bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbon Isotope Ratio of the Coaly Matter from the Basal Part of the Proterozoic Vindhyan Supergroup
Authors: Krishnamurthy R. V. , Bhattacharya S. K. , Mathur S. M. 
Published: November 2024

Abstract
The stable carbon isotope ratio (13C/12C) of the carbonaceou matter from the basal part of the Vindhyan sub-group, estimated to be about 1200 Ma old, has been measured and the values support a biogenic origin for the incorporated carbon.
Isotopic Composition of Deccan and Ocean Ridge Basalts: Implications for their Mantle Sources
Authors: MacDougall J. D. 
Published: November 2024

Abstract
Isotopic data suggest that the mantle sources for ocean ridge basalts and some continental flood basalts, particularly the Deccan, may be in the same global depleted convecting mantle. If this is the case, the upwelling Deccan mantle source must have mixed with small amounts of an ancient enriched mantle component, similar to that detected in some kimberlites, prior to interaction with the crust. Such a scenario appears to be required by the facts that the isotopic composition of the depleted end members is approximately constant throughout the Deccan but different from ocean ridge basalts, and the oxygen isotopic composition of the most depleted Deccan sample is characteristic of mantle values. The wide variability in isotopic composition of Deccan and some other continental flood basalts is then the result of crustal processes, as has been suggested by many authors.
The Geochemistry of Uranium and Thorium Isotopes in the Salt Lakes and Adjacent Ground Waters of Rajasthan
Authors: Baskaran M. , Krishnaswami S. , Bhandari N. 
Published: November 2024

Abstract
The concentrations of 238U, 234Th and (234U238U) activity ratios and major ion chemistry of several water samples from the salt lakes and their adjacent ground waters in Rajasthan have been measured. 234Th concentration in all the samples, except in one high alkalinity water from the Sambhar Lake, are quite deficient relative to its parent 238U the average (234Th/238U)activity ratio being 0.12. This deficiency corresponds to a mean residence time of - 5 days for 234Th in these waters. In the high alkalinity water, 234Th concentration is at near equilibrium with 238U, yielding a residence time much longer than radioactive mean life. The long residence time of Th in high alkalinity waters may result from the complexing of 234Th by (CO3)-2 ion. 238U concentration in some of the ground waters near the salt Iakes are high, the highest being in a Didwana sample, 565 dpm/l, The Didwana samples also have the highest (234U238U) activity ratios observed for Indian waters. The high uranium concentration in the Didwana ground water is suggestive of uranium rich aquifer solids.
Mineral Chemistry and Petrology of the Manganese Silicate Rocks of Vizianagaram Manganese Belt, Andhra Pradesh
Authors: Bhattacharyya Samit 
Published: November 2024

Abstract
The manganese silicate-carbonate rock or manganese protore occurring asa conformable band within Khondalite Group of rocks, represents metamorphosed impure manganiferous sediments comprising manganese carbonate admixed with silica and clay. This manganese protore differs from gondite as well as kodurite and resembles queluzite and hence this protore is equated with the queluzite type. The significance of the presence of knebelite (manganese olivine) in the protore as an indicator of an original carbonate-bearing sediment has been discussed. Besides, mineralogy and chemistry of the various constituent minerals of the prot ore have been presented.
Geochemistry of feldspars from the Ambalavayal Molybdenite Prospect, Kerala
Authors: Santosh M. 
Published: November 2024

Abstract
Major and trace element geochemistry of coexisting alkali feldspar and plagioclase pairs from granite and alkali feldspars from the associated pegmatites of the Ambalavayal molybdenite prospect in Wynad district, Kerala, are presented. The element levels in both the feldspars show an overall comparability with the values reported from elsewhere. The nature of distribution of elements between coexisting feldspars is generally consistent with their crystal chemical behaviour. X-ray studies of alkali feldspars show a triclinic symmetry with the triclinicity values ranging from 0.2955 for feldspar from the granite to 0.6742 for feldspar from the pegmatite. Mol per cent feldspar end members range from Or56.43Ab40.52An3.05in alkali feldspar of the granite to Or74.00Ab22.51An3.19 in alkali feldspar of the pegmatite. The crystallization temperature of the alkali feldspar-plagioclase pairs in the granite is estimated to be between 704-740°C and that of alkali feldspar in the pegmatite to be between 525-580°C.
Soft-Seditnent Recumbent Folding in a Slump-Generated Bed in Jharia Basin, Eastern India
Authors: Ghosh S. K. , Mukhopadhyay Abhijit 
Published: November 2024

