bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetic and Sedimentological Studies of Netravati and Gurpur River-Bed Sediments, West Coast of India
Authors: Manjunatha B. R. , Shankar R. 
Published: November 2024

Abstract
Magnetic susceptibility and sedimentological studies have been carried out on Netravati and Gurpur river-bed sediments along the west coast of India to throw light on the distribution and movement of magnetic minerals in the riverine environment. The sediments studied are coarse to fine sands, platy to leptokurtic and poorly to well sorted. Granule to medium size sands dominate in the upstream segment. whereas very fine sand and silt+clay are either absent or of negligible importance. Netravati river-bed sediments have a two-fold higher bulk susceptibility than Gurpur sediments because the Netravati drainage basin has magnetite quartzites, amphibolites and garnetiferous biotite gneisses in contrast to granitoids found in the Gurpur drainage basin. This trend of susceptibility is seen for the 13 particle size fractions studied.
Magnetic minerals are concentrated in poorly sorted, fine grained sediments of Netravati river and in leptokurtic sediments ofGurpurriver. They are particularly enriched in the size range of 0.063-0.125 mm and to a lesser extent in the &gt;4 mm fraction. Downstream decrease in susceptibility of both bulk samples and particle size fractions reflects on the vicinity or otherwise of sampling sites to the source of magnetic minerals in the drainage basin.
On the basis of bulk susceptibility data, it is.estimated that about 87% of sediment in the Netravati main river is derived from Kumaradhari river and 13% from Netravati (upstream) tributary. However. about 78% of particles &gt;0.35 mm in size in Netravati main river are contributed by Kumaradhari river and 22% by Netravati (upstream) tributary. The bulk susceptibility of Ourpur river sediments shows that the Venoor hole is the dominant sediment contributor (83%) to the main river when compared to Hosangadi hole (17%). In contrast, Hosangadi hole contributes ca. 63% of the fine particles (0.55-1.0 mm) to the Gurpur main channel. This discrepancy could be attributed to the higher susceptibility of coarse fraction (&gt; 1 mm) of Gurpur (main) river when compared to its tributaries.
Magnetite is the most important mineral that accounts for nearly a half of the susceptibility. Magnetite weight percentage and susceptibility are significantly correlated (r=O.50). About 21 % of the suspectibility is explained by ilmentite and garnets. Amphiboles, pyroxenes and other weakly magnetic minerals account for ca. 27% of the susceptibility. The residual fraction, censtituting ca. 60% of sample weight, explains only 8% of the susceptibility of samples.
X-Ray Diffraction Study on Neogene Shales from the Patharia Anticline, Eastern Bangladesh, with Emphasis on Smectite Clay Dehydration and Implications
Authors: Badrul Imam M. 
Published: November 2024

Abstract
Mineralogical composition of Neogene shales from the Patharia structure, as determined by X-ray diffraction analysis, includes quartz, illite, kaolinite, clllorite and mixed layer illite/smectite as major and feldspars as minor components, with calcite, dolomite and siderite in tsace amount. High degree of tectonic stress rather than the above mineralogy is believed to be responsible for high density of shales from the patharia-5 well. Progress illillitization of randomly interstratified illite/smectite is the rnost important diagenetic change observed with increasing burial depth. Transition from random to ordered inter layering in illite/smectite is suggested to have taken place at about 3000 m in the Palhuria- 5 well. Considering the huge volume of shale in the Neogene Group, sliicctitc dehydration, as a result of diagenetic conversion to illite, appears to have made available significant volume of interlayer water for migration into the pore water system in the subsurface. This may have played important role in the generation of overpressure at depth as well as structural shaping of the Patharia anticline.
Geochemistry, Age and Origin of Perur Granite, Chittoor District, Andhra Pradesh
Authors: Divakara Rao V. , Subba Rao M. V. , Rama Rao P. , Pantulu G. V. C. 
Published: November 2024

