bluuebunny/crossref_metadata_2025_split huggingface dataset:
Occurrence of Late Cretaceous Cherty Limestone on Baratang Island, Andaman, India
Authors: Badve R. M. , Rajshekhar C. , Kundal P. 
Published: November 2024

Abstract
A red cherty limestone containing rich Globotruncana assemblage of Maestrichtian age is reported from Japani Gole Jetty (NE corner) of Baratang Island, Andaman, India.
Gravity and Seismicity of the Cuddapab Basin and Surrounding Places
Authors: Krishna Brahmam N. 
Published: November 2024

Abstract
The seismicity reported in the Cuddapah basin and surrounding places is examined in the light of the zones of weaknesses/faults indicated by the Bouguer anomaly map of that region. Most of the epicentres seem to fall in the vicinity of the faults inferred from the gravity data. Gravity data suggests that the Ongole region is a junction of different trends of gravity anomalies which explains the reported seismicity there. A roughly NW-SE trending fault, indicated by gravity, seems to be responsible for the seismicity in Macherla-Vinukonda region. The seismicity and the alignment in a roughly NE-SW direction of the exposed nepheline syenite bodies adjoining the eastern margin of the northeastern part of the Cuddapah basin seem to be associated with a fault inferred from gravity. The seismicity in Nellore region is due to the reactivation of faults associated with the buried sedimentary basin which is detected by gravity and confirmed by bore-hole data. The bordering faults of the Palar basin, whose configuration is clearly delineated through gravity, are responsible for the seismicity reported there. A major part, at least, of the main thrust fault of the eastern margin of tbe Cuddapah basin does not seem to be seismically active.
Retrogression of Charnockite to Biotite Gneiss/Carbonated Gneiss in Attur Valley, Tamil Nadu
Authors: Khan Saleem Ahmed , Janardhan A. S. 
Published: November 2024

Abstract
Field and mineralogical studies, supplemented by chemical analyses of charnockite and its derivative gneisses from one of the quarries between Ramalingapuram and Seshanchavadi along Attur valley have revealed retrogression of charnockite to biotite gneiss and onto ankerite-dolomite-bearing gneiss, involving addition of potassium and loss of iron, magnesium and sodium. The presence of two kinds of plagioclase and biotite in the retrogressed gneiss is indicative of chemical inequilibrium with a tendency to recrystallize into a lower grade mineral assemblage. The retrogression could have taken place at about 350°C and a pressure of 4 kb, with the influx of fluids richer in H2O and CO2. The co-existence of biotite and muscovite also requires fluids richer in H2O, and CO2 to a limited extent. The CO2- and H2O rich fluids are probably linked to major carbonatite-alkaline syenite intrusions emplaced along NNE and ENE lineaments.
Mineralogy of Tin Ores from Koraput District, Orissa
Authors: Acharya B. C. , Das S. K. , Sahoo R. K. , Patnaik B. C. , Das N. K. 
Published: November 2024

Abstract
Tin along with Nb and Ta occurs both as primary mineral in pegmatites and as detrital mineral in the colluvial, eluvial and alluvial placers in Matili-Mundaguda area of Koraput District, Orissa. Cassiterite is commonly associated with soda plagioclase, microcline, perthite, quartz and muscovite, and it invariably contains inclusions of columbite-tantaIite, tapiolite, pyrochlore and fergusonite varying from 0.4 to 18% by volume and 3 to 400 microns in size. Minerals, like ilmenite, magnetite, lepidolite, pyrite, chalcopyrite and sphalerite are also associated with cassiterite. Nb and Ta is present in cassiterite both in solid solution as well as separate mineral phases.
Geochemistry of Felsic Volcanics from Gurapratap Singh and Diri, Pali District, Rajasthan (Part-I, Major Elements)
Authors: Srivastava R. K. , Maheshwari A. , Upadhyaya Rajani 
Published: November 2024

