bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geochemistry and Petrogenesis of Dolerite Dykes In and Around Kolar Schist Belt, South India
Authors: Sahoo Jayaram , Balakrishnan S. 
Published: November 2024

Abstract
The Kolar Schist Belt and adjoining areas of Dharwar Craton are considered to be accreted terranes. Two distinct sets of dolerite (diabase) dykes, trending E-W and N-S are found in the area. The major minerals in the dykes are plagioclase feldspars (50-65 mol. % anorthite) and c1inopyroxenes (augite, sub-calcic augite and magnesian pigeonite).
The Kolar dyke samples are essentially tholeiitic except for one sample which resembles a basaltic komatiite. Mineral, as well as, whole rock chemistry of the dyke samples indicate an iron enrichment trend. The modelling of major and trace elements of Kolar dykes suggest that their parental magmas must have been derived from Fe- enriched sources with higher Fe/Mg ratios than primitive mantle. Source for parental magma to the basaltic komatiite dyke has been inferred as garnet lherzolite, whereas, for all others it could be komatiite with variable Fe/Mg ratios.
The Kolar dyke samples are enriched in light rare earth elements (LREE) and have variable abundances of heavy rare earth elements (HREE) relative to chondrites. The modelling of major, trace, and rare earth element data indicate that the generation of parental magmas took place from sources similar to komatiites, by low percentages (&lt;30%) of partial melting, within the lithosphere at pressures less than 3GPa. Magmas representing the dyke samples could have undergone small extents of fractional crystallisation and assimilation of granitoids. It is suggested that the partial melting of lithospheric sources is related to its stretching and elevation of geothermal gradient, possibly, as a result of intrusion of picrite/kornatiite melts into the lithosphere.
Fluid Inclusion Evidence for Amphibolite-Granulite Facies Transitional Metamorphism in Delhi Supergroup of Rocks
Authors: Sachan Himanshu K. 
Published: November 2024

Abstract
The Deri-Ambaji massive sulphide deposits are associated with the Precambrian rocks of Delhi Supergroup. Detailed fluid inclusion studies of quartz associated with the host rock of sulphide deposit as well as with ores show high density CO2 (1.05-1.08 g/cm3) as the dominant fluid phase and C02-H20 (0.94-0.98 g/cm3) and minor H2O inclusions are also present. The isochore for the high density fluid inclusions indicate the pressure limit of 7.5 Kbars, at the upper temperature limit 800°C, which is in accordance with the estimation by mineralogic thermobarometery. The lower P-T limit is of 2.5 Kbar at 500°C, which indicates that the transition of upper amphibolite to granulite facies of metamorphism has taken place in the area. The P-T path delineated from combined mineralogical and fluid data is characterised by T-convex nature, which is indicative of isothermal crustal uplift, probably promoted by extensional tectonics.
Indications of Hydrocarbon Generation in the Coal Deposits of the Rajmahal Basin, Bihar: Revelations of Flourescence Microscopy
Authors: Singh Mahendra P. , Singh Prakash K. 
Published: November 2024

Abstract
Application of Fluorescence microscopy to the organic petrological study of Rajmahai Coals has been done with a view to have a correct qualitative and quantitative assessment of the Liptinite constituents of these low rank coals. The study has revealed the presence of hydrogen rich constituents which were recorded as mineral matter under white incident light due to their greater resemblance to clay minerals, being dark grey to black in colour. These constituents are bituminite, flourinite and exsudatinite which occur in considerably high concentrations and are proved to be a kind of expelled hydrocarbons. Further, it has been observed that the concentration of these expelled secondary constituents is much higher in the basal parts of the coal seams suggesting high activity of their generation in the over-pressured zones of the coal seams. Besides, the study suggests that the "birthline" or maturation level desired for the generation of liquid hydrocarbon is 0.5% Ro mean.
Ground Water Quality in Weathered Singhbhum Granite around Karanjia, Southern Bihar, India
Authors: Mahato Dharun 
Published: November 2024

Abstract
Selected samples of well and spring waters from the weathered profiles of Singhbhum Granites show strong control of soil mineralogy. Felspars, mica, quartz and some mafic minerals in the bed rocks weather to kaolinite rich top soils in the cultivated lands. Soils at higher slopes are lateritic. Lime concretions are common and quartz is ubiquitous.
The HCO3/SiO2 mole ratio in the waters is in the range predicted for alteration of augite to kaolinite and plagioclase to montmorillonite. The silica level is above quartz solubility and generally below solubility of amorphous silica. Kaolinite and potassium are thermodynamically stable in ground water environment.
Cyclic Volcanism and Sedimentation in the Mahakoshal Greenstone Belt, District Sidhi, Madhya Pradesh
Authors: Tripathi S. C. , Mishra M. N. 
Published: November 2024