Abstract
The homophanous coarse-grained granite near Perur, Chittoor district, Andhra Pradesh ranges in composition from granite (normative) to granite-quartzmonzonite (chemical) and records a Rb-Sr whole rock isochron age of 2549 ± 39 Ma. Variation observed in the major and trace element concentrations (SiO2 = 67.09-73.83%; Al2O3 = 12.76-14.51%; total iron = 2.31-4.97%; MgO = 1.03-3.66%; Cr = 7-102 ppm; Rb = 169-223 ppm and Sr = 128-423 ppm) and the low CaO (less than 2%) in the granite suggest that it is a crustal remelting (CR) type granite formed by the anatectic remelting of an intermediate source rock. The high total REB (201.38-245.63 ppm), their well fractionated nature (LaN/YbN= 17.83-22.32) and the negative Eu anomaly of the granite support that the source rock was intermediate in composition having hydroxyl-bearing minerals like biotite and hornblende.
The Rb-Sr whole rock age (2459 ± 39 Ma) of the granite is similar to that of Closepet, Lepakshi and Hyderabad granites suggesting that this granite has formed along with the other K-rich granites by extensive crustal remelting during the Archaean-Proterozoic Transition (APT).
Mineralogy and Textural Features of Settupalle Syenites, Prakasm District, Andhra Pradesh
Authors: Srinivasan T. P. , Chalapathi Rao N. V. 
Published: November 2024

Abstract
The Settupalle igneous complex is characterised by syenitic variants with distinct mineralogic assemblages. The variable perthitic patterns, nature of plagioclase, fayalite-quartz assemblage in Settupalle syenites clearly suggest that the Settupalle igneous complex has evolved under fluctuating pressure and temperature conditions. The mineral chemistry of K-feldspar and plagioclase suggests that K-feldspar assemblage in these rocks indicates their subsolvus nature. The probable crystallization sequence of rocks is fayalite clinopyroxene syenite (FC-Syenite) - fayalite quartz syenite (FQ-Syenite)-hornblende syenite - quartz syenite - nepheline syenite in that order.
Arrested Charnockite Formation in the Palghat Region, South India
Authors: Ravindra Kumar G. R. , Srikantappa C. 
Published: November 2024

Abstract
Exposures of in-situ charnockitisation of gneisses in widely varying geological associations, related to differing mechanisms of dehydration and prograde metamorphism, are recorded from the Palghat region, southern India. Mineral reactions in gneiss-charnockite prograde profiles indicate hornblende + biotite breakdown in the presence of quartz to produce orthopyroxene within structurally controlled and/or compositionally modified portions of the gneisses. Chemically the gneisses and arrested charnockite zones are granitic in composition whereas the associated banded charnockites (regional granulites) are tonalitic to granodioritic in composition, Geothermobarometric data indicate high temperature and high pressure early granulite-facies (regional granulite) metamorphism at 780 - 880°C and 9-10 Kbar. The fluid species in both types of charnockites and gneisses are characterised by CO, and mixed CO2-H2O inclusions.
The banded charnockites largely pre-date major deformation and the early Palaeozoic time of development of arrested charnockites. A definite time gap between the formation of banded charnockites and arrested charnockites is indicated. Arrested charnockites in the Palghat region are formed along (1) structurally controlled zones, (2) in compositionally favourable zones of modified paleosomes, (3) in melt portions of migrnatitic gneisses and (4) along margins of invading alkaline dykes. These are interpreted as different processes triggered by emplacement of igneous bodies and movement of CO2, enriched melts through the crust, producing sequential interrelated events like dehydration, partial melting, metasomatism and wall-rock alteration, leading ultimately to charnockite formation. The present field dispositions of arrested charnockite are inferred as only an expression of varying response of rock types to changing physico-chemical conditions (e.g. PT and fluid regime) with time during metamorphism.
Additional Agnostid Trilobites from the Middle Cambrian of Kashmir
Authors: Shah S. K. , Parcha S. K. , Raina A. K. 
Published: November 2024

Abstract
A new agnostid genus Trilagnostus from Middle Cambrian of Kashmir is described in addition to Pagetia griesbachi and Pagetia sp. from the same level at the Solvan-Menevian boundary. Diplagnostus is also being reported and described in the same succession at the top of Menevian. This form helps in demarcating the Middle - Upper Cambrian boundary in the sequence.
Age of Deccan Volcanism Across KTB in Krishna-Godavari Basin: New Evidences
Authors: Raju D. S. N. , Jaiprakash B. C. , Kumar Arun , Saxena R. K. , Dave Alok , Chatterjee T. K. , Mishra C. M. 
Published: November 2024

Abstract
The latest Paleontological data suggest that the duration of Deccan trap eruption in Krishna-Godavari basin varies from place to place and could be anywhere between &lt;0.5 Ma and 6 Maacross KTB. Three groups of fossils viz., Planktic foraminifera, Nannoplanktics and Dinoflagellate cysts suggest that the initiation of volcanism was during latest Maastrichtian within the upper part of Abathomphalus mayaroensis Zone, Micula murus Zone and Triblastula utinensis Zone between 67 and 66.5 Ma. There are conflicting evidences in dating the upper age limit of the volcanics probably due to diverse methods employed in calibration of forarniniferal and nannoplanktic scales or selective retrieval of very small sized planktics of zones P0 and P1 in well cuttings.
Neogene Planktic Foraminiferal Biochronology of the Central Indian Ocean DSDP Sites 237 and 238
Authors: Singh A. D. , Srinivasan M. S. 
Published: November 2024

