bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uraniferous Organic Matter in the Sandstone-Type Uranium Ore from Domiasiat, Meghalaya, India
Authors: Krishna Rao N. , Sunilkumar T. S. , Narasimhan D. 
Published: November 2024

Abstract
Uranium in the sandstone-hosted uranium deposit at Domiasiat, Meghalaya is mainly associated with organic matter (OM), which is also enriched in several trace elements, viz. Zn, Pb, Ni, V, Co, Ba, Sn, Mo, Cr, Ag, P etc. This paper is an attempt to characterize and discuss the origin of the OM and the associated uranium.
The OM occurs in several forms - lumps, layers, veins, dispersions, fracture fillings, coatings and impregnations. Based on structural features and optical properties, seven types of OM are identified. The structural and compositional features indicate that the OM is type II kerogen with macerals mainly belonging to liptinite group. Some of the primary structures have acted as loci of deposition of uraninite and other inorganic minerals like pyrite, marcasite, sphaleri'te and apatite, thereby giving rise to certain interesting textural features. Development of asecondary granular structure and bIades of secondary OM are features related to maturation. Uranium occurs in the form of uraninite of three generations, minor coffinite and a distinct organo-uranyl complex.
Both the South Khasi granite batholith and the tuffaceous matter related to Sylhet Trap episode appear to be the source for various inorganic elements enriched in the OM. From structures and association it appears that uranium fixation in the OM has taken pIace both due to anaerobic reduction by bacterial H2S and complexation to form organo-uranyl complexes. The latter, on maturation, was reduced to form fine precipitates of uraninite dispersed in the OM. It is suggested that the maturity of OM, extending up to semi-anthracitic stage, has taken place due to radiolysis and radiogenic heat.
Mineralogy of Panchpatrnali Bauxite Deposit Based on XRD, IR, DTA and SEM Studies
Authors: Som S. K. , Bhattacharya A. K. 
Published: November 2024

Abstract
Mineralogy of bauxite profile, after khondalite parentage, at Panchpatmdi area, Koraput district, Orissa is studied by XRD, JR, DTA and Optical/electron microscopy. XRD shows thedominance of kaolinite in saprolite, whereas IR and DTA results confirm its presence in the entire profile. All the above studies confirm the strongly disordered nature of kaolinite. Gibbsite, geothite, hematite, diaspore and allophane are present in the entire profile with the intermittent occurrence of boehrnite, anatase, and futile. Microscopic investigation reveals poIycyclic crystalisation of gibbsite and ultimately resilicated to kaolinitevia dlophane. Transformation of alurninious parent minerals to gibbsite is direct without the intermediate kaolinite stage. Evidences are presented to show that gibbsites are later transformed to kaolinite due to ground water activities.
Mineral Chemistry and Geochemistry of the Mesocratic Quartz Syenite Intrusions from Vikurthi and Kotappakonda, Guntur District, Andhra Pradesh
Authors: Madhavan V. , Srinivas M. , Mallikharjurna Rao J. , Chalapathi Rao N. V. 
Published: November 2024

Abstract
The paper presents the mineral analyses and the major, trace and rare earth element geochemistry of the subalkaline syenites from Vikurthi and Kotappakonda in the Guntur district of Andhra Pradesh. A comprehensive model is proposed wherein these and other similar rocks from the Cuddapah intrusive province are envisaged as the differentiated products of an intermediate magma of trachybasaltic composition, which, in turn, has been derived by the differentiation of a parental gabbro magma.
Petrochemistry of a Gametiferrous Chlorite Schist Horizon from the Sandur Schist Belt, Karnataka
Authors: Bhat S. S. , Bhattacharya A. , Dasgupta H. C. , Dasgupta D. 
Published: November 2024

Abstract
Petrology and mineral chemistry of garnetiferrous chlorite schists belonging to Deogiri formation in the Sandur schist belt have been studied. Mineral assemblages and chemical data on muscovite, biotite, chlorite, garnet from the Deogiri chlorite schists indicate low grade regional metamorphism under greenschist facies condition. Mineralogy of the metabasics associated with Deogiri chlorite schists and with the overlying Donimalai formation in this region, except near the peripheral contacts, also suggest greenschist facies metamorphism for the schist belt. Mineralogy and chemistry of Deogiri metabasalts indicated ocean floor type of alteration/metamorphisrn for the Deogiri metabasalts. Rocks close to the granite contact have seemingly undergone an episode of thermal metamorphism which is distinct from the regional metamorphism of the entire schist belt and possibly isolated both in space and time.
Detrital Origin of Fuchsite-Bearing Quartzites in the Western Dharwar Craton, Karnataka, India
Authors: Argast Scott 
Published: November 2024

