothened due to chemical etching of the grains as the latter were in contact with sea water subsequent to the Pleistocene-Holocene transgression. Similar sand in cores obtained from east of the palaeobeach indicates its extension beneath Recent sediments. The thickness of palaeobeach sand increases landward. The cores studied have recorded tbe marsh Get black colour and abundance of vegetative matter), beach (coarse sands) and inner shelf (clayey silt) environments that prevailed at the core site as the sea transgressed. It is proposed that the outer shelf sands were not covered by Recent sediments because of the insufficient supply of sediments from the small, west-flowing rivers of Peninsular India, entrapment of sediments in estuaries, and onshore transport of sediments in the West coast region.
Deformational History and Shape Analysis of Folds in the Metamorphic Rocks of the Petermann Ranges, East Antarctica
Authors: Bejarniya B. R. , Joshi A.
Published: November 2024

Considered earlier to be very little defonned, the granulite facies rocks of the Petennann Ranges, East Antarctica, reveal three phases of folding and two episodes of ductile shearing. These metamorphic rocks preserve the F1 folds as small scale, rootless, intrafolial features with tight to isoclinal profiles, and F2 folds as mesoscopic features with close to tight profiles. F1 and F2 folds are coaxial and broadly coplanar having axial surfaces marked by pervasive NW-SE striking foliation. F3 folds are open, upright with N-S to NNW-SSE axial planes and impart local swings in the regional foliation. The early ductile shears produce a strong mylonitic fabric and are synchronous to F1, while occurring as thin wavy zones, the later shears are post F2.

Shape and geometric analyses of representative folds show that F1 folds belong to class 2 and 1C at low and high limb dips respectively and are fonned dominantly by flexural flow. F2 folds exhibit geometric features of class 1C at low as well as high limb dips and owe their origin to buckling with a flexural slip component and flattening.
Quartz Grain Surface Textures as Indicators of Depositional History of Beach and Strand Plain Sediments Along the North Kerala Coast
Authors: Samsuddin M. , Ramachandran K. K. , Dora Y. L.
Published: November 2024

SEM analysis of quartz grain surfaces from the strand plain show many of the characteristic textures that are produced under sub-aqueous environments with second generation features of wind action. It is inferred that the initial stage of deposition of the strand plain sediments was associated with a wave dominated environment. With emergence of this coast, the strand plain sediments were exposed to sub-aerial action, thus registering both sub-aqueous and sub-aerial action features.
Thermodynamic Data for Dolomite and Kutnahorite from the Experimental Decarbonation Curves
Authors: Tareen J. A. K. , Fazeli A. R. , Basavalingu B. , Bhandage G. T.
Published: November 2024

The P-T stability field of rhombohedral double carbonates, CaMg (CO3)2 (dolomite) and CaMn (CO3)2 (kutnahorite) has been studied up to 2 kb of PCO2. The dolomite decomposes to CaCO3 (ss)+MgO+CO2 and the kutnahorite to CaCO3 (ss)+MnO+CO2. The kutnahorite was considered to be completely disordered (R¯3C) near the decomposition temperature while the dolomite was found to be in ordered state at the decomposition temperature, though both were considered to stabilise with ordered structures at lower temperatures. The standard enthalpy and free energy data retrieved for the ordered dolomite is ; ?H0f = -2331.64±2.07 kJ/mol, ?G0f = -2168.59±2.07 kJ/mol., and for the disordered kutnaborite, is; ?H0f = -2093.46±3.77kJ/mol, ?G0f = -1944.80±3.77kJ/mol. The new data on dolomite are atIeast 7 kJ more negative than the earlier reported values. In the low temperature region the double carbonate field is preceded by a metastable two carbonate field of M'CO3 (ss) and M"CO3 (M' = Ca, M" = Mg, Mn) phases. This is considered to be the likely stage in the natural process of dolomite or kutnahorite formation.
Raoceras, A New Cretaceous Ammonoid Genus from Southern India and Some Observations on the Distribution of Pachydiscids in India
Authors: Ayyasami K.
Published: November 2024

A new Cretaceous pachydiscid ammonoid genus Raoceras, with the type species AmmonitesKuluturensis Stoliczka, is proposed. The Genus is restricted to the Coniacian. Its affinity with other pachydiscid ammonoid genera, the associated fossils in the field and its stratigraphic status are given. The known pachydiscid species in various marine Cretaceous basins of India are listed and correlated.
Foraminiferal Events Across K/T Boundary and Age of Deccan Volcanism in Palakollu Area, Krishna-Godavari Basin, India
Authors: Jaiprakash B. C. , Singh Jagmohan , Raju D. S. N.
Published: November 2024

Temporal distribution of planktonic and benthonic foraminifera across the K/T boundary in the Palakollu deep well section of Krishna-Godavari (KG) Basin, India, suggests that the lower Deccan trap flows have erupted during Zone M-18 of the latest Maastrichtian (66.5-65.5 m.y.) to Danian and the upper flows in lower Zone P2 of the Early Paleocene (6 1.2-60.7 m.y.). The span of volcanism will be approximately 6 m.y.