bluuebunny/crossref_metadata_2025 huggingface dataset:
Radium Content of Some River Waters of India
Authors: Chatterjee S. D. , Banerji Partha
Published: November 2024

The radium content of river waters collected from eighteen different Indian rivers has been measured. The river water can usually be classified into two categories: limpid and turbid. The radium content of limpid waters has been found to be lower (~10-16g/ml) than that of its turbid Partner (~10-15g/ml). In the latter case, the radium contents both of the filtered component and the sediment have been separately measured. The sediment invariably exhibits a higher value.
Theralite-Melteigite-Carbonatite Association in Mer Ring of Mundwara Suite, Sirohi District, Rajasthan
Authors: Chakraborti Manas K. , Bose Mihir K.
Published: November 2024

The theralite-melteigite-carbonatite association is being reported from Mundwara alkaline suite in the Sirohi district, Rajasthan. The assemblage occurs in an arcuate ring around the central plug of Mer. Theralite (composed mainly of plagioclase, pyroxene, and nepheline) and melteigite (composed mainly of pyroxene and nepheline) are feldspathoid bearing basic and ultrabasic rocks, having high colour index and are closely associated with fine to coarse grained carbonatites in the south eastern part of the ring.
Acanthoceras from the Upper Cretaceous Rocks of South India
Authors: Chiplonkar G. W. , Phansalkar V. G.
Published: November 2024

Five species of Acanthoceras Neumayr are described here of which two species are new. Aeanthoeeras rhotomagense represented by two varieties-sussexiense (Mantell) and confusum (Gueranger), and Acanthoceras sanetorum Matsumoto are being reported for the first time.
Lithostratigraphic Classification of the Blaini, Infra Krol, Krol and Tal Formations-A Review
Authors: Bhargava O. N.
Published: November 2024

The Blaini, Infra Krol, Krol and Tal Formations constitute one conformable sequence. The palaeontological data pertaining to these Formations when screened collectively form an orderly pattern which suggests that the Blaini represents an Upper Carboniferous-Lower Permian; Infra Krol, Upper Permian-Lower Triassic; Krol, Upper Triassic-Uppermost Jurassic/Lowermost Cretaceous and Tal, Lower to Upper Cretaceous/Lower Palaeocene ages respectively. In this pattern the odd one out is the Permian fauna from the 'Tal '. It is surmised that the Permian fossils are not from the Tal but in all probability from the Boulder Slate Sequence (Bijni Unit) which rests as a klippe over the Tal-Nummulitic seccession.
Trace Fossils and Environment of Deposition of the Sedimentary Succession of Jabalpur, Madhya Pradesh
Authors: Kumar S. , Tandon K. K.
Published: November 2024

Well preserved Ichnogenus Ophiomorpha Lundgren and Thalassinoides Ehrenberg are recorded from the Mottled Nodular Sandstone Member of the Lameta Formation. The Thalassinoides type burrows are also quite common in the Upper Limestone Member and Upper Sandstone Member. On the basis of the presence of trace fossils and primary sedimentary structures it is concluded that the Jabalpur Formation and Green Sandstone Member of the Lameta Formation are fluvial deposits.
Sediments of the Western Continental Shelf of India-Environmental Significance
Authors: Shankaranarayana Guptha M. V.
Published: November 2024

The degree of fragmentation and colour of the skeletal fragments, colouration in benthic foraminifers have been studied in surficial sediment samples collected from forty stations from the continental shelf region between Ratnagiri in the south and Indus canyon in the north. The abundance peaks of fragmented shells correspond to the terrace depths of -65, -75, -85 and -92 m in the outer shelf region off Ratnagiri which indicate the different phases of eustatic sea levels. It is inferred from the occurrence of abundance peaks at similar depths in the other regions of the continental shelf that they must correspond to the presence of lowered strands. The disposition of the black shells in a linear fashion parallel to the coast line at the depths mentioned above also supports the proposition.
Metamorphic History of the Sandur Schist Belt, Karnataka
Authors: Roy Abhinaba , Biswas S. K.
Published: November 2024