Abstract
The felsic volcanics of Gurapratap Singh and Diri are mostly welded tuffs and belong to andesite-dacite-rhyolite association; they are a part of the Malani volcanic suite of Precambrian age. The volcanics are cut by rhyolite porphyry (comagmatic with volcanics) and a younger dolerite dyke. A few flows of ultrapotassic rhyolites are also found which do not conform to the main trend and presumably mark a different phase of magmatic activity.
The chemical data on 91 samples of different rock types and Harker diagrams reveal a systematic variation in all major elements with the progress of differentiation, suggesting that the entire sequence except the ultrapotassic rhyolite is cogenetic and that the changes have been controlled by some sort of fractional crystallisation mechanism. The principal component analysis of the data reveals that in the earlier stages, the fractionating phases were soda-lime plagioclase and a mafic phase and in the later stages K-feldspar became a dominant phase. This is supported by phenocryst assemblages in these rocks. The suite also has very high inter-elemental correlation indicating that the rocks are cogenetic and a single process was responsible for their evolution. The mixing line calculation also confirms the operativeness of a single process.
Geochemistry of the Archaean Greywackes from the Northwestern Part of the Chitradurga Schist Belt, Dharwar Craton, South India-Evidence for Granitoid Upper Crust in the Archaean
Authors: Srinivasan R. , Naqvi S. M. , Uday Raj B. , Subba Rao D. V. , Balaram V. , Gnaneshwar Rao T. 
Published: November 2024

Abstract
Turbidite greywackes of the northwestern part of the Chitradurga Schist Belt constitute a part of &gt;2.6 Ga Cbitradurga Group of Dharwar Supergroup. They consist of a detrital assemblage of mono- and poly-crystalline quartz, microcline and plagioclase feldspar. and volcanic rock fragments. Quartz content and Na2O/K2O ratios show their quartz intermediate character. In this respect and also in their high FeO(t)+ MgO content they are similar to other Archaean greywackes. The TiO2 content. K2O/Na2O, Al2O3/CaO+Na2O and Al2O3/SiO2 ratios plotted against Fe2O3(t)+MgO, although assign an island arc environment for these greywackes, do not unequivocally discriminate between continental and oceanic island arc setting. The Chitradurga greywackes are highly enriched in Zr, Cr and Ni indicating a mixed felsic and mafic source. The contribution from contemporary volcanism in the basin could be significant. The QFL proportions indicate a dissected arc and/or recycled orogenic nature of the provenance. The chemical index of alteration varying from 58 to 63 and Al2O3/Na2O ratio less than 6, indicate relatively unweathered nature of source rock and chemical immaturity of the sediment respectively. The REE patterns show wen-defined negative europium anomalies which reflect granitoid upper crust in the provenance during the Archaean.
Computer Classification of Landsat Data for Targeting Gem-Bearing Tracts in Karnataka State, India
Authors: Ramanamurthy M. V. , Reddy U. S. N. 
Published: November 2024

Abstract
Precious and semi-precious stones are found associated with colluvial/gravel landforms and in schistose rocks associated with vein quartz/pegmatites. Utilising the LANDSAT-4 digital data, computerised classification has been adopted using known gem-bearing locations as training sets with the principal objective of delineating possible target areas for gemstone prospecting in Bangalore, Tumkur, Mandya and Mysore districts of southern Karnataka, India.
Sedimentology of the Middle Siwalik Subgroup of Mohand Area, Dehra Dun Valley, India
Authors: Kumar Rohtash , Nanda A. C. 
Published: November 2024

Abstract
The Middle Siwalik Subgroup of Mohand area (1800 m thick) is divided into three units: (1) sandstone-mudstone interval (340 m), (2) thickly bedded multi storied sandstone (1060 m), and (3) conglomerate-sandstone-mudstone interval (400 m). Three major facies are recognised, namely: conglomerate, sandstone, and mudstone facies. Sandstone is the dominant litho-facies and displays frequent erosional surfaces along which mud-clasts are present. The common sedimentary structure is trough and planar cross-stratification.
Palaeo-flow measurements of trough cross-stratification show prominent modes in SE and NW directions. However, planar cross-stratification shows a high order of deviation in mean vector azimuth from trough cross-stratification. The fining-up in grain-size from erosional surface (Se facies) to mudstone (Fm facies) through trough and planar cross-stratified sandstone (St-Sp facies) and ripple drift laminated sandstone (Sr facies) has been recognised.
The mudstone intervals are almost negligible, while mud-clasts and suspension load in the sandstone (channel facies) are high (to to 25%). The absence of mudstone unit in multi storied sandstone complex may be attributed to the extensive and frequent avulsion on the large braided alluvial fan. This study reveals that sedimentation pattern of multi storied complex is similar to that of modern radial fan of Kosi river.
In-Situ growth of Authigenic Minerals and Micronodules in Some Pelagic Sediments from the Central Pacific
Authors: Roonwal G. S. , Vijaya Kumar U. 
Published: November 2024

