bluuebunny/crossref_metadata_2025 huggingface dataset:
Quaternary Facies and Palaeoenvironment in North and East of Sambhar Lake, Rajasthan
Authors: Sundaram R. M. , Pareek Suresh
Published: November 2024

Quaternary landforms in the northern and eastern proximity of the Sambhar lake in Rajasthan are products of depositional, structural and erosional processes. The depositional landforms are made up of four fluvial and two each lacustrine and aeolian facies. The structural and erosional landforms are carved out of Precambrian hard rocks. Each of the four fluvial facies essentially comprises a sequence of upward fining sediments characterised by a pedogenic cap except for the youngest one viz. laterocalcrete, calcrete and brown loamy soil. Amongst the two lacustrine facies, the older is marked by the presence of saline deposits and the younger by saliferous sediments. Of the two aeolian facies, the older is represented by longitudinal dunes, undulatory mounds and sandsheets while the younger by barchans and obstacle dunes. The depositional facies have evolved in a sequence which indicate subtle variations in a predominantly arid climate. The presence of fluvial sediments forming the lake base contradicts the earlier observation which suggested an aeolian base for these lacustrine sediments.
Ductile Shear Zone Between Shantinagar-Uppalchelka in Khammam District, Andhra Pradesh
Authors: Mukhopadhyay Indrani , Ray ]yotisankar , Nath Sudipto
Published: November 2024

This paper describes the results of field investigation and structural geology of the rocks of the area between Shantinagar - Uppalchelka in Khammam district of Andhra Pradesh (latitudes 17°14'15" to 17°18'43" N and longitudes 80°41'40".to 80°44'44" E). A zone of silicification (quartz - mylonite with well preserved colour banding) with patches of tectonic conglomerate (quartz-pebble) is found to occur within the generally dominant amphibolites. Structural analysis indicates the dominant influence offolding deformation (plungeoffold axis 42° -> 74°) in the area. All microstructural elements (e.g. polygonization, subgrain formation, "core-mantle" structure, ribbon like appearance of quartz grains) are deduced to be related to ductile deformation, recovery phenomena and recrystallisation process. Progressive development of tectonic conglomerate fabric and decrease in grain size are typically indicative of incremental strain magnitude across shear zone in the studied area. A "thin skinned" tectonic model invoking a network of thrusts has been proposed.
A Total Package in Utilisation of Low Rank Coals and Related Fossil Fuels
Authors: Sen Subhasis , Sen Meera
Published: November 2024

Occurrence of petroleum and natural gas in intimate association with coal in various coalfields has led to the development of the concept that a large part of hydrocarbons are generated from coal and plant derived sources, especially from the exinite group of coal macerals. In certain part of North East India, it was observed that coals record, exceptiona1ly high volatile matter and hydrogen content. These coals have been found to yield very high amount of tar. The associated carbonaceous shales, shaly coal and durainous layers of these areas may contain appreciable amount of exinites and may virtually grade into hydrocarbon source rock.

In the Gondwana basins inferior layers like shaly coal, durainous coals and carbonaceous shales are integral part of the coal seams which may sometimes contain considerable quantum of exinite - the principal hydrocarbon generating coal macera1. In case of beneficiation of the low rank coals, these materials are likely to be incorporated in the high ash fractions as rejects. The authors consider that to derive full benefit, high ash low rank coals should be subjected to low temperature carbonisation. The tar or hydrocarbon crude thus obtained from different sources could be brought to a central pool for further treatment for conversion to petroleum substitute fuels and chemicals. Ammonical liquor and gas are additional by-products of the process whereas the soft coke or char can be beneficiated and utilised for power generation and various other purposes. The high ash content of the coals would give rise to serious ecological threat and problems of waste disposal which can be profitably surmounted by converting fly ash to construction materials like bricks and road metal.
Magnetostratigraphy of Vindhyan Supergroup
Authors: Poornachandra Rao G. V. S. , Bhalla M. S.
Published: November 2024

In the absence of conventional radiometric dating and fossil evidence, magnetostratigraphy is considered to be a very powerful tool to correlate rock formations. Often the magnetozones are used as bench marks in correlation of rocks as the geomagnetic field reversals are ubiquitously synchronous. The Vindhyan sedimentation in the Indian stratigraphy represents a very important time period between 1400-400Ma with lithounits quite suitable for recovering the geomagnetic field signatures. With the recently obtained results from the Senui Group, palaeomagnetic field during the main Vindhyan Groups namely the Semri, Kaimur, Rewa and Bhander periods is available. It is quite interesting to note that all the formations investigated from these groups reveal both normal and reversed polarities of the palaeomagnetic field. Using this information a magnetic polarity time scale (GPTS) is constructed for the Vindhyan Supergroup during the late Proterozoic. When correlated with the Russian magnetostratigraphic scale for the Riphean period, it is noticed that the geomagnetic field during the late Proterozoic is similar to that of the Phanerozoic with superchrons at some periods and frequent reversals at others throughout the Precambrian.
Relationship Between Electrical Transverse Resistance and Hydraulic Transmissivity of Phreatic Aquifers in Basalts
Authors: Muralidharan D. , Shankar G. B. K.
Published: November 2024

An attempt has been made to extend the empirical relationship between geoelectric parameters and hydraulic properties of an aquifer put forth by Kelly (1977) for the phreatic aquifers of Deccan Trap basalts. Results of pumping tests, resistivity surveys and hydrogeochemical analysis from Godavari-Purna basin were utilised. A linear relationship between Transverse Resistance and Transmissivity of phreatic aquifer was obtained. The linear relationship was extended to other similar basaltic areas for validation.
The Sandur Schist Belt and its Adjacent Plutonic Rocks Implications for Late Archaean Crustal Evolution in Karnataka
Authors: Chadwick Brian , Vasudev V. N. , Ahmed Nazeer
Published: November 2024

