bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tectonomagmatic History of the Precambrians in Bellary District, Mysore State
Authors: Krishna Murthy M. 
Published: November 2024

Abstract
A chronostratigraphic classification of the Precambrians in Bellary district, Mysore State, based on tectonomagmatic cycles in the evolution of geosynclinal facies is presented for the first time by the author. The older metamorphics are grouped under 'Archaeans' (2500 m.y. and above) and the Dharwars, under Proterozoic (2500-900 m.y.), Structurally four kinds of folds are described. The first cycle of folding, F1, consists of the earlier formed anticlines and synclines plunging northerly or NNW. The second cycle, F2, comprises asymmetric cross-folding of the earlier structures, plunge being parallel to the direction of plunge of the earlier folds. The third, F3, and the fourth, F4, cycles of folding consist of antiforms and Synforms on bedding and en echelon drag folds. the structural pattern in the district reveals that all the different tension and stress expressions are together consistent with orle general stress field, a horizontal compression.
On Some Calc-Silicate Rocks Around Sitarampuram, in Visakhapatnam District, Andhra Pradesh
Authors: Choudhuri R. , Banerji K. C. 
Published: November 2024

Abstract
Occurrence of a few bands of calc-silicate rocks is found to be restricted to an area bounded by lats. 18°13'-18°16'N and longs. 83°7'-83°10'E around Sitarampuram. These bands are characterised by the assemblage of minerals like clinopyroxene, calcic plagioclase, wollastonite, scapolite, grossularite and sphene. besides secondary minerals like epidote-clinozoisite and chlorite.
The close association and gradational relationship of (bands 2 and 3) the calcsilicate rocks with the khondalite and charnockite points to the identical condition of metamorphism attained by all the three concerned litho units i.e, under the pyroxene granulite facies condition. Retrograde metamorphism, perhaps, is responsible for the formation of the secondary minerals like epidote clinozoisite and chlorite.
The field evidences, petrological studies and chemical analyses, suggest that the calc-silicate bands are products of metamorphism of sediments, varying in composition from calcareous sha limestone.
On the Stratigraphy and Tectonic History of the Iron Ore Bearing and Associated Rocks of Singhbhum and Adjoining Areas of Bihar and Orissa
Authors: Banerji A. K. 
Published: November 2024

Abstract
The iron ore bearing rocks of Singhbhum and the adjoining areas of Bihar and Orissa consist of two groups with distinct lithological characters. One of these occurs within the Noamundi basin in the western part of the Singhbhum granitic platform, while the other occurs in the Gorumahisani-Badampahar ranges in the eastern part of the platform. Detailed studies indicate that the iron ore bearing rocks of the Noamundi basin (Noamundi group) rest with a slight break on the Jagannathpur lava which is considered equivalent to the Dhanjori lava. Hence the Noamundi group is assigned a stratigraphic position above the Dhanjori group. The iron ore bearing rocks of the Gorumahisani-Badampahar region (Gorumahisani group) underlie the Dhanjori group and hence are assigned a stratigraphic position below these rocks. Each of these rock groups has been affected by independent cycles of deformation, metamorphism and igneous activity as a consequence of which these rocks have been welded into the fabric of the Singhbhum granitic platform. The successive orogenic cycles have been provisionally dated on the basis of geochronological data provided by Sarkar et al, and a revised stratigraphic succession for the rocks of the region has been suggested.
Geochemistry of Garnets from the Precambrian of South Karnataka
Authors: Anantha Iyer G. V. , Narayanan Kutty T. R. 
Published: November 2024

Abstract
Field features and the mineralogical relations of rocks in the Precambrian of South Karnataka indicate progressive increase in intensity of metamorphism from greenschist facies in the north-west through amphibolite facies in the middle to granulite facies in the southern and south-western parts of the State. Chemical analyses of fifty garnets developed in the amphibolite and granulite facies rocks of Karnataka are furnished. The cell edges of these garnets have been determined accurately by X-ray powder diffraction, using the extrapolation technique of Nelson and Riley. The changing pattern of chemical composition and cell edges of garnets enable recognition of successive zones of progressive metamorphism in the amphibolite facies terrain in the Precambrian of South Karnataka.
Fission Track Ages of Some Alkaline Rocks of India
Authors: Nagpal M. K. , Nagpaul K. K. , Bose Mihir K. 
Published: November 2024