Abstract
Sediment samples from NS Transect in the Central Pecific Ocean, comprising the Areas C. D. F and G investigated with the help of scanning electron microscopy reveal in-situ formation of several authigenic minerals within pelagic sediments, which affect their surface texture and morphology. Zeolite crystals developed in-situ are noted in the siliceous ooze in the north equatorial Pacific (Area C). Micronodules with well developed initial growth lines, formed authigenically are commonly observed in the siliceous debris-rich calcareous ooze of south equatorial Peciflc (Area F). Quartz and feldspars of detrital origin are also found in the sediment. Dissolution of biogenic debris is noted in them. However. undissolved radiolarian oozes are common particularly in the sediments from south Pacific. Authigenic phillipsite needles are identified in the sediments from Area G which falls within the Marquesas Fracture Zone.
Mineralogy of Laterite-Bauxite Profile of Paduvari Plateau, South Kanara
Authors: Khanadali S. D. , Devaraju T. C. 
Published: November 2024

Abstract
The laterite-bauxite profile of Paduvari plateau, which bears evidence of having been derived by the in-situ chemical weathering of essentially early Precambrian granodiorite-tonalite gneisses, shows: (1) The overall predominance of gibbsite in the entire profile except in the lithomarge zone, (2) the abundance of kaolinite in the lithomarge zone and enrichment of goethite/hematite in the ferruginous laterite crust, (3) the general downward increase of kaolinite and upward increase of gibbsite, (4) the consistent occurrence of allophane, in minor amounts, in the entire profile, (5) evidence of formation of gibbsite both by direct alteration of feldspars of the precursor rock aqd by desilication of kaolinite, (6) occurrence of nearly all the minerals, which were present in the precursor rock, as resistant relics, (7) occurrence of zircon of the same shape and size as those in the precursor rock, and (8) the high crystallinity and the more common tight framework-type of microtexture of bauxites and aluminous laterites suggesting the formation of these deposits under extremely good leaching conditions, high above the water table.
Avian Eggshells from the Lower Miocene Rocks of Eastern Kutch, Gujarat
Authors: Jain R. L. 
Published: November 2024

Abstract
Eggshell fragments were collected from three spots a few metres apart from the Lower Miocene rocks of Eastern Kutch, Gujarat. The crystalline structure of the shells, the slender closely packed columns and horizontal layering suggest that these are of avian type and may belong to Ratites (?).
Morphological Characteristics of Zircons from Khondalite-Charnockite Assemblages of South Kerala, India
Authors: Narayanaswamy  , Soman K. 
Published: November 2024

Abstract
Description and size data are presented for zircons separated from Precambrian rocks of south Kerala, comprising garnet-sillimanite-graphite gneiss (khondalite), charnockite, garnet-biotite gneiss and garnet-Quartz-feldspar neosome.
Zircons from khondalite are rounded, do not show much overgrowth features and are typical of granulites of sedimentary parentage. Zircons in charnockite show unimodal frequency curves and self-nucleated RMA nature. suggestive of magmatic origin. Those from garnet-biotite gneisses do not show any linear. RMA trends, and the terminally rounded zircons in them do not show any angle between length and c-axis suggesting a mixed source. Zircons from garnet-quartz-feldspar neosome show features, suggestive of migmatitic origin.
Mineral Ages of Pegmatites from the Palghat Gap Region in Kerala and Their Tectonic Significance
Authors: Soman K. , Thara K. G. , Arakelyants M. M. , Golubyev V. N. 
Published: November 2024

Abstract
Of the three styles of deformation recognised in the Palghat Gap area, the D3 period is conspicuous with a major pegmatite emplacement phase, associated with the migmatization event. Dating of mica from pegmatites belonging to this stage (both concordant and cross-cutting) has yielded ages ranging from 484 to 512 m.y. The pegmatite emplacement is suggested to be towards the closing stage of a retrogressive metamorphic event, associated with crustal uplift in the Palghat Gap region, which laid the tectonic frame-work for the formation of the gap later.
Arcbaean Baryte Deposits of Southern Africa
Authors: Reimer Thomas O. 
Published: November 2024