Six formations are defined in a new lithostratigraphy of the volcanic and sedimentary rocks of the schist belt. The formations (Yeshwantnagar, Deogiri, Raman Mala, Donimalai, Taluru, Vibhuti Gudda) young consistently northeast, except for a part of the Taluru Formation in the northeast of the belt. We propose the new term Sandur Group to include these formations. Their combined thickness of c.35 km is in part an effect of thrust thickening. The Sandur Group was deposited in mainly shallow marine environments in a setting comparable with that of unstable mixed-mode basins. An incomplete, upright, synclinal sheath fold dominates the structure in the east of the schist belt, and another incomplete synclinal sheath fold occurs in the west, its hinge areas and northeastern limb having been cut out by a steepened thrust (the Sandur valley discontinuity). The margins of the belt were intruded by syntectonic, multipulse granites with magmatic and crystal-plastic solid-state linear and planar fabrics and the granite emplacement outlasted deformation. HT/LP metamorphism of the schist belt was contemporaneous with deformation and granite emplacement.

The granites are an integral part of the Late Archaean polyphase granite complex in eastern Karnataka and contiguous parts of Andhra Pradesh and Tamil Nadu, for which we propose the term Dharwar batholith. Published isotopic age data show that its western part includes anatectic granites and relies of Peninsular Gneiss (>2900 Ma), but the eastern part is dominated by juvenile granites. The batholith accreted onto the Archaean foreland to the west comprising Late Archaean marginal basins of the Dharwar Supergroup (Kudremukh. Bababudan-Ranibennur, Chitradurga-Gadag) and their basement of Peninsular Gneiss (>3000 Ma) during Late Archaean plate convergence with NE-SW shortening and sinistral transcurrent displacements. The steep linear belts (Kolar, Ramagiri, Kushtagi. etc.) and irregular tracts (Sandur, Hutti) of volcanic and sedimentary rocks ineastem Karnataka formed as intraarc basins above the evolving Dharwar batholith.
The Fertile Granite at Allapatna, Mandya District, Karnataka : A Possible Parent to Rare Metal Pegmatites of Southern Karnataka
Authors: Sarbajna Chanchal , Krishnamurthy P.
Published: November 2024

The Allapatna granite has been found to be a low-calcic (CaO-0.85%), peraluminous (A/C+N+K ratio = 1.04) and potassic type (K2O=4.75%), enriched in Rb(362), Ga(25), Cs(3), Nb( 19), U(l3), Ta(18), Th(38), Pb(55) and strongly depleted in Ba(333). Such abundances together with low K/Rb ( 118.9), Ba/Rb (0.92) and Th/U (2.92), and high Rb/Sr (3.45) ratios than normal granite indicate their highly fractionated and fertile character and strongly suggests that the Li-Cs-Ta (LeT) rich rare metal bearing pegmatites of Marlagalla and nearby areas may have been derived from such a parental granitic magma.
Talchir Sedimentation in Jayanti Gondwana Basin: A Case of Glacio-Lacustrine Low Slope Prograding Delta Sedimentation
Authors: Sen D. P. , Banerji Tapas
Published: November 2024

Reconstruction of sedimentation pattern and palaeogeographic model during Talchir sedimentation in Jayanti Gondwna basin has been attempted in the present paper.

The Talchir rocks in the basin consist of three distinct facies assemblages : Finer facies assemblage (Unit I) representing lake bottom sediments emplaced by two sets of processes namely - suspension from sediments introduced into the lake by interflow and overflow currents and turbidity current triggered by slumping in lake floor and delta front.

Sandstone facies assemblage (Unit II) representing mainly low slope (~5°) delta deposits. Channels, interchannel and bar sediments fonn the topset of the delta. The foreset beds are difficult to identify because of very low slope of the delta margin.

The upper coarser facies assemblages (Unit III) introduced into the lake by various glaciogenic processes. The most dominant process was range of gravity flow processes generated on the steeper slope in the subaerial part to the south of the lake margin. Sudden change of slope from steep in the subaerial part to gentle in the lake margin has restricted the distribution of the facies along the southern low slope lake margin.

The depositional model is that of a low slope, prograding glacio-fluvial delta advancing over glacio-lacustrine sediments. The model suggested is a modification of available glacio-lacustrine model of moderate to high slope glacial lakes.
Plate Tectonics or an Expanding Earth?
Authors: Shields Oakley
Published: November 2024

Some geological problems are more readily solved by a rapidly expanding earth than by a constant sized earth (plate tectonics). These include some Triassic terrestrial organisms whose distributions span the Panthalassa and Tethys oceans, extreme degrees of global structural symmetry, and Jurassic-Cenozoic expansion of the Pacific basin and its perimeter.
Pycnodus lametae (Pycnodontidae), a Holostean Fish from Freshwater Upper Cretaceous Lameta Formation of Maharashtra
Authors: Mohabey D. M. , Udhoji S. G.
Published: November 2024

A well-preserved, nearly complete skeleton of the holostean fish Pycnodus lametae, is described from the freshwater Upper Cretaceous Lameta Formation of Bhatali in Chandrapur district of Maharashtra. Earlier, the genus was known only by its partly-preserved crushed skull. However, isolated crushing teeth are widely known from the Lameta and Interttappean sediments of Peninsular India. Other associated fishes include Holostei: Lepidotes deccanensis, Lepisosteus indicus; Teleostei: Clupeidae, Osteoglossidae, Enchodus, Eoserranus: and myliobatoids including Dasyatis and Igdabatis.
The Granitoids of Pindar-Sarju-Ramganga and Goriganga Valleys of Higher Kumaun Himalaya
Authors: Kaur Manudip , Chamyal L. S.
Published: November 2024

