bluuebunny/crossref_metadata_2025_split huggingface dataset:
Charnockites and their Colour
Authors: Howie R. A. 
Published: November 2024

Abstract
The characteristic dark colour of charnockite is due to thin pale greenish or brownish yellow veins and stringers throughout the rock. These veins are seen particularly in the feldspars but also occur in quartz and other minerals. The colour is removed from charnockite if it is leached as chips or thin slices with warm hydrochloric acid, when the rock becomes almost identical in appearance with a normal Ieucocratic granite. In thin section the yellow veins can then be seen to have disappeared. Chemical analyses show that the material leached out contains appreciable iron, and comparison of analyses of the rock before and after acid treatment shows that the leaching has decreased the amount of iron present. From this and other evidence obtained on heating, the colour of charnockite is attributed to the presence of a yellowish mineral containing ferric iron, which occurs in veins and wisps throughout the light minerals giving them their characteristic dark olive-brown appearance in hand specimen. The exact nature of this mineral is still problematical.
Although recent work has demonstrated that some charnockitic rocks have almost certainly been derived by the metamorphism of rocks laid down contemporaneously with the surrounding sediments and probably have originated as sediments, it is maintained that the charnockite series of the type area around Madras represents a regionally metamorphosed suite of rocks of original igneous parentage.
On a New Fossil Fish Known from an Otolith from the South Indian Cenomanian
Authors: Sambe Gowda S. 
Published: November 2024

Abstract
A brief reference is made to the abundant occurrence of fish ossiculiths in the Odhium Clay member of the Utatur Group of the Trichinopoly District, South India. The first fossil otolith (sagittal) from India in the same clay has been shown to be the first Cenomanian otolith of the world. After discussing the relationship of the Indian otolith to the already known Mesozoic otoliths, new Linnean taxa of the rank of family (Lycoclupeidae) , genus (Lycoclupea) and species (menakiae) are instituted. Although the age of the new taxa is Upper Cenomanian, a suggestion as to its probable range in time, from Cenomanian to Dogger, is made for future verification.
Modal Composition Variations in the Dalima Biotite Granodiorite Member of the Singhbhum Granitic Complex
Authors: Chatterjee P. K. , Saha A. K. 
Published: November 2024

Abstract
Analysis of variance and polynomial trend surface techniques are used to determine the levels of variability and geographic variability, of five modal attributes and specific gravity of the Dalima Biotite Granodiorite. It is found that modal analyses from one measurement area in one hand specimen collected from one exposure in the pluton gives a reasonable estimate of that exposure, but that more than one exposure per one-square-mile grid is needed to estimate the variability within the grid. There are significant differences between the samples from each one-square-mile grid. The degree 6 polynomial trend surface maps of the modal attributes and specific gravity, based on149samples, represent good appraisals of the regional variability; there is good correspondence between the trends of primary foliation and the compositional contours of the trend surfaces. The structural evidence of the existence of two distinct intrusive units within the pluton is supported by (a) comparison of the cumulative frequency distributions of the modal attributes, and (b) the distinctive patterns of the individual trend surfaces for the two units. Compositional and structural evidences suggest that the western unit is the older of the two.
The Lonar Crater-Some Geochemical Data
Authors: Venkatesh V. 
Published: November 2024

Abstract
If the Lonar depression is a meteorite crater, a giant meteorite several-fold richer in nickel and cobalt than the basaltic country rock, should have produced localised enrichment of these metals. Weathering and secondary dispersion, aided by favourable centripetal drainage conditions, should have produced anomalous concentrations of the metals in plants, soil and silt at the site. This is not borne out by the average and below average values of the metals in geochemical samples from the crater area; and recent experimental sampling in the meteorite crater of Arizona also showed similar lack of anomalous metal values. The use of geochemical anomalies in recognising meteorite craters should, therefore, await investigations in other established craters.
Charnockitic Rocks of Tinnevelly District, Madras
Authors: Narayanaswamy S. , Lakshmi Purna 
Published: November 2024