Abstract
Paraconglomerates, with pebble- or boulder-sized phenoclasts of laminated clay in a matrix of medium grained massive. sandstone, occur toward the top of a turbidite sequence in the Talchir Formation at the N. W. corner of the Jharia Coal Basin in eastern India. The soft-sediment folds within the shale phenoclasts are dominantly recumbent. An analysis of the geometry of the structures suggests that a mass of sand with interlayered clay units was liquefied or fluidized. This in its turn generated a plastic mass flow in the course of which tenacious clay yielded slabs which were subsequently rotated and deformed. When the down-slope movement of the sand body had slowed down or had come to rest on the basin floor, the piled up mass of soft sediments was flattened under its own load and the contortions of the clay phenoclasts acquired their recumbent character.
Proterozoic Basic Dyke Activity in Kerala Along the Western Continental Margin of India
Authors: Radhakrishna T. , Poornachandra Rao G. V. S. , Mitchell J. G. , Venkatesh A. S. 
Published: November 2024

Abstract
Palaeomagnetic data on the basic dyke rocks of Palachal (Cannanore district) and Agali (Palghat district) regions of Kerala in the southwestern part of India are presented. Palachal dyke has obtained stable vectors of D and I at 200Oe and possesses a single thermally discrete component with blocking temperatures at the Curie temperature of magnetite, whereas the Agali dyke has shown unstable behaviour to the AF and thermal demagnetisation tests. The Palachal dyke possesses a southwest negative NRM remanence (D = 225.5°; 1 = 48.5°; K = 48.52; α 95 = 7.24) and a pole position (44°N; 135°E) which is closer to that of Gwalior Traps (1830 ± 200m.y.) or Group IV dykes of Proterozoic age. K-Ar ages of 1668 ± 31 m.y. and 1660 ± 25m.y. have been obtained for the Palachal dyke and it is compatible with the Palaeomagnetic results. The basic dyke activity jn the southwest is not solely related to the rifting of western continental margin of India as earlier suggested but is in part of Proterozoic age.
Petrography and Geochemistry of the Tosham Hill Felsic Volcanics, Haryana
Authors: Pareek H. S. 
Published: November 2024

Abstract
Explosion breccia, tuff and felsite constitute the felsic volcanic rocks at Tosham Hill. Petrographically, the groundmass of tuff is distinct from that of felsite in being associated intimately with particles of iron ores. Geochemically, these rocks arc classified as potassic rhyolites and dacites. The trace elemental data show that explosion breccia is higher in Ba (230, 250ppm) than tuff and felsite (1O-60ppm); B(220ppm) and Sn (180 ppm) values predict significant economic concentrations of the latter at depth: quartz-porphyry dyke may perhaps be correlated with the Malani episode.
Geochemistry of the Archaean Gneiss Complex and Associated Rocks of the Kanakapura Area, Karnataka, South India
Authors: Mahabaleswar B. , Vasant Kumar I. R. , Friend C. R. L. 
Published: November 2024

Abstract
The area of present investigation forms a part of the Archaean high-grade gneiss terrain of Karnataka. The rocks comprise both acid and basic lithologies and involve the late Archaean Closepet granite. Petrographically the acid rocks span the range, tonalite to granite, whilst the basic rocks are amphibolites and two-pyroxene granulites. The acid 'rocks have calc-alkaline affinities and resemble those from the transition zone to the east. Trace elements show them to be relatively undepleted with K/Rb ratios of &gt;500. Simulated REE patterns of gneisses reveal that there are three broad groups: two of which are steep, but at different REE abundances, suggesting high pressure evolution; and one relatively flat group suggesting low pressure evolution. The basic rocks have a tholeiitic affinity, but are clearly separate, the granulite facies types being slightly more magnesian. The trace element chemistry of these basic rocks has been disturbed by migmatization. The REE patterns of Closepet granite are steep and may be related to the partitioning of accessory minerals such as allanite. An attempt is made to establish the relative position of the granulite facies metamorphism with respect to the regional fabric and retrogression.
Marine Magnetic Profiles from the Direction Bank to the Kori Bank, Western Continental Shelf of India
Authors: Ramana M. V. , Subrahmanyam V. , Subba Raju L. V. 
Published: November 2024