In the Higher Kumaun Himalaya granitoids are widely distributed and occur as bands, lenses or sheet-like bodies. They include different varieties of gneissic granites (schistose, foliated, augen and porphyroblastic). The field, petrographic as well as chemical data indicate that the granitoids of Kumaun Higher Himalaya are formed due to metasomatic transformation of metasediments by alkalirich emanations. The geochemistry of these reveal their calc-alkaline, peraluminous, S-type nature and compositionally mainly represent granite. Trace elements discriminate the granitoids in the syncollisional environment.
Occurrence of Cochlichnus Hitchcock in the Vindhyan Supergroup (Proterozoic) of Madhya Pradesh
Authors: Kulkarni K. G. , Borkar V. D.
Published: November 2024

A trace fossil occurring in an unusual and peculiar way was found in the upper Bhander Sandstone (Bhander Group, Vindhyan Supergroup) from near Sagoni, district Damoh, Madhya Pradesh. It is an unbranched, smooth, meandering trail, preserved in negative epirelief on the upper surface of a ripple marked sandstone. Individual trails, preserved within nineteen consecutive troughs without crossing crests anywhere, are restricted to only one of the flanks of the ripples. Trail-bearing flanks are on one and the same side of their respective troughs. This trail, identified as Cochlichnus Hitchcock is assigned a Vendian age.
Petrochemistry of the Eastern Part of Piparan Granite, Doda District, Jammu Lesser Himalaya
Authors: Jamwal M. M. S. , Raina A. K. , Dhar B. L.
Published: November 2024

Piparan Granite batholith, in the southwest of Pir Panjal, Jammu Lesser Himalaya, is exposed within the Older Metamorphics (Precambrian). The granite is Ieuco- to mesocratic composed of quartz (32%), perthitic K-feldspar (27%), plagioclase An13-28 (23%), micas(13%), garnet, apatite, zircon and ilmenite (8%). It is of two mica monzogranitic composition. Its major and trace element concentrations are comparable to the average crustal granite. The differentiation of the rock favours a normal trend with a positive correlation of alkalies and a negative trend of magnesium against silica. The granite is S-type (ilmenite series) and peraluminous, produced as a result of syntectonic crustal anatectic process at a temperature range of 650°-690°C, 3-5 kb PH2O and at a depth of approximately 20-30 km.
Some Aspects of Petrology of the Granites of the Western Himalaya
Authors: Sharma T. R. , Sharma K. R.
Published: November 2024

Several granite plutons occur in the Great and Lesser Himalaya in Ladakh, Jammu and Kashmir. These granites assume batholithic to sub-batholithic dimensions and are composed of quartz, orthoclase, microcline, plagioclase, muscovite, biotite, hornblende and tourmaline besides epidote, apatite, futile, zircon, magnetite, ilmenite and sphene as accessories. These granites are peraluminous as the molar proportions of Al2O3 is greater than the molar proportions of (K2O+Na2O+CaO). High molar AI2O3/ (K2O+Na2O+CaO) ratios and normative corundum are indicative of the generation of these granites due to partial fusion of crustal materials.
Laterite Profile Geochemistry in Outlining Supergene Gold Deposits: A Case Study from Nilambur, Kerala
Authors: Omana P. K. , Santosh M.
Published: November 2024

A natural example for exceedingly pure gold was recently identified from the laterite weathering profiles of Nilambur, northern Kerala. The laterites are highly ferruginous and nodular, containing saprolite and clayey horizons. Within the various horizons in the laterites, gold is found as small grains or nuggets. In many cases, the oxidised zone contains high concentrations of gold, closely associated with iron oxide/hydroxide matrix and was observed to be crystalline. This occurrence supports dissolution and reprecipitation of gold during weathering.

Laterite samples from different horizons of two representative vertical sections of the weathering profiles in the Maruda area of Nilambur have been analysed for major. minor and trace elements, including gold in this study. The distribution of Fe, Al, Si, Ca, Mg, Na, K, P, Ti and Mn in these profiles can be correlated with the element mobility patterns associated with tropical weathering environment. The results indicate that a predominantly acidic environment is generated during lateritization, which is conducive to gold mobility. Our study confirms that the concentration of naturally purified gold in the laterites was achieved by acidic oxygenated fluids in the weathering front.
Hydrogeochemistry of the Upper Ganges River, India
Authors: Bhatt Kailash P. , Saklani Shailendra
Published: November 2024

Analyses of more than fifty water samples were conducted to evaluate the chemistry of the Upper Ganges River system. Major ion concentrations were measured for the Alaknanda, Bhagirathi and the Upper Ganges River. High velocity water of the livers may lead to excessive mass transport over the rock weathering. Mechanical weathering plays a major role at the sources of the tributaries, where alpine glacial environment persists. However, chemical weathering is a major factor in determining river water chemistry in downstream temperate areas. Results indicate Alaknanda has more alkalinity and hardness as compared to the Bhagirathi. Rocks of Sub-and Lesser Himalayas have greater influence on total water chemistry, compared to Precambrian rocks of the Higher Himalayas. Rocks of the Higher Himalaya are major source of sodium and potassium ions in the river water, whereas Sub-and Lesser Himalayan rocks are major contributors of calcium, magnesium and sulphate ions. Na/Na + Ca ratio and ranges of TDS for the river system suggest that chemistry of Upper Ganges River and its tributaries is dominated by rock weathering processes.
Factor Analysis of Benthic Foraminifera from Coastal and Estuarine Sediments of Kovalam-Tuticorin, South India
Authors: Jayaraju N. , Reddeppa Reddi K.
Published: November 2024