Abstract
Attempt has been made to date the alkaline suites of India on the basis of fission track analysis of apatite. The alkaline plutons of the Eastern Ghats Belt appear to be related to a late Precambrian tecto-igneous activity though all the intrusions may not be strictly synchronous. New age data on some alkaline rocks from the Deccan volcanic province indicate the related magmatism to be older than the available age level for the bulk of Deccan lavas. The apparently isolated occurrence of alkaline complex of Mundwara in Sirohi, Rajasthan has been related to Deccan volcanicity on the basis of apatite ages.
Geochronology of the Dharwar Craton - A Review
Authors: Venkatasubramanian V. S. 
Published: November 2024

Abstract
The relevance of isotope age data in delineating the genetic relationships between the broad types of Archaean terrains of the Dharwar craton - viz., the greenstone belts, the granites and migmatites and the granulite facies complexes - is pointed out. The main results of the Rb-Sr isochron measurements carried out in this laboratory are summarized. The conglomerates have yielded the highest ages observed in this study, (3250 ± 150 m.y.), while two emplacement events at 2950 m.y. and 2600 m.y. have been observed in the migmatites and gneisses with evidence of metamorphic overprinting at 2300 m.y. and 2000 m.y., the latter being reflected in the Closepet event. While a whole rock isochron of 2475 m.y. has been observed for Chitradurga granites, the age relationships between the greenstones and granites still remains to be solved.
Apatite-Magnetite Veins of Kasipatnam Hill, Visakhapatnam District, Andhra Pradesh
Authors: Mahendra A. R. 
Published: November 2024

Abstract
The Kasipatnam hill along the foot of the Eastern Ghats 60 km north-west of Vishakapatnam is largely made up of charnockites and associated rocks surrounded by khondalites constituting a domal structure. These are intruded by numerous dykes and veins made up mostly of apatite, magnetite and vermiculite with minor amounts of zircon, allanite, scapolite, actinolite and diopside. The mineralisation is structurally controlled, being restricted to shear joints and fractures cutting across the charnockitic rocks. The mode of occurrence, mineralogy, zoning, wall-rock alteration and paragenesis of the apatite-magnetite-vermiculite veins are described and their origin discussed. Possible affinity to carbonatite complexes is indicated.
Fold Interference Patterns in the Sausar Group, Northern Nagpur District, Maharashtra, India
Authors: Agrawal V. N. 
Published: November 2024

Abstract
The Precambrian metamorphic rocks of the Sausar Group of the northern Nagpur district, Maharashtra have a polyphase structural history. Three distinct fold phases (F1-Fs) have affected these rocks. The first folds which are tight to isoclinal structures of general' similar type' are developed throughout the region, while structures related to later deformations show a discontinuous development. The first folds have been refolded into a set of close to tight structures (F2) on axial surfaces oriented close to earlier axial direction and dipping steeply S. The superposition has given rise to Type 3 interference pattern which is manifest both in the map pattern and on the scale of outcrops. Fs fold phase has produced open, nearly upright folds with axial traces running N/NNE and axes plunging generally steeply S., the steep plunges resulting from the superposition of these folds on steeply dipping limbs of early structures. In contrast to the much simpler pattern shown by the map in the domains of major Fs folds, the outcrops reveal on a small scale a conspicuous development of Type 1 interference pattern largely in the hinge zones of the late structures, resulting from the superposition of minor Fs on minor F2 structures.
The style of structures of different generations and the pattern of their development in the region seem to suggest that the intensity of deformation has gradually declined from F1 to Fs and that the concentration of fold movements has varied rather rapidly within small areas of the fold belt during later phases causing discontinuous development of related structures.
Blueschist Facies Metamorphism in Daling Rocks from A Part of Kalimpong Hills, Eastern Himalayas
Authors: Roy Subimal Sinha 
Published: November 2024

Abstract
Blueschist facies assemblages are identified in the metagraywacke and associated metabasics occurring in the lower structural levels of the Daling-Darjeeling thrust block, which tectonically overlies the parautochthonous Gondwana-Buxa sequence. These rocks belong to an intermediate position between the pumpellyite-prehnite-quartz facies and the lawsonite-glaucophane-jadeite facies. A temporal and spatial relation of the blueschist facies metamorphism and the Barrovian regional metamorphism is demonstrated, and a transition from the blueschists to the greenschists from lower to higher structural levels is also indicated. The mineral paragenesis restrict the lower and upper limits of pressure-temperature magnitudes at about 300°C/5 kb and 400°C/7.5 kb respectively. The problem related to the age and geotectonic implications of blueschist metamorphism in these rocks are briefly discussed.
Interspecific Association of Heavy Minerals and its Application in Comparison of Strata and Provenance Studies
Authors: Gundu Rao C. 
Published: November 2024