Abstract
Total magnetic field intensity measurements along two parallel NW-SE tracks from the Direction Bank to the Kori Bank show correlatable magnetic anomalies. High frequency positive anomalies observed northwest of Kathiawar coast terminating at about 21°N are interpreted due to the magnetic basement i.e, basalts at a depth of about 2 km. A low amplitude negative anomaly observed around 21°N (between 69°E and 70°E) may be due to the westward extension of the Narmada-Son lineament. Absence of significant anomalies south of these high frequency anomalies may be due to thin Traps or greater thickness of sediments. High amplitude and broad wavelength negative anomaly observed off Bombay (l9°N, 71.5°E) is interpreted as due to contact or faulting of Precambrian formations and Deccan Traps.
A Parametric Approach to Terrain Analysis and Geomorphic Regionalization of Pravara River Basin (Maharashtra)
Authors: Kale Vishwas S. , Rajaguru S. N. 
Published: November 2024

Abstract
A detailed micro-level statistical analysis has brought out the spatial variation in the terrain of Pravara and Mula sub-basins. Principal component analysis has aided in establishing three groups of inter-related variables; and the Factor Analysis has been able to synthesize patterns of six geomorphic variables into a single comprehensive pattern labelled as 'Morphogenetic Regions'. The multivariate analysis has been able to derive equations of high predictive and descriptive value. Such an approach to terrain analysis has been found to be very fruitful than the conventional morphometric analysis.
Granite Rock Standard Sample: NGRI-G
Authors: Govil P. K. , Ahmad S. M. 
Published: November 2024

Abstract
As a part of standard rock sample preparation program, NGRI has prepared a standard rock sample of granite for chemical analysis of granite rock samples using instrumental methods of analysis and to calibrate the instruments. International granite rock standards prepared by United States Geological Survey are no available and, thererore, it was felt necessary to prepare our own standards for different rock types.
The sample is homogeneous and gives reproducible values for all the major and minor oxides and ten trace elements. Replicate analysis at NGRI using XRF, AAS, Spectrophotometer and at other laboratories in USA and West Germany have given confident results. Proposed values for nine oxides and seven trace elements are given in this paper and the sample is offered to be used as a geochemical reference standard for granite samples.
Trends in Grain-Size Measures of the Quaternary Sediments off the Vengurla Coast, Maharashtra; With Reference to Beach Morphology and Tectonic Evolution
Authors: Sukhtankar R. K. 
Published: November 2024

Abstract
Field studies along the coast of Vengurla, Maharashtra, reveal presence of stabilised dunes, older and younger raised beaches apart from the present intertidal zone. From these geomorphic features, a fall in sea-level to the extent of about 4 m and 1 m during the Holocene period is suggested.
The sediments constituting these geomorphic features have been examined for their grain-size characteristics. Statistical parameters, such as: mean size, standard deviation and skewness have been compared from each geomorphic unit. The comparison indicates reversals in their trends of variation, which have been ascribed to transgressional cycles.
It is suggested that tectonic control, which operated either through a relative fall in sea-level or an emergence of the Indian shield during the Holocene period is responsible for the accretionary nature of the beach.
Birmania Phosphorites: Petro-Mineralogical Characters and Palaeogeological Implications
Authors: Husain Viqar , Banerjee D. M. 
Published: November 2024

Abstract
The lower Palaeozoic (possibly Cambrian) phosphorites of Birmania in Western Rajasthan are pelletal as well as microcrystalline. Carbonate fluorapatite is the only mineral phase in these phosphorites. Petrodiagenetic and mineralogical studies indicate primary precipitation of apatite directly from the basinal waters. Suggestions have been made for an extensive Cambrian sea encompassing the phosphogenic provinces of Western Rajasthan, Hazara in Pakistan and Mussoorie hills of Kumaun Himalayas.
Petrogenesis of the Angadimogar Syenite, Kerala and its Taphrogenic Affiliation
Authors: Santosh M. , Nair N. G. K. 
Published: November 2024

Abstract
A syenite pluton occurring ncar Angadimogar in Cannanore district. northern Kerala and emplaced close to the continental margin and along a NW-SE trending faultlineament is reported. Alkali feldspar constitutes the dominant mineral with subordinate albitic plagioclase and quartz. corresponding to nordmarkitic composition. The syenite shows unique assemblage of accessory minerals. namely hornblende, riebeckite. crocidolite and acmite with diopside, bi.otite. zircon, sphene and calcite. High alkali content, with dominance of Na20 over K20, moderate transition dement contents and low Rb values are characteristic. Petrochemical features suggest melt equilibration from a K-rich, Rb-depleted mantle source, with subsequent amphibole and alkali feldspar fractionation. Significant increase in fO2, fH2O and peralkalinity towards the residual stage is deduced. The syenite belongs to the group of Late Precambrian-Early Palaeozoic alkaline intrusives of the region, with its generation and emplacement correlatable with the taphrogenesis of the western continental margin of lndia.
Late Miocene Planktonic Foraminifera of Interview Island, Bay of Bengal
Authors: Sharma V. , Kumar Ravindra 
Published: November 2024