The Sandur schist belt is predominantly characterised by greenschist facies of regional metamorphism, which increases to amphibolite facies near the periphery of the schist belt. The higher facies rocks are marked by the appearance of metamorphic index minerals like garnet, andalusite, staurolite and cordierite. Study of the 'Si - Se' tectonites suggests that metamorphism is progressive, where chlorite and micas grow 'synkinematically' and garnet, andalusite, staurolite and cordierite grow post-kinematically with reference to first phase of folding (F1). Static growth of garnet, andalusite, staurolite etc., following the first phase of folding (F1), and their subsequent rotation with reference to second phase of folding (F2) clearly indicates a time gap between F1 and F2. Formation of assemblages of higher grade metamorphic minerals along the border region of the schist belt, is possibly due to influx of additional heat from some source (? intrusi ve granite) at a late tectonic stage.
Superposed Folding in the Lower Vindhyans of Dala-Gurma Area, Mirzapur District
Authors: Sharma R. P.
Published: November 2024

The Semri and Kaimur Series in the Son valley region have undergone two phases of deformation. The first phase structures are penetrative recumbent folds, minor puckers and kinks. The second phase structures are open folds of varying wave lengths. The deformation is a post-Kaimur event. Markundi fault seems to have existed before folding.
Crustal Structure Along Kavali-Udipi Profile in the Indian Peninsular Shield from Deep Seismic Sounding
Authors: Kaila K. L. , Roy Chowdhury K. , Reddy P. R. , Krishna V. G. , Narain Hari , Subbotin S. I. , Sollogub V. B. , Chekunov A. V. , Kharetchko G. E. , Lazarenko M. A. , Ilchenko T. V.
Published: November 2024

Deep Seismic Sounding (DSS) studies were initiated for the first time in India under a 3-year Indo-Soviet collaboration agreement starting 1972, along a 600km long roughly ENE-WSW profile which lies near 14°N latitude, extending from Kavali on the east coast of India to Udipi on the west coast.

A crustal section is depicted along the Kavali-Udipi profile, showing a large number of reflectors from about 2 km to about 50 km depth. The 600 km long section consists of 17 major blocks, besides a few smaller ones. It is cut up by 15 major deep faults and two major low angle thrusts. In addition there are 5 faults/thrusts extending to intermediate depths. The geological evolution of this part of the shield probably began in Early Proterozoic with the formation of the Dharwar geosyncline between Parnapalle and Agumbe, This was divided into two parts by the uplift of the block where Closepet granites are now exposed. The Dharwars in the eastern part are now almost completely eroded, exposing their basement. The Moho here is at an average depth of 35-36 km, going down to 38 km below Dharmavaram. In the western part, where there is a large thickness of Dharwars still present, Moho is more or less flat at a depth of 38 km, going down to 41 km below Holalkere and rising about 36 km below Chennagiri, The basement of the schist belt here varies from 4 to 7 km in depth.

The Cuddapahs must have been deposited starting near Parnapalle eastward due to en-echelon type faulting. Moho goes down from 34km below Parnapalle to 40 km below Duttaluru. The block between Maidukuru and Malepadu subsided later to create a fresh depression in which the Kurnools were deposited. In general, the basement of the Cuddapahs is at a depth of 8-10 km. The Cuddapahs, on their eastern margin, have been subjected to a major low angle thrust.
Geochemistry of Archaean Granites of the Indian Shield: A Review
Authors: Saha A. K.
Published: November 2024

Archaean granites and granite gneisses are known to occur in (a) the Iron Ore Province of Singhbhum-Orissa region in eastern India, (b) the Granite-Greenstone Belt of Karnataka and Andhra Pradesh, (c) the Granulite Belts of Tamil Nadu and Kerala and (d) the Bundelkhand-Rajasthan Precambrian province.