Abstract
Interspecific association means the significant association of heavy minerals due to more than chance causes alone. p-F multivariate model helps in establishing significant associations among heavies estimated from a set of samples. Attempts are made to analyse three sets of samples of Lower, Middle and Upper Siwaliks from a vertical profile in the Punjab. Application of the method in comparison of strata and provenance studies is discussed.
Etchplain Development of Malabar Uplands-A Suggestion
Authors: Pardhasaradhi Y. J. 
Published: November 2024

Abstract
Soon after the foundering of the western block there was a period of intense planation of the west coast acting landward. This was followed by deposition of marginal deposits of Miocene and a relative uplift of the entire western segment raising the Kerala plains to more or less their present position. Geomorphic processes toward the development of a planar surface continued. A tentative scarp limit is drawn roughly parallel to the west coast which limits the uniformly developed high level landforms and the erosion outliers on the east and the estuarine courses to its west. Features observed suggest this landscape of Malabar uplands to have developed as an etchplain. A main period of lateritisation of this surface must have been initiated in late Tertiary-early Cainozoic times. Towards the closing period of the main lateritisation and soon after, the planar surface was monoclinally warped roughly parallel and close to the west coast. This warped surface has contributed sediments to shelf deposits during recent times. This surface can be traced at certain places to form sea stacks and even surviving under the shelf deposits close to the coast. The etchplain development of the Malabar uplands could be extended to the rest of the lateritised landscape of the west coast.
Compositional Variations in Chromites from Sukinda Orissa, India
Authors: Mitra Sachinath 
Published: November 2024

Abstract
The chromite-bearing ultramafic pluton in Sukinda, Orissa, was emplaced in two horizons in the Iron Ore Series rocks which were subjected to shearing deformation and hydrothermal activity, followed by silicification. These processes in most cases completely transformed the early silicates to chlorites and produced, in some cases, compositional zoning in the periphery of chromite grains. The chromite grains and samples from different horizons show variations in composition, reflectivity and latticeparameter. Eight analyses of separated chromite samples are presented along with spot microprobe analyses for Cr, Mg, Fe and Al; these reveal not only marked compositional differences among discrete grains but also show distinct compositional zoning in individual grains.
Electron Probe Microanalyses of Chlorites from Low Grade Metamorphic Rocks of Tennant Creek Area Central Australia
Authors: Ramamohana Rao T. 
Published: November 2024

Abstract
Electron probe microanalyses of 47 chlorites from the Lower Proterozoic rocks, , Porphyroidal' rocks and from magnetite lode structures of Tennant Creek field are presented. Recrystallisation of chlorite, progressive in Warramunga rocks and retrogressive in 'Porphyroidal' rocks was contemporaneous and took place under lower greenschist facies conditions during regional deformation. Chlorite in the magnetite lode structures had formed ahead of the sulphide mineralisation in the Warramunga rocks subsequent to regional metamorphism and was due to metasomatic alteration of the wall rocks. Chlorite occurs with muscovite in all the three rock groups studied.
Structurally, the majority of the analysed chlorites have an octahedral cation total short of the stipulated 6.0 per half unit cell. This deficiency is systematically related to the difference between AlvI and AIIV; the former is half the latter and confirms Foster's (1962) conclusion. The generalised relationship is (R3+ - AlIV) : (6.0 - AlIV- R2+) : : 2 : 3. Most of the analysed chlorites have AlvI greater than AlIV and the value of 1.5 reported here for (AlvI - AlIV) may be the limit in natural chlorites. The majority of the analysed chlorites fall on the composition field of ripidolite or brunsvigite or diabantite. The occurrence of diabantite variety in the Tennant Creek field is the first report of its kind from any low grade metamorphic terrain.
Petrology of the Anorthosite Suite East of Bela, District Gaya, Bihar
Authors: Sinha Jayanta K. , Bose Mihir K. 
Published: November 2024