Abstract
Quartzites in the Nuggihalli (Banavara), Holenarsipur, JavanahaIli, Bababudan and Chitradurga schist Belts were evaluated using petrographic and chemical methods. All the examined quartzites originated as clastic sandstones, none as inorganically precipitated cherts. Chromium is introduced to the oldest quartzites in the form of detrital chromite. Fuchsite is forming in association with this chromite during metamorphism. There is no evidence for significant contributions of hydrothermal Cr. There are secular trends in median Cr/Al2O3, Cr/Fe2O3, Cr/Zn and K2O/AI2O3 ratios. These trends are consistent with the gradual evolution of mafic and sialic sedimentary source tenanes over the interval from approximately 3.5-2.5 Ga ago. The compositions of the quartzites from Javanahalli and Bababudan Belts are sufficiently different to suspect, but not prove, they are from different sources.
Foraminifera from the Nodular Limestone, Bilthana, Gujarat: Stratigraphic Significance
Authors: Rajshekhar C. , Atpalkar Suresh 
Published: November 2024

Abstract
On the basis of field and microfaunal evidences the Nodular Limestone of Bilthana and Man River Sections are considered to be the same lithounit, though different stratigraphic nomenclatures have been used for these two regions. This Limestone is bioclastic in nature and is not of chemical origin as was thought by earlier workers.
The hitherto unreported foraminifera from the Nodular Limestone of Bilthana, consist of planktonic as well as benthic foraminifera. The former is represented by Heterohelix globulosa, while the latter represent the species of Lagenammina, Scherochorella, Ammobaculites, Haplophragmoides, Spiroplectammina, Trochammina, Textularia, Dentalina, Vaginulina and Frondicularia. The presence of simple Lituolid genera such as Ammobaculites, Haplophragmoides and Trochammina indicates prevalence of shallow water (within shelf condition) during the deposition of this limestone at Bilthana.
Graphite Occurrences in Southern Kerala: Characteristics and Genesis
Authors: Radhika U. P. , Santosh M. , Wada H. 
Published: November 2024

Abstract
Graphite is commonly associated with the metapelites of upper amphibolite to granulite grade in the Kerala Khondalite Belt (KKB). A number of distinct associations of graphite are identified in this study such as: (I) strataboundand stratiform disseminations in metapelites, (2) veins, coarse flakes, pods and lenses associated with pegmatites, (3) enrichment along shear zones, (4) flakes and books in calc-silicate-charnockite associations and (5) residual concentrations in weathered rocks and laterites. While graphite disseminations in the metapelites (khondalites) occur as small flakes oriented parallel to the metamorphic fabric, the vein and pegmatite hosted graphites are found as coarse Rakes and books. Graphite which fills mesoscopic shears and faults also form coarse aggregates. X-ray diffraction studies indicate a high degree of crystallographic ordering for all the graphite types. Scanning Electron Microscopy reveals perfect crystal forms for graphites from the vein and pegmatite assemblages. Carbon stable isotope analysis of twenty three graphite samples are presented. The disseminated graphite yielded d13C values in the range of -17.5 to -32.1 per mil, characteristic of biogenic origin. Graphite associated with pegmatites shows d13C in the range of -10 to -15.1%, while those from shear planes have values ranging from -8.2 to -12.4%. Heavier carbon enrichment in these cases is suggestive of precipitation from CO2-rich fluids. The mechanisms which lead to the precipitation of graphite from CO2-rich fluids are evaluated. Thermodynamic considerations indicate that introduction of CO2-rich fluids into country rocks under low fO2, will result in the precipitationof graphite on a quantitative basis. The vein-, pegmatite-, and shear-hosted graphite in Kerala may therefore represent large scale infiltration of CO2,-rich fluids along structurally controlled pathways.
Reappraisal of the Delhi Stratigraphy in the Ajmer-Sambhar Sector, North-Central Rajasthan
Authors: Fareeduddin  , Reddy M. S. , Bose U. 
Published: November 2024