Abstract
The charnockitic rocks of the Tinnevelly district are conformable in strike and dip with the enclosing gneissic rocks and nowhere show cross-cutting intrusive relationship. The geological structure consists of an earlier period of folding about a NW-SE axis, followed by a second stage cross-folding about a NNW-SSE axis, and discordance of rock types as well as structural elements in the north-east part of the district by a zone of thrust. The charnockitic rocks thus appear to have been subjected to two periods of deformation, granitic intrusion and metamorphic episodes.,
The mineralogical compositions, lithological associations, mutual field relationships and structural history of the district, suggest that Tinnevelly charnockitis represent a geosynclinal association of sediments, basic volcanics and intrusives, folded and refolded during possibly two periods of orogeny, accompanied by granitic and migmatitic activity and deep-scated plutonic palingenetic recrystallisation.
Petrography and Origin of Miliolite Limestone of Western Saurashtra Coast
Authors: Shrivastava P. K. 
Published: November 2024

Abstract
The Miliolite Limestone of the Western Saurashtra coast consists of a succession of mostly high-energy calcarinites, calcirudites, coquinoid bands, and minor carbonate-mud. Petrographic examination of these rocks shows that the sediments were formed under shallow, warm, agitated waters of tropical sea shores. These are mainly calcareous beach deposits which have been cemented by secondary calcium carbonate precipitated from sea water which was saturated with it. There were minor variations in the beach environment which are reflected in the associated sediments. The occurrence of these rocks over the Tertiary coastal plains and in the interior of the Deccan Trap country indicates a higher stand of the sea during Pleistocene time than at present.
Differentiation of Alkali Basaltic Magma Towards the Salic Ends
Authors: Bose Mihir K. 
Published: November 2024

Abstract
Alkali basaltic magma fractionating towards the salic ends, in plutonic environment,. shows characteristic crystallisation behaviour for which both magma chemistry and physical conditions seem to be responsible. Both pressure and iron enrichment of the magma appear to inhibit reaction relation of olivine with the rest liquid. The hydrous magma may experience prolonged precipitation of chain-silicates whose field of crystallisation is extended at the expense of plagioclase and olivine. Both pyroxene and amphibole show parallel trend in compositional variations by inviting calcium, titanium and aluminium along with a progressive Fe-Mg diadochic replacement with fractionation. Compositions of the precipitating mafic phases highly influence the nature of residual liquid which may thus show wide variation in silica saturation. High pressure fractionation of an alkalic basic magma under favourable condition may even lead to a peralkalic silica rich differentiate.
Larger Foraminifera from the Subathus of Beragua-Jangalgali Area, Jammu & Kashmir State
Authors: Singh Pratap 
Published: November 2024

Abstract
A rich assemblage of the larger foraminifera has been recorded for the first time from the Subathus of Beragua-Jangalgali Area, Jammu & Kashmir State. Eleven species of the larger foraminifera belonging to four genera represented by three families, have been studied and described in this paper. This foraminiferal assemblage suggests a Laki (Lower Eocene) age for these formations. The Subathus of the present area have been correlated with the other similar formations occurring in India. The micropalaeontological investigation of the area leads to the conclusion that the Subathus were deposited in neritic environment.
A Contribution to the Methodology of Palaeocurrent Determination
Authors: Sharma B. L. , Damle G. V. 
Published: November 2024

Abstract
Palaeocurrent directions in sandstone around Jodhpur (Vindhyan or early Palaeozoic) were determined by measuring direction of cross-bedding, grain orientation, quartz 'c' axis orientation, and also with the help of asymmetrical ripples. A comparison was made of the results derived from these different methods. It was found that there is a fairly good agreement between the directions derived from the study of grain orientation, quartz 'c' axis orientation and cross-bedding. Usually asymmetrical ripples also agree and indicate the general direction of the palaeocurrent; hut occasionally asymmetrical ripples turn out to be climbing ripples and indicate a direction opposite to the true palaeocurrent direction. This paper attempts to correlate the results obtained by different methods and concludes that a fairly good correlation exists between the results obtained by different methods. The grain orientation studies indicate that there is an up-current imbrication of the elongate quartz grain a in general; but in the case of fore-set surface in the cross-bedded strata, they tend to be parallel to the fore-set bedding and therefore develop a down-current imbrication. It is also found that existence of climbing ripples may indicate the necessity of caution and should be used only to assess the depositional strike.
Quantitative Differences in the Living Benthic Foraminifera of Vellar Estuary, Tamil Nadu
Authors: Ramanathan Rm. 
Published: November 2024