Abstract
Anorthosite suite east of Bela in Gaya District, Bihar, comprises: Anorthosite (s. sir.); gabbroic anorthosite and (meta-) gabbro. The rocks occur as isolated blocks and pods in granitoids. Plagioclase in the anorthositic rocks has bimodal character, compositional range from Anso to An73, low structural state and high K/Rb ratio. The chief mafic constituent in the suite is hornblende. Fe-Ti oxide minerals (ilmenite and ilmenomagnetite) occur as pockets associated with the suite. The anorthosite suite may represent detached blocks of an original labradorite type massif. Some significant attributes of the investigated suite have been compared with those of the neighbouring Bengal anorthosite massif.
Biozonation of the Uttatur Group, Trichinopoly, Cauvery Basin
Authors: Narayanan V. 
Published: November 2024

Abstract
Twenty-five species of planktonic foraminifera are identified from the marine sedimentary formations of the Uttatur Group cropping out in Trichinopoly area of the Cauvery Basin. Five zonal subdivisions are proposed for the Uttatur Group on the basis of local planktonic forminiferal sequences. These zones range in age from Albian to Early Turonian. The proposed zones are: Hedbergella planispira assemblage zone and Planomalina buxtorfi Range zone for Albian; Rotalipora evoluta Range Zone and Rotalipora reicheli Range zone for Cenomanian and Marginotruncana helvetica - M. sigali Assemblage zone for Turonian. A correlation between the Uttatur Group and its coeval in Trinidad, North America, Southern Europe and North Africa is attempted in terms of the established planktonic foraminiferal zones.
Palynological Evidence for the Age of Sriperumbudur Beds Encountered in a Borehole at Orikkai near Conjeevaram, Tamil Nadu
Authors: Ramanujam C. G. K. , Varma Y. N. R. 
Published: November 2024

Abstract
A rich and excellently preserved spore and pollen flora has been recovered from the core samples. The Orikkai assemblage comprises spores of bryophytes, and pteridophytes and pollen grains of conifers and cycads. The nonsaccate and saccate pollen grains of conifers consisting of species of Araucariacites, Callialasporites and Podocarpidites constitute the predominant elements. The trilete spores are also found in considerable numbers.
The presence of species of Aequitriradites (A. spinulosus,A. verrucosus) Cooksonites (C. variabilis), Coptospora, Impardecispora (I. apiverrucatus), Foraminisporis, Contignisporites (C. glebulentus etc.), Cicatricosisporites (C. australiensis, C. hughesi etc.), Microcachrydites (M. antarcticus), Polycingulatisporites (P. reduncus), Staplinisporites (S. caminus), Turaucosporites (T. segmentatus) , and Crybelosporites, clearly indicates an Early Cretaceous (Neocomian-Aptian) age for these beds. The palynoflora of Orikkai compares favourably with the other Early Cretaceous floras of India. Further, the Orikkai palyno-assemblage also shows significant resemblances with the Early Cretaceous assemblages of Australia and South America.
Carbonate-Orthopyroxene-Chrome Tremolite Rocks (Sagvandites) from Mavinahalli, Mysore District, Karnataka State
Authors: Janardhan A. S. , Srikantappa C. 
Published: November 2024

Abstract
Carbonate-orthopyroxene-chrome tremolite rocks and their variants occur in close association with the ultramafics emplaced into the high grade metamorphic terrain of Sargur schist complex, around Mavinahalli village. The country rocks exhibit mineral assemblages typical of upper amphibolite to lower granulite facies of metamorphism and show signs of extensive migmatisation. The above mineral assemblages are very much similar to the rock types termed as 'Sagvandites', originally reported from Norway. Field evidences, petrography and petrochemistry of these rocks clearly show that they represent original ultramafic rocks metasomatically recrystallized due to circulating CO2 (+Si02) rich solutions, at metamorphic temperatures of 630°C and at pressures of at least 6 kb.
Abor Volcanics of the Arunachal Himalaya
Authors: Jain A. K. , Thakur V. C. 
Published: November 2024

Abstract
The Abor Volcanics of the Arunachal Himalaya are typically exposed along the Dihang Valley as penecontemporaneous lava flows, sills, dykes, volcanic breccia and metatuffs.
Although the Abor Volcanics are so far considered contemporaneous to the Panjal Volcanics of the North-West Himalaya, they are typically associated with probable Precambrian-Middle Palaeozoic Siang and Mid Groups and are distinctly older to the Gondwana. Thus, Late Precambrian-Lower Palaeozoic volcanic activity is widely manifested in the Himalaya from Kashmir to Arunachal Pradesh and is represented by the Baifliaz Volcanics in Kashmir, Mandt-Darla Volcanics (in parts) in Himachal Pradesh, penecontemporaneous lavas in Garhwal Group in Kumaon and Garhwal, Karnaprayag Volcanics, Bhowali Volcanics and Abor Volcanics. This volcanism is older to an equally widespread Late Palaeozoic volcanism of the Kashmir Himalaya and Eastern Himalaya.
Specific Capacity of Wells in Some Hard Rocks of Karnataka
Authors: Viswanathiah M. N. , Sastri J. C. V. 
Published: November 2024

