bluuebunny/crossref_metadata_2025_split huggingface dataset:
Basement-Cover Relationship in the Khetri Copper Belt and the Emplacement Mechanism of the Granite Massifs, Rajasthan, India
Authors: Gupta Pratip , Guha D. B. , Chattopadhyay B. 
Published: November 2024

Abstract
The Precambrian Khetri Fold Belt in northern Rajasthan, India, is bifurcated by the transverse Kantli Fault into the North Khetri Belt (NKB) and the South Khetri Belt (SKB). A new stratigraphic and structural framework has been proposed for the NKB and the SKB. The NKB and the SKB evolved independently and show different basement-cover relationships. The Proterozoic cover sequence on either side of the Kantli Fault differ significantly from each other in litho-characteristics, specially in the content of felsic-volcanics. The 1832 ± 3 Ma old synsedimentary felsic volcanism in Proterozoic sequence is considered to be coeval with the Jasrapura Granite dated at 1844 ± 7 Ma.
Geochronological data from several granite bodies suggest a plutonic event around 1500 ± 200 Ma which constrains the third phase of deformation in the basement rocks. TWo types of granites are recognised; one akin to the Hercynian-type peraluminuous, compositionally restricted ilmenite-bearing S-type granite and the other Caledonian-type, compositionally restricted I-type granite.
Both forceful ballooning and forceful permitted type processes were responsible for the plutonic activity. Significant amongst the first-type are the Udaipurwati Granite and the Chapoli Granite; the former shows stretching of the sodium-rich early consolidated intrusion as a result of inflation of the potassium-rich central part of the magma balloon.
A general readjustment of the isotopic systems within minerals occurred around 700 - 800 Ma or even later, possibly a Pan-African event, which has been correlated with widespread granitic activity in western Rajasthan.
Behaviour of Stretching Lineations in the Salem-Attur Shear Belt, Southern Granulite Terrane, South India
Authors: Chetty T. R. K. , Bhaskar Rao Y. J. 
Published: November 2024

Abstract
A rare occurrence of both steep and shallow plunging stretching lineations within a single outcrop, has been described from the Salem-Attur shear belt, and the regional variations in the orientation of stretching lineations are discussed in terms of transpressional tectonics in the Cauvery shear system, southern granulite terrane, South India.
Morphotectonic Evolution of the Laterite Profiles over Sukinda Ultramafics, Jaipur District, Orissa
Authors: Som S. K. , Joshi R. , Roy P. K. , Mukherjee M. M. 
Published: November 2024

Abstract
Sukinda ultramafic field of Jajpur district, Orissa is capped by thick lateritic duricrust. Two generations of laterite are inferred in the studied area. The older laterite (in situ) is capped by transported laterite (younger). The entire area is divided into two subareas (A1 and A2) Physiographically, three terraces are identified in A1 area, of which, the oldest one (T3) comprises of insitu lateritic hard crust. The other two terraces (T2 and T1) are made up of valley fill deposits, which are later lateritised. The area A2 shows the lateral continuity of T3 terrace of A1 area along with valley fill deposit of T1 terrace and the absence of T2 terrace. Drainage analysis show the A1 area is structurally more disturbed than A2 area. Correlation of geomorphological evolution and lateritisation indicates three stages of development in the A1 area. Lateritisation was initiated on a comparatively flat ground (T3 terrace) and subsequent destabilisation of the area developed the younger terraces (T2 and T1) with the modification of older laterite profile.
Subsurface Control on Salt-Affected Regions of Indo-Gangetic Basin
Authors: Srivastava Ajay , Singh Ramesh P. 
Published: November 2024

Abstract
Visual interpretation of IRS-lCWIFS image has revealed some important geomorphic features controlled by the fluvial dynamics of the river and the subsurface structural features. Geomorphological features present in this region have been studied and correlated with the subsurface structural features and associated tectonic changes which have occurred in the recent past. Faizabad Ridge is the main tectonic element in the southern part of Indo-Gangetic plain and it has been found to playa key role in the evolution of the contemporary topography. The striking similarities have been observed in the occurrence of subsurface features and geomorphological features allover the peripheral regions of the Faizabad ridge. The severe problem of soil salinity/alkalinity occurring in this patt of the Indo-Gangetic plain is attributed to the changes which occurred in Paleogene period associated with the evolution of the Faizabad ridge in the basement.
Gas-Hydrates - A Synoptic View
Authors: Subrahmanyam C. , Reddi S. I. , Thakur N. K. , Gangadhara Rao T. , Sain Kalachand 
Published: November 2024