Abstract
The supracrustals occurring in the northern sector of the South Delhi Fold Belt (SDFB; main Delhi Synclinorium of Heron, 1953) between Ajmer-Pushkar valley and Sarnbhar Lake in north-central Rajasthan are classified into Anasagar migmatites and the overlying Ajmer Formation comprising Taragarh quartzites and Kalyanipura arkose-pelite-greywacke sequence. The Anasagar migmatites and paragneisses are intruded by Iatero genic granite(1600 Ma) and post orogenic ultramafic and alkaline rocks. Four folding and two shearing movements characterize these rocks. Three metamorphic zones could be identified in these supracrustals with grade increasing towards west: staurolite-kyanite grade (middle arnphibolite facies) in the eastern sector, sillimanite-muscovite grade (upper amphibolite facies) in the central sector, and orthopyroxene-plagioclase and orthopyroxene-sillimanite grade (granulite facies) in the western sector.
The Anasagar and Ajmer supracrustals are deposited in an Early Proterozoic ensialic basin in the Archaean BGC (Banded Gneissic Complex) protocontinent and differ from the other tectono-stratigraphic units of the SDFB in respect of lithological organisation, metamorphism and magmatism besides the latter being decisively of Upper Proterozoic age. The authors, therefore suggest a separate and older stratigraphic status to these supracrustals and delink from the rest of the SDFB stratigraphy.
Late Quaternary Variations in Sedimentation Rate in the Laccadive Trough, Southeast Arabian Sea
Authors: Shankar R. , Manjunatha B. R. 
Published: November 2024

Abstract
Radiocarbon measurements of a core from the Laccadive Trough, SE Arabian Sea have yielded ages which show that sediments from the Pleistocene, Holocene and a transition zone can be recognized by virtue of colour variation. The mean sedimentation rate decreases from 4.11 to 3.15 cm/103yr for Pleistocene and Holocene respectively, witha peak of 6.36 cmcm/103yr determined for the transitional zone. A sediment slump or turbidite emplacement resulting from higher terrigenous influx during the transition period has been inferred. This is in contrast to the bioclastic turbidite of the central continental margin-pelagic region (off Bombay-Ratnagiri sector of western India). The decrease in sedimentation rate from Pleistocene to Holocene can be most likely ascribed to entrapment of riverine sediments in estuaries and continental shelf, as a result of Holocene sea level rise.
The mean sedimentation rate in the Laccadive Trough (3.84 cm/103yr) is lower than that on the northwestern continental margin of India (4.6-9.8 cm/103yr) because of relatively low terrigenous influx from the small west-flowing rivers of Peninsular India. The Holocene sediment thickness in the Laccadive Trough is 35 cm as against 50 cm in the northeastern Arabian Sea. The onset of environmental conditions representative of Holocene is estimated at ca. 9300 yr B.P. which corroborates the date proposed for the northern Indian Ocean.
Geochemistry and Origin of the Granite Gneisses of the Almora Group from Dhunaghat area, District Pithoragarh, U.P.
Authors: Singh B. N. , Goel O. P. , Joshi Mallickarjun , Sheraton J. W. 
Published: November 2024

Abstract
The Precambrian Almora granite gneisses containing numerous schistose enclaves occuras thick and thin bands within the medium-grade Saryu metasediments of Almora Group. Petrography and major and trace element geochemistry of the granite gneisses indicate that they are strongly peraluminous, S-type granites, and were derived by partial meltingofthe meta-arkose/metapelites.
Symplectites in High-Grade Pelitic Gneisses of Usilampatti, Tamil Nadu: P-T Conditions and Geochemistry
Authors: Subba Rao D. V. , Nirmal Charan S. , Narayana B. L. , Naqvi S. M. 
Published: November 2024

Abstract
Occurrence of fine-grained, fingerprint-like symplectic intergrowths of cordierite, K-feldspar and quartz formed due to the retrogressive, garnet breakdown reactions following decompression during uplift, is reported here from metapelites of Usilampatti area. These metapelites consisting of cordierite, garnet, hypersthene, biotite, hercynitic spinel, sillimanite, K-feldspar assemblage were metamorphosed at 6.5-7.5 Kb and 750-800°C. The symplectites were formed at 600-670°C and 5 Kb pressure. The textural and mineralogical evolutions in these metapelites indicate a rapid decompressional P-T evolution. Petrological and geochemica1 data suggest that these metasediments were derived mostly from an evolved basement source of granodiorite-granite composition with a minor basic component.
Potassium - Argon Ages of Dolerite Dykes in Late Archean/Early Proterozoic Closepet Granite
Authors: Dayal A. M. , Padmakumari V. M. 
Published: November 2024