Abstract
Specific capacities of forty wells from the hard rocks of Karnataka-granites (19 to 103 Ipm/m drawdown) ; basalts (13 to 199 Ipm/m drawdown); Bhima limestones (12 to 180 Ipm/m drawdown); laterites overlying basalts (3 to 223 Ipm/m drawndown); Bhima shales (9 to 55 Ipm/m drawdown) and chlorite schists (29 to 135 Ipm/m drawdown) have been determined. The yield of wells in general ranges from 35 to 199 klpd from these tested wells. It is found that in general (i) specific capacity increases with an increase in cross-sectional area of the wells and (ii) specific capacity decreases with increase in recovery time.
An Account of the Bottom Sediments off Andaman Islands, India
Authors: Venkatesh K. V. 
Published: November 2024

Abstract
The sediments comprise sand, sandy silt, silty sand and clayey silt. Variation in their distribution with depth is discernible. Studies on the grain size parameters of the sediments reveal that the inclusive graphic mean vary from 2.3 to 7.0, inclusive graphic standard deviation 1.2 to 2.9 phi, inclusive graphic skewness -.07 to +.71 and kurtosis 0.6 to 5.4. Generally sand is extremely leptokurtic, positively skewed and better sorted than the rest of the sediments. Presence of two energy environments has been noticed.&lt;/P&gt;&lt;P&gt;The phosphate content in the sediments varies from 0.12 to 0.47% and calcium oxide from 3.0 to 27.15%. It is observed that, unlike CaO, a higher percentage of P2O5 is prevalent in the near shore sediments than those of the deep offshore.
The Empirical Relations of Different Variables in Some Folded Anisotropic Media from the Delhi Rocks Around Biliawas, Central Rajasthan
Authors: Roday Prakash P. 
Published: November 2024

Abstract
Two new parameters, continuity index (I) and continuity ratio (C/DC), are suggested as measures of anisotropy, which determine the initial instabilities and the types of displacement patterns produced in multilayer media. Both parameters have high significance for anisotropic media having small t/L values for individual competent layers and low values of mean spacing (S). In reality, the values of t/L are dependent upon the continuity index (I). The parameters seem to affect the finite displacement patterns of only the highly or moderately anisotropic media. For complexes of low anisotropy, the parameters are ineffective. The parameters appear to control the bulk displacements but on relatively smaller scales, t/L and S would continue to produce finite patterns characteristic of high anisotropy. Type 1 and type 3 patterns appear to be distinguishable from each other by the presence of double-hinged structures and second order fold pairs in the latter as these are developed under greater differential stress, accompanied by modification of original type 2 reverse conjugate kinks with progressive shortening between ends of layers.
Upper Jurassic Nautiloids from Kutch
Authors: Kanjilal S. 
Published: November 2024

Abstract
Nine species, belonging to genera Cenoceras Hyatt, Pseudaganides Spath and Paracenoceras Spath, from the Callovian and Oxfordian horizons of Habo Hill in Kutch (Gujarat), W. India are recorded. Most of the examples come from the Oxfordian beds. Two of the species namely, Cenoceras kutchensis and Paracenoceras inflatum are new. Cenoceras is being recorded for the first time from India and from a higher horizon.
Igneothermally Altered Coal of Lish-Ramthi Valley, Darjeeling District
Authors: Kar P. 
Published: November 2024

Abstract
Chemical analysis of the coke shows that volatile matter and moisture content increase away from the igneous contact. Resistivity measurement of the samples shows that the resistivity of the natural coke increases away from the igneous contact. Microscopic constituents according to the properties under reflected polarized light can be divided into three groups: (i) Mosaic unit; (ii) Macerals with cell structure and (iii) Homogeneous mass without cell structure. Mosaic units are altered products of reactive vitrinite. 'Sphere' of both larger and smaller dimensions are present in the altered mass of the natural coke. Inert vitrinites are high reflecting masses without bireflectance and anisotropism. Macerals with cell structures present are the fusinite and semifusinite in the coal. Some lamellar masses present in the coal are strongly anisotropic and bireflecting. Under crossed nicols they get divided into several ribbon like masses with alternate light and dark bands.