bluuebunny/crossref_metadata_2025 huggingface dataset:
Reservoir Induced Microearthquakes Around Tarbela Dam, Pakistan Himalaya
Authors: Chander Ramesh , Sarkar Irene
Published: November 2024

The Tarbela reservoir is situated on the lndus river in the Pakistan Himalaya. A telemetred seismic network has been in operation around the reservoir site since 1973, about a year prior to its initial impoundment. Recently, a detailed statistical investigation of post-impoundment seismicity around this rcservoir for a period of seven years has been reported in the literature. Evidence has been presented there for relatively high probability of increased microearthquake activity at shallow depths in the crust beneath the Tarbela reservoir during periods of low water levels. We argue that, although this is important evidence on the question of whether reservoir induced seismicity can occur in the Himalaya, there is need for further detailed seismicity observations around the present and future reservoir sites in these mountains.
Recent Ostracoda of the Tekkali Creek, East Coast of India
Authors: Varma K. U. , Shyam Sunder V. V. , Naidu T. Y.
Published: November 2024

Twenty-five ostracode taxa are recorded from the Tekkali Creek, East Coast o f India. Of these the following three new spxies are describ:d in detail: Hemicyiheridea bhatiai, Loxoconcha tekkaliensis and Neomnonoceratina jaini, while Neosinocyihcre dekrooni and Paijenborchella (Eopaijenborchella) mlaiensis are being reported for the first time from the Indian waters.
The Century-Old Problem of the Pali-Parsora-Tiki Stratigraphy and its Bearing on the Gondwana Classification in Peninsular India
Authors: Dutta Prodip K. , Ghosh Santosh K.
Published: November 2024

The stratigraphic relationship between the Pali-Parsora-Tiki formations in the South-Rewa Gondwana basin remains unresolved after more than a century. We believe that this is primarily related to the flawed methodology used in addressing Ihe problem. The stratigraphic soIulion was, exclusively, lied to fossil-based age data which is an interprelative element in any stratigraphic analysis. Field relationships such as lithological associations, petrological character and order of superposition that contradicted the fossil-based stratigraphy were ignored. The contradictions, however, were explained by "Conjectual" faults, also an interpretative criterion that was invoked to explain the stratigraphy. The conventional hierarchical approach to stratigraphy, beginning with physical criteria followed by biostratigraphy and chronostratigraphy, was missing.

The sequence encompassing the Pali, Tiki, and Parsora formations can be divided into two well defined lithostratigraphic units. A feldspathic sandstone-red mudstone association characterizes both the Pali and Tiki formations and is considered, in this paper, as a single lithostratigraphic unit. Tentatively and informally, the unit is named as Pali-Tiki Formation. The second unit, a quartzose sandstone-conglomerate and variegated clay association typifies the Parsora Formation. The Pali-Tiki Formation can be traced almost continuousIy from the Pali area to Tiki village. The field relation clearly demonstrates that the Parsora unconformably overlies the Pali-Tiki.

Based on vertebrates, plants and palynological criteria, the Pali-Tiki formation has been assigned latest Permian/Early Triassic to Middle Norian age. The Parsora Formation spans from a little above Middle Norian to well within Early Jurassic. The Glossopteris flora that flourished in the Permian continues across the Permo-Triassic boundary into the Pali-Tiki Formation. The Dicroidium flora appears at the base of the Pali-Tiki Formation and demarcates the Permo-Triassic transition. In the Parsora Formation both Glossopteris and Dicroidium floral assemblages are present and extend, at least, up to the Early Jurassic. These observations go against the fundamental tenet of a two-fold classification scheme for the Gondwana System in peninsular India. This work supports a three-fold classification for the Gondwana system, solely based on floral content. If the floral elements are taken away, the physical straligraphers can make a strong case for a two-fold division based on lithology, petrography and the widespread unconformity throughout peninsular India. A unified classification scheme using both biological and physical pilrameters does not seem to work.
Rb-Sr Ages on the Granite and Pegmatitic Minerals from Bastar-Koraput Pegmatite Belt, Madhya Pradesh and Orissa, India
Authors: Ramesh Badu P. V. , Pandey B. K. , Dhana Raju R.
Published: November 2024

isotopic date on 12 samples of the Paliam and Darba granites of the Bastar Craton in Central India have defined an isochron age of 2308 ± 48 Ma. with initial Sr-isolopic ratio of 0.7354 ± 0.0097. Mineral ages on perthite, biolile and muscovite from tin- and rare metal-minearlised as well as non-minearlised pegmatites of the Bastar-Koraput Pegmatite belt within this craton have indicated two important dates of about 2050 and 1620 Ma. These dates are interpreted as (a) emplacement of the granite around 2300 Ma., (b) derivation of the pegmatites from this parent granite around 2050 Ma and (c) reselling of Rb-Srsystem at about 1620 Ma., concomitant with the metamorphic/uplift event in the nearby Eastern Ghats. The very high initial 87Sr/86Sr ratio of 0.735 for granite indicates thai they are crustal derived, possibly from a metasedimentary source.
Departures from True Ellipticity of Principal Sectional Boudin Shapes and their Mechanical and Kinematic Implications
Authors: Roday Prakash P. , Katpatal Yashwant B.
Published: November 2024

Any ?1 ?3 principal sectional boudin shape is considered to depart from the ideal ellipse and its overall shape could be described in terms of the average four values of the exponent, p, one for each quadrant. Based on this, some principal shapes and their geometrical variations are characterised and possible mechanical and kinematic significance of each shape outlined. The values of the exponent, p, were calculated using a digital computer.
Complexation of Fluoride Ions with Alum-Flocs at Various pH Values during Coagulation and Flocculation
Authors: Raju D. V. , Janardhana Raju N. , Kotaiah B.
Published: November 2024