Abstract
Seasonal quantitative distributions of the species of the living benthic foraminifera forming the greater part of the foraminiferal population in the Vellar estuary, South India have been studied. Recorded physico-chemical factors have played an important role in controlling the relative abundances of this microfauna. Estuarine foraminiferal assemblage in general shows a quantitative increase with increasingly marine conditions.
Petrology of the Intrusive Alkalic Suite of Koraput, Orissa
Authors: Bose Mihir K. 
Published: November 2024

Abstract
The late Pre-Cambrian intrusive suite of Koraput, Orissa comprises of alkali-gabbro-calc-alkali syenite-perthite syenite (perthosite)-nepheline syenite, arranged in the sequence of emplacement. Alaskitic granite develops as a direct offshoot from the hydrous alkali-gabbro magma during fractional crystallisation.
Chemical, optical and X-ray data for the rock forming minerals have been furnished, and the trend of mineralogical variation during fractionation of the magma has been traced. Structural states and geothermometric significance of the feldspars are investigated. The alkali feldspafs in the suite reveal a compositional variation tending to approach the temperature minimum on Ab-Or join. Nephelines both in syenite and pegmatite show a marked variation from the ideal composition. The major mafic silicates, namely pyroxene and amphibole, essentially show a parallel trend of variation being progressively richer in ferrous iron at the expense of magnesium while the entry of calcium in the chain structures is not much affected. The trend of increasing Fe/Mg ratio with fractionation is also imprinted on biotite. The iron-titanium oxides indicate the change of physicochemical conditions in fractionating magma.
Variations of major elements and of some trace elements as related to respective diadochic major elements have been discussed. The alkalic suite shows a progressive increase in alkali metals with advancing differentiation as reflected through increasing differentiation index though peralkalinity is never reached but in granite. Magmatic evolution in the development of the alkalic complex has been elucidated.
Metamorphic Control of the Origin of Secondary Fe-Ti Oxides in the Noritic Rocks Around Saltora, West Bengal
Authors: Roy Asit Kumar 
Published: November 2024

Abstract
Sub-parallel bands of noritic rocks occurring as concordant inclusions within anorthosite are abundant around Saltora (23°31'12'' N and 86°56'20" E). At places they occur as concordant intrusions in the surrounding country rocks which comprise acid and basic gneisses, granulites and migmatites. Noritic rocks are the hosts for Fe-Ti oxides of two generations, viz. primary and secondary. Secondary Fe-Ti oxide is almost exclusively ilmenite, whose proportion increases with increasing alteration of pyroxene in the noritic rocks. This trend of variation supplemented by the petrographic variation of the noritic rocks suggests that the secondary ilmenite is a product of diapthoresis, a process that involved the redistribution of Fe+2, Fe+3 and Ti+4 between the silicate and oxide phases under a low partial pressure of oxygen.
Two Faunal Associations from the Maleri Formation of the Pranhita-Godavari Valley
Authors: Kutty T. S. 
Published: November 2024

Abstract
In the course of a study of the Maleri formation of the Pranhita-Godavari valley exposed between Maleri and Dharmaram, a number of new fossil localities have been found. The present paper gives a brief description of two distinct faunal associations in the area. Their relationships to the rock types are discussed, and some suggestions are made as to the probable environments represented by the two associations.
Superimposed Folding in the Transitional Rocks (Precambrians) and its Influence on the Structure of South Eastern Margin of the Vindryan Basin, Jabalpur District, Madhya Pradesh
Authors: Choubey V. D. 
Published: November 2024