In the Iron Ore Province of Singhbhum region, the Older Metamorphic tonalite-gneiss (OMTG-c. 3200 Ma) has strong geochemical resemblance with the 'Ancient tonalite-gneiss' of Barberton. South Africa. The low initial 87Sr/86Sr ratios (0.7018-703) for the total-rock Rb-Sr isochrons indicate derivation of the tonalitic melt from the mantle perhaps in a two-stage process. The magmatic units of the composite batholith of Singhbhum Granite (2900-3000 Ma) show distinctive trends of fractional crystallisation for the three successive but closely related phases. Multivariate analysis of variance of the trace-element data indicates statistically significant differences among the phases while Rsmode Factor analysis suggests operation of significantly different processes of trace-element distribution in the three phases. The geochemical relationship as well as the high initial 87Sr/86Sr ratio of 0.711 ± .009 suggest that the three magmatic phases were derived by partial melting successively in the same source region of the crust. The Bahalda metasomatic unit of Singhbhum Granite shows certain abnormal trends of trace-element variations in the sequence: hornblende schist?hornblende diorite?shornblende (-epidote) granodiorite. These have been explained by assuming that during progressive granitisation, (a) ionic charge and electronegativity have been relatively ineffective and (b) certain trace-elements are preferentially incorporated in some preexisting minerals.

The Peninsular Gneiss and associated Archaean granitic bodies in the Granite Greenstone Belt of South India show wide compositional variations ranging from migmatitic and tonalitic gneiss through granodiorite to K-rich adamellite. These rocks show clusters of Rb-Sr isochrons at 3200-3300Ma, 2900-3000Ma and around 2600Ma. Enrichment of nickel and chromium in parts of these gneisses has been reported. Although a metasomatic origin of the Peninsular Gneiss has been suggested, the low initial 87Sr/86Sr ratios (0.701-0.704) do not support this view and instead indicate direct or multi-stage derivation of the granitic melt from the mantle. Occurrence of several abnormal U-Th enriched granite bodies within Peninsular Gneiss is of special interest.

The Bundelkhand Granite is a composite body of several granitic and gneissic units and appears to be dominantly adamellitic - monzonitic in composition (2555 ± 55 Ma), but has numerous xenoliths and rafts of migmatite and gneiss, mostly of granodiorite and tonalite composition.

It appears that in the Indian shield, the oldest gneisses and granites (> 3000 Ma) are dominantly tonalites while adamellitic granites become more and more abundant in the younger assemblages.
Some Studies on Hydrologic Parameters of Groundwater Recharge in Andhra Pradesh
Authors: Karanth K. R. , Srinivasa Prasad P.
Published: November 2024

Broad correlation is recognized between infiltration characteristics and basin yields. Rainfall infiltration factor has been estimated by different methods for different soil groups and topographic characteristics, as ranging from 5 per cent in predominantly hilly catchments to as much as 40 per cent in plain sandy catchments. Infiltration from applied irrigation also constitutes one of the major sources of groundwater recharge, and is found to vary from 30 per cent to over 80 per cent depending on depth of water table and soil characteristics. A linear relationship between the paddy field infiltration ratio and the logarithm of uniformity coefficient of soil is inferred from the studies. The infiltration from tanks is estimated to range from 2 to 114 mm per day.
Geochemistry of the Archaean Metavolcanic Rocks of Kolar and Hutti Gold Fields, Karnataka, India
Authors: Ananta Iyer G. V. , Vasudev V. N.
Published: November 2024

Geochemical data on Archaean goldfields metavolcanics (2.7 b. yrs) have been plotted on major and minor element discriminant diagrams to define the magma type and to formulate the tectonic environment model for the origin of these ancient volcanic rocks. The meta basalts of Kolar and Hutti (Karnataka, South India), Norseman (Eastern Goldfields, Western Australia). Steynsdorp (Barberton, South Africa) and Yellowknife (Canada), plot within the field of mid-ocean ridge basalts (MORB). The marginal basin basalts (MBB) of South Sandwich Islands of Scotia Arc Region of Phanerozoic age also plot within the field of MORB. Unlike the depleted MORB, the MBB are enriched in certain large ion lithophile (LIL) elements with higher Rb/Sr, Ba/Sr and lower K/Ba ratios. Further, in contrast to MORB, they exhibit slightly enriched LREE patterns. The LIL element enriched goldfield volcanics of Kolar, Hutti, Norseman, Steynsdorp and Yellowknife, with their slightly enriched LREE patterns, compare more favourably with MBB than with MORB. Based on geochemical features and geological setting, marginal basin model is proposed as the most favourable tectonic environment for the generation of gold bearing Archaean greenstone belts of Kolar and Hutti.
Rb-Sr Chronology of the Khetri Copper Belt, Rajasthan
Authors: Gopalan K. , Trivedi J. R. , Balasubrahmanyan M. N. , Ray S. K. , Anjaneya Sastry C.
Published: November 2024