This study investigates the present faunal geographical boundaries and environmental limits of foraminifera in the southeast coast of India. Ninety samples were examined. The raw data of foraminiferal population was analysed with the R-mode factor analysis program. Twelve factor assemblages, explaining 74% of the observed variance emerged from this test. The statistically most important assemblage is Ammonia beccarii, Asterorotalia dentata. The last assemblage is represented by Rectobolivina raphana. These assemblages reflect the hyposaline to hypersaline conditions and sandy to muddy sand substrate environment. The cross plot of the first two factors shows the separation of two groups as lower, which is dominated by Miliolids and seconded by Rotaliids and upper group is predominately represented by Rotaliids. Physico-chemical parameters could be the reason for the separate grouping of the species.
Association of Authigenic Apatite with Uraniferous Organic Matter at Domiasiat, Meghalaya and its Genetic Implications
Authors: Sunilkumar T. S. , Narasimhan D. , Krishna Rao N.
Published: November 2024

The occurrence of authigenic apatite with uraninite, pyrite, sphalerite and galena within organic matter is a characteristic feature of the sandstone-type uranium deposit at Domiasiat, Meghalaya. Apatite occurs in the form of thin hexagonal basal plates and its identification is confirmed by x-ray diffraction. The authigenic apatite in this specific association points towards diagenesis in euxenic conditions of marine affinity.
Geochemical Changes Due to Weathering Under Different Environmental Conditions in Parts of Eastern Ghats
Authors: Suryanarayana K. , Krishna Rao G.
Published: November 2024

Geochemical changes in weathering profiles from khondalites, charnockites and leptynites at different altitudes in the Eastern Ghats were studied. Chemical changes of major oxides (SiO2, Al2O3, Fe2O3) and minor oxides (CaO, MgO, K2O, Na2O) in the weathering profiles and the percentage of net loss or gain of each constituent reveal that climate and topography have significant role on their behaviour.
Markov Chain Analysis of the Shallow Marine lBhuj Sandstone of Early Cretaceous Age, Kachchh Basin, India
Authors: Shukla U. K. , Khan Z. A. , Singh I. B.
Published: November 2024

Cyclic characteristics of lithofacies of the shallow marine Bhuj Sandstone were studied statistically, using embedded Markov chain analysis and the concept of entropy. Data came from thirteen measured sections. The upward transmissions from one sedimentary lithofacies to another are plotted on a 5×5 matrix and a transition tree is constructed. Results strongly suggest that the Bhuj Sandstone was influenced by a Markovian mechanism and accumulating in well-defined depositional environments; the vertical distribution of lithofacies was controlled by a number of natural processes. The preferential upward transition path of lithologic and depositional envitonment changes are as follows: Carbonaceous siltstone/shale (A) (Coastallagoon) ? Coarse-grained cross bedded Sandstone (8) (Estuarine channel) ? interbedded sandstone siltstone (C) (Tidal flat-tidal channel) ? silty sandstone (D) (Sandflat - shoal) ? Bioturbated sandstone (E) (Shelf Sheet sand) ? Carbonaceous siltstone/shale (A) (Coastal lagoon).

This sequence is an asymmetrical cycle. It can be identified into a progradational event (lithofacies A-D) and a transgressive event (lithofacies E). The statistical results concur with the sedimentological evidence for depositional environments.

Entropy plots of the E(pre) and E(post) values of each lithological state correspond to the type A-4 category (Hattori, 1976), signifying lower and upper truncated asymmetrical cycles. The values of E (system) fall just on the boundary of the area allocated for the neritic environment. The area occupied by the Bhuj Sandstone evidently represents the domain of deposits of a coastal complex of estuary, lagoon and tidal flat environments, deposits for which Hattori had no data base.
Inventory of Glacier Basins in Himachal Himalaya
Authors: Dobhal D. P. , Kumar Surendar
Published: November 2024

Himachal Pradesh has over 80% of mountain terrain. The inventory of glacier in such a terrain is carried out by the Remote Sensing Techniques (RST). About 10% of the lotal mountainous area in the Himachal Himalaya is covered with permanent snow and ice. The whole mountainous area has been divided into six basins as defined by the outlet of the glaciers. Six hundred and one glaciers have been identified in these basins. Studies show that the distribution of these glaciers is uneven. Majority of glaciers are concentrated in the Chandra-Bhagha (200), Beas-Parvati (80), Ravi (54), Malung (40), Spiti (159) and Satluj (68) basins. The summer snow line fluctuates between 4000 to 5000 m (mst). The total area of these basins is about 48,034 sq km, of which 4,516 sq km is covered by permanent snow. Hence, the total mountainous area of Himachal consists of about 60% of seasonal snow cover and 10% area is permanent snow and ice covered, the remaining 30% area is snow-free in the lower altitudes.
Marine Magnetic Studies over the Laccadive Ridge, Indian Ocean
Authors: Satyanarayana Y. , Murty G. R. K. , De Chanchal
Published: November 2024

Laccadive ridge is a prominent feature in Indian Ocean, off west coast of India .Marine magnetic survey carried out across the ridge between 8° and 12°N reveals that the ridge is associated with strong magnetic anomalies of the order of 200 to 400 nT. A significant low magnetic trend is present over the topographic high of the ridge. The results of spectral analysis and two-dimensional modelling of the data suggest the possible presence of an anomalous basic body, with varying thickness. The inclination and declination obtained indicate that the basic body may be derived from same volcanic activity as of the onshore traps associated with normal remanent magnetism.
Flood Studies in India: A Brief Review
Authors: Kale Vishwas S.
Published: November 2024