Abstract
Emplacement of the Closepel granite around 2.6 to 2.5 Gaage was the last major event in the crustal formation process in the Dharwar Craton. This granitic body has been intruded by a number of dykes mainly trending E-W or NE-SW between Madhugiri and Tumkur. Potassium-argon ages on these dykes range from 2.5 Ga to 1.2 Ga and can be classified into three different phases. The first phase (2.5-2.4 Ga) dyke activity might be correlated with emplacement of the Closepet Granite. The second phase (1.8-1.6 Ga) of dyke activity could be associated with hypabyssal magmatism connected with the Proterozoic Cuddapah Basin formation and volcanism. The last phase (1.4-1.2 Ga) represents the middle Proterozoic dyke activity during which emplacement of Rapakivi granites and alkaline magmatism were reported.
Structural Styles and Role of Basement Configuration in Hydrocarbon Accumulation Patterns: Cauvery Basin, India
Authors: Prabhakar K. N. , Chandola S. K. , Kumar Rohit , Paul Rama 
Published: November 2024

Abstract
An integrated analysis of basement map and fault patterns has revealed that the Cauvery basin came into existence in a tensional regime which existed during the taphrogenic fragmentation of eastern Gondwanaland (Late Jurassic-Early Cretaceous). The main trend of tectonic elements is NE-SW and it changes to NNE-SSW towards southern part of the basin. This change of trend is attributed to post-rift kinematics associated with counterclockwise movement of the Sri Lankan massif away from the Indian craton. The orthogonal trends which form transfer zones are responsible for conservation of regional extensional strain.
It is observed that there is a good correlation between hydrocarbon occurences, transfer zones and fault sets. Synthesis of tectonic, geochemical and lithostratigraphic data has led to better understanding of the role of Basement Configuration in hydrocarbon accumulation patterns.
Statistical Modelling of Exploration Data for Grade Potential of the Phosphorite Deposit, Khatamba Blocks, Jhabua District, Madhya Pradesh
Authors: Sarkar B. C. , Nayak V. K. , Srinivas Rao P. 
Published: November 2024

Abstract
The Phosphorite deposit (74°25' to 74°26'E : 22°58' to 23°00'N), Jhabua district, Madhya Pradesh, is one of the productive deposits in India, and has evoked great interest with regard to its phosphogenesis, stromatolite association and resource potential. It is a sedimentary-stromatolite type of deposit within the Precambrian metasediments of the Aravalli Supergroup and represents the southern extension of the well known Jhamarkotra phosphorite deposit of Rajasthan. The geological set-up shows that the phosphorite occurs in two separate host rocks of older carbonate and younger chert sediments. Geological Survey of India (Khan et al. 1979), using conventional cross-section method, estimated the weighted average grade of the Khatamba Blocks from the available 21 intersections in 12 trenches as 28.60% P2O5. In the present study, statistical modelling of exploration data of the Khatamba Blocks, using histogram plots, probability diagrams and skewness and kurtosis parameters for 20 intersections reveals a 3-parameter log-normal distribution for accumulation (grade-thickness) and thickness values. The graphical estimate of the average grade from the probability diagrams is 29.59% P2O5 and that estimated by computer is 29.40% P2O5.
A computer programme ONEPOP.FOR in interactive FORTRAN77 has been developed for statistical modelling of the exploration data. Using this approach the grade. estimated for phosphorite deposit of the Khatamba Blocks shows a marginal increase in the value of average grade of P2O5, content as compared to the estimate made by conventional method.
Geochemistry and Petrogenesis of Shonkinite and Associated Alkaline Rocks of Tiruppattur Carbonatite Complex, Tamil Nadu
Authors: Saravanan S. , Ramasamy R. 
Published: November 2024

Abstract
Shonkinite occurring in the carbonatite complex of Tiruppattur, Tamil Nadu is essentially composed of equal proportions of anorthoclase and augite with accessories of olivine, hastingsite, biotite, apatite and magnetite. The carbonatite complex comprises alkaline rocks emplaced in two adjacent structural basins of Sevvattur and Jogipatti. The chemical composition of shonkinite is intermediate between melanocratic rocks, alkali syenites and soda-rich alkali syenites of the Sevvattur structural basin and highly potassic alkaline rocks of the Jogipaui structural basin. Both these basins constitute the carbonatite complex of Tiruppattur. The study of geochemistry of clinopyroxenes in the co-magmatic alkaline series of the carbonatite complex reveals that both the groups of alkaline rocks were derived from shonkinitic parent magma by convection current aided differentiation and fractionation of mafic cumulates with intermittent immiscible separations of carbonate and silicate liquids.
Offshore Structural Trends from Magnetic data over Cauvery Basin, East Coast of India
Authors: Subrahmanyam A. S. , Lakshminarayana S. , Chandrasekhar D. V. , Murthy K. S. R. , Rao T. C. S. 
Published: November 2024