Rubidium and strontium determinations are reported for the Udaipur and Saladipura granites from the Khetri copper belt. The whole-rock data define a Rb-Sr isochron corresponding to an age of 1480 ± 40 m.y. and initial Sr ratio of 0.7131 ± 0.006. This age is older than previously believed, but consistent with the generally high age of post-Delhi intrusive rocks so far dated in the region. Biotites associated with these rocks give younger ages around 700 m.y, This indicates mobilisation of Sr isotopes in a later metamorphic event. It is significant that this secondary event is almost synchronous with the intrusion of granites to the west and south of the Aravalli mountains.
A New Stegosaurian Dinosaur from Upper Cretaceous Sediments of South India
Authors: Yadagiri P. , Ayyasami K.
Published: November 2024

The paper records the occurrence of a stegosaurian dinosaur with partial skull, tooth, sacrum, pelvic elements, armour plates and spike, from the marine Cretaceous rocks' of the Trichinopoly Group, Tamil Nadu. The bed yielding the dinosaurian fossils is assigned Coniacian age on the basis of rich ammonoid fauna which includes Kossmaticeras theobaldianum. The dinosaur is described as a new genus and species Dravidosaurus blanfordi. The stratigraphic and palaeontological significance of this report in indicating the survival of armoured dinosaurs till the close' of Mesozoic in the southern part of India is discussed.
Quantification of Foraminiferal Biofacies and Reconstruction of Palaeobiogeo-Graphy of the Cauvery Basin
Authors: Banerji Ranjit K. , Sastri V. V.
Published: November 2024

The paper deals with broad principles of quantified foraminiferal palaeoecology involved and their application in reconstructing the palaeoenvironments for different stratigraphic units (Upper Jurassic-Lower Palaeogene in age) exposed in the western part of the Cauvery Basin. The parameters used are the functions of structurally related characteristics and morphogenetic diversities of the foraminiferal fauna which are resultant of the environmental requirements, tolerance and preferences. The first sedimentary cycle started with fresh water deposits which soon gave way to brackish water and later continued under dominantly marine influence. The major transgressive phases during Neocomian-Albian, Senonian and Paleocene are better reflected in the quantitative bio-facies analysis. Along certain palaeomarginal highs, the environment favoured reef development where terrigenous influx was minimum. The strand-line progressively shifted since Lower Cretaceous times from west to east. The shift during Lower-Middle Eocene was more prominent and a delta front progressively started building with regression in the region bordering the western margin. The resultant sediments now cover a greater part of the exposed area and form the youngest exposed stratigraphic unit of this Basin.
Upward Regressing Energy Sequences in a Limestone Section from the French Jura
Authors: Dahanayake Kapila
Published: November 2024

Textural and compositional studies of a limestone section from the Upper Jurassic of the French Jura Mountains reveal a series of sequences of lithofacies, each sequence marking a progressive reduction of water turbulence (energy). The Limestones are oolitic, pelletiferous and oncolitic packstones, wackestones and mudstones.
Palaeobiology and Organic Geochemistry of Archean Helen Iron formation, Michipicoten Area
Authors: Karkhanis Suresh N. , Goodwin A. M. , Ponnamperuma Cyril
Published: November 2024

Diamond Drill Core (D. D. H. U-2-647) samples of approximately 2.75 b.y. old Helen Iron Formation of Michipicoten area in the Superior Province of the Canadian Shield have been examined for morphological and molecular fossils. Evidence shows two types of bioforms - simple micron-sized filamentous microstructures resembling present day iron bacteria and laminated structures designated as cryptalgal mats.

Organic geochemical studies have shown that a variety of organic compounds is present. These include n alkanes, isoprenoid hydrocarbons pristane and phytane and fatty acids. The exact syngenetic nature of these compounds will be evaluated in the future by appropriate control experiments such as permeability measurements, diffusion studies, etc.