This paper provides a brief outline of the flood studies in India in the field of geomorphology, meteorology and hydrology. The review clearly shows that, though the general characteristics of floods have been known for a long time, our scientific understanding of the floods remains incomplete to a surprisingly large extent. Existing studies seem to concentrate in two areas. The first deals with hydrometeorological analysis of flood producing rainfall and associated synoptic conditions. The second area is related to streamflow analysis and the estimation of design floods. Both the research areas place considerable emphasis on statistical analysis and modelling. This trend is likely to continue in future. While a quantitative approach to the problem is indispensable in predictive models, it is felt that future opportunities to improve our understanding of this recurring natural hazard should include research into the natural trends and the behaviour of floods on longer time scale, and increased evaluation ofthe impact of anthropogenic activities on the river systems.
High Dams in Central Himalaya in Context of Active Faults Seismicity and Societal Problems
Authors: Valdiya K. S.
Published: November 2024

India's two highest dams would be located close to the active faults that have been repeatedly reactivated in the Quaternary. These heavy structures are being built in the region of high seismicity where the probability of occurrence of major earthquakes appears to be very high. The probable high-magnitude earthquake will release quite a few hundred times more energy than the earthquakes for which the Tehri Dam is designed. The 50 percent failure probability accepted by the dam builders is at alarming variance with the globally accepted minimum standard of 16 percent (safety level of at least 84%). Impoundment of water in reservoirs upstream of the darns is likely to intensify and trigger landslides in the large reservoir areas particularly in the zones of active faults. Submergence of upstream lands in the most productive and populated valleys in Uttarakhand and western Nepal would cause great loss of forest and agricultural resources. In view of the horrifying implications of high dams it would be prudent to go in for a large number of smaller dams at much lower costs and risks, and which would confer greater benefits to all.
Stratigraphic Succession of Precambrian of Singhbhum: Evidence from Quartz Pebble Conglomerate
Authors: Sinha K. K. , Krishna Rao N. , Shah V. L. , Sunilkumar T. S.
Published: November 2024

Though the stratigraphic succession in the Precambrian of Singbhum-Orissa region of the Indian shield given by Saba et al. is widely accepted, there are several contentious issues whieh have been hotly debated over the years. The occurrence of uraninite and pyrite bearing quartz-pebble conglomerate at the base of Iron Ore Group (lOG) as well as the Dhanjori Group has indicated the necessity for a revision in the stratigraphic succession in view of the temporal significance of such conglomerate the world over.

The conglomerate contains a significant population of zircon, chromite and shows a typical minor and trace element composition. The zircon has morphometric properties similar to those found in several members of the Singhbhum Granite Complex. The presence of detrital chromite and high Cr content indicate the occurrence of older mafics/ultramafics in the provenance along with the Singhbhum Granite Complex. It is suggested that some mafic and ultramafic members presently grouped within the IOG may represent such "older greenstones". The IOG as well as the Dhanjori Group with basal QPC horizon lie over a basement of Singhbhum Granite-Greenstone Complex. From available evidences it is surmised that both IOG sensu stricto (the BIF sequence and associated ferruginous cherts. greywackes and acid-intennediate volcanics) and the Dhanjori Group represent late Archaean (2500-3000 Ma) supracrustals and hence are nearly coeval. The Singhbhum Group north of the shear zone represents early Proterozoic supracrustals.
Further Zircon U-Pb Age Data for the Daginkatte Formation, Dharwar Supergroup, Karnataka Craton
Authors: Trendall A. F. , de Laeter J. R , Nelson D. R. , Bhaskar Rao Y. J.
Published: November 2024

SHRIMP U-Pb analyses of zircons from a rhyolite sample collected from the Daginkatte Formation of the Chitradurga Group (Dharwar Supergroup), close to the type locality, give an age of 2601 ± 6 Ma (1s 23 of 24 analysed grains). This is within error of the 2614 ± 8 Ma (2s 11 grains) recently reported by A.P. Nutman and his colleagues in 1996 from a sample of acid volcanic schist of the same formation, about 25 km along strike. Combining Nutman et aI's (1996) published data with the new analyses reported here gives a pooled age of 2606 ± 6 Ma (n = 34, 1s, ?2 = 1.31), within error of both of the separately determined ages. Having regard to the reported uniform lithology of the Daginkatte Fonnation, the pooled age is probably that of a short magmatic event during which it was formed, and provides a firm constraint relevant to this stratigraphic level of the Chitradurga Group; however. it is now important to determine whether the rhyolitic rocks of the Daginkatte Formation are intrusive or extrusive.
A Precise Zircon U-Pb Age for the Base of the BIF of the Mulaingiri Formation, (Bababudan Group, Dharwar Supergroup) of the Karnataka Craton
Authors: Trendall A. F. , De Laeter J. R , Nelson D. R. , Mukhopadhyay D.
Published: November 2024

SHRIMP U-Pb analyses of zircon grains from two thin dark shales believed to be syndepositional ashfall tuffs close to the base of the banded iron-formation (BIF) within the Mulaingiri Formation of the Bababudan Group (Dharwar Supergroup) of the western Kamataka Craton provide a precise age for the onset of BIF deposition in the basin. Sample 120019C, from the exact base of the BIF, gave an age of 2720 ± 7 Ma, while sample 120018C, 14.5m above the base, gave an age of 2718 ± 6 Ma. The second sample contained younger grains which may have been affected by a late thermal event.
Ammonoid Stratigraphy of the Spiti Shale Formation in Spiti Himalaya, India
Authors: Pathak D. B.
Published: November 2024