Abstract
Large-scale occurrence of gas-hydrates in the marine sediments of outer continental margins is by now well-known. While the methods of tracing gas-hydrate enriched zones, like identifying markers such as bottom simulating reflectors and blanking zones on seismic reflection sections, are well-established, quantification and resource assessment of gas hydrates still remain hazy. Investigations over the classical gas-hydrate enriched Blake outer ridge on the U.S. Atlantic margin have provided new insights into the environs of gas-hydrate occurrences. Deep sea drilling results in this area indicate that the estimates of gas-hydrate from geophysical measurements could be less by an order of three in comparison with those obtained from drilling. Several factors like bathymetry, sediment thickness and sedimentation rates, sea bottom temperature and total organic carbon content, which control gas-hydrate formation, indicate that the shallow sediments in the offshore regions of India could be potentially enriched in gas hydrates. National agencies like the Oil & Natural Gas Corporation, Gas Authority of India Ltd., National Geophysical Research Institute, National Institute of Oceanography and others are now actively involved in assessing the true potential of this anticipated future energy resource. The environmental aspects of gas hydrates like large-scale release of methane gas into the air and slope instabilities and submarine landslides in the continental margins resulting in catastrophic events, however, need to be kept in mind.
Fossil Microbiota from the Vaishnodevi Limestone, Himalayan Foothills, Jammu: Age and Palaeoenvironmental Implications
Authors: Venkatachala B. S. , Kumar Ashok 
Published: November 2024

Abstract
Vaishnodevi Limestone is a distinctive landmark succession in the Jammu Himalaya. Significant biotas have been identified from a well exposed chert outcrop near Bidda and shale near Muttal. The chert biota is dominated by mat forming crustose, coccoid, chroococcacean cyanobacteria that include Eoentophysalis belcherensisand Palaeopleurocapsa wopfnerii. The other coccoid taxa are Myxococcoides grandis, Gloeodiniopsis lamillosa, Eogloeocapsa avzyanica, Sphaerophycus cf., S. medium, Eosynechococccus moorei, E. grantiis, Siphonophycus kestron, S. robustum, Oscillatoriopsis sp., Circumvaginalis elongatus, Archaeoellipsoides major, and A. minor. Stratigraphically this is the oldest biota thus far known from the Vaishnodevi Limestone and is assigned a palaeoproterozoic-Mesoproterozoic age.
The Muttal biota is composed of Siphonophycus kestron, S. robustum, Oscillatoriopsis sp., Calyptothrix spp., Eosynechococcus medius, Archaeotrichion contortum, Archaeollipsoides bactriformis, A. grandis, A. obesus, Arctacellularia ellipsoidea, Nostochomorpha prisca, Paleonostocalia irregularia, Leiosphaeridia laminariala, Leiosphaeridia sp., Lophosphaeridum spp., Micrhystridium spp., Sphaerocongregus sp., Obruchevella sp., Chuaria sp., Kildinosphaera sp., Spiromorpha indet. and vase shaped microfossils (VSMs). The Muttal biota is from the topmost shale unit of Vaishnodevi Limestone and is assigned a Neoproterozoic age.
It is concluded that the age of the Vaishnodevi Limestone spans the entire Proterozoic and deposited in a supratidal to intertidal and subtidal environment within a shallow shelf regime.
Bioclastic Shore Deposits: Indicators of Late Quaternary High Sea in Saurashtra, Western India
Authors: Bhatt Nilesh , Patel M. P. 
Published: November 2024

Abstract
The high energy coastal segment between Okha and Diu in Western Saurashtra is characterised by typical kind of raised bioclastic shore deposits. These occur up to 15 m (max.) above present day mean sea level and about 5 km inland. Variously described as "coast fringing rocks", "Chaya Formation", "ancient beach rocks", "shell limestones", etc., these possess poorly sorted allochems and lithic fragments of coarse sand to gravel size, mostly cemented by aragonitic micrite and occasionally fibrous aragonitic and high magnesian calcite, their pores being infilled by second generation of low magnesian sparry calcite cement. On the western coast of Saurashtra, they underlie coastal dunes and sheets of rniliolitic limestone and form gently seaward dipping sheets and their surfacial exposures are encountered southward only up to Kadwar, near Diu. However, they occur at the base of deep quarries of miliolitic limestone between Kadwar and Mahuva. Looking at the available reliable Th230/U234 and ESR dates of fossil shells from these deposits, they represent a higher sea level during the oxygen-isotope sub-stage 5e. On the South Saurashtra coast, the high coastal cliffs of miliolitic limestone exhibit presence of raised shore platforms and notches which may be related to this high sea after considering the influence of tectonism.
The Tectonic Segments of Northeastern India and Associated Gold Mineralisation
Authors: Sengupta P. R. , Agarwal N. K. 
Published: November 2024