Presence of pristane and phytane is indicative of high photosynthetic activity. Predominance of n-C16 (palmitic) acid is significant in view of it being the major constituent of the cell membrane of an organism.

The morphological and molecular evidence and previously reported carbon and sulphur isotope data further substantiate the existence of autotrophic organisms and reducing bacteria in Archean times and they were operative during accumulation of these ancient Precambrian chemical sediments.
Textural Analysis of Red Sediments from Visakhapatnam District, Andhra Pradesh
Authors: Raman C. V. , Rao A. T.
Published: November 2024

The red sediments of Recent age confined to the slopes of hill ranges and along the coast of Visakhapatnam and Bhimunipatnam are classified into inland and coastal red sediments. The textural analysis reveals that the inland red sediments are poorly sorted with negative skewness, and the coastal red sediments are better sorted and positively skewed. Beach samples are well sorted Showing both positive and negative skewness. In the light of skewness patterns it is concluded that the coastal red sediments were laid down in a depositional environment, whereas inland red sediments belong to an erosional or non-depositional environment and further that these clastic red sediments are immature and have formed under a fluvial environment.
On Olivines and Pyroxenes of Amjori Sill, Similipal Complex, Mayurbhanj, Orissa
Authors: Chennakesavulu N. , Sahu K. C.
Published: November 2024

Olivine is found to have a short range of composition. Orthopyroxenes take up a significant amount of wollastonite molecule in the later stage. Clinopyroxenes show a large scatter in the endiopside-augite field. Fractionation of Fe and Mg among the minerals characterises crystallization from a slowly cooled layered intrusive. The trend of crystallization, of all the three minerals conform to a tholeiitic parentage.
Basement Slices within the Cover Sediments Near Hakegora and Jaikan, South of Tatanagar, Singhbhum District, Bihar
Authors: Mukhopadhyay Dhruba , Dasgupta Sabyasachi , Dhar Kunal
Published: November 2024

A sequence of metasediments with conglomerate at the base, unconformably overlies the Singhbhurn Granite. The direction of younging in the arkose-conglomerate is towards north, away from the granite border. Wedges of basement granite were emplaced as thrust slices within the metasediments at the earliest stage of deformation. The soda granite also occurs as a sheet like concordant body and is highly deformed and in places rnylonitized. The soda granite may also represent a tectonically emplaced slice of the basement.
Alkaline Magmatism in the Deccan Volcanic Province
Authors: Bose Mihir K.
Published: November 2024

Alkaline magmatism in the Deccan volcanic province is characterised by i) relative spatial restriction, being manifested in the western and northwestern parts of the province, ii) development of alkaline rock assemblages in plug like bodies and hypabyssal minor intrusions, iii) alignment of magmatic activities along three (or four) volcanotectonic belts meeting near the gulf of Cambay, iv) pronounced fractional crystallisation of parent alkali basaltic magma often leading to wide spectrum of rock composition and v) relative rarity of effusive alkaline rocks.

The ultimate derivative of fractionating alkaline basic magma is usually a hypersolvus foid syenite. Alkaline ultrabasic rocks (melteigite-ijolite) in association with carbonatites are developed in a few plugs. Alkaline minor intrusions of wide compositional variation, are largely associated with subvolcanic plugs and a few volcano tectonic belts. In comparison, effusive alkaline rocks are rare in the province. Manifestation of alkaline lavas together with picritic basalts and spilite in western India reflect unique structural setting of this terrain.

Available petrological, geomorphological and geophysical data all point to a plume activity in the present Cambay region and this appears to be the major controlling mechanism for alkaline magmatism.
Inverted Metamorphism in the Sikkim-Darjeellng, Himalaya, India
Authors: Banerji P. K. , Guha P. K. , Dhiman L. C.
Published: November 2024

Inverted metamorphic sequences from chlorite zone phyllites grading progressively upwards into staurolitc/kyanite zone schists and gneisses with associated granitic bodies occur intermittently in the Lower Himalaya from Kumaon to Sikkim. In Sikkim-Darjeeling area, this progressive metamorphism is broadly late-kinematic with respect to the polyphase fabric elements in the metasedimentaries and is broadly coeval with the emplacement of metasomatic/anatectic granitic masses, which occur as low to moderately dipping sheets within both greenschist and amphibolite facies metasediments and carry I-type enclaves. Locally, strong, gravity induced polarity has concentrated metasomatic transformations along the hanging wall sections of the granite.