Abstract
The author outlines the general geologic setting of the Transitional rocks (Precambrians) of the Jabalpur district, describes the principal characteristics of folding, records the divergence in orientation, and suggests an explanation for the regional tectonic setting. The folds occur in a thick sequence of sub-metamorphic rocks which have been subjected to repeated folding. Two successive phases of folding have been recognised; major folds of the first phase account for the over all structural pattern shown by the lithologic units; while the second phase occurs mostly as minor folds. The major folds are isoclinal to overturned folds and their axial planes and fold limbs strike north-east and dip steeply, the fold axes plunge steeply towards NE. The general strike of the axes and axial planes of the later phase is north-west, plunging SE.
Along the south-eastern margin of the Vindhyan basin where it abuts against these repeatedly deformed rocks, a flat elongated dome has been developed around labera and Katangi. Regarding the mode of formation of the dome structure, it is suggested that it has resulted from the interference of two sets of folding in the basement rocks and the subsequent tectonic movement direction lay close to the axial plane of the second fold set.
Blaini Tillites Near Rishikesh and their Origin
Authors: Gaur Girish C. S. , Dave V. K. S. 
Published: November 2024

Abstract
The Blaini Formation exposed near Rishikesh, U.P., has been studied and an attempt has been made to describe its origin. It has been suggested that the lower laminated sequence and limestone were deposited during the west base glaciation; it was followed by a period of dry base glaciation during which deposition of massive tillite and limestone took place. The turbulent waters supersaturated with respect to CaCo3 have probably deposited the limestones. This sequence was followed by an interglacial period during which shales intercalated with siltstone and sandstone, and variegated shales were deposited. The second glaciation (dry base) was of a shorter duration and deposited limestone and upper tillite. Lastly, during the waning phase of the second glaciation, deposition of the topmost bleached pink and grey shales took place.
Silurian-Devonian Boundary in the Indian Subcontinent
Authors: Gupta V. J. 
Published: November 2024

Abstract
In the present paper an attempt has been made to define the boundary between the Silurian and Devonian systems of Pakistan, Kashmir, Ladakh, Lahaul, Spiti, Kumaon and Nepal on the basis of the available palaeontological and stratigraphical data from these regions.
Petrological Studies in Parts of the Closepet Granite Pluton, Mysore State
Authors: Divakara Rao V. , Aswathanarayana U. , Qureshy M. N. 
Published: November 2024

Abstract
With the object of investigating the mode of origin of the Closepet granite, Mysore state, India, integrated geological, geochemical and geophysical studies have been made of the northern part of the pluton as also the adjacent Chitaldurg and Hosdurga granites and Penmsular gneiss. The Joints (post-emplacement'l) in the Closepet granite and the ratios of mineral pairs indicate that (i) the grey and the pink varieties of the Closepet granite and the Chitaldurg granite are comparable to many respects and might have had a common mode of origin, (ii) the Hosdurga granite is distinguishable from the above granites in having a lower amount of quartz and K-feldspar and higher amounts of plagioclase and mafics and (iii) the Peninsular gneiss markedly differs from the Closepet and Chitaidurg granites, and departs from them in the same direction as the Hosdurga granite but in a more accentuated way. A two-stage model for the origin of the Closepet granite is supported by the following petrological evidence presence of two generations of quartz, unzoned anhedral plagioclase, replacement of plagioclase by microcline and the presence of perthite and myrmekite along With K-feldspar and quartz. The Closepet granite was apparently formed by palingenesis (starting from the Peninsular gneiss) and metasomatism involving enrichment in Si, K and Na, among other elements.
The Nature and Origin of the Blue Dust in Precambrian Sedimentary Iron Ores
Authors: Sahu K. C. , Gurav R. P. 
Published: November 2024