Abstract
Gold in Northeastern India is broadly distributed in three distinct tectonic segments viz., a) The Peninsular Shield extension comprising, mainly Precambrian to Tertiary lithostratigraphic components, b) The Patkai-Arakan-Yoma Mobile Belt comprising Cretaceous-Tertiary gently folded belt, and c) The Brahmaputra-Surma Plains comprising Quaternary clastic derivatives. The first two domains have primary source rocks of gold and PGE while gold has been recovered from the alluvium in the third domain. There is a need for conceptually sustained gold exploration efforts in the region.
The Grain-Size Behaviour and Morphoscopy of Supraglacial Sediments, South of Schirmacher Oasis, E. Antarctica
Authors: Asthana Rajesh , Chaturvedi Arun 
Published: November 2024

Abstract
The present study embodies the description of textural characteristics and quartz grain morphology (under SEM) of sediments occurring in three micro-environments on the polar ice sheet. Coarse to fine grained, largely ill-sorted sediments with a polymodal distribution reflect a varying magnitude in the velocity of the transporting medium. A dominant saltation population with little suspension and lack of rolling population is revealed by cumulative curves which suggests transportation of these supraglacial sediments by wind. The quartz grains bear two generations of mechanical textures and a third phase of chemical textures attributed to glacial and aeolian environments.
Permian Gondwana Sedimentation in Yellandu (Singareni) Coalfield, Andhra Pradesh, India with Notes on Regional Paleogeography and Tectonic History
Authors: Tewari R. C. 
Published: November 2024

Abstract
The Yeliandu coalfield of Andhra Pradesh contains an 850 m Permian Gondwana rocks composed of Barakar, Barren Measures and Raniganj Formations. They are characterised by fining upward cycles. The sandstones are channel shaped, sheet-like and multistoried, and planar and trough cross bedded. The shales are massive to laminated and form thin lenses in the Barakar, but moderately thick sheets in the ovelying Barren Measures and Raniganj Formations. The coal seams are thin and lensoid. Paleocurrent studies suggest consistently northhwesterly dispersal direction areally and temporally. Evidence indicates that initially braided streams at the onset of Early Permian Barakar sedimentation became meandering through time into Barren Measures and Raniganj Formations of Middle and Late Permian, respectively. The close similarity in lithofacies depositional environment and dispersal direction of Permian rocks of Yellandu coalfields and those of neighbouring Pranhita-Godavari basin in the east. and their geological and tectonic setting suggest that the Yellandu coalfield was part of the Godavari basin until the Late Permian or Early Triassic.
Evaluation of Low-Field Hysteresis Loop and Magnetic Susceptibility of Tertiary Basalt from Jos Plateau: Nigeria
Authors: Garde S. C. , Ojelabi E. A. 
Published: November 2024

Abstract
Low-field hysteresis (LFH) loop and relative magnetic susceptibility (RMS) values in a field of 0.5 to 10 Oe has been used to evaluate the stability of magnetic directions of Tertiary basalts from Jos Plateau Nigeria. Graphs of magnetic moments (MM), susceptibility (S) and relative magnetic susceptibility (RMS) against applied field (AF) were plotted. The results showed that in a field of 0.5 to 1.5 Oe, the MM varied linearly with the AF while for Af &gt; 1.5 Oe MM remained approximately constant. Rocks having stable tilted lines without any Rayleigh loop have relative susceptibility values in the range of 0.2 to 0.245 and =0.3 at 10 Oe, an indication of their being paiaeomagnetically stable. Rocks having thin Rayleigh loops had corresponding RMS values in the range 0.15 to 0.19. On the other hand wide loops were found to correspond to RMS value in the range =0.145.
New Record of Sauropod Nest-Sites in Lameta Formation from Jhalod, Panchmahals District, Gujarat
Authors: Roychowdhury Manas , Saha T. K. , Guha Dipayan , Munshi R. L. 
Published: November 2024

Abstract
Sauropod nest-sites having well-preserved tubocanaliculate types of eggs have been found within the Lameta Formation at Ihalod taluka, Panchmahals district, Gujarat. Four morphotypes of eggs have been distinguished based on thickness and microstructure of eggshell. Dinosaur eggs have been found in three horizons in the same stratigraphic section indicating a site fidelity which is for the first time being reported from the Lameta Formation of India.
Petrology and Geochemistry of Mixed Oxide-Silicate Facies Banded Iron Formations from Sandur Schist Belt, India
Authors: Manikyamba C. 
Published: November 2024