This 'inverted' metamorphism, as well as positive gravity anomaly gradients and shallow focus seismicity in this sector, are correlative with differential vertical displacements, which have exposed the naturally inverted metamorphic sequences along footwall sections of moderately dipping intrusive masses. LANDSAT and air photo interpretations of various types of linears and lineaments with supporting indications from the location of hot springs, lakes, water falls, abrupt changes in river gradient, truncation of marker bands and erraticity in terrace distribution, suggest that the area has been witnessing differential uplift along a number of regional and local sub-vertical fault surfaces including a number of geofaults, some of which are transverse to the axis of the range in a crypto-aulacogen style. This tectonic regime appears to be an integral part of postorogenic processes in Sikkim-Kumaon Himalaya possibly extending eastwards up to Arunachal Pradesh.
Diagenetic Features in Sulphides of Dariba-Rajpura Deposit, Udaipur District, Rajasthan
Authors: Pandya M. K. , Solanki S. L. , Pandya T. K.
Published: November 2024

Mineralisation is mainly confined to kyanite-graphite-quartz-mica schist, meta chert (chert and its recrystallised form) at places interbanded with quartzite, calc silicate rock, and impure marble. Sulphide ores reveal a variety of diagenetic structures: diagenetic dykes, diagenetic fracture filling, stylolite seams in sulphide-cherty rock and cementation of silicate minerals by sulphide grains.
Uranium Mineralisation in Sikar District, Rajasthan
Authors: Narayan Das G. R. , Sharma D. K. , Singh Govind , Singh Rajendra
Published: November 2024

Uranium mineralisation of segregated type consisting mostly of uraninite and less commonly of brannerite has been noted in the pink quartzo-feldspathic or aplitic emplacements along shear zones in Rohil-Ghateshwar-Khandela-Diara and Saladipura area in Sikar district of Rajasthan. Ilmenite, molybdenite, pyrrhotite, chalcopyrite and pyrite are noted along with uraninite.

Mineralisation is controlled by structure and generally occurs along linear shears that are parallel to the main tectonic lineament. In Ghateshwar area, the mineralised quartzo-feldspathic emplacements have undergone refolding along with the rest of the formations. Uranium mineralisation is near to the main tectonic lineament that passes through the axis of the Ajabgarh synclinorium. Integrated radiometric and hydrogeochemical surveys have indicated continuity of the uranium bearing quartzo-feldspatbic emplacements along a 16 km belt.

The Salwari fluorite occurrence 10 km NE of Khandela is a post feldspathic emplacement and probably formed during the final phases of mineralisation.
Pebble Strain Analysis in the Raghunathpalli Conglomerate of Gangpur Group, Orissa, India
Authors: Chaudhuri A. K. , Pal A. B.
Published: November 2024

Shape analysis of a large number of pebbles from a 60 km stretch of the basal Raghunathpalli conglomerate in the Gangpur Group in eastern India, indicates that a flattening strain on originally constricted pebbles during the earliest folding episode gave rise to the present shape of the pebbles. The longest and the intermediate axes of pebbles lie invariably on the schistosity developed parallel to the axial planes of the earliest isoclinal folds. Though the Gangpur Group shows a remarkable multideformation plan, the pebbles show mainly the effects of the earliest deformation.
Depositional Environments of the Binge Bay Near Karwar, West Coast of India
Authors: Kumar Surendar
Published: November 2024

A large part of the area of the Binge Bay is floored by well sorted, medium to fine sand. The mean size of the sediments generally decreases with increasing depth and distance from the land. Variation in skewness from the Anjidiv Island to the middle of the Bay can be related to the mixing of two or more grain size populations in various proportions. An overall decrease in the weight per cent of total heavy mineral contents also is observed from the beach to the middle of the Bay. Fine muddy sediments are found in the regions of the main bathymetric low. Such variations occur as a result of decrease in velocity of the transporting tidal currents. The sign of the skewness is sensitive to the environment.
Experimental Water/Rock Interaction Studies on Thermal Waters of the West Coast of Maharashtra, India
Authors: Muthuraman K. , Mathur P. K.
Published: November 2024