Ammonoid biostratigraphy of the Spiti Shale Formation is being discussed in light of new data. Their systematics supported by stratigraphic details of the collected ammonoids have resulted in the organization of a set of 9 distinct successive ammonoid assemblages ranging in age from Oxfordian to Berriasian i.e. from 154 Ma to 130 Ma. The chronostratigraphically significant Jurassic/Cretaceous System and Kimmeridgian/Tithonian Stage boundaries have been identified. The ranges of species of Spiti Shale ammonoids are presented here for the first time.
The Talkad Sand Dunes in Mysore District of Karnataka - their Description, Evolution and Origin
Authors: Srikantia S. V. , Anantharamu T. R.
Published: November 2024

Situated along the left bank of the river Cauvery, Talakad represents a typical riverine sand dune. The point bar deposit along the left bank of the Cauvery is the main source of the sand. However, this stretch, in the upstream has a weir built some 400 years ago which diverted water from the Cauvery into the Madha vamantri canal, which resulted in the lowering of the level of water in the point bar deposit downstream thereby exposing its sand to monsoonic winds blowing from SW to NE towards Old Talkad. The settlements and also the NW to SE blowing cross wind in the valley acted as barriers for the sand laden monsoonic winds with the consequent development of sand dunes which on gradual migration buried temples and many old settlements.
Significance of Fossils from the Rajpipla Limestone, Cretaceous of Narmada Basin Gujarat
Authors: Rajshekhar C.
Published: November 2024

Mega fossil (fragments of Lame11ibranch shells, Gastropod, and Echionoid spines) in thin section and micro fossils (Benthic foraminifer Textularia sp.?) are being reported for the first time from the Rajpipla Limestone of Bagh Group.
Tungsten Mineralisation at Khobna, Maharashtra Fluid Inclusion Studies
Authors: Narasimhan D. , Krishna Rao N. , Panchapakesan V. , Sahu K. C.
Published: November 2024

Fluid inclusion study has indicated two distinct stages of mineralisation: one with higher TH and lower salinity (greisens) and the other with lower TH and slightly higher salinity (quartz vein) conditions. These mark the formation conditions of wolframite and scheelite respectively.
Rare Earth Element Geochemistry of a Sediment Core from the Lower Bengal Fan
Authors: Ramesh S. , Ramasamy S.
Published: November 2024

The Post Archaean Australian Shale (PAAS) normalised Rare Earth Element (REE) distribution pattern of a 4m box core from the Lower Bengal Fan clearly exhibits different types of patterns according to the climatic fluctuations of Late Quaternary period. Based on the vertical profiles of REEs, SLight REE/SHeavy REE ratio, Ce^ and SREE the climatic boundaries were further confirmed. The influence of continental sediments with a rugher rate of sedimentation are reflected in higher concentration of SREE in glacial periods. The above observations suggest the Late Pleistocene - Holocene boundary at 45-50 cm depth, the Last Glacial Maximum at 50-120cm depth and Glacial (I) stage at 150-290cm depth in the core studied. Warmer periods of Interglacial stages (II) and (I) correspond to 120-150cm and 290-400cm depths.
A Tidal Island Model for Carbonate Sedimentation: Karondia Limestone of Cretaceous Narmada Basin, India
Authors: Akhtar K. , Khan D. A.
Published: November 2024

The Cretaceous sedimentary sequence of Narmada basin comprise a lower clastic formation (Nimar Sandstone) and an upper carbonate sequence (Karondia Limestone). The depositional model of limestones was reconstructed by identifying 8 microfacies which were regrouped into 5 facies associations. The carbonate sequence of the study area was interpreted to be deposited on a ramp without a striking break in the slope of the ramp and where shelf margin was not developed. The vertical arrangement of facies of Karondia Limestone forms a shallowing upward sequence. It shows much lateral and vertical variation which can be attributed to deposition on a platform dotted by a mosaic of exposed banks or island separated by subtidal areas with the whole complex shifting both laterally and vertically in response to hydrodynamic conditions through time.
Petrogenesis of the Perinthatta Anorthosite, Northern Kerala, India
Authors: Nambiar C. G. , Soney K. P. , Radhakrishna M.
Published: November 2024

The anorthosite pluton has textural and trace element characteristics typical of a magmatic cumulate. A soda-rich intermediate magma is inferred to be the parent. Rare earth element based modelling shows that the anorthosite was derived from a parental melt having hundred times chondritic REE with a slightly fractionated pattern probably derived by the melting of granulitic or edogitic source.
Ooid Turbidites from the Western Margin of the Bengal Fan Sediments
Authors: Suresh N. , Bagati T. N.
Published: November 2024

Sedimentology, mineralogy and geochemistry of ooid sand beds in deep sea gravity cores (water depth >2818 m) reveal that they were derived from continental shelf by turbidity currents. The presence of ooid turbidites at two different levels suggests two periods of turbidity current activity. The first activity probably took place during the Last Glacial Maximum in Late Pleistocene and the second activity prior to the stabilization of sea level in the Early Holocene.
Nabaviella acanthomorpha N. Sp, a Sponge Spicule from the Precambrian-Cambrian Boundary Interval in the Tethys Sequence of Northwestern Kashmir
Authors: Tiwari Meera
Published: November 2024