Abstract
Several ordered cycles of volcanism and sedimentation have been recorded from the Mahakoshal greenstone belt in the eastern part of the Sidhi district, Madhya Pradesh. Each cycle is characterised by pillow lava-pahoehoe toes, bomb agglomerate. volcanic breccia and tuff, culminating with the deposition of massive chert under quiescent conditions. The volcanics and the sediments exhibit linear distribution and were deposited as a result of eruptions along ENE-WSW trending fissures, parallel to the margins of the belt. The deposition of volcanics and sediments took place over thin Archaean sialic crust where tholeiitic magma differentiated at a depth of less than 15 km.
Origin of Grunerite Schist-Hosted Magnesite Mineralization in Copper Mountain Area, Sandur Schist Belt, Karnataka
Authors: Krishna Rao B. , Hanuma Prasad M. , Vasudev V. N. , Sethumadhav M. S. 
Published: November 2024

Abstract
Magnesite mineralization in the Copper Mountain areaofthe Sandurschist belt occurs scattered in a 5 km long and 50 to 200 m wide grunerite schist unit of Late Archaean age. Magnesite occurs mostly as less than a cm to about 50 cm thick parallel to subparallel veins. The veins are confined to gently dipping joints and tensional fractures transecting the steeply dipping bedding and schistosity of the host rock. Magnesite is cryptocrystalline and is associated with minor amounts of dolomite/magnesian calcite, calcite, cryptocrystalline silica and iron oxyhydroxides. Magnesite veins are essentially of cavity filling origin. Field setting, rock and mineral chemistry and stable isotope data indicate that magnesite was precipitated at ambienttemperatures from descending meteoric waters enriched in biogenic and atmospheric CO2 and Mg2+, the latter derived from the upper weathered portion of the host grunerite schist.
Calcite Fabric from the Southern Part of the Chitradurga Schist Belt, Karnataka
Authors: Prasanna Kumar V. 
Published: November 2024

Abstract
On the basis of calcite orientation, the temporal relations between crystallisation, folding and formation of foliation in the Chitradurga schist belt are attempted. Stress orientation at the time of deformation and spatial orientation of the hinge lines of syncrystallisation folds have been determined. While syntectonic recrystallisation seems to be the dominant mechanism, pressure solution and intracrystalline deformation might also have played a role in fabric development.
The Magnitude of Hiatus and Sea Level Changes Across KIT Boundary in Cauvery and Krishna-Godavari Basins, India
Authors: Raju D. S. N. , Jaiprakash B. C. , Ravindran C. N. , Kalyansunder R. , Ramesh P. 
Published: November 2024

Abstract
A Major hiatus of varying time span ofiess than 1 Ma to greater than 30Ma encompasses the Cretaceous/Tertiary boundary (KTB) in several parts of the Cauvery, Krishna-Godavari (KG) and other pericratonic basins of India. The succession in the north and northeastern parts of Cauvery basin is apparently continuous, whereas in other areas of this basin, either the sediments of Late Maastrichtian or Middle-Late Maastrichtian or even Middle Campanian-Maastrichtian are unrepresented due to erosion/nondeposition. A north-northeasterly tilt within the Cauvery basin with some tectonic blocks subsiding is inferred during Late Maastrichtian. An additional event of global significance that occured across orvery close to the KTB in KG basin is volcanism within alimited duration of 3.8 to 5.5 Ma equivalent to Deccan volcanism. The succeeding transgression in Paleocene-Early Eocene was in pulses at levels ranging from Zone PI-P7. This hiatus appears to be linked with the rise of a giant hot mantle plume just prior to the eruption of Deccan volcanism during Abathompalus mayaroensis Zone of Latest Maastrichtian around 66.5Ma to 67.5Ma.
Copper Mineralization in Machanur Area of the Dharwar Craton, Karnataka
Authors: Koti M. V. , Tenginkai S . G. , Ugarkar A. G. 
Published: November 2024