Abstract
Qualitative and quantitative planktic foraminif~raal nalyses of the Central Indim Ocean DSDP Sites 237 and 238 provided 34 important events during the Neogene. A comparison of the chronoIogica1 succession of ihese planktic foraminiferal events, with the other tropical Indian Ocean and Southwest Pacific DSDP Sites reveals remarkable similarity. Therefore, these Neogene foraminiferai events [First Appearance (FA) and Last Appearance (LA)] are considered as synchronous within the tropical Indo-Pacific except Gq. dehiscens LAD, Gr. margaritae FAD, range of Gr. tumidaflexuosa, Gr. crassaformis FAD, Gr. truncatulinoides FAD, and Gs. obliquusLAD, which are diachronous reflecting their paleobiogeographic control. Stratigraphic ranges of planktic foraminifera enabled recognition of 20 zones from the late Early Miocene to Pleistocene.
Two hiatuses (NH3 at Site 238 and NH4 at Site 237) associated with severe carbonate dissolution were identified. These hiatuses havealsobeen recordedatabout the same stratigraphic intervals in several deep sea sections in the Pacific and represent an important oceanographic event, useful for inreroceanic correlation.
Petrological and Geochemical Constraints on the Petrogenesis of the Jaspa Granitic Pluton, Lahual Region, NW Himalaya
Authors: Rameshwar Rao D. , Sharma Kewal K. 
Published: November 2024

Abstract
Several granitic plutons were emplaced in the Lesser and Higher Himalayas of India during early Paleozoic. Jaspa pluton of Lahual region is one such pluton, where the granitoids are intrusive into the low-grade Haimantas made up of phyllitic and quartzitic rocks. The petrochemical studies of the Jaspa granitoids show two successive phases of intrusion. The early phase is dominated by Biotite-Muscovite Granite (BMG) of Ordovician age. Compositionally these rocks are similar to the biotite-granites of Shingo-La of Higher Himalayan range, which are around 50 km to the north of the BMG rocks. The younger phase is represented by tourmaline bearing leucogranites (TLG), which occur as minor phase generally along the marginal parts of the BMG rocks.
The BMG rocks in comparison to TLG rocks have relatively high concentrations of CaO, MgO, TiO2, Fe2O3(T), Nb, Zr, Sr, Pb and Th and low concentrations of SiO2, Na2O, P2O5, Rb,Ga and U. They distinctly plot as two geochemical populations on different variation diagrams. The BMG rocks are characterised by enriched REE concentrations and show fractionating bends, while the TLG rocks have low REE concentrations and show less fractionated trends and depleted HREE pattern. The field, petrographic and geochemical studies suggest that the two phases of Jaspa pluton, the BMG and the TLG rocks were generated from the partial melting of the continental crust in which two chemically different source types were involved.
Morphological Variations in Some Islands in the Gulf of Mannar, India
Authors: Ramanujam N. , Mukesh M. V. , Sabeen H. M. , Preeja N. B. 
Published: November 2024

Abstract
Islands in the Gulf of Mannar are sedimentary landforms developed during the low strand of sealevel during the last interglacial period. The reefs commenced to grow along with the pace of rising sea level. Islands such as Van, Koswari, Kariashuli, Viangushuli inTuticorn region can be called as Tuticorin group of islands. The size, shape and orientation of the reef along with the wave parameters are crucial in determining the development and instability of the islands. Oval or elliptical shape of the reef, small reef area and orientation along with the major wave direction are favourable for the development of the islands, The non-elliptical shape, bigger size of the reef and irregularity in rim topography are hindrances to their development. Apart from the said factors the sea level rise and mining of reef materials are also causative factors.
Geological Evolution and Uranium Mineralisation of Chhinjra Area, Kulu District, Himachal Pradesh
Authors: Sen D. B. , Kumar Suresh , Gangadharan G. R. 
Published: November 2024