The major element chemistry of the thermal waters along the west coast of Maharashtra State, India, vis-a-vis volcanic thermal waters is discussed. The conventional geothermometry used for evaluating the deep temperatures from the chemistry of surface manifestations is found to be not reliable for these waters. This is thought to be due to the basic nature of the country rocks, which may form the deep reservoirs for these thermal waters. In order to verify this, hydrothermal experiments with a basic tuff and rhyolite under identical P-T conditions were conducted. These experiments yielded different chemical solutions. The results of the present experiments as well as those carried out elsewhere in the world, indicate that the chemistry of the west coast thermal waters cannot be explained by normal shallow water/rock interactions alone. Some seawater admixture appears to be probable in these thermal waters before interactions took place at elevated temperature.
Petrological and Structural Studies of the Manganiferous Horizons and Recrystallised Ultramafics around Gundlupet, Karnataka
Authors: Janardhan A. S. , Shadakshara Swamy N. , Ravindra Kumar G. R.
Published: November 2024

Petrography and chemistry of hitherto unreported manganiferous horizons and associated recrystallised ultramafics (sagvandites) - key horizons in the Precambrian high grade terrain around Gundlupet are discussed. The occurrence of spessartine-rich garnets from an area of dominant upper amphibolite grade of metamorphism suggests that bulk chemistry was the most important controlling factor. In their mineralogy, and decrease of MnO% in garnets during subsequent migmatisation, the manganiferous horizons exhibit remarkable similarity to the khondalites of the Eastern Ghats. The sagvandites and the other lithologies, occurring now, as huge enclaves in the granite/gneissic terrain are similar to the Sargur Supracrustals.

Structural studies show that the area has suffered from three deformational episodes. The early N-S episode of the Sargurs are rotated to N 60° E and then to E-W. The dominant N 60° E episode is possibly connected with large scale granite emplacementfmigmatisation and the E-W shears are due to the prominent Moyar-Bhavani shear.
Gudmundite from Base Metal Sulphide Deposit of Askot, Pithoragarh District, (U. P.)
Authors: Seetharam R.
Published: November 2024

Gudmundite occurs as a common mineral constituent in the polymetallic ores of Askot. Three distinct modes of formation of gudmundite have been observed: (a) as a product of decomposition of tetrahedrite, (b) as a substitution product in cubanite and (c) as a reaction rim around breithauptite. The breakdown of tetrahedrite to chalcopyrite-gudmundite intergrowth signifies the retrograde metamorphism of this high temperature ore body. The eutectoid intergrowth between cubanite and gudmundite has resulted from a late stage hypogene replacement by addition of antimony.
Heavy Mineral Assemblage of the Siwalik Group of Nepal Himalaya
Authors: Chaudhri R. S. , Gill G. T. S.
Published: November 2024

The heavy mineral assemblage of the Siwalik Group of Nepal Himalaya comprises non-opaque minerals like zircon, tourmaline, rutile, garnet, epidote (including zoisite and clinozoisite), staurolite, kyanile and sillimanite. The opaque minerals include ilmenite, magnetite, hematite and limonite. Staurolite serves as the marker mineral for the Lower Siwalik Formation, kyanite for the Middle Siwalik Formation and sillimanite for the Upper Siwalik Formation.

The over all heavy mineral assemblage and the mineralogical and textural properties of the various mineral species are suggestive of the derivation of a major part of the Siwalik sediments from metamorphic, acid and intermediate crystalline rocks.
Structure of the Western Termination of the Bhavani Lineament
Authors: Nair P. K. R. , Prasannakumar V. , Mathai Thomas
Published: November 2024

On the basis of structural investigations in an area of over 150 sq. km forming the western termination of the Bhavani lineament, the validity of the simple shear strain model adopted by Katz to explain movements along the lineament is examined. The model explains satisfactorily the formation of the first two of the three generation of folds recognised as well as the associated foliation and mineral lineation whereas it cannot be applied in the case of the last generation of folds.
Age Data on Pegmatites Of South Kerala and their Tectonic Significance
Authors: Soman K. , Nair N. G. K. , Golubyev V. N. , Arakelyan M. M.
Published: November 2024