Abstract
A sequence of clayey to sandy limestone exposed on the eastern coast of Interview Island, Bay of Bengal is studied for foraminiferal content. Twenty-seven species of planktonic foraminifera are reported. The species assemblage consisting of Globorotalia plesiotumida, Globigerinoides extremus, Neogloboquadrina acostaensis and Globorotalia (Tenuitella) anfracta suggests a Late Miocene age for the limestone unit. The assemblage is referable to Zone 17 of Blow (1969) and Zone 17A of Srinivasan and Kennett (1983) and represents the Neillian Stage (Srinivasan, 1978).
Tectonically-Controlled Gold Mineralisation in Chigargunta Area, South Kolar Schist Belt, Chittoor District, Andhra Pradesh
Authors: Mukherjee M. M. , Natarajan W. K. , Shashidharan K. 
Published: November 2024

Abstract
Several parallel to sub-parallel auriferous mineralised zones of economic significance occur over a strike length of 3 km and spread over a width of about 1 km in 'Chigargunta area of South Kolar schist belt. The host rocks for mineralisation are metamorphosed basalt and acid tuff ('Champion gneiss'). The mineralised zones represent ductile shear zones transecting the regional north-south trending schistosity (S2) at low angle. The pre-existing planar and linear fabrics of the rocks have been rotated into parallelism with the shear zone. The shear zones display mylonitic foliation with prominent downdip lineation, folds of variable orientation, boudinaging and crenulations. Such deformation features are confined only to these strongly tectonised zones believed to have evolved by simple shear deformation. A progressive grain size reduction accompanied by hydrothermal retrogressive metamorphism of the amphibolite facies host rocks culminates laterally into the centre of the mineralised zones with lower grade greenschist assemblage. Nondilatant pegmatite veins and some high temperature alteration minerals indicate possible strain heating. The auriferous lodes occurring in Kolar Gold Field might have a simiiar tectonic evolution.
Argentiferous Roquesite (CUInS2) From the Tosham Tin Prospect, Bhiwani District, Haryana
Authors: Seetharam R. 
Published: November 2024

Abstract
The sheared rhyolite-metasediment contact of the Tosham Hill is well-mineralised with disseminations and thin veins of very fine grained pyrite, pyrrhotite, chalcopyrite, sphalerite, galena, cassiterite, stannite, bismuthinite, rutile, hematite, wolframite and roquesite. Roquesite occurs intimately associated with chalcopyrite and is replacing it. The approximate reflectance of roquesite in white light measured in air was 20.7% and its average Vickers microhardness value was 229. Qualitative analysis of roquesite carried out with the help of the Laser microanalyser showed presence of major amounts of copper and indium and minor amount of silver. Based on the physical, optical and micro-chemical data, roquesite has been identified as the argentiferous variety, This is the first report of the occurrence of roquesite from India.
Hydrogeomorphic Classification of the Marginal Gangetic Alluvial Plain in Uttar Pradesh, India, Using Satellite Imageries
Authors: Bajpai V. N. , Gokhale K. V. G. K. 
Published: November 2024

Abstract
On the basis of multispectral analysis of LANDSAT imageries, the Marginal Gangetic Alluvial plain has been lithologically and geomorphologically classified. Distinct morphological divisions mapped include, uplands, ravines, floodlplains and rocky tracts. The upland morphology is typically represented by the cis- and transregions of the Ganga and Yamuna rivers. The ravines have characteristic patterns and reflect distinctly the influence of soil texture, basement structure and relief. While dendritic patterns are common in areas with shallow basement indicating limited infiltration, irregular pattern of deep headward erosion are common in areas of high relief. The flood plains formed by rivers of the Ganga and Yamuna system exhibit variations in morphology corresponding to the variations in the sediment load and grain size. The rocky tract is typical of flat-topped ridges and escarpments with sporadic alluvial patches.
Abandoned channels, intersecting ridges controlled by joints and depressions filled with alluvium within the rocky tract, which offer potential sites for ground water development have been identified.
Mineralogy and Mineral Chemistry of the Manganese-Poor and Manganiferous Iron-Formations from the High-Grade Metamorphic Terrain of Southern Karnataka, India
Authors: Devaraju T. C. , Laajoki K. 
Published: November 2024