Complexation of fluoride ions by the addition of lime and alum to fluoridc-spiked tap water was investigated at varying pH values through the Jar-test technique. The results obtained indicate that the optimum pH for higher complexation of fluoride ions with alum-floc will range from 5.8 to 6.3 depending upon the amount of fluoride present in the solution. Hydrogen bonding on polynuclear complexes of partially hydrolyzed Al(III) as well as physical sorption of F- ions on Al (OH)3(s) floes by Van der waal's forces are the possible mechanisms for F- ion removal from water.
Petrological Status of Hornblende Quartzite and Associated Rocks of Basantgarh Area of Sirohi District, Rajasthan
Authors: Munshi R. L.
Published: November 2024

Petrographic and petrochemical study of the reported metagreywacke/hornblende quartzite band near Basantgarh reveals compositional variation along its length. The band is made of both igneous and metasedimentary rocks which are represented by Ieucocratic amphibolite, gneisses and schists. Chemically the leucocratic amphibolite is similar to the plagiogranites and possibly derived by differentiation of a melt which was protolith for the metabasites of the area.
Petrographic and Magnetic Studies of a Columnar Sill and a Dyke from the Deccan Traps
Authors: Subbarao K. V.
Published: November 2024

A critical petrographic investigation together with magnetic studies such as the variation of susceptibility with temperature and hysteresis have been carried out on basalt samples drilled across a dyke and a columnar sill from the Deccan Traps. In the case of columnar basalts, not much variation has been found in the grain size but display increase in shattering of the grains towards the edge of the column. In contrast, the dyke samples are tachylitic at the edge grading to fine-grained basalt in the middle.

The magnetic hysteresis studies indicate an increase of single-domain (SO) mineral grains from the margin to the centre of the columnar basalt. Low temperature susceptibility studies clearly indicate Ihe presence of some multidomain (MD) componcnt of pure magnctite in the cdge samples where as it is barely noticeahle in the s.1l1lple from the cenlre. Samples from the dyke show systematic variations of rhe magnetic parameters. These magnetic variations can be undcrstood in terms of titanomagnctite composition and domain states of thc grains among samples from across the dyke.
Lobachevskian Inversion as a Tool for Better Feature Detection in Structural Analysis
Authors: Krishnakumar K. R. , Rao S. V. L. N.
Published: November 2024

When conventional methods of curve-fitting for the contoured plots on an equal area net fail to be satisfactory. Lobachevskian inversion may be performed on the original plots and finally the inverted plots can be regressed to a straight line for validating the accuracy of the best-fitting arc.
Early Miocene Radiolarian and Planktonic Foraminiferal Biostratigraphy, North Passage Island, Andaman Sea
Authors: Sharma V. , Srinivasan M. S. , Mahapatra A. K.
Published: November 2024

The Early Miocene sequences of North Passage Island iu the Andaman Sea have been studied for their siliceous and calcareous microfossil assemblages. 95 species of radiolaria and 27 species of planktonic foraminifera belonging to these two major groups of microfossils have been documented. An integrated radiolarian ancl planktonic foraminifera1 biostratigraphy is presented.
Size Frequency Distribution of Quartz Sand Particles in Untransported Sediments: Its Significance
Authors: Patro B. C.
Published: November 2024

The arithmatic probability plots of Size Frequency Distribution (SFD) of untransported in-situ quartz sand accumulations (herein called the 'in-situ sediment'), at the top, slope and foot of a quartzite ridge, generated by thermal disintegration of the source rock (quartzite) show 2 to 4 straight line segments indicating the presence of 2 to 4 log normally distributed sub-populations. The phi standard deviation, sf,increases with decreasing size of the sub-populations indicating a smaller size-spread in coarser sub-populations and wider size-spread in finer sub-populations. These results are shown to be in cornplete consonance with the modus operandi of thermal disintegration. Sand grains of 1.00 mm and finer sizes are shown to be recalcitrant to thermal disintegration. The semblance in the pattern of SFD curves of in-situ sediment as well as those of detrital sediments reader the reliability of the SFD curves as discriminators of transportational/depositional environments questionable.
Geochemistry and Petrogenesis of the Champawat Granitoids Occurring around Dhunaghat, District Pithoragarh, Uttar Pradesh, India
Authors: Singh B. N. , Goel O. P. , Joshi Mallickarjun , Sheraton J . W.
Published: November 2024

Early Cambrian Champawat granitoids from Dhunaghat area, emplaced between medium-to high-grade metapelites of the Saryu Formation and low-grade melapelites of the Gumalikhet Formation of the Almora Group, show wide variations in their modal and chemical composition, ranging from granodiorite to granite. Biotite-rich mafic enclaves within the granitoids may represent restile, possibly modified by metasomatism. Chemical data for the calc-alkaline Champwat granitoids show some dcgree of fractional crystallization, although processes such as restite unmixing and different degree of melting may also have been important for the observed variation trends.