K/Ar mica age of chrysoberyl-bearing pegmatites from four localities of Trivandrum district, Kerala ranges from 445 to 474 m.y., with a mean around 460 m.y. There is a close agreement between the ages of the concordant and cross-cutting pegmatites, between muscovite and biotite ages, as also between various size fractions. Chrysoberyl occurs within feldspars in association with quartz and muscovite. Since the formation of chrysoberyl-quartz association requires a higher pressure or temperature, the reported age would indicate the time of emplacement of the chrysoberyl-bearing pegmatites at the closing phase of a major tectonomagmatic event. It is interesting to note that these pegmatites of south-western India are younger compared to those of other localities viz., Rajasthan, Bihar. Nellore and Mysore.
Chromian Edenite from the Sinduvalli Ultramafic Body Karnataka, South India
Authors: Srikantappa C. , Friend C. R. L.
Published: November 2024

The occurrence of chromian edenite, confined to the degraded chromitite layers of the Sinduvalli ultramafic body is reported. Field, petrographic and chemical studies suggest that its development has occurred during the prograde metamorphism of the layered body. The enrichment of silicate phases in chrome-amphibole and chloritesis attributed to re-equilibration of chromite during the metamorphic episodes affecting the area and the formation of 'ferritchromit'.
Further Evidence of Biogenic Nature of Dodguni Microbiota, Dharwar Craton, India
Authors: Suresh R.
Published: November 2024

Evidence of life from Dharwar greenstone belts has been reported by previous workers. Biologic origin of these forms, however, has been doubted. Filamentous bodies described from the Dodguni cherts have been considered to be mineralogic artifacts, The present study adduces fresh evidences gathered from examination of thin sections under scanning electron microscope, microchemical tests, and organic geochemical studies, in support of biogenic origin of these microfossils.
Sedimentology of the Kakarhatti Limestone, Simla Hills (H.P.)
Authors: Bagati T. N.
Published: November 2024

Three major microfacies viz., micrite, sandy micrite and sparite recognised recur at various stratigraphic levels. Illite and chlorite are the only clay minerals present. By analogy with recent carbonates, the carbonate microfacies of the Kakarhatti limestone indicates deposition in shallow marine conditions, oscillating between supratidal and intertidal. The main diagenetic features observed are reduction in porosity, silicification, pressure solution and recrystallization.
Mode of Occurrence and Origin of Magnesite Deposits in Parts of Mysore District, Karnataka
Authors: Venkataramana P.
Published: November 2024

Magnesite occurs as a network of veins and bands within serpentinised peridotite and cap-rock (birbirite). Three stages by which the original peridotite is altered to give rise to magnesite and birbirite are recognised. Geochemical studies indicate that by the action of weakly acidic (with dissolved CO2) water vapour, the original ferromagnesian minerals in peridotite broke down releasing Mg2+ and to a minor extent Si4+ to be precipitated as magnesite and quartz in favourable locales. Ca2+, Al and Fe2+ were retained in the silicate matrix. Al and Fe2+ precipitated as hydroxides while Ca2+ formed CaCO3(calcite and aragonite).

The approximate P-T conditions at which magnesite crystallised is suggested to be between 500 to 1000 bars and 150 to 250°C respectively with XCO2 in the fluid phase around 0.05. Magnesite formation is related to late-stage hydrothermal activity associated with ultramafic-mafic magmatism in the area.
The Effects of Transportation on Roundness and Shape of River Tamar Sands, S. W. England
Authors: Samad Abdus
Published: November 2024

The study on roundness and shape of the sand grains shows that both roundness and sphericity decrease as the grain size decreases. The sand sizes (0.5-0.063 mm) studied show no evidence of becoming rounded as a result of attrition during transportation. The study also reveals that a downstream decrease in sphericity values is mostly the result of a decrease in roundness produced mainly by progressive downstream decrease in the mean size of sediments (size sorting), rather than to sorting on the basis of shape.
Rb-Sr and Pb-Pb Whole Rock Isochron Ages of Basement Gneisses in Karnataka Craton