Abstract
Detailed analysis of magnetic and bathymetric data over shelf and slope regions of Cauvery basin, east coast of India. between Mahabalipuram and Vedaranyam demarcated three major offshore lineaments trending N-S, NE-SW and E-W. The N-S lineation has been interpreted as due to dyke intrusions. NE-SW lineament reflects the offshore extension of a major basement depression, viz., the Pondicherry depression. E-W lineation, south of Porto Novo reveals a basement high suggesting the seaward extension of Kumbakonam ridge within the Pondicherry depression. The present analysis gives mosaic of a deep seated graben block flanked by rift related volcanic intrusives over the shelf region of the basin.
Geotectonic and Seisnlic Risk Implications of Ground Level Changes in the Dehradun Region during the 1905-28 Period
Authors: Gahalaut V. K. , Chander R. 
Published: November 2024

Abstract
We interpret here the ground elevation changes along the Saharanpur - Dehradun - Mussoorie line as brought out through the levelling surveys of 1905-07 and 1926-28. These data can be simulated with a model of slips, varying in amount between 3 ± 3 and 16 ± 8 cm, on the same subsurface detachment on which the great Kangra earthquake of 1905 may have occurred as argued elsewhere in the literature. Since ground elevation changes occurred in the Dehradun region during the Kangra earthquake also, we suggest that slips related to plate tectonics on the detachment lead to ground elevation changes partly aseismically during periods between great earthquakes and partly coseismically at the times of such earthquakes. The annual rates of slips obtainable from the above numerical results being much less than the estimated rate of 18 ± 7 mm/year for plate convergence accommodated at the Himalaya, we conclude that earthquake generating strains accumulated in the Dehradun region during the 21 years between the two levelling surveys.
Late Palaeozoic Plant-Geography of the Peri gondwana and Evolution of the Kashmir Basin
Authors: Bajpai Usha , Maheshwari Hari K. 
Published: November 2024

Abstract
A typical Gondwanan Flora comprising species of Trizygia, Glossopteris, Vertebraria, etc. is known from the Kashmir Basin. At certain levels, however, the flora contains some exotic elements, such as Lobatannularia, Sphenophyllum, Kashmiropteris (Protoblechnum/Comsopteris) and Rhipidopsis. All these elements are important constituents of the Cathaysian Flora. In southern Xizang, too, a plant bearing horizon contains elements of both Gondwanan and Cathaysian floras.
REE in Precambrian BIF of Granulite Gneiss Belts of Tamil Nadu
Authors: Subba Reddy N. , Prasad C. V. R. K. , Balaram V. 
Published: November 2024

Abstract
Rare Earth Element (REE) distribution in 10 samples of Precambrian BIF of granulite gneiss belts of Tami! Nadu suggest that the BIP derived their constitutents of iron and silica from hydrothermal source. The BIP thus formed were metamorphosed to granulite fades metamorphism along with the associated volcanogenic products and sediments.
Gondwana Sedimentation in the Chintaiapudi Sub-basin Godavari Valley, Andhra Pradesh
Authors: Lakshminarayana G. 
Published: November 2024

Abstract
A 3000 m thick Gondwana lithic fill consisting of multifacies associations were preserved in a NW-SE oriented intracratonic Chintalapudi sub-basin set across the Eastern Ghat Complex (EGC). Sedimentation commenced with the deposition of diamictite-rhythmite sequence of the Talchir Formation in glacio-lacustrine environment. The succeeding sandstone-coal cyclothems of the Barakar Formation were formed in fluvial-coal swamp complex. The fluvial streams flowed across the EGC, originating somewhere in the southeast beyond the East Coast of India. Phase-wise upliftment of the EGC during Mesozoic imparted changes to the Permian intercontinental drainage system which started supplying increased aJll'lOunt of detritus to the basin. Basin marginal faults were first formed at the beginning of Triassic. Alluvial fans originated in the east and southeast and northwesterly flowing braided streams deposited the conglomerate-sandstone sequence of the Kamthi Formation. The Early Jurassic uplift of the Mailaram high in the north imparted westerly shift to the braided rivers during the Kola sedimentation . Due to prominence of Kamavarapukota ridge in the south by Early Cretaceous, the drainage pattern became centripetal and short-lived high sinuous rivers debouched into the basin. The silting up of the Chintalapudi sub-basin with tbe sandstoneclaystone sequence of the Gangapur Formation marks the culmination of the Gondwana sedimentation, perhaps, coinciding with the breakup of India from the Gondwanaland.