Abstract
In the course of study of the Precambrian sedimentary iron ore deposits of Noamundi in Singhbhum district of Bihar and of Goa, extensive occurrences of powdery iron ores known as Blue Dust have been observed and examined. Field features like the nature of occurrence, textural, structural, and mineralogical character of the Blue Dust have been observed in detail. Shape and size analysis of the mineral grains of the powdery ore have been made and their chemical, X-ray and DTA data presented to explain the mineralogy and chemistry. Etch tests and dissolution experiments have been carried out on standard ore pieces at different pH and temperature for different lengths of time to produce material equivalent to the powdery iron ore. From the above data and experiments, and with the theory of anisotropic dissolution of hematite, the mechanism of formation of the Blue Dust has been explained.
Mechanical Analyses of Middle Siwalik Sandstones from Ramnagar, Nainital District, Kumaon Himalaya
Authors: Tandon S. K. 
Published: November 2024

Abstract
Studies have been carried out on the size characteristics of Middle-Siwalik sandstones collected from the tract lying between Ramnagar and Kalagarh with a view to interpret the environment of deposition. Statistical parameters have been obtained from the weight frequencies recorded from the mechanical analyses of these sediments. Analysis on the Wentworth's size classification reveals that the sediments are composed essentially of fine and very fine sands, the former being predominant. It is seen that the coarser fraction behaves differently from the rest of the sediments and has been incorporated in response to fluctuations within the tectonic framework. Overall conditions of sedimentation remained more or less similar.
Dharwar Stratigraphy
Authors: Srinivasan R. , Sreenivas B. L. 
Published: November 2024

Abstract
Reconsideration of the stratigraphy of the Dharwars of Mysore State in the light of new data suggests that they are Paleoproterozoic and overlie Charnockites of Archean age. Classification of Dharwars based on tectonomagmatic and atmospheric evolution leads to a four fold divison. Pregeosynclinal shelf stage iS represented by two cycles of platformal sedimentation and magmatism; the earlier, under oxygen deficient conditions, on mafic platforms built by subaerial lavas, Is represented by Bababudan Series, and the latter under oxygenic conditions accompained by alkaline ultramafic intrusions gave rise to Dodguni Series. The geosynclinal Stage represented by pillow-Iava-greywacke-Iron ore deposition (third cycle of magmatism and sedimentation) constitutes the Grey trapRambennur Series. Early tectonic plagioclase granites-Champion gneisses syntectonic migmatites-Peninsular gneisses and late to post-tectonic alkali metasomatic granites Closepet granites (fourth, fifth and sixth magmatic cycles) developed during the folding and metamorphism of Dharwar geosynclinal pile. The inversion of geosyncline witnessed apogeosynclinal molasse red bed Sedimentation (fourth cycle of sedimentation) represented by G. R. Series. Paleoproterozoic epidiorites and post-Paleoproterozoic dolerites cratonised the area.
Petrology and Geochemistry of the Ultramafic Intrusion of Keshargaria, Singhbhum, Bihar
Authors: Saha A. K. , Bose M. K. , Sankaran A. V. , Bhattacharyya T. K. 
Published: November 2024

Abstract
An ultramafic body flanked on either side by tholeiitic dolerite occurs as a minor intrusion in the Singhbhum granite, southwest of Keshargaria (22°36' : 85°56'). The ultramafic body varies from pyroxene-rich harzburgite to olivine-rich poikilitic harzburgite, the latter being conspicuous in the central part of the intrusion. A crude planar structure defined by enstatite crystals is developed towards the contact walls. The constituent mafic silicates, arranged in paragenetic order, are: forsteritic olivine, enstatite, diopsidic augite (malacolite), phlogopite and plagioclase, the last three phases appear to represent intracummulus crystallisation.
The central part of the intrusion is relatively enriched in olivine whereas the marginal parts are in an advanced stage of differentiation relative to the central zone, indicated by lower Mg/Fe and Ba/Rb ratios in the former. This spatial variation in degree of differentiation is considered to have been induced during flowage of the crystal-iquid mush. The ultramafic intrusion is non-uniform in chemical and mineralogical compositions and does not represent unaltered mantle material. The significant deviation from the mantle composition is in higher aluminium and ferric iron and lower magnesium in the investigated peridotite. The Keshargaria ultramafic body which is one of several such bodies associated with the Newer Dolerite intrusions, represents a stage of fractionation of mantle derived magma.