Abstract
Several shear-controlled and fracture-filled/disseminated type uranium occurrences are known in the Rampur Window. This paper presents the geology and genetic aspects of fracture-filled type of mineralisation in Chhinjra area on the basis of recent stratigraphical, geochronological and tectonic data. Based on the angular unconformity between Manikaran quartzites and overlying chlorite phyllites, the geological evolution of Chhinjra area has been reconstructed in two stages: Pre-unconformity and post-unconformity. Each stage is characterised by different phases of deformation with typical structural style and accompanying mineralisation processes. Four major tectonic events can be recognised here, namely 2500 Ma, 1200 Ma, 700 Ma and 55 Ma. Each event has left its imprint on the rocks as well as uranium mineralisation of Chhinjra area.
Neogloboquadrina, Pulleniatina and Sphaeroidinellopsis-Sphaeroidinella Lineages in the Northern Indian Ocean: Their Paleoceanographic Relations and Biostratigraphic Significance
Authors: Singh A. D. 
Published: November 2024

Abstract
The evolutionary gradation and ancestor-descendant relationship within planktic foraminiferal lineages Neogloboquadrina, Pulleniatina and Sphaeroidinellopsis-Sphaeroidinella, from DSDP sites 214, 219 and 237 (Northern Indian Ocean) are discussed. The study suggests that the evolutionary diversification among these lineages are closely linked with the major oceanographic changes during the Neogene. The phyletic lineages are placed within chronologie framework in order to find out the reliability of vital taxa of these bioseries for biostratigraphic correlation.
Lamprophyre Dykes in the South Delhi Fold Belt Near Pipela, District Sirohi, Rajasthan
Authors: Fareeduddin  , Kirmani I. R. , Srivastava B. L. , Reddy A. B. , Bhattacharjee J. 
Published: November 2024

Abstract
Lamprophyre dykes are reported from the southern part of the South Delhi Fold Belt (SDFB), near Pipela, about 3 km SE of Sarupganj in Sirohi district of Rajasthan. They occur as sub-volcanic intrusives in the Ajabgarh supracrustals and follow a WNW -ESE to E-W trends. They show porphyritic and panidiomorphic textures with biotite and magnetite occurring as euhedrru phenocrysts ina cryptocrystalline matrix. One large Jamprophyre body shows acompositionallayering. Widespread alteration (chloritisation of biotite and potash depletion) suggests that they are not cogenetic with the post-Cretaceous, fresh lamprophyres of the Mundwara area. Probably these dykes are emplaced during the waning stage of the Late Proterozoic tectonomagmatic cycle of the South Delhi Fold Belt.
Chemical Variations in the Tertiary Carbonates Of Southwestern Kutch, Gujarat - A Statistical Approach
Authors: Kumar Arun , Ratha D. S. , Nandy Partha 
Published: November 2024

Abstract
Tertiary carbonates from Kutch have been analysed for chemical constituents such as Ca, Mg, Mn, Fe, Sr, Ba and insoluble residue. Vertical distribution of these elements shows a gradual decrease in Ca and Sr and increase in Mn, Fe, Ba and insoluble residue from older to younger beds. R-mode factor analysis of chemical data is interpreted. The first factor loaded on IR-Mn-Fe-Ba is considered to be the effect of clastic deposition, chemical co-precipitation and adsorption by clay minerals. The second factor loaded on Ca, Sr, Ba and Mg explains their syndeposition, leading to the formation of limestones.
U-Pb Isotopic Study of Zircons from a Few Granitoids of Delhi-Aravalli Belt
Authors: Sivaraman T. V. , Raval U. 
Published: November 2024

Abstract
U -Pb isotopic analysis of zircons of three granitoids from Chhapoli, Kishangarh and Ajmer localities in the Delhi fold belt of Rajasthan, shows that these granitoids have been emplaced around 1700 Ma and were thermally disturbed at -70 Ma resulting in Pb loss in these zircons. Later studies by other workers on rhyolites, carbonatites and lamprophyres from Rajasthan and Gujarat, corroborate the -70 Ma event which was possibly a period of intense regional magmatic activity in this region. This Cretaceous thermal episode, when evaluated in the light of the paleogeography of the Indian plate, strongly suggests that the reactivation of this part of the subcontinent may be due to: (a) the continental breakups along the west coast at ~80 and 64 Ma, (b) plausible passage of this part of the Indian continental lithosphere (CL), over the Reunion mantle plume between 80 to 60 Ma and (c) the earliest phase of the India - Eurasia Collision. It is also found that the existing knowledge of the geophysical anomalies (such as geothermal signatures, seismicity, gravity, magnetic and electrical conductivity) over the Delhi Aravalli mobile arm (DA-MA), Kutch, Jaisalmer- Mari- arch (JM-A), and Cambay graben - the latter two being parts of the NNW-SSE trending Madagascar-Dharwar mobile arm (MD-MA)- also support this inference.
Mineralogy and Genesis of Ironstone Ooids, Subathu Formation (Eocene) in the Tal Valley, Garhwal Himalaya
Authors: Mundepi Anil K. , Bagati T. N. 
Published: November 2024