The Champwat intrusives are also characterized by enrichment of Y, Zr, Th, U, Nb, La, Ce, Pr and Nd and show affinities with "A"-type (anorogenic) granites.
Sea Levels Along Visakhapatnam Coast: A Geomorphic Explanation
Authors: Prudhvi Raju K. N. , Khan Ahmed Raza , Ramesh Y.
Published: November 2024

About 120 km of shoreline in north coastal Andhra Pradesh on either side of Visakhapatnam is rocky with a number of headlands aad bays. Surfaces and caves in rocks along this shoreline were mapped, to explain their relation to sea level stands of Holocene. The physiographic status of surfaces at several locations was worked out in terms of their number and area versus altitude. The seaward margins of hills mapped at many sites along the southern part of the shoreline show a distinct orientation of the outline and dominance of a class of surfaces different from those along the northern stretch. This variability is attributed to the concentration and release of energy of longshore drift and to the variable orientation of the shoreline. Surfaces between elevations of 5 and 1 metre above msl dominate the shoreline. The geomorphic characteristics of these surfaces conform well with those of the storm wave platforms. Sea caves are very few and are associated with either horizontal and/or inclined joints or foliation planes. The 'inactive' cliffs with their toes at about 2 metres above msl along with rocky floors/surfaces with sand cover, point to a sea level stand of 1.00-1.50 metres above the (present) mean low tide level (mltl).
Late Eocene-Early Oligocene Biostratigraphy of Mansa-Indrora Area, Cambay Basin
Authors: Jaiprakash B. C. , Kumar P.
Published: November 2024

Late Eocene-Early Oligocene succession from two well sections of north-eastern margin of Cambay Basin was analysed for their foraminifera1 content. It has yielded rich larger foraminifera a few planktonic and benthonic foraminifera. Three larger foraminiferal biozones have been recognised for the succession in geologically ascending order. These are Nummulites fabianii Partial Range Zone (? 39.4 m.y. to 37.4 m,y., i.e., ? P 15 to 16); Discocyclina dispansa - Nummulites fabianii Concurrent Range Zone (37.4 m.y. to 36 m.y.. i.e., Zone P 17) and Nummulites fichteli Partial Range Zone (36 m.y. to? 35 m.y., i.e., Zone P18), The environment of deposition has varied from shallow marine to inner and outer shelf conditions in the course of the development of the succession.
On the Occurrence of Uvigerina danvillensis and Hantkenina trinidadensis from Cambay Basin
Authors: Jaiprakash B. C. , Raju D. S. N.
Published: November 2024

Uvigerina danvillensis Howe and Wallace and Hantkenina trinididecrsis Bronnimann are described and illustrated from Late Eocene succession of Cambay basin. The presence of these two species at two levels indicates possible incursions of moderately deep marine conditions in an inner shelf set-up.
Granulometric Analyses of Pelites Using a Sedigraph: Examples from a Volcano-Sedimentary Environment
Authors: Mascarenhas Antonio
Published: November 2024

This article presents granulometric data of pelites (less than 40 microns) of mixed composition from a volcano-sedimentary environment. The Sedigraph serves as an useful tool in the analyses of silt-clay fraction of marine sediments. A cumulative curve from 40 to 1 micron can be obtained in 20 minutes. Pelites analysed show wide variations in grain size characteristics with the median value oscillating between 22 and 3 microns. In general, two fine grain size facies, each showing significant variations, are deciphered. Parabolic facies represents coarse silts whereas logarithmic facies comprise medium to fine silts. The type of grain size curves largely depends on the abundance of carbonate and pyroclastic mineral content of individual pelites. As compared to total pelites, their decalcified fractions sometimes show a significant shift of the grain median towards finer sizes. The intricacies of grain size studies of pelites of mixed composition are described in this paper.
The Association of Hypersolvus-Subsolvus Granites: A Study of Malani Igneous Suite, India
Authors: Kochhar N. , Dhar S.
Published: November 2024

Detailed field, petrological and the Chemical studies of lhe Jalor granites, Western Rajastan show that the Jalor magnatism is not exclusively peraluminous in nature but has peralkaline Component closely associated in space and time. The Jalor complex is a classic example of hypersolvus-susolvus granite association. The Similar abundances of trace elements such as Ba, Th, U, Ga, Y and Zr in the hypersolvus and the subsolvus granites suggest that both magmas have common Source and are coeval. the hypersolvus granites show enrichment of LREE as compared to the subsolvus granites, but the subsolvus granites have more pronounced Eu anomaly. Tectonic significance of the find also discussed.
The Molar Al2 O3 /(CaO3+Na2O+K2O) Ratios as Discriminant Constraint for Oceanic Plagiogranites and Continental Trondhjemites
Authors: Sarvothaman H.
Published: November 2024

The plots of leucocratic, soda-rich siliceous rocks on K2O-SiO2 and Rb-Sr diagrams often provide tenuous conclusions with regard to the discrimination of oceanic plagiogranites from continental trondhjemites. Analytical methods for the generation of REE and Sr-isotope data, the effective constraints for discrimination of the above-mentioned lithotypes, are confined to specialized and sophisticated laboratories. The specifically calculated molar Al2O3/(CaO+Na2O+K2O) ratios (AlCNK), coupled with the SiO2/Al2O3 ratios, of a large number of proven oceanic plagiogranites and continental trondhjemites are assessed to test whether these ratios can be applied as effective discriminant constraints. The major finding of this work is that oceanic plagiogranites are essentially low-alumina and metaluminous types. while continental trondhjemites are exclusively high-alumina and peraluminous types; the separation between the two groups is distinct and clean.
A Reappraisal of the Stratigraphy of Bailadila Group, Bacheli, Bastar District, M.P.
Authors: Khan M. W. Y. , Bhattacharyya T. K.
Published: November 2024

The metasedimentary sequence of Bailadila Group exposed in Bacheli area, south Bastar is studied in detail. Based on field relations, structural disposition, conglomerate ocurrence and petrographic characters, Bailadila Group is divided into three Subgroups, which in turn comprise five formations. Formal stratigraphic formationidentified are namely, Bhansi metabasalt-metapelite, Bacheti metasiliclastic, East Ridge Shale, Loa Conglomerate and shale Kailash Nagar Iron Formation. Based on the Stratigraphic continuity, the metabasalt-metapelite association (Bengpal) underlying the feldapathic quartzite (Bacheli metasiliciclastic-Bailadila) is proposed to be included as basal formation of Balladila Group.