Abstract
Mixed oxide-silicate facies banded iron formations are found as thin bands in the Eastern Volcanic Block of the Sandur schist belt They consist of haematite, magnetite, cummingtonite-grunerite and chert/quartz. Chemical constituents are SiO2, Fe2O3 and FeO with no appreciable concentration of any other oxide. This composition is reflected in their trace and REE data, such as high order depletion in geochemical twins like Zr-Hf, V-Sc and Nb-Ta. The REE patterns are highly depleted (SREE 0.96 to 9.98 ppm) with Nd/Yb varying between 2 and 5. Cherty BIFs from this belt, metamorphosed to lowest greenschist facies. show almost identical geochemistry. The available data from this belt and other places indicate that unless impurities from terrigenous and volcaniclastic sources are present, metamorphism from lowest greenschist facies to granulite facies does not make an appreciable change in their trace and REB constituents.
Contrasting Isotopic Mantle Sources for Proterozoic Lamproites and Kimberlites from the Cuddapah Basin and Eastern Dharwar Craton: Implication for Proterozoic Mantle Heterogeneity Beneath Southern India
Authors: Chalapathi Rao N. V. , Gibson S. A. , Pyle D. M. , Dickin A. P. 
Published: November 2024

Abstract
Kimberlites intruding the Precambrian basement towards the western margin of the Cuddapah basin near Anantapur (1090 Ma) and Mahbubnagar (1360 Ma) in Andhra Pradesh have initial 87Sr/86Sr between 0.70205 to 0.70734 and eNd between +0.5 to +4.68. Mesoproterozoic lamproites (1380 Ma) from the Cuddapah basin (Chelima and Zangamarajupalle) and its NE margin (Ramannapeta) have initiail 87Sr/86Sr between 0.70520 and 0.7390 and eNd from -6.43 to -8.29. Combined Sr- and Nd-isotopic ratios suggest that lamproites were derived from "enriched" sources which have time-averaged higher Rb/Sr and lower Sm/Nd ratios than the Bulk Earth whereas kimberlites were derived from "depleted" source with lower Rb/Sr and higher Sm/Nd ratios. Calculated TDM model ages suggest that the lamproite source enrichment (~2 Ga) preceded that of kimberlites (~1.37 Ga). Our work demonstrates the existence of isotopically contrasting upper mantle sources for southern Indian kimberlites and lamproites and provides evidence for a lateral, isotopically heterogeneous mantle beneath the Cuddapah basin and eastern Dharwar craton. The significance of our results in the context of diamond exploration is also highlighted.
Coverage of Indian Earth Sciences in International Bibliographic Databases: GeoRef, GeoSEARCH and MINLIB
Authors: Wilson Graham C. , Mendelsohn Jennifer 
Published: November 2024

Abstract
A comparative survey has been made of three keyword-indexed bibliographic computer databases, focusing on their holdings pertaining to the Indian subcontinent in general and India in particular. The selected databases include two very large, commercially available systems of the broadest scope, namely GeoRef (U.S.A.) and GeoSEARCH (including GeoArchive, U.K.) and a much smaller research database with selective bias toward economic geology and other themes (MINLIB, Canada). Qudstions of coverage, degree of overlap and applicability of these and other databases are addressed, with an eye to the evolving use of this technology in India. In terms of number of articles recovered for the ten States &gt;150,000 km2 in area. Bihar received the densest coverage (1.95 records/100 km2) with Karnataka second (1.64), the least-intensive coverage falling to the largest State, Madhya Pradesh (0.62) and Maharashtra (0.69).
Mineral Chemistry and Genesis of Phlogopites from the Gabbros of Ravipadu, Prakasam Province, Andhra Pradesh, India
Authors: Vijay Kumar K. , Ratnakar J. 
Published: November 2024

Abstract
In the Ravipadu gabbro pluton (RGP), Prakasam province, Andhra Pradesh, phlogopites occur as coronal rims along the interfaces between plagioclase-olivine, pIagioclase-ilmenite and rarely plagioclase-clinopyroxene, and as independent grains grown at the expense of intercumulus pyroxenes.
The changes observed in the chemical composition of phlogopites are in the contents of MgO, FeO1 and TiO2 SiO2 and Al2O3 do not show much variation and K2O is almost constant, Na2O is low and CaO is absent. Calculated end members are rich in phlogopite, Ti-phlogopite and eastonite components.
The phlogopites faithfully record the progressive iron enrichment trend of the original phases and consequently that of tholeiitic parental magma. It is established that in a single phlogopite the Mg number, and Mg, Fe, and Ti contents are controlled by its habit, whereas in a series of rocks the phlogopite composition is steered by the composition of host rock. Concentrations of A1 and K in the Ravipadu phlogopites are independent of chemistry of minerals that are consumed and also evolutionary history of the parental magma but are a signature of "chemical collaboration" of interacting fluid with original mineralogy. Textural features and geochemical traits of the phlogopites suggest probable attainment of perfect equilibrium between the fluid and primary phases during the formation of phlogopites in the RGP.
Geology and Petrochemistry of the Deccan Spilitic Basalts at and around Daman, India
Authors: Sethna S. F. , Javeri Priya 
Published: November 2024