Abstract
The iron-formations of the high-grade metamorphic terrain of Southern Karnataka comprise both Mn-poor (av. 0.3% MnO) and Mn-rich (av, 7.4% MnO) types. The two types are distributed throughout the 1273km2 area studied. Each type occurs constituting a large proportion of an individual body and within each body, complex variations from one type to the other, both along and across the strike, might exist. Despite their high-grade metamorphism the rocks have preserved primary sedimentary banding; there are, however, no relics of original textures or minerals. A very striking mineralogical feature of these iron-formations is the common occurrence of pyroxenes and garnets as major mineral phases in addition to magnetite and quartz. Mn-rich types are typically enriched in garnet whereas the Mn-poor types are generally almost devoid of it or contain' a small proportions of it. Pyroxenoids appear in the Mn-rich iron-formation analysing over 6% MnO. The other minerals of restricted occurrence include ferroactinolite, grunerite, Ksfeldspar (orthoclase-microcline), plagioclase (An 20-25), olivine, biotite and chlorite. Apatite is the most common accessory; zircon is scarce.
A detailed electronprobe microanalysis has revealed; (1) the low MnO content of less than 2%,1%,0.4% and 0.03% respectively, of garnet (70-81% almandine), orthopyroxene (ferrohypersthene-eulite ; 30-22 En), clinopyroxene (augite-ferroaugite to saliteferrosalite) and magnetite in the Mn-poor iron-formation, (2) the high MnO content of 10-20.5%, 2.5 to 15%, 2.25 7.5 and 0.2-0.3% respectively of garnet (almandine 30-54 - spessartite 39-49), orthopyroxene (manganoan ferrohypersthene-rnanganoan eulite), clinopyroxene (manganoan augite-ferroaugite to manganoan salite-ferrosalite) and magnetite in the Ma-rich iron-formation, (3) the occurrence of pyroxenoids varying in character from pyroxferroite to pyroxmangite with the Fe: Mn ratios either just below or above 1 : 1, (4) the common occurrence of (exsolution) intergrowths of one pyroxene in the other, (5) the occurrence of Mn-poor magnetite (≤0.03%MnO) carrying abundant exsolutions of hercynite and Mn-poor (around 1% MnO), ilmenite in the Mn-poor iron-formation and (6) magnetites (around 0.3% MnO) carrying Mn-rich ilmenite (MnO 15-30%) exsolutions in the Mn-rich iron-formation. An empirical study of the Mg-Fe-Mn distribution in the co-existing pyroxene and garnet has shown that these have crystallised in equilibrium metamorphic conditions corresponding to granulite facies. Estimations based on better suited pyroxene-garnet compositions occurring in the associated granulite facies rocks have indicated the formation of ironformations of the area at temperatures of 720-820°C and pressures of 7-11 Kbars.
Mineral Composition, Textures and Deformation in Late Archaean Banded Iron-Formation Rich in Magnesioriebeckite and Aegirine, Bababudan, Karnataka, Southern India
Authors: Chadwick B. , Garrioch N. H. G. , Ramakrishnan M. , Viswanatha M. N. 
Published: November 2024

Abstract
Assemblages rich in magnesioriebeckite, aegirine and magnesian siderite (var. pistomesite) characterise parts of the Banded Iron-Formation low in the Mulaingiri Formation of Bababudan, Electron microprobe analyses show that aegirine contains up to 53.29 wt% Si02, 0.17 wt% A1203, 32.20 wt% TotFeO, 0.23 wt% MgO and 14.09 wt% Na20; and magnesioriebeckite contains up to 55.57 wt% Si02, 0.07 wt% Al103, 29.16 wt% TotFeO, 8.53 wt% MgO and 7.37 wt% Na20. These abundances are broadly in accord with previously published results from wet analytical techniques.
A diagenetic or very low-grade metamorphic texture of randomly oriented needles of magnesioriebeckite and granoblastic-polygonal quartz in chert mesobands is transitional into a texture dominated by long prisms of magnesioriebeckite intergrown with elongate grains of quartz which forms an LS tectonic fabric. Aegirine and magnesian siderite have locally replaced magnesioriebeckite in this fabric. The carbonate also forms small ring structures, interpreted as deformation phenomena, in parts of some mesobands.
The pre- and syntectonic textures of magnesioriebeckite are regarded as the products of percolating solutions rich in Na+ and Mg++ interacting with the host during diagenesis, very low-grade burial metamorphism and progressive deformation. The tectonic LS fabric appears to have been initiated early during deformation with textural modifications taking place during buckle shortening and layer-parallel shearing.