Further, high LaN/YbN(10.41-15.89(ratio and Eu/Eu* (0.56-0.64) negative anamolies suggest a sialic continental crust.

It is also proposed that metavolcania-clastic association at chandenar and Tulsi Dongar being similar in lithoassociation to the proposed Bhansi Formation should also be considered of Bailadila Group.
Early Tertiary Ostracodes from the Pondicherry Formation, Pondicherry
Authors: Nagori M. L.
Published: November 2024

Thirteen ostracode species are recorded from the upper marlstone unit of Pondicherry Formation. Of these four species are new. These are :Bythocypris indica, Cytherelloidca pondicherriensis, phalcocythere (Phalcocythere) bireticulata, and Phyrcocythere nodosa, The present paper describes and illustrates the new species. The finding of a species of the genus Phyrocythere extends the geographic limits of the genus from Saudi Arabia to India during Early Territary.
A Note on Sulphide-Oxide Mineralisation in Carlsberg Ridge Basalts
Authors: Banerjee R. , Iyer S. D.
Published: November 2024

Pillow basalts from the Carlsberg Ridge at 3°35'N contain disseminated chalcopyrite, pyrite, and magnetite. The euhedral shape of the pyrite grains indicate them to be early formed and grown unobstructed while magnetite occurs as skeletal crystals. These opaque minerals indicate their origin from a rapidly cooled silicate melt and probably resulted by a process of liquid immiscibility during lava emplacement.
Geochemistry of the Gondwana Sandstones from the Areas of Adilabad and Karimnagar Districts, (A.P.)
Authors: Sayyed M. R. G.
Published: November 2024

The Gondwana sandstones from the present area of study, are studied with the help of geochemical discriminating parameters. Most of these parameters suggest a 'Passive Margin setting for the deposition of these sandstones. Excepting Upper Barakar and Upper Kamthi sandstones, other sandstones are chemically immature. These sandstones were deposited in plate interior or in the intracratonic basin and in general the basin of deposition could have been largely fluctuating.
Geochemistry of Sedimentary Organics of West Bokaro and Daitonganj Coal Fields, Bihar
Authors: Mishra C. S. , Samanta U. , Jain S. , Misra K. N.
Published: November 2024

Hydrocarbon source rock charactcristic of three formations - Barakar, Karharbari and Talchir of Gondwana graben in West Bokaro and Daltonganj coal fields are presented in this paper. Talchir Formation is lean in organic matter, whereas Barakar and Karharbari formations deposited in continental peat swamp environments, are rich in organic matter. The organic matter is mainly gas prone with subordinate liquid hydrocarbon generation potential. Maturation parameters such as vitrinite reflectance, T-max of rock eval pyrolysis and methyl phenanthrene index (MPI) indicate that the studied samples are in catagenetic zone of hydrocarbon generation.
Ostracoda from the Eocene Beds of Tarkeshwar, Surat-Broach Region, Gujarat
Authors: Khosla S. C.
Published: November 2024

Twenty ostracode species are recorded from the Eocene beds of Tarkeshwar, Surat-Broach region, Gujarat. The overall faunal evidence suggests a late Middle Eocene age for these beds.
57Fe Mossbauer Study of Low Aluminous (Low Ca) Orthopyroxene from Sukinda, Orissa (India) and its Petrogenetic Implication
Authors: Mitra Sachinath
Published: November 2024

A low Al, low Ca enstatite from within an orthopyroxenite dyke rock in the Sukinda chromite field was physico-chemically investigated by use of 57Fe Mossbauer spectroscopy XRF and XRD. The parameters of the fitted 57Fe Mossbauer spectra show the presence of Fe3+ in the octahedral M1 site of pyroxene structure.

The room temperature Mossbauer results show three doublets corresponding to Fe2+ (Ml), Fe2+ (M2) and Fe3+ (M1) sites. The QS values in two samples are found to be 2.80 and 2.96 mm/s for Fe2+ , (M1), and 1.89 and 2.08 mm/s for Fe2+ (M2) doublets. In both samples Fe3+-(M1) gives IS values 0.38 and 0.56 mm/s and QS values 0.48 and 0.49 mm/s. From their dependence on XFe21M1and XFe21M2 distributions the bond distances of tetrahedral and octahedral sites have been measured.

In the present case Fe3+ in the orthopyroxene structure is presumed to have been formed primarily at the stage of its crystallisation from a melt having requisitely high fO2. The temperature recorded by the Sukinda orthopyroxenile body has been estimatcd as 800°C from the distribution of Fe2+ - Mg over Ml and M2 sites. From the Fe3+/Fe2+ ratio the oxygen fugacity has been calculated as log fO2 = -6.189, which suggests that crystallisation of Sukinda orthopyroxene took place in the lower crustal regions rather than in the mantle.
Gold-Silver Decoupling in Weathering Front: Implications for Gold Exploration in Lateritic Terranes
Authors: Santosh M.
Published: November 2024

The differential solubilities of gold and silver in low temperature fluids lead to Au-Ag decoupling in the weathering front. Selective extraction of silver from the primary ores, or differential precipitation of gold at the fluid front can generate supergene gold deposits with enhanced grade. Gold grains formed by each process will be characterized by distinct evolutionary trends in grain morphology and chemistry. In the laterite-hosted gold mineralization of Nilambur, gold fineness (1000 Au/Au+Ag) increases from 921 in the primary veins to an absolute 1000 in laterites, with a concomitant four-fold increase in grain size. The kinetics and growth of gold particles are dictated by the degree of supersaturation, size of the critical nucleus and the free energy of nucleation, together with time-integrated fluid-rock ratio.