Abstract
The major Southern African baryte deposits of Archaean age are of stratiform nature -and can be subdivided into two main groups. (1) Volcanogenic-exhalative deposits in the Swaziland Super-group of the Barberton greenstone belt, as well as possibly in similar rocks in Botswana and Zimbabwe. These deposits, with a strike length of up to 9 km, are frequently associated with sulphide mineralization. (2) Placer deposits in the Fig Tree Group of the Barberton belt. These formed through erosion of contemporaneous and/or mostly older volcanogenic-exhalative baryte deposits over a well-documented intraformational unconformity. The baryte beds contain notable quantities of detrital chromite as well as traces of detrital gold, molybdenite, and other heavy minerals. The zone extends over at least 12 km along strike of the schist belt and possibly up to 45 km if a number of minor occurrences of uncertain stratigraphic position are included.
The various type of vein deposits found in greenstone belts and the intervening granite/ gneiss terrane are of little importance from a genetic or economic point of view.
The stratiform baryte occurrences in greenstone sequences can be considered as good indicators for spatially related syngenetic base metal deposits.
Ore Petrological Aspects of Copper Mineralisation Near Kalyadi, Hassan District, Karnataka
Authors: Ravindra B. M. , Krishna Rao B. , Vasudev V. N. 
Published: November 2024

Abstract
Low-grade copper sulphide mineralisation around Kalyadi is localised in an early Precambrian volcanosedimentary suite, characterised by cyclic sedimentational features. The rocks have been intruded by ultramafics, granite and dolerite. The supracrustals have been subjected to three phases of deformation and low-grade metamorphism.
The Fe-Cu sulphide mineralisation is stratiform and stratabound, represented by pyrite. chalcopyrite and pyrrhotite. The salient features of tbe mineralisation suggest that the sulphide ore material derived from volcanic exhalatives was deposited along with their volcanosedimentary host rocks syngenetically about 3.0 b.y. ago. The mineralisation is essentially a sulphide facies of iron-formation. Banded ferruginous quartzite also exists in the area, suggesting consanguineous sulphide-oxide facies relationship. The ore has been deformed and metamorphosed along with the host rocks resulting in mobilisation and moderate enrichment.
Quench-Textured Alkali Olivine Basalts from Jungel-Valley, Mirzapur District, Uttar Pradesh, India
Authors: Kumar Vinod , Agarkar P. S. 
Published: November 2024

Abstract
Alkali olivine basalts of Jungel metavolcanic suite in Bijawar greenstone belt of Central India display various morphologies of quench crystals indicative of rapid cooling or supercooling. There is resemblance between crystal growths of the present area and those described from submarine basalts and experimentally produced crystals under disequilibrium conditions. Stratigraphy, structural and petrographic characters of these rocks demonstrate that they represent an ancient oceanic crust.
Magnetic Anomalies and Tectonics of Gosthani River Basin in the Eastern Ghats of India
Authors: Venkateswara Rao V. , Radhakrishna Murthy I. V. , Rao A. T. 
Published: November 2024

Abstract
Magnetic anomalies in the Gosrhani river basin in Andhra Pradesh indicate a suite of charnockitic rocks at depth. The emplacement of these rocks is explained by folding leading to an apical graben development followed by subsidence, uplift and erosion.
The Son Valley Greenstone Belt-Some Aspects of Precambrian Shield Geology, Peninsular India
Authors: Choubey Vishnu D. , Gupta Arindam 
Published: November 2024

Abstract
An elongated linear belt of distinct meta-volcanic and sedimentary assemblage of low-grade metamorphism and tight folding in the Son Valley are described. The contact between the two tectonic units is marked by intense overthrusting and shear deformation. Its persistent regional trend suggests some fundamental fracture pattern across the Precambrian shield. The metavolcanic and sedimentary assemblages are characteristic of Precambrian greenstone belt in Son Valley.
Differentiated Gabbro-Granophyre Composite Sill from Ramagiri Greenstone Belt, Andhra Pradesh
Authors: Ramakrishnan M. , Sundaravanan D. 
Published: November 2024