Abstract
The physico-chemical and X-ray diffraction analysis of the oolitic ironstone belonging to the lower part of the Subalhu Formation (Eocene) reveal the presence of major berthierine and chamosite with minor amounts of hematite, limonite and rarely glauconite. Quartz. polycrystalline quartz, siderite and chert are important accessories .
The ironstone ooids having the alternate coalS of berthierine/chamosite and ferric oxide were formed under changing physico-chemical conditions. Mineralized solutions containing iron and silicates replaced the carbonate ooids and other detritus during diagenesis. The ooids were fractured and distorted due to intergranular solution readjustment during compaction and later tectonics.
Nature and Palaeoweathering of Source Rocks and Palaeoclimates for the Gondwana Sandstones from Pranhita-Godavari Valley, Andhra Pradesh
Authors: Sayyed M. R. G. 
Published: November 2024

Abstract
The Gondwana sediments from the Pranhita-Godavari valley were analysed for major elements and some petrographical characters to find out the nature of the source of rocks, their palaeo weatbering and the palaeoclimatic conditions. The results of this study indicate that source rocks were mainly granitic in composition which had undergone K-metasomatism. Most of the major elements show large fractionation and mobilisation during weathering and transport while the intensity of weathering was highly variable under humid to subhumid climatic conditions.
A Semi-Quantitative Approach to Detect Aquifers in Hard Rocks from Apparent Resistivity Data
Authors: Muralidharan D. 
Published: November 2024

Abstract
Resistivity sounding technique is conventionally adopted for ground water exploration in hard rock areas. From the interpretation and layer parameter evaluation alone, deciphering the actual depth to aquifer zone and delineating the thin high yielding fracture zones is found to be difficult. In many cases, the high yielding zones are found to be well within the bedrock signal part of the sounding curve. A non-conventional way of examining the apparent resistivity data of soundings was attempted for the soundings conducted over different hard rock terrains. The interpretation yielded a factorial depth relation with the yielding aquifer zones hidden in the bedrock signal. This approach has been used successfully in many areas of investigation. A theoretical base for the observed depth relation is at developmental stage.
Accretionary Evolution of the Ramagiri Schist Belt, Eastern Dharwar Craton
Authors: Zachariah John K. , Mohanta Manoj K. , Rajamani V. 
Published: November 2024

Abstract
The gold mineralized Ramagiri Schist Belt is a volcanic dominated, late Archaean belt in the eastern Dharwar Craton. Based on the lithological association, mode of occurrence of rocks, geochemical characteristics of mantle derived rocks and the metamorphic grade of rocks, the belt is divided into three blocks that are tectonically interleaved with and surrounded by granitic rocks of distinct histories. The eastern block has amphibolite facies rocks, dominantly basic metavolcanics having light rare earth element (LREE) depleted patterns with minor banded ferruginous quartzite (BFQ). The central block includes mafic and felsic volcanics, pyroclastics, gabbroic and felsic dykes, argillites and BFQ. The volcanic rocks as well as the intrusives have LREE enriched patterns. The central block has dominantly greenschist facies rocks. The western block is made up of fine grained metabasalts with well preserved pillow structures at places, and retrogressed chlorite-actinolite and chlorite-carbonate schists in shear zones, serpentinite and BFQ. These rocks have flat to moderately LREE depleted patterns. The associated serpentinite is of residual origin, probably representing obducted pieces of Archaean oceanic lithosphere. Available age information and required tectonic settings of the volcanics necessitate subduction related magmatism and corroborate the idea of crustal genesis by accretionary processes in the eastern Dharwar Craton during late Archaean.
Mid-Continental Rift - A Hypothesis
Authors: Baride M. V. 
Published: November 2024

Abstract
The paper presents a new hypothesis on the possibilities of the opening up of a Mid Continental Rift (MCR) in the southern block of the Indian Shield based on the background data on seismic centres, continental rift, and seismo-tectonic studies.
It is suggested that, due to locking at the northernmost part, there is progressive NE-E drifting of the Indian subcontinent and, therefore, a rotational movement is taking place with the southern tip moving faster than the main land. This has created a major weak zone along Ongole to Cutch. Due to this movement, fractures will open up along the Narmada-Son. This will also give rise to major seismicity along and adjoining Ongole to Cambay areas resulting in MCR along Narmada-Son lineament in geologic time.