Abstract
Major, trace and rare earth element analyses of spilitic basalts and some dolerite dykes and microprobe mineral analyses of a spilitic basalt are reported. It is postulated that these rocks represent subaqueous flows erupted under fairly shallow water which was insufficient for complete spilitisation of the basalt. The process of metasomatism under subaqueous conditions is considered to have been responsible for the alteration of tholeiite to spilite.
Extension of the Intracratonic Mahanadi Rift Towards the East Coast of India - An Inference from Aeromagnetics and Gravity
Authors: Atchuta Rao D. , Rao Ch. Rama , Bhaskara Rao D. S. 
Published: November 2024

Abstract
Interpretation of the total intensity aeromagnetic anomaly data and the residual gravity data of the pericratonic Mahanadi coastal basin, situated in the east coast of India has brought out NW-SE trending dislocations cutting across these basins and extending into the shelf area. This structure may be inferred as the possible extension of the NW-SE trending intracratonic Mahanadi rift. Depth estimates on the regional aeromagnetic anomalies have brought out a deep-seated sub-basement magnetic marker horizon at depths of 5-6 km in the inferred rift zone and it rises to around 2 km on either side in the onshore region. The trends in the residual gravity map around Cuttack suggests a tectonic environment possibly related to the location of triple junction at this point. This zone lies between shot points SF60 and SP70 of the Konark-Mukundpur DSS profile where it is reported that the energy has been heavily attenuated (at near distances) leading to large jumps in travel time. This zone of anomalous behaviour coincides with the inferred triple junction and calls for further detailed studies.
Trondhjemite and Granodiorite Assemblages from West of Barmer: Probable Basement for Malani Magmatism in Western India
Authors: Pandit M. K. , Shikhawat L. S. , Ferreira V. P. , Sial A. N. , Bohra S. K. 
Published: November 2024

Abstract
The pre-Malani basement, occurring to the southwest of the Malani Igneous Suite in western India is represented by an older, biotite trondhjemite (gneiss) and a younger, hornblende granodiorite. These granitoid assemblages (hitherto mentioned as unclassified granitoids) denote tectonically uplifted basement for the volcano-plutonic Malani magmatism. Biotite trondhjemite with well-developed gneissic fabric is significantly deformed as compared to hornblende granodiorite, which is slightly deformed. The basement granitoids exhibit a well-defined temporal and spatial relationship with each other, and are further intruded by Malani rhyolite/basic dykes. Well-preserved magmatic fabric of rhyolite/basic dykes suggests that the intrusive activity post-dated any deforrnational event. The geochemical signatures of the basement granitoids - moderate silica, high Sr, low FeO/MgO ratio and moderate alkali abundance, are quite distinct from the A-type geochemistry of Malani rhyolite dykes - high silica, high HFSE abundance, high FeO/MgO ratio and high alkali abundance, thus invoking different sources and emplacement history.
Pedogenic Alteration in the Overbank Sediments, North Bihar Plains, India
Authors: Sinha Rajiv , Friend Peter F. 
Published: November 2024

Abstract
The Quaternary successions exposed by excavation in the top 1.5-3.0 m of alluvial tract along a traverse in parts of the Indo-Gangetic plains are analyzed. The traverse extends across some 100 km of the interfan area between the Gandak and Kosi megafans of northern Bihar, eastern India. Most of the successions exhibit a fining upward grain size distribution, bottoming in sand or silt. though the overlying silts or clays are often interrupted by beds of coarse silt and sands. Radiocarbon dating suggests that all of the material was deposited during the last 2500 years and post-depositional pedogenic alteration has taken place. Micromorphological study of this subtle alteration shows (a) weathering of primary grains, (b) decomposition of plant and shell material, (c) carbonate dissolution and precipitation, (d) iron oxide/hydroxide accumulation and (e) illuviation of clays. The minor degree of alteration is contrasted with that reported in other areas of the Indo-Gangetic plains and it is concluded that the north Bihar plains, with an average accumulation rate of the order of 1 mm/a over 103 years has been an area of exceptionally high sedimentation.