Abstract
The differentiated gabbro-granophyre composite sill, emplaced in the basic tuffs of Ramagiri greenstone belt, represents the first record of such an intrusion in the Eastern Dharwar craton. The sill consists of four differentiated gabbroic units, namely, the carbonated, mafic, normal and knotted gabbro forming a locally inverted stratigraphy along a steep fold limb in the belt. A faintly layered quartz diorite band, visually resembling anorthosite but compositionally different in having euhedral zoned feldspars and quartz-plagioclase "granophyric ' intergrowths, occurs in association with the differentiated gabbroic units but is separated from it by a later metadoleritic amphibolite dyke. The granophyric quartz diorite and the associated quartz gabbro are not directly related to the other four differentiated gabbros of the composite Ramagiri sill. The quartz diorite is chemically similar but tectonically dissimilar to continental trondhjemites forming tbe root of island arcs and is different from oceanic plagiogranites and continental granophyres in terms of their K2O, Si02, Rb and Sr contents, although such rocks are not uncommon in the ocean floor. Such quartz diorites are believed to have been formed by fractional crystallisation of oceanic tholeiite magma which interacted with sea water to produce low potassic trends, as distinct from the more potassic granophyre differentiates of continental layered sills. These non-continental granophyres in basic sills, together with the associated pillow lavas and pelagic sediments indicate a nascent oceanic to transitional environment generated by rifting of the basement gneisses to produce the Ramagiri greenstone belt.
Hydrothermal Synthesis of 1:1 and 2:1 Type Mg-Ni Layer Lattice Minerals, Their Structural Characterization by X-ray, Infra-Red and Optical Absorption Spectra
Authors: Ghosh D. C. , Mukherjee A. B. 
Published: November 2024

Abstract
Hydrothermal synthesis of 1:1 type and 2:1 type trioctahedral hydrous layer lattice minerals covering the entire Mg-Ni compositional range is reported. Electronprobe microanalyses and X-ray diffraction data conform to the serpentine-type and talc-type chemistry and structure of these phases. Infra-red absorption spectra for the frequency range 4000-600 cm-1 have been presented to characterize, their OH stretching vibrations, OH libration and the general lattice vibration modes. Optical absorption spectra between 2500 nm and 300 nm supplement the infra-red absorption data and clearly establish the d-d transition bands at about 1099 nm, 658 nm and 380 nm as caused by octahedrally coordinated Ni2+. Uniformity of the conditions- of synthesis between 250°C and 300°C and 350 bar PH20 and the X-ray, infra-red and optical absorption spectra confirm the stability of the entire Mg-Ni compositional range under low pressure-temperature epizonal/hydrothermal conditions.
Ampbibolites of the Marutha Gold Prospect in the Precambrian High-Grade Terrain of South India
Authors: Prasannakumar V. , Nair P. K. R. , D'cruz Eric 
Published: November 2024

Abstract
At Marutha, located in the high-grade granulite terrain of South India, gold in association with pyrite and chalcopyrite occurs along the contacts of quartz veins with amphibolite. Structures of the area were produced during two deformational events. Gold-bearing quartz veins were formed before the onset of second deformational event. Amphibolite of Marutha, geochemically comparable with the metavolcanics of Kolar and Hutti, is derived from low-K-tholeiitic basalt and has no komatiitic affinity. Tholeiitic basalt is the probable source of gold at Marutha.
Lopolithic Intrusion of Basalt in the Intertrappeans at Amboli Hill, Jogeshwari, Bombay
Authors: Tolia Nita , Sethna S. F. 
Published: November 2024

Abstract
At Amboli Hill, in Jogeshwari, is exposed a spectacular columnar jointed basalt outcrop which has been inferred to represent a sill-like body into the intertrappean beds. The structural deformation of the intertrappeans gives a distinct saucer-shaped bottom giving the impression of a lopolith. Petrographic and chemical studies of the basalt indicate that the rock is tholeiitic in composition and does not show any significant variation in mineral content and chemical composition across the exposed thickness of the body. The intertrappean beds are predominantly made of volcanic breccias with thin intercalations of sedimentary beds. Detailed study of the petrography and chemistry of the breccia fragments indicate that they are of spilitic character which leads to tbe conclusion tbat the rock is a hyaloc1astite formed by subaqueous eruption of the basaltic lava.
Sedimentary Environmental Discrimination Using Grain-Size Analyses
Authors: Jahan Chowdhury Sarwar , Majumder Tapash Kumar , Roy Mrinal Kanti 
Published: November 2024

Abstract
A multivarite statistical strategy, which reduces the sample-variable matrix to a set of interpretable graphical relationship by multigroup discriminant procedure, is used to maximize the information extracted from grain-size data of three known environments liker iver, beach and dune and an unknown environment of deposition of Tertiary clastics of Bangladesh. This makes the Euclidean distance in the discriminating space to be a valid and convenient criterion for classification/assignment so that the field of influence of each group can be easily visualized and this is conveniently used for the Classification of Tertiary (Miocene-Pliocene) clastics of the folded flank of Bengal foredeep of Bengal Basin where deposition took place in fluvial environment and sediments were carried by meandering river.