Chemical propagation and physical dislocation of Au during weathering place limitations on the application of conventional exploration techniques, and interpretation of anomalies defined from geochemical surveys on bulk samples. Two cases arc identified in this study: "shadow gold" - where overlying prominentanomaly is unrelated to the barren reef bcneath; and "masked gold"- where the potential of the underlying protore is masked by a weak signal in the overlying anomaly. It is suggested that the gradients in Au conlent within individual grains. and the trends in morphological evolution of gold particles are potential pathfinders for gold exploration in lateritic terranes.
Geophysics in Town Planning - A Case Study
Authors: Lal Babu
Published: November 2024

Geophysical surveys as aid to urban evaluation in the Vidyadhar Nagar area adjacent to Jaipur city, Rajasthan, have been conducted. DC resistivity surveys over area covered by sand and dunes indicated the presence of a moderately thick surface layer underlain by a potable aquifer zone of substantial thickness over quartzite bedrock of even topography deepening towards southwest. The results of the magnetic survey show, in general, normal structural behaviour barring a high in the southwest part of the area. The high is explained as due to an intrusive feature at a considerable depth, hence inconsequential for town planning. Subsequently, Jaipur Development Authority has undertaken construction of urban complex with a high rise structure in the area. The paper presents the geophysical results along with chemical analysis of ground water and computer studies. The soundings reveal the suitability of the area for urbanisation, considering the presence of moderately thick surface horizon underlain by a promising aquifer formed over the quartzite bedrock of even topography and disposition. The order of the resistivity obtained and the chemical composition of ground water show the ground water to be of good quality for drinking purpose.
A New Occurrence of Kimberlite Near Kotakonda, Mahboobnagar District, Andhra Pradesh
Authors: Kameswara Rao T. , Sarma K. J.
Published: November 2024

A Kimberlite dyke, with the appearance of a conglomerate due to the presence of mega and macro-crysts of olivine resembling pebbles, is located for the first time near Kotakonda, at about 10 km SSE of the known kimberlitic occurrences of Maddur area. Its massive look, lack of country rock xenoliths, local trachytic texture and concentration of megacrysts of olivine and orthopyroxene reflect hypabyssal nature. It consists mainly of rounded and corroded mega and macro-crysts of serpentine pseudomorphs of olivine and subordinate ortho- and clinopyroxene set in a fine-grained matrix containing microphenocrysts of euhedral olivine, monticellite. perovskite, spinel, apatite, calcite, ilmenite, magnetite, chromite and pyrite. The intergranular space is occupied by phlogopite, serpentite and carbonates. The major element chemistry of Kotakonda kimberlite, with low Niggili Si and high K and Mg values and alkali- and alumina-poor and cafemic-rich nature, matches well with that of kimberlite pipes 2,3,4 and 7 of Vajrakarur and kimberlites of Russia and Greenland. Its REE data agrees with that of 'basaltic kimberlites' of south India. The Kotakonda and Maddur kimberlite occurrences, possibly representing thc northern loci of kimberlitic activity of Vajrakarur area, show a rise of + 10 mgl over the background value in the regional gravity picture and fall within the zone of intersection of NE-SW and NNW-SSE lineaments, which could be a manifestation of mantle uplift and crustal thinning, thereby opening a new vista for the search of kimberlites.
Geomorphology and! Neotectonic Activity of Time Gandak Mega-Fan and Adjoining Areas, Middle Gangetic Plains
Authors: Mohindra Rakesh , Parkash B.
Published: November 2024

Based on remote sensing mapping, field study of morphology and soils, and laboratoty analysis of soils, the Gandak mega-fan and adjoining areas are divided into ten major geomorphic units - Gandak Floodplain, Young Gandak Plain, Older Gandak Plain, Oldest Gandak Plain, Old Rapti Plain, Old Ghaghra Plain, Ganga-Ghaghra Interfluve Plain and floodplains of the Ganga, Ghaghra and Rapti. The present study indicates that the Gandak river has shifted over its mega-fan from west to east from the Oldest Gandak Plain to Gandak Floodplain over a distance of about 105 km. One way shifting is due to slow eastward neotectonic tilting of the mega-fan. As the Gandak shifts across the mega-fan, it leaves behind numerous ponds, channels, lakes etc., which, with time, get integrated into fewer channels and drainage improves. Slow tilting has resulted in deposition of a flick ( > 1.7 m) vertical accretion silt layer over most of the mega-fan, even on the proximal portion deposited by the braided Gandak Channel. It has also been responsible for higher degree of soH development from east to west on the Gandak mega-fan. The whole region of the Gandak mega-fan is subsiding, but in the area of the Young Gandak Plain the sedimentation rate is slow and is not keeping pace with subsidence. This has resulted in impeded drainage, waterlogging and ponding on a large scale.
Magnetic Susceptibility Stuldies of Surficial Sediments from the Deep Arabian Sea
Authors: Shankar R. , Subbarao K. V. , Kolla V.
Published: November 2024

A wide variety of processes such as volcanic activity, submarine and continental weathering, aeolian transport and authigenesis can account for the magnetic susceptibility of the deep Arabian Sea sediments. Preliminary studies of the magnetic fraction indicate that it is predominantly composed of pseudo-single domain and viscous magnetite. It is found that magnetic susceptibility can be used to estimate the approximate iron content of marine sediments.
P-T Conditions of Pelitic Granulites and Associated Charnockites of Chinwali Area, West of Delhi Fold Belt, Rajasthan
Authors: Fareeduddin  , Shankara M. A. , Basavalingu B. , Janardhan A. S.
Published: November 2024