Abstract
Copper mineralization in Machanur is confined to the fracture and breccia zone (shear zone) traversing mainly pink porphyritic granite of the Closepet granite suite (2,400-2,000 my.) including minor diabase dykes and pegmatites, The mineralization is fractule-controlled cavity filling epiigenetic hydrothermal type. The associated wall-rock alterations are chloritization, saussuritizalion, sericitization and silicification of the host-rocks. The mineralization consists essentially of chalcopyrite and pyrile with subordinate bornite, chalcocite, covellite, digenite and linnaeitc. Native copper occurs but rarely. Hematite(specularite) and magnetite are commonly associated with the mineralization. Three stages of mineralization have been inferred. It is suggested that the second stage has been dominated by precipitation of chalcopyrite. The paragenetic scquence is suggestive of high fO2 condition in fluid at the beginning and progressive increase of Cu/Fe ratio and high fS2 condition in fluid during the main Cu deposition stage.
Mineralising Fluid Ascent Direction in the Sulphide Assemblage of Mosaboni, Singhbhum, Bihar
Authors: Nayak B. K. , Panchapakesan V. 
Published: November 2024

Abstract
Distribution pattern of fluid inclusion homogenisation temparatures and assay of copper ores hove been uscd to ascertain the mineralising fluid ascent direction. Thetrigonametric relationships to calculate the parameters of this direction have been derived which show that the bearing of ascent of ore fluids isN 53.°E-S 53°W having plunge 38° and rake 77°. There is high probability of encountering rich ores underneath 30th level in a direction opposite to fluid ascent at selected locations.
Petrofacies, Provenance and Tectonic Setting of Nimar Sandstone (Lower Cretaceous), Rajpipla-Jobat Area
Authors: Akhtar K. , Mujtaba Khan M. , Ahmad A. H. M. 
Published: November 2024

Abstract
The Nimar Sandstone were studied with a view to understanding the nature of the Narmada basin and its tectonic setting during an important event which took place on a global scale. The sandstones are predominantly quartzarenitcs composed mainly of several varietics of quartz, mica, rock fragments, feldspar and heavy minerals derived from the underlying Plecambrian basement. An integrated approach suggests that the Nimar Sandstone was derived from fault-bound uplifts of continental basement rocks and accumulated without much transport in the incipient rift belt of the Narmada basin.
Organic Matter and Carbonate in the Southwest Continental Shelf of India
Authors: Mohan P. M. , Victor Rajamanickam G. 
Published: November 2024

Abstract
Twenty five sediment samples, from seven traverses, were collected from the southwestern continental shelf of India. A variation in the organic matter from zero to 1 1.26% and carbonate from 7 to 96% is noticed. The stations located off the river mouth areas show high amount of organic matter and low amount of carbonate content, whereas outershelf sediments display high amount of organic matter and carbonate contents. However, in between these two zones, at the depth of 35 to 65 m, the concentration of organic matter and carbonate is found to have a considerable decrease in amount. It is inferred that this zone might be a paleo beach environment admixtured with present day marine environment.
Snout Fluctuation Study of Chhota Shigri Glacier Lahaul and Spiti District, Himachal Pradesh
Authors: Kumar Surendar , Dobhal D. P. 
Published: November 2024

Abstract
The snout fluctuation of Chhota Shigri Glacier has been examined for the period of 1962 to 1989. This period can be characterised as one of general retreat. The morainic levels at different positions and altitudes show the past extension of the glacier, eventhough then is no documented record of past advance and retreat of the glacier. But on the basis of the different morainic deposits the nature of past extension and deglaciation history of the glacier can be inferred. There are six such morainic levels recognised in the field. On the basis of these deposits the total retreat of glacier is calculated as about 2.5 km. since its break from the main Chandra Valley glacier, The present fluctuation study (1 962- 1989) shows that the glacier has been almost retreating expect in 1987 when it advanced about 17.5m. The totd recession of glacier during the period of 26 years was about 195m with an average rate of 7.5m/yr.
Groundwater Recharge Process Model in a Granitic Terrain - A Long Term Analysis
Authors: Narasimha Reddy T. , Prakasam P. , Subrahmanyam G. V. , Nageswara Rao T. , Prakash Goud P. V. , Harish K. , Gurunadha Rao V. V. S. , Gupta C. P. 
Published: November 2024

Abstract
Dulapally watershed in granitic terrain covers about 34 sq. km lying north of Hyderabad City in semi-arid tropics. Groundwater recharge has been estimated considering the soil-plant and agroclimatological conditions from daily rainfall and pan evoporation data during 1974 to 1990. The average annual recharge over 16 years worked out to be 124 mm. The temporal variation of the recharge estimates have been validated through simulation of well hydrographs in a nested squares finite difference aquifer model by feeding them as temporal input during transient condition.
A Geophysical Approach to the Problem of Seismicity in the Indian Shield
Authors: Reddi A. G. B. 
Published: November 2024

Abstract
An earthquake is but a culmination of stress build-ups that go on over a period of time at various brittle-ductile transitions located mainly within the crust. Mapping such transitions must therefore form an integral part of any effort at understanding the seismicity of a region. However, this aspect has been grossly neglected, most of our concerns so far revolving round faults and allied structures that only provide a mechanism for stress dissipation as distinguished from stress accumlation.
As a matter of fact, any holistic approach to the problem must invariably include within its ambit an investigation of the thickness and composition of the crust on the one hand and surface heat flow on the other, since these are known to have a direct bearing on the seismic propensity of a region. For instance, a thicker than average crust or a higher than normal heat flow (with consequent thinning of the lighter upper crust) could signify a potential seismogenic area. The same thing could be said of areas where strong rheological stratification is suggested at depth by the presence of say, low velocity layers, seismic reflectors or electrical conductors.
There is a distinct possibility of many of these situations finding expression in gravity maps which could consequently provide a very reasonable basis for effctive selection of areas for detailed follow-up, by more complex methods. Adopting this principle, a broad geophysical strategy has been mooted for the active consideration of geoscientists in the country. While it may be debated and improved upon in regard to detail, its overall implementation as a national project is an imperative dictated by the ominous prospect of a more and more common recurrence of earthquakes in the peninsula in the years ahead.
Braided-Fluvial Depositional Model of Late Triassic Gondwana (Mahadeva) Rocks of Son Valley, Central India: Tectonic and Paleogeographic Implications
Authors: Tewari R. C. 
Published: November 2024

Abstract
About 800 m thick late Triassic Gondwana (Mahadeva) rocks of Son valley, central India are composed of pebbly to gritty, very coarse to coarse and medium sandstone, and thin to thick beds of grey, micaceous and red shale. Sandstone bodies are channel-shaped to sheet-Like and multistoreyed, characterised by large scale trough and planar cross-beds. Interbedded shale beds are laminated. Palaeocurrent analysis based on 192 measurements of trough cross-bedded cosets reveals northwesterly (321° ± 46°) palaeodrainage and palaeoslope throughout the late Triassic Gondwana sedimentation.
Lithofacies characters, nature and geometry of sedimentary structures and palaeocurrent attributes suggest that the late Triassic Gondwana rocks of the Son valley area were deposited by a widespread system of bed load (braided) streams which flowed dominantly from southeast to northwest. Indeed, there is uniformity in the northwesterly palaeolope during Permian and Triassic Gondwana sedimentation in this area. Implicitly, the Gondwana basin under study should have extended northward down the palaeoslope beyond its present limit across the north boundary fault (? Narmada - Son lineament).
Delineation of Faults, Using Deep Seismic Sounding Refraction Data, West Bengal Basin
Authors: Reddy P. R. , Koteswara Rao P. , Venkateswarlu N. , Prasad A. S. S. S. R. S. 
Published: November 2024

Abstract
A systematic analysis of refraction data obtained in West BengaI basin, has been carried out to bring into focus the utility of the seismic refraction data in delineating fault zones. The study clearly points out the different conspicuous signatures present in the refraction travel time data, associated with the shallower fault zones affecting the top sedirnentry column and the crystalline basement.
Evidence of Palaeoclimatic Fluctuations in Miliolite Rocks of Saurashtra, Western India
Authors: Patel M. P. 
Published: November 2024

Abstract
Detailed studies of various miliolite occurrences of Saurashtra have revealed fluctuations in the palaeoclirnate witnessed in the course of deposition and consolidation of the dune material during Middle and late Upper Pleistocene. The entire process of formation of miliolite rocks is indicative of alternating arid and humid phases. During protracted arid phases strong wind actions were effective whereas during brief wet phases fluvial erosion & deposition and pedogenesis were brought about. The various evidences in support of palaeoclimatic fluctuations include: (i) the presence of erosional surfaces separating the miliolite deposits by intercalated redsoil horizons, cross-beddedand horizontally bedded miliolite deposits, two cross-bedded miliolite sequences with reversed dips and the two superimposed unidirectional cross-bedded miliolite sequences with different angles of dipin the coastal cliffsections, (ii) the occurrence of intercalated red beds and fluvial debris (sand/silt/gravel) within miliolite sequences as seen in some of the river and well sections, together with slope-wash debris between two miliolite layers substantiating small scale intervening periods of quiescence, (iii) a well defined junction between the two different major cycles of aeolian accumulation marked by the surfaces of non-deposition, erosion and honeycomb weathering at the top of the lower cycle as encothered in some of the well sections, (iv) burial of animal burrows by a younger cycle of miliolites devoid of animal burrows in some exposures and (v) the presence of diagenetically formed coated grains, vadose calcite silt around the ooliths & intraclasts, and its occurrence between two generations of cement in thin section also provide aclue to the minor breaks in diagenetic environment.
Pliocene - Pleistocene Benthic Foraminifera and Abyssal Circulation Changes at Arabian Sea DSDP Sites 220 and 223
Authors: Gupta Anil K. , Roy Abhra , Naik Pradyumna , Chatterji Santanu 
Published: November 2024

Abstract
Pliocene-Pleistocene benthic foraminifera were analysed from arabian Sea Deep Sea Drilling Project (DSDP) sites 220 and 223. At site 220 the most dominant taxon is Nuttallides umbonifera showing peak abundances in the Early Pliocene, Early and latest Pleistocene possibly representing intervals of highly carbonate-undersaturated bottom waters. The species diversity [H(S)] and equitability (E') trends show inverse relationship with N. umbonifera percentages. At relatively shallower site 223, the benthic assemblage is dominated by Cibicides wuellerstorfi, Oridorsalis umbonatus and Uvigerina hispido-costata through Plio-Pleistocene. N. umbonifera shows peak abundances only in the beginning of the Pliocene. This species shows an abrupt decrease to near extinction near the Plio-Pleistocene boundary and occurs very rarely and sporadically in the Pleistocene at site 223. C. wuellerstorfi and O. umbonatus show increased percentages in the earliest Pliocene, late Early Pliocene, and a short lived peakin the Early Pleistocene (samples 2-5), indicating presenceof relatively warm, oxygenated, and less corrosive bottom water at this site. The peaks of U.hispido-costata at site 223 are inferred to reflect intervals of high surface productivity due to intense upwelling off the Arabian coast.
Fluid flow during contact metamorphism: Petrographic evidence from the uranium prospect at Tummalapalle in the southwestern part of Cuddapah Basin, India
Authors: Dhana Raju R. , Roy Madhuparna , Panda Arjun , Vasudeva Rao M. 
Published: November 2024

Abstract
In the uranium prospect at Tummalapalle in the southwestern part of Cuddapah basin, fluid flow during contact metamorphism is documented in a vein-mineral-assemblage of a metadolerite intruding the carbonate rocks and shale of the Vempalle Formation of the mid-Proterozoic Lower Cuddapah Supergroup. The minerals in the vein are calcite, quartz, Mg-chlorite and Fe-chlorite formed in that order due to fluid-infiltration-driven volatilization reactions involving CO2- and H2O- fluid having an external source in the nearby sedimentary rocks. The observed sequential vein-mineral assemblage is considered as a petrographic evidence of 'infiltrating fluid mechanism during metamorphism', proposed first by Ferry (1980), as well as for 'batch volatilization' of Valley (1986).
Mineral Chemistry of Mafic Chain Silicate Minerals in the Torappadi Layered Complex of the Southern Granulite Terrain
Authors: Ray Jyotisankar 
Published: November 2024

Abstract
The chemistry of the mafic chain silicate minerals in the Torappadi layered ultramafic-mafic complex occurring in the southern granulite terrain of the Indian shield has been presented. The pyroxene compositions are found to be sympathetically related to the whole-rock chemistry; further the orthopyroxenes are discriminated to be metamorphic in terms of chemical parameter. All amphiboles of the complex are 'calcic' and their compositions spread from magnesio-hornblende to edenitic homblende/tschermakitic hornblende depending upon the rock-chemistry. Pyroxene geothermometry (assuming complete disordering) using different methods reveals a comparatively large range for a particular rock (up to 181°C). Amphibole geothermometry, on the other hand, gives consistent temperature values (716°-804°C) which has been taken as the range of temperature of equilibration of the whole complex. Estimation of pressure with amphibole-compositions yields a mean value of 4.16 kb. It has been suggested that Torappadi rocks correspond to shallow level - low pressure granulite equivalent to a depth of ca. 10- 17 km.