A new species of sponge spicule Nabaviella acanthomorpha is described here, which occurs in association with an assemblage of small shelly fossils (SSF) from the Precambrian-Cambrian boundary sequence, exposed in Pohru Valley of northwestern Kashmir, with an obvious biostratigraphic potential to understand the Precambrian-Cambrian boundary in the succession.
Diversity and Distribution of Recent Ostracoda in the Continental Shelf Sediments off Pentakota and Kalingapatnam, Central East Coast of India
Authors: Naidu T. Y. , Varma K. U. , Shyam Sunder V. V.
Published: November 2024

Twenty-nine species of Recent Ostracoda have been identified from the continental shelf sediments off Pentakota and Kalingapatnarn, Central East Coast of India. Of the twenty-nine species, five species are abundant, nine species are common and fifteen species are rare in occurrence. The distribution and diversity of the Ostracoda suggest that the inner and outer shelf environments are more favourable than the middle shelf of Pentakota whereas the inner shelf is more favourable than the middle and outer shelf environments off Kalingapatnam. On the whole, the Pentakota shelf environment is more favourable for the Ostracods to survive than Kalingapatnam shelf.
Mineral Replacement of Plant Roots in Fluvial Sediments of the Link Channel of Krishna River, Near Yedurwadi, Belgaum District, Karnataka
Authors: Achyuthan Hema , Ghate S. N. , Rajaguru S. N.
Published: November 2024

Micromorphology, XRD analyses and SEM studies of rhizoliths from Late Middle Pleistocene yellowish brown silty fluvial sediments of Yedurwadi reveal that calcium carbonate has a localized source. Silica and calcium carbonate are formed by the plant roots through their metabolic activity creating a favourable microenvironment for the processes of SiO2 and CaCO3 precipitation and replacement.
Petrology of Post -Archaean Magmatic Rocks in the Eastern Indian Craton
Authors: Sengupta S. , Ghosh Mitra , Gangopadhyay P. , Chattopadhyay A.
Published: November 2024

Minor rhyolite intrusives spatially associated with granophyric granites occur along the eastern and southwestern fringe of the Archaean Singhbhum Granite batholith in the eastern Indian Craton. Some minor trachyte dykes occur within the batholith and both are of post-Archaean age. On the basis of major and trace element studies it has been inferred that a process more complex than simple fractional crystallisation has controlled the observed chemical variation in both the rocks. However, the two are genetically unrelated and have been generated from different sources. All the rhyolites, which are scattered as small bodies over an extensive area, are produced from similar source compositions. The chemical variation among the rhyolites is the result of a difference in degree of melting and the samples enriched in LREE and other incompatible elements represent a lower degree of partial melt. Composition of the rhyolites suggests that neither muscovite nor aluminosilicates were present in the source. The likely source is therefore the trondhjemites and mafic-ultramafic rocks constituting the Archaean crust of the region. Similar source for rhyolites distributed over a large area indicates a homogeneous composition for the Archaean crust.
A S-Isotopic Study of the Baryte and Galena from Quartz-Baryte Veins at Rasimalai, North Arcot Ambedkar District, Tamil Nadu
Authors: Dhana Raju R. , Prasad R. N. , Pande D. D. , Panneer Selvam A. , Kumar Mary K.
Published: November 2024

This study shows d34S values for the study of co-existing baryte and galena, respectively, are in the ranges of +6.9 to 8.0% and -6.0 to - 9.8%0. Such narrow ranges make biogenic sedimentary source for sulphur less likely and suggest magmatic source. Sulphur isotope values indicate a hydrothermal system with a T of ~440°C, pH 5±1 and Log f02 of -34 to -37.
Early Proterozoic Rare Metal and Tin Pegmatites near Kawadgaon, Bastar, M.P.: An Example of Vertical Pegmatite Zonation
Authors: Singh Yamuna
Published: November 2024

The paper reports, for the first time, the occurrences of several almost non-metasomatized rare metal zoned pegmatites of small- to medium-dimensions near Kawadgaon in the Bastar. Columbite- tantalite and beryl occur mainly close to quartz core. Beryl is Ubiquitous. Replacement units are almost absent in the Be and Be-Nb-Ta pegmatites whereas, they are prominent in the cassiterite pegmatites.

Spatial distribution of rare metal and tin pegmatites of the study area suggests a distinct vertical zonation. At lower level, Be and Be-Nb-Ta-minetalization took place whereas, at higher level, albitization and Sn-mineralization are observed. Tin seems to have behaved as incompatible element at lower level, where high K/Na ratios and reducing conditions attended the crystallization. With the fractionation of substantial amounts of microcline perthite in the Nb-Ta pegmatites at lower level, Na and volatiles have increased and enriched Sn to form cassiterite in association with albite in the upper level pegmatites. Non-albitized pegmatites do not contain any tin mineralization, which is suggestive of Na-Sn geochemical affinity.

Systematic mining of pegmatites and their gravels will yield considerable quantities of cassiterite, besides columbite-tantalite and beryl.
Morphology of the Volcanic Ash from the Kukadi River Section, Pune District, Maharashtra
Authors: Karmalkar N. R. , Ghate S. N. , Mishra Shiella , Rajaguru S. N.
Published: November 2024

An ash bed varying in thickness from 20 cm to 2 m occurs within the lower part of 10 m thick yellowish-brown clay and calcareous silt unit that contains occasional lenses of calcrete, gravels and channel lag gravels both at the base and top of the sequence. The volcanic ash has yielded a K/Ar age of 1.4 Ma. The volcanic ash is highly siliceous in composition with SiO2 content varying between 72 to 78%. It is dominantly constituted of silt sized angular glass shards, and pumice fragments with sharp edges. Petrography, SEM and chemical composition of the glass shards helps in relating the ash morphology to magma composition and the type of eruption. On the basis of petrographic and morphological characters displayed by the volcanic ash, the formation of the glass shards is attributed to magmatic processes.
Calcrete and Gypsum Crusts of the Thar Desert, Rajasthan, their Geomorphic Locales and Use as Palaeoclimatic Indicators
Authors: Rakshit Prabal , Sundaram Raghavan Minakshi
Published: November 2024