A brief account of the petrology and structure of medium grade pelitic granulites and associated charnockites occurring as slivers in the Anasagar migmatitic gneiss is given. These granulite slivers have been traced along strike up to 40 km and may cover a much wider area. Cordierite bearing pelitic granulites associated with charnockites around Chinwali were chosen for estimating metamorphic P-T conditions. The pelitic granulites are represented by the assenlblage opx-cord-gt-bio--silli-plag-k felds- qtz. Biotite-fibrolite intergrowths grow on cordierite which has opx inclusions. Garnet is often smeared with graphite. Metamorphic conditions of petite show peak pressures of 7.5 kb at 640°C. Charnockites generally record retrogressive pressure conditions of 5.7 - 4.0 kb. The mineralogy of the Chinwali granulites and P-T condition compare well with that of Sandmata granulites. The presence of these granulites, north of Ajmer, in basement migmatitic gneisses suggest the presence of an older deep crustal fragment (ca. 1.7 Ga) along the northwestern margin of the Aravalli Delhi Mobile Belt (ADMB) and belies the prevailing concepts of eastward crustal thickening and westward age polarity in the western Indian shield.
Textural Studies of the Surficial Sediments of Muvattupuzha River and Central Vembanad Estuary, Kerala
Authors: Seralathan P. , Padmalal D.
Published: November 2024

The Muvattupuzha river and the Central Vembanad estuary have been studied mainly for grain size spectrum and textural parameters such as phi mean, standard deviation, skewness and kurtosis. In general, the grain size spectrum shows a marked gradation downstream. The observed variation is in consonance with the energy conditions controlled by the profile of the river as wellas the natural and man-made obstacles encountered in the river channel. In the estuary, the textural pattern is highly complicated owing to the fluctuation in the physico-chemical conditions prevailing in the system. Further, seasonal maintenance dredging activities by the Port authorities also have a considerable bearing on the sediment dispersal pattern of the estuary. The CM model worked out for the fluvial system perfectly agrees with the transportational and depositional regimes of the river and the estuary.
Petrology and Petrogenesis of Syenites from the Cuddapah Basin, Andhra Pradesh
Authors: Madhavan V. , Mallikharjuna Rao J. , Srinivas M. , Natarajan R. , Sayeed Ausaf
Published: November 2024

Rare bodies of syenites of alkaline or subalkaline character occur as intrusions in the rocks of the Cuddapah Supergroup within the Cuddapah basin. The alkali syenites (found at Racherla, Idamakallu and Giddalur) are mainly composed of riebeckite (arfvedsonite), ilmenite, orthoclase and the subalkaline syenites (located at Gundlapalle) comprise hedenbergite, and microcline-perthite. Accessory quartz is invariably present in both the syenites. These intrusive bodies display contrasting mineralogical and geochemical characteristics. The quartz- and hypersthenenormative subalkaline syenite has the attributes of a ferrosyenite and has been subjected to hydrothermal alteration which not only resulted in the formation of secondary minerals like nontronite, amphibole, biotite and magnetite- all at the expense of hedenbcrgite, but also partly converted the Fe+2 into Fe +3. These subalkaline syenites are characterized by an extreme paucity of Mg, has low to moderate contents of Ba, Sr, Rb, Zr and REE. The quartz, hypersthene and acmite- normative alkali syenites (lusitanite) on the other hand are abnormally enriched in Ti; Rb is low but Ba, Sr, Ce, Nb, Nd, Ta, Sm, La, Zr am also the ratios K/Rb, Ti/Zr, Ce/Y and HREE/LREE are conspicuously high.

The syenites of the Cuddapah basin, seem to have crystallized under contrasting conditions. While the alkali syenites crystallized under high PH2O, the crystallization of subalkaline syenite took place under dry arid reducing conditions signifying a closed system. It is envisaged that the subalkaline ferrosyenite of Gundlapalle was formed by low-pressure crystal fractionation of a continental tholeiitic basaltic magma. The alkali syenites, on the other hand, are postulated to have crystallized from a mantle-derived, hydrous, alkaline magma enriched in Large Ion Lithophile Elements and Light Rare Earth Elements.
Triassic Palynoflora from the Krishna-Godavari Basin (India) and its Stratigraphic Significance
Authors: Prasad Bijai , Jain A. K.
Published: November 2024

Triassic palynomorph assemblages are recorded from the subsurface sediments of the Krishna-Godavari Basin. Four palynological assemblage zones, ranging in age from Smithian to Norian are identified in different well sections. These assemblages closely resemble Early to Late Triassic palynoflora of northwestern Australia and represent the Onslow type palynoflora.

