bluuebunny/crossref_metadata_2025_split huggingface dataset:
Syngenetic and Epigenetic Features and Genesis of tbe Bauxite-Bearing Laterite of Boknur-Navge Plateau, Belgaum District, Karnataka
Authors: Krishna Rao B. , Satish P. N. , Sethumadhav M. S. 
Published: November 2024

Abstract
Bauxite-bearing laterite of Boknur-Navge plateau, Belgaum district, Karnataka, exhibits textural, mineralogical and geochemical features of both syngenetic and epigenetic origin. While the syngenetic features of the lateritic residuum developed during a major episode of residual weatheringof'the source rock (Deccan basalt), the epigenetic features originated during an episode of secondary alteration of the pre-existing lateritic material.
Residual weathering of basalt took place in three stages and culminated in the formation of a well-differentiated lateritic residuum consisting of vermicular laterite and massive (textureless and pisolitic) bauxite. Lateritic weathering, under the activity of slightly acidic meteoric waters, involved leaching of ∼90% SiO2, ∼60% Fe2O3 and almost all the K, Na, Ca and Mg from the weathered zone leading to the relative enrichment of Al. Part of the dissolved Si, Fe and AI of the circulating waters were subjected to local migration and reprecipitation, resulting in the segregation of AI-rich (bauxite) and Fe-Si-rich (laterite) units within the laterite profile.
Secondary products derived from the alteration of the bauxite and laterite show zonat variation in their mode of occurrence, textures, mineralogy and chemical composition. During the secondary alteration, the bauxite and laterite of the ∼10 m thick bauxite-bearing laterite zone were subjected to 1) silication and ferrification at the upper horizon, 2) silication at the intermediate horizon, and 3) minordesilication at the lower horizon. Among the three types of alterations, silication is widespread. The 'late-or post-bauxite' episode of alteration of the lateritic residuum was probably brought about by the action of highly acidic meteoric waters charged with Si.
SHRIMP U-Pb Geochronology of the Closepet Granite and Peninsular Gneiss, Karnataka, South India
Authors: Friend C. R. L. , Nutman A. P. 
Published: November 2024

Abstract
Zircons separated from a sample of Peninsular gneiss (82-KD 14) from Kabbaldurga quarry, and a homogeneous Closepet granite (KO84-13) from near Ramnagaram have been dated with the ion microprobe SHRIMP. The Peninsular gneiss sample, a metatexite, contains an arrested charnockite transition and constitutes an amphibolite-granulite close pair. It was split into amphibolite facies, transitional and granulite facies (charnockite) domains prior to zircon separation.
Zircon populations separated from each domain are morphologically similar and have the same U-Pb isotopic systematics suggesting that they record events common to both the amphibolite facies and granulite facies domains. The pooled data yield a U-Pb age of 2963 ± 4 Ma (20s) for the gneiss protolith at Kabbaldurga, with a few older inherited zircons found as cores in magmatic zircon. A concordant U-Pb age of 2528 ± 5 Ma was obtained for newly grown zircon and overgrowths, interpreted to have formed during a migmatisation event which led to the formation of the Closepet granite.
Zircons separated from the Closepet granite sample gave a concordant age of 2513 ± 5 Ma, interpreted as the time of crystallisation of the granite. This age was obtained from both zircon cores and overgrowths which are indistinguishable in age and arc both interpreted to have formed during the melting event. In preserved cores no indication of any inherited grains with a significantly older history was found.
This is the first precise age on the Closepet granite. The slight age difference between the metatexite event (2528 ± 5 Ma) and the granite age 2513 ±5 Ma) may indicate the length of time of the event during which the Closepet granite formed. The data provide a minimum constraint on the age of the charnockite event in the region.
Mechanism Solution of Burma-India Border Earthquake of August 6, 1988
Authors: Banghar A. R. 
Published: November 2024

Abstract
This paper presents the focal mechanism solution for the Burma-India border earthquake of August 6, 1988. Use was made of the first motions of P waves and polarization (or first motions) of S waves. The mechanism solution is characterised by a predominant component of thrust faulting. The deduced orientation of the axis of compression is northeasterly. This orientation of the axis of compression is nearly parallel to the trend of tectonic features in the epicentral region of this event.
Orbulina universa d' Orbigny in Late Pleistocene Sediments of Northern Indian Ocean
Authors: Jaiprakash B. C. 
Published: November 2024

Abstract
The genus Orbulina d' Orbigny 1839 in the Late Pleistocene sediments of the Northern Indian Ocean is represented by abundant population of O. universa d' Orbigny 1839 and rare O. bilobara d' Orbigny 1846. Temporal variation in the abundance and test size or O. universa has been analysed for their inter-relationship and paleoclimatological implications. The results suggest an inverse relationship between abundance and test growth which corroborates Allan Be's (1973) observations on Recent O. universa from Indian Ocean.
Exploration of Metallic Minerals and their Discrimination Using Partial Extraction of Metals by Electrolysis (PEXMEL) Method
Authors: Banerjee Buddhadeb , De S. S. , Das L. K. 
Published: November 2024

Abstract
Partial electrolytic extraction of metals can be effectively utilised for direct detection of polymetallic minerals in addition to their discrimination which is a difficult task by other geophysical exploration techniques. The principle lies in trapping the metallic cations from the electrolyte formed by leaching of the ore body at depth by a direct current supply impressed on ground surface and analysing the electrolyte chemically for determination of different metallic contents diagonising the target.
Field tests have been successfully carried out with this approach over known and unknown mineralised bodies at Kendadih, Seraikella areas in Singhbhum district, India.
Tin and Rare Metal Pegmatites of the Bastar-Koraput Pegmatite Belt, Madhya Pradesh and Orissa, India: Characterisation and Classification
Authors: Ramesh Babu P. V. 
Published: November 2024

Abstract
The Bastar-Koraput Pegmatite Belt (BKPB) in southeastern part of the Bastar Craton of Penisular India extends over 80km in a NW-SE direction from Dantewada in the Bastar District of Madhya Pradesh to Salimi in thc Koraput District of Orissa. The pegmatites of BKPB are typically associated with tin and rare metal (Nb, Ta, Be and Li) mineralisation in the form of cassiterite, columbite-tantalite, beryl, lepidolite and amblygonite. Based on the study of over 200 pegrnatites in the Tongpal-Mundval-Dammoguda sector, the pegmatites of BKPB are characterised in terms of mode of occurrence, size, shape, internal zoning and mineralisation. Considering the mineralogy, internal zoning and associated mineralisation, the pegmatites of BKPB are classified into five types, viz., I-Simple, unzoned biotite or muscovite-microcline prgmatiles without tin and rare metal minerals, II-Partly differentiated, muscovite-microcline pegmatites with beryl, III-Fully differentiated muscovite-microcline pegmatites with beryl, columbite-tantalite and cassiterite, IV-Replaced lepidolite-albite-muscovite pegmatites with amblygonite, cassiterite, beryl anti colurnbite tantalite and V-Replaced muscovite-albite pegmatites with cassiterite and beryl. The five types of pegmatites have diagnostic sizes and shapes and form a paragenetic sequence with increasing internal evolution from types-I to V. Such a classification aids in prospecting for tin and rare metal minerals since pegmatitcs of types-III to V in BKPB are highly potential for these metals.
Alluvial Fan Qrigin of the Bagra Formation (Mesozoic Gondwana) and Tectono-Stratigraphic Implications
Authors: Casshyap S. M. , Tewari R. C. , Khan Abdullah 
Published: November 2024

Abstract
The Bagra Formation of the Mesozoic Gondwana sequence of Satpura basin has been considered as a facies equivalent of the underlying Denwa, and assigned a late Triassic age. The present study reviews the above contention, prompted by distinctive lithofacies assemblage, depositional setting and tectonic framework of the Bagra Formation, and its variable relationship with the underlying strata.
The Bagra Formation as a whole comprises conglomerate assemblage in the lower and middle parts and sandstones with intercalated lenses of shale in the upper part. The lower conglomerate facies occurring northward is clast - to matrix supported and poorly sorted; it is finergrained, better sorted, including thin lenses of cross-bedded sandstone southward in middle part of the formation. The overlying cross-bedded sandstone and shale facies is the most important assemblage in the distal south. The coarse grained nature of the sediments, the upward- fining distribution and lateral changes in gross lithofacies and stratification types, and paleocurrent data suggest that the Bagra conglomeratic sequence was deposited as an alluvial fan system that prograded southward from a highland source located immediately to the north. In sharp contrast, the fluvial system was directed dominantly northward and source area located southward for the underlying Permo-Triassic Gondwana sediments, including Denwa.
It is argued that a late Triassic age of the Bagra Formation is questionable, in as much as a substantial stratigraphic break in sedimentation is called for after the deposition of Middle Triassic Denwa. The Bagra may well be late Jurassic-early Cretaceous in age based on its relationship with the overlying JabaIpur Formation.
A Two Stage Model for the Development of Karitoran Shear Zones, District Lalitpur, Pradesh, Central India
Authors: Roday Prakash P. , Diwan P. , Pal Amiya 
Published: November 2024

Abstract
The rocks described as esmeraldites in the southern part of Centra1 Indian Bundelkhand granitic massif are suggested to the typically those formed by heterogeneous simple shear and by development of retarded runway shear instabilities in host granites.
The development of shear zones appears to have occurred under two different stress fields. The early stress field was subhorizontal and nearly equatorial with low values of ESE trending s3 and low ¯s in statistically isotropic material (elastic response). This produced positive dilational shear zones marked by intrution of pegmatite, filling en echelon tensile fissures. The early shear zones were converted into regular ductile shear zone at a later stage under a subhorizontal meridional stress field within highly compressive NNE trending s3 and high ¯s (viscous response within previously weakened zone). This produced a subvertical or steeply dipping ESE trending fabric. Only this two-stage model is able to explain the development of these zones. Finite strain determinations are made from deflected basic dykes, deformed quartz veins and based on the angular relationship between C and S surfaces. The dilation during early episode is indeteminate because of rotation during latershearing. The shear along fabric suggests that the foliation failed to rotate with rotating ?1 ?2 planes of the simple shear. The finite strains computed on the basis of angular departures between fabric and zone walls are therefore slightly underestimated.
Basal Aravalli Volcanism : Evidence for an Abortive Attempt to form Proterozoic Ensialic Greenstone Belt in Northwestern Part of Indian Shield
Authors: Raza M. , Khan Shamim 
Published: November 2024

Abstract
Early Proterozoic mafic volcanic rocks, occurring at the base of Aravalli Supergroup of northwestern Indian shield, have komatiitic, tholeiitic compositions. In discrimination diagrams based on immobile minor and trace elements they show a close affinity with MORB, However, the immobile incompatible element patterns and element ratios resemble those of enriched continental tholeiites which erupt at the time of initial rifting. Geochemical and geological evidences suggest a transitional nature of basal Aravalli sequence between Archaean greenstone belts and younger continental suites. It appears that the basal Aravalli volcanism was an attempt to form a Proterozoic greenstone belt on the stable continental crust through lithospheric rifting and lava eruption. The attempt failed with cessation of volcanism, probably due to falling geothermal gradient and basin subsidence by sediment loading. The occurrence of similar rock associations in other shields of the world indicates the existence of particular tectonic-thermal regimes during the early Proterozoic.
Nearshore Coastal Sedimentation in the Early Cretaceous Ranipat Formation of Saurashtra Basin, Gujarat, Western India
Authors: Aslam M. 
Published: November 2024

Abstract
The Early Cretaceous Ranipat Formation of Saurashtra basin is divisible into three distinct lithofacies assemblages: 1) crossbedded sandstone facies assemblage characterised by coatse to medium-grained, planar and trough crossbedded sandstone with occasional thin layers of silty mud or reactivation surfaces; 2) plane-bedded sandstone facies assemblage composed of interbedded white to clean white, medium to fine-grained sandstone, siltstone and shale with a low-diversity of shallow water trace fossils; and 3) thin-bedded sandstone and mudstone facies assemblage characterised by interbedded fine to very fine-grained sandstone, small scale planar and trough crossbedding, horizontally bedded, ripple cross-laminated, way and lenticular bedding, flaser and herringbone crossbedding with the dominant ichnogenera being Skolitbos and Ophiomorpha. These lilhofacies assemblages indicate that the Ranipat sandstone was deposited in a tidal, intertidal, and shallow subtidal shoreline environment. The mineralogy, texture, and paleocurrent data also rcveal that the sediments were brought to the Ranipat basin, largely by southwesterly streams/distributaries, with occasional dispersal and redistribution by northwesterly to northerly oriented longshore and/or tidal currents of the nearby coastal environment.
Working Values for Major, Minor and Trace Elements for Meta-Basic Reference Sample (MB-H)
Authors: Rathi M. S. , Khanna P. P. , Mukherjee P. K. , Purohit K. K. , Saini N. K. 
Published: November 2024

Abstract
Proposal for the preparation of a metabasic reference sample (MB-H) from the Himalayas has attracted the participation of twenty four laboratories of repute from thirteen countries beside India. Tables of compiled data (1818 total individual results in all) are presented in this paper. Working values/information values have been assigned for 37 major, minor and trace elements including REEs after rigorous statistical as well as subjective data evaluation.
Geochemistry and Tectonic Significance of Late Archaean-Early Proterozoic Metabasalts from Bacheli, Bastar District, Madhya Pradesh
Authors: Khan M. W. Y. , Bhattacharyya T. K. 
Published: November 2024

Abstract
The fine grained, massive metabasalts of Bacheli-Kirandul areas, Bastar district, M.P., characterized by a greenschist facies mineral assemblage have been studied for their major, trace and REE geochemical distribution pattern. On Jensen's AFM Plot and diagrams of relatively immobile elements; these metabasalts fall in the tholeiitic basalts to basaltic andesite field.
Large scatter in Na2O/K2O, K/Rb and RblSr ratios suggest to alteration effects, while high MgO content ascribes to the oxidative diagenesis. Relatively immobile and HFSE element discriminant diagrams point to an island arc/convergent plate setting. The depletion in Nb and Ta relative to Th and LREE in these samples may be relict from a previous tectonic event.
Inferences drawn from geochemical tectonic discriminant diagrams have been evaluated in the light of additional geological data, and an ensialic rift setting for these volcanics is envisaged.
Multi-Mode Generation of Carbonate Tabular Intraclast Deposits: Unnamed Proterozoic Formation, Maharashtra
Authors: Sarkar Subir , Chakraborty Partha P. , Bose Pradip K. 
Published: November 2024

Abstract
Breccia and pebbly massflow products are present in abundance in basin slope deposits of an unnamed marine Proterozoic fonnation in Maharashtra. Seven distinctive genetic modes have been identified and attributed to slump, slide, spring sapping and evaporite dissolution. The clasts are tabular in form and intraclastic in origin. The observations suggest caution against the prevailing tendency to equate occurrence of tabular intraclasts with shallow depositional regime. In order to ascertain their sedimentological significance, a clear understanding of their genetic processes is thus warranted.
Origin of Polyphase Gneisses Associated with the Krishnarajpet Greenstone Belt, Dharwar Craton
Authors: Rama Rao P. , Diyakara Rao V. 
Published: November 2024

Abstract
Hornblende, biotite and feldspar rich gneisses (HG, BG and FG respectively), in that order of formation are associated with the Krishnarajpet schist belt in Dharwar craton, a greenstone belt coeval with, and similar to, the Holenarasipur and Nuggihalli schist belts. These gneisses show compositional differences with SiO2, K2O and Rb increasing and TiO2, Al2O3, Fe2O3, CaO, MgO, Sr, Zr and Ni decreasing from HO to SO and FG. The overall REE is more in BG (SREE = 332.90), while it is similar in HG (SREE = 173.36) and FG (SREE = 159.03) with comparable LREE/HREE ratios (BG = 12.71; HG = 10.26; FG = 10.95). The overall chemistry of the three phases suggests a single source of origin for all the phases. While the field characteristics suggest successive origit from HG to BO and FG, the chemical signatures also support this mode of origin from HG to FG through BG. Available geochronological data on the gneisses indicate that probably the HG, a partial melt of the mafic schists of the greenstone belt, wns recycled at lower crustal levels in Late Archaean foming BG and FG. The time gap between the phases appears to be less but no detailed age data exist on the different phases to support this.
Holocene Deep-Sea Benthic Foraminifera and Watermasses in the Indian Ocean and the Red Sea
Authors: Gupta Anil K. 
Published: November 2024

Abstract
The distribution of Holocene deep-sea benthic foraminifera in 19 core top samples from the Indian Ocean and the Red Sea is examined to understand the faunal-watermass associations. Relative percentages of significant taxa have enabled to identify distinct assemblages associated wth different watermasses in the Indian Ocean and the Red Sea. The first assemblage in the Indian Ocean is marked by the dominance of Nuttallides umbonifera. This assemblage is found below 4000 m where bottom water is highly carbonate-undersaturated and is influenced by Antarctic Bottom Water (AABW). The second assemblage is characterized by Uvigerina hispido-costata dominance with Cibiddes wuellerstorfi as a subsidiary species. This assemblage is associated with the lower tongue of North Indian Deep Water (NIDW) between 2500 and 4000 m water depths. U. hispido-costata has higher abundances at sites lying below upwelling zone off the Arabian coast in relatively high dissolved oxygen deep water. The third assemblage is dominated by Uvigerina proboscidea between 1500 and 2500 m depth. Globocassidulina pacifica/subglobosa, Pullenia bulloides and C. wuellerstorfi are secondary constituents. This assemblage characterizes high productivity regions (equatorial belt) with relatively low oxygen levels in deep water. The Red Sea Deep Water (RSDW) assemblage is dominated by Bolivina subreticulata and characterizes highly saline, warm, oxygen-poor deep water. Other species of this assemblage are Textularia agglutinans, Astrononion umbilicatulum, Miliolinella subrotunda and Ophthalmidium acutimargo.
Formation and Tectonic Evolution of Granulites from the Biligiri Rangan and Niligiri Hills, S. India: Geochemical and Isotopic Constraints
Authors: Janardhan A. S. , Jayananda M. , Shankara M. A. 
Published: November 2024

Abstract
The granulites of the Biligiri Rangan (BR) and Niligiri Hill ranges are characterised by distinct field, geochemical and isotopic signatures. The B.R. Hill granulites contain a significant metasedimentary component (pelite-BIF-Mn-horizons), whilst metasediments are rare in the Niligiri granulite terrain. Lithologic and structural continuity between the two terrains cannot be demonstrated as they are separated by E-W running Moyar shear zone. Isotopic data suggest that B.R. Hills and Niligiri granulites have had different pre-crustal histories. Sm-Nd model TDM ages and U-Pb zircon concordia upper intercept age suggest that the protoliths of B.R.Hill quartzo-feldspathic charnockites accreted at 3.4Ga. On the other hand, Sm-Nd model TDM ages indicate that the magmatic protoliths of Niligiri granulites differentiated from mantle at 2.6 Ga.
Geochemical data from the B.R. Hills charnockites, particularly low-Mg numbers (0.2-0.3), low content of transition and HFS elements and strongly fractionated REE patterns with HREE depletion, suggest that their magmatic protoliths were derived by partial meltingof young, hydrated oceanic crust, in which garnet and amphibole were important residual phases. The high content of transition elements together with low total LREE and less-or unfractionated REE patterns of the B.R. Hills mafic granulites imply the derivation of their protoliths from long term depleted mantle sources. On the other hand the high Mg numbers (0.5-0.6), high content of transition and HFS elements, moderately fractionated REE patterns with HREE enrichment suggest that the protoliths of the Niligiri granulites are interpreted to have formed by melting of metasomatized mantle wedge with olivine and spinel as residual phases.
The Niligiri terrain was accreted onto the Dharwar Craton at C.2.6 Ga and the two terrains witnessed a common major granulite event at 2.51 Ga.
Distribution of Iron Cations in Natural Chromites at Different Stages of Oxidatio - A57Fe Mossbauer Investigation
Authors: Pal Tapan , Moon Hi-Soo , Mitra Sachinath 
Published: November 2024

Abstract
57Fe Mossbauer spectroscopic investigation of natural chromites from two chromite deposits of India (Sukinda and Byrapur) documents partly inverse spinel structure arising out of oxidation. The spectral fitting was based on allowing a disordering distribution of Fe2+ and Fe3+ ions at tetrahedral (A) and octahedral (B) sites. Mossbauer investigation of the samples taken from the physico-chemically distinct two horizons of Sukinda viz. brown are and grey ores, and Byrapur area revealed three types of iron ion distribution as: Fe2+(A), Fe3+(A) and Fe2+(B) (GC-group); (b) Fe3+(A1), Fe3+(A2) and Fe2+(B) (BC-2 group), and (c) Fe3+(A1), Fe3+(A2) and Fe3+(B) (BC-1 group).
The distribution pattern of iron cations at A and B sites was linked to the degree of oxidation. The stages of oxidation could be modelled from normal to inverse fonn. A model suggesting 'electron localisation' at the B-sites makes the intermediate stage. Iron site occupancy determined by Mossbauer spectroscopy of the presently studied samples indicates that these fall under three groups of oxidation stages. An early stage of oxidation is shown by samples of group GC, intermediate stage by group BC-2 and final stage by BC-1 group of chromite samples. The imprint of progressive oxidation manifested by Fe cation site occupancy has been correlated with the Fe2+/S:Fe ratios, obtained for each group of samples.
Rank Evaluation of the Neyveli Lignite Deposit on the Basis of Reflectance Parameter
Authors: Singh Alpana , Singh D. B. 
Published: November 2024

Abstract
The Neyveli field is well known for Tertiary lignite deposits in India. The reflectance of organic constituents (humioite macerals) has been measured to find out organic maturation level (rank) of the main lignite seam lying either at same time level or at different time levels in space. The deposits are of sub-bituminous C stage (ASTM) with the mean refectance (Ro max. in oil) range from 0.34 to 0.42% (average 0.39%). Evidences from rank study indicate that the quality of lignite deteriorates towards southern part of the field.