Calcrete and gypsum crusts in Churu-Bikaner areas of the Thar desert, are presently found buried under a cover of aeolian sediments. Non-pedogenic and pedogenic calcrete types occur in various geomorphic locales like, channels, flood plains, pediments etc. Also, different non-pedogenic channel and lacustrine basin-fill gypsum crusts are noted. The occurrences of surface and near surface calcrete, gypsum crusts, their presence in representative sub-surface sequences of fluvio-aeolian sediments indicate climatic vicissitudes in the Late Quaternary from humid to arid and vice versa.
Point Bar Complex of an Exhumed Channel in Upland Interfluve of the Ganga Plain, India
Authors: Singh I. B. , Shukla U. K. , Srivastava P.
Published: November 2024

Facies architecture and evolutionary history of a point bar complex of exhumed channel on the upland interfluve surface of the Ganga Plain is presented. The point bar complex is made up of four distinctive sequences, each characterized by a specific lithofacies association and grain size, where successive sequence shows decrease in grain size and reduced channel width denoting reduction in the discharge of the channel. The top of each sequence represents a hiatus surface marked by dense bioturbation. The flow in the exhumed channel was towards south and southwest. At the end of the deposition of third sequence neotectonic activity caused uplift, tilting of the surface and disruption of the river channel. A facies model of such deposits is proposed.
A Note on Oxygen and Carbon Isotopes of Magnesite and Dolostone of Mesoproterozoic Gangolihat Dolomite (Formation), Pithoragarh District, Uttar Pradesh
Authors: Kumar S.
Published: November 2024

Nine samples of sparry magnesite and five samples of dolostone of the Mesoproterozoic Gangolihat Dolomite (Formation) of the Chandak area, Pithoragarh are analysed for stable isotopes of carbon and oxygen. d18O for dolostone varies from -10.8‰ to -9.0‰ (SMOW) with mean as -10.1‰ (SMOW) and for magnesite it varies from -16.8‰ to -11.8‰ (SMOW) with mean as -14.0‰ (SMOW). d13C for dolostone varies from -1.6‰ to 0.6‰ (PDB) with mean as -0.0‰ (PDB) and for magnesite it varies from -2.2‰ (PDB) to 0.1‰ (PDB) with mean as -1.0‰ (PDB). Thus, magnesite and dolostone show distinctly different isotopic signatures and hence magnesite must have formed from isotopically different fluids than those which produced dolostones. Magnesite is not syndepositionally produced but must have formed at some later stage by hydrothermal solutions.
Importance of Recharging Depleted Aquifers: State of the Art of Artificial Recharge in India
Authors: Raju K. C. B.
Published: November 2024

Though India is blessed with good rainfall, large amount of it is lost through runoff and it cannot be impounded on the surface for want of suitable sites for storage. The varied hydrogeologic conditions prevalent prevent rapid infiltration into groundwater reservoirs. 'There is thus an imbalance between recharge and groundwater development in many parts of the country. The over-extraction of groundwater resources has affected the agricultural economy and has caused serious shortage of water for drinking. It is imperative that runoff which is going waste should be harvested and utilised for recharging depleted aquifers.

Realising this many artificial recharge projects have been taken up by the Central and State Groundwater Departments. There are other agencies who have come up with methods for recharging depleted aquifers. Results obtained are impressive.
X-ray Diffraction Studies on Graphites from Dharwar Craton
Authors: Sharma S. R. , Parthasarathy G. , Kumar B.
Published: November 2024

We report here., the results of powder x-ray diffraction studies on six graphite samples from the Archaean metasedimentary rocks of Dharwar craton, with the motivation of correlating the graphitization process of carbonaceous matter during metamorphism with metamorphic grade. Our studies show that interplanar spacing d(002) and crystallinity Lc(002) for all the studied samples are very close to that of well crystallized graphite.

The observed decrease in full width at half maximum (FWHM) of the (002) diffraction peak from 0.20 to 0.102 Å. increase in crystallite size, Lc(002) from 408 to 800 Å and graphitizing degree from 86 to 362 indicate different metamorphic grades. Our results indicate that the rocks from Hampapura are of low metamorphic grade and those from Arjun Bettahalli are highly metamorphosed. The peak metamorphic temperatures of metasedimentary rocks are estimated to be around 600±50°C. The temperature estimates based on graphite crystallinity studies and the temperatures estimated by silicate mineral geothermometry studies of the coexisting mineral assemblages were found to be consistent.
Light Rare Earth Elements (LREE) in Perovskite from Kimberlites of Andhra Pradesh, India
Authors: Chalapathi Rao N. V.
Published: November 2024

Electron microprobe analyses of ground mass perovskites from kimberlites of Andhra Pradesh, India, reveal that their LREE oxide contents range from 0.88 to 1.97 wt% in case of the Mahbubnagar kimberlites and 2.57 to 5.37 wt% in the Anantapur kimberlites, with Ce being the most abundant in every case followed by Nd and La. Chondrite-nonnalized REE distribution patterns of perovskites show good correlation with the respective whole-rock REE distributions thereby displaying the dominant role played by perovskite in controlling the kimberlite REE distribution patterns. Results of this study also show that the perovskites from Indian kimberlites, compared to those in Group 11 kimberlites (Orangeites) of South Africa, have relatively impoverished LREE.