It is suggested that the subsurface sedimentary sections in this basin, which have yielded typical Smithian to Norian palynoflora, and are termed as "Chintalapudi Sandstones", be referred to as Maleri sequence or its equivalents.
A Petrochemical Study of the Gabbroic Rocks of Warikwah, Baramulla District, Kashmir Himalaya
Authors: Fotedar B. K. , Raina A. K.
Published: November 2024

A gabbroic pluton of 4 sq km areal extension crops out at Warikwah, Baramulla District, Kashmir Himalaya. The three rock types in the pluton are recognized as norite, gabbro and quartz gabbro which are the products of differentiation under low PH2O conditions in that order. The parental magma is considered to be of tholeiitic nature and is derived from a deep source as reflected by major and trace element variation. After the emplacement in an orogenic (collisional) tectonic setting, the pluton has undergone low-grade. amphibolite facies metamorphism.
Radioactive Fossil Placer (Cyrtolite-Hematite Ironstone) from the Boleng Area, East Siang District, Arunachal Pradesh, India
Authors: Singh Rajendra , Dhana Raju R. , Singh A. K.
Published: November 2024

A zirconium-rare earth (RE)-thorium-uranium fossil placer with about 60-84% heavy and resistant minerals is recorded in association with quartzite and metagreywacke of the Proterozoic Miri Group from the Boleng area in East Siang District of Arunachal Pradesh. The heavy minerals occur as thin layers with variable thickness of a fraction of a cm to a maximum of 12 cm. The mineralised rocks are hard, highly compact, very heavy (sp. gr. 3.96-4.66), massive (at places, banded) and exhbit clastic texture with rounded to subrounded and well sorted fine grains of heavy minerals pointing to a long distance of transportation. Mineralogically, it consists of 46-61% opaques (mostly Ti-hematite), 9-13% rutile, 3-9% cyrtolite, 0.7-4.5% monazite and 0.2-0.9% thorite, all set in 10-30% sericitic matrix. Chemically, it is markedly different from the widespread unconsolidated coastal and inland placers, and analyses about 43-62% iron oxides, 1.7-5.4% Zr02, 0.5-3.1 % (RE,Y)2O3, 0.1-0.5% ThO2, and 0.01-0.9% U3O8. Chondrite-normalizcd REE-pattems show light REE enrichment and heavy REE depletion, with (Ce/Yb)cn ratio of 9-10 and markedly negative Eu-anomaly (Eu/Eu: 0.18-0.22). Generally, consolidated placers (fossil placers) are monazite-rich, whereas unconsolidated placers are, zircon-rich and viewed in this light, the cyrtolite (zircon)-rich fossil placer from the Boleng area is a rare occurrence.
Study of Groundwater Occurrence and Mixing in Pushkar (Ajmer) Valley, Rajasthan with d18O and Hydrochemical Data
Authors: Datta P. S. , Bhattacharya S. K. , Mookerjee P. , Tyagi S. K.
Published: November 2024

Stable isotopic composition of groundwaters and their hydrochemistry have been used for investigating possible existence of both palaeo-water and replenishable groundwater in Pushkar (Ajmer) Valley, Rajasthan. Causes of salinity increase in some of the groundwaters and intermixing of saline and fresh groundwaters have also been studied. The d18O values of water samples show a wide range varying from -6.3‰ to +4.0‰, indicating different sources of origin of these waters. There is a depletion of d18O with increasing depth of water table which may be due to stratification in groundwater with shallower zones being recharged from relatively modern rainfall. The chemical composition of groundwatlbrs shows a wide variation with electrical conductivity ranging from 150μmhos/cm to 8400μmhos/cm. Linear relationship between d18O and Cl- is a clear indication that the groundwaters are freshwater intermixed with different amounts of a saline endmember. Highly depleted, low salinity groundwaters seem to be of palaeo-origin. The most probable genesis of the 18O enriched, high salinity groundwater is from an originally evaporitic environment.
On Some Aspects of the Stratigraphy, Depositional Environment and its Bearing on Uranium Mineralisation in Parts of the Singhbhum Shear Zone, Bihar
Authors: Virnave S. N. , Mukhopadhyay T. K. , Krishnabadri N. S. R.
Published: November 2024

A review of the geology and controls of uranium mineralisation in the Singhbhum Shear Zone between Narwapahar (Lat. 22°44'N; Long. 86°15'E) in the west, to Ghatsila (Lat. 22°25'N; Long. 86°20'E) in the southeast and up to Dalmas in the north is presented in the light of new data based on facies analysis and palaeo-current studies of the conglomerate and associated meta-sediments in the area.

Synthesis and integration of geologic data have led to the following.conclusions:

a) The facies variation and its distribution pattern in the area demonstrate fluviatile conditions of deposition with upwatd fining and thinning sequences.

b) The sedimentary sequence shows progressive younging towards north without any obvious break, or juxta-position of the older over the younger.

c) The nature of Jaduguda sedimentary facies assemblage is indicative of a fluvial fan with conglomerate gray-wacke-arenite assemblage representing proximal fan facies. On the basis of facies model, the area north of Subarnarekha river represents a meandering fluvial pattern.

d) Uranium mineralisation is distinctly stratabound with characteristic facies association.
Finite Strain from Orientational Fluctuation of Ellipsoidal Particulate Axes: Combination of Sine and Cosine Functions
Authors: Katpatal Yashwant B. , Roday Prakash P.
Published: November 2024

Under large finite tectonic deformation and under a condition of low viscosity contrast, the axial orientational fluctuation method based on sine functions alone underestimates the values of a and b measured in the field. It is found that a better estimate of a and b and therefore of Rs could be obtained by using both sine and cosine functions. The parameters l, m and n introduced never equalise a, b and k respectively except when k = n = 0 (I = 1, m = a, k = n = 1 (1 = m but both greater than unity) and k = n = a (1 = a, m = 1). Usage of this method enhances the latitude of the ratios based exclusively on sine functions, thereby giving higher values of a and b despite small degree of orientational fluctuation of axes of ellipsoidal particles.
Uplifted Late Quaternary Debris Fan in the Upper Spiti Valley (H.P.) and its Environmental Significance
Authors: Kumar R. , Bagati T. N. , Mazari R. K.
Published: November 2024

Sediment build up, structure and geomorphic setting of alluvial fans can serve as good clues for the reconstruction of Quaternary events in a region where they are located. Alluvial fans assume greater importance especially in young orogenic belts like the Himalaya where there has been an interplay of rapid uplift and global climatic change during the Pleistocene. In this paper an attempt has been made to study the genesis of a small relict debris fan in the upper Spiti valley in the Tet hys Himalaya (H.P.) and to elucidate its sedimentational style in local climatic and tectonic set up. The fan has been essentially constructed by debris flows and subordinate stream deposits during seasonal melting and episodic events of the late Quaternary. While climate remained much the same local tectonic activity leading to upliftment of the fan and diversion of the feeder channel ceased further accretion of the fan beyond its present size. Minor warmer climatic oscillations within the main cool phase are observed.
Fluids and Heat along the Himalayan Plate Boundary and their Plausible Expulsion into the Subcontinent
Authors: Raval U.
Published: November 2024

The subduction/collision processes and consequent great Himalayan uplift are studied in the light of the plausibility that large amount of aqueous fluids may accumulate at the boundary due to (a) compaction of oceanic and marginal basin sediments, (b) various metamorphic episodes and (c) meteoric water facilitated by high topography. This would imply that during the major phase transitions in the dynamics of the plate margin, transient reservoirs of fluids and attendant heat would develop along the orogenic belt. Manifestations of related tectonomagmatic and metamorphic processes along the Himalayan arc are therefore assessed. It is noticed that epicenters of the large earthquakes, and major river-sources and morphogenic peaks seem to occur over certain nodal zones along the collision boundary as also the leucogranitic plutons. We also examine the possibility of fluid expulsion from the topographic/collision front into the foredeep basins and continental interior. It is seen that linear trends of relatively 'large' activity seem to exist over the Indian platform which nearly coincide with its basement heterogeneities (BHs) which in tum form part of the mobile belts. These BHs appear to extend upto the Himalayan arc and would thus act as subterranean links between the boundary processes and intraplate region. In particular large distance migration of fluids and thermal energy may take place through focussing offlow along these BHs because during at least the major tectonic episodes the in situ hydraulic conductivity and/or permeability along the BHs could be sufficiently raised. The plausibility of the BHs acting as hot fluid channels, is quite crucial since it may play a controlling role in the development (or remobilization) of (i) ore-deposits and hydrocarbon fields, and (ii) many geophysical features of the continental crust such as brittle-ductile transition, low velocity layer (LVL), anomalously high conductive layer (HCL), deep seismic reflectors, hydrothermal circulation, high heat flow, seismicity, etc. It is shown that indeed some of these features have been inferred along the BHs. From this possibility a tectonothermal framework emerges which may be able to integrate a number of physicochemical processes and geophysical signatures having basic as well as applied significance.
Fluorite Mineralization in the Kalpatta Granite: A Fluid Inclusion Study
Authors: Satish Kumar M. , Santosh M.
Published: November 2024

The granite pluton at Kalpatta in northern Kerala is a member of the Late Precambrian magmatic suite emplaced proximal to transcrustal faults in southern India In this study. we report the find of fluorite mineralization within late pegmatite phase associated with the granite. Both purple and colourless fluorites are associated, with X-ray diffraction pattern indicating perfect crystalline nature. Wet chemical analyses show CaF2 contents of 92 and 96 % for purple and transparent fluorites respectively. Primary fluid inclusions in both fluorite categories belong to aqueous bi-phase type, with Th between 150-180° C, and salinity in the range of 3 to 9 wt. per cent NaCl equivalent. Qurtz associated with fluorite contains CO2-H2O inclusions with Th(C02) between 8 to 15° C (density 0.85-0.90 g/cm3). The nature of mineralizing fluids suggests that fluorite crystallization occured from low temperature hydrothermal solutions derived as end-products of the frctionation of volatile- and alkli-enriched felsic magma. The mineralization is regarded as a finger-print of the alkaline affinity of Pan-African magmatism in Kerala.
Quaternary Geology and Morphotectonic Evolution of the Lower Sind Basin, Marginal Gangetic Plains, M.P. and U.P.
Authors: Mishra M. N. , Shrivastava R. N. , Upadhyaya M. C. , Shrivastava M. P.
Published: November 2024

The lower reaches of the Sind River, a tributory of the Yamuna, exhibits a thick accumulation of Quaternary alluvium deposited by the ancient river system of the Ganga and the present Sind River. The alluvial sequence comprises the Older Alluvium and the Younger Alluvium which are divisible into three lithostratigraphic units, viz., the Gohad-Mau-Mihona Formation, the Bera (Sijroli) Formation, and the Sind Formation. Six geomorphic units, namely, the Denudational Hill, the Jaswantnagar Surface, the Gohad-Mau-Mihona Surface, the Bera (Sijroli) Surface, the Sind Surface, and the Ravinous Tract are identified in the study area between 270 m and 100 m above MSL. The alluvial surfaces, constituting the fluvial terraces and the recent floodplains, reflect a complex process of aggradation and down cutting by the rivers during the morphotectonic evolution of the basin in Late-Quaternary and Recent period. Evidences of two episodes of neotectonism, which could be genetically related to the Himalayan orogenic movements of Late Pleistocene-Holocene period, are identified in the area of study.
Systematics and Significance of Microbialite (Stromatolite) Stratifera undata from Mussoorie Syncline, Lesser Himalaya
Authors: Sharma Mukund , Mathur V. K. , Srivastava M. C. , Shukla Manoj
Published: November 2024

A microbialite morphospecies Stratifera undata has been recorded in the Blaini Formation of Mussoorie Syncline and is systematically described. It is inferred that this mat complex was deposited in an upper intertidal region in subtropical climate. The age of this microbialite morphospecies is suggested to be Upper Riphean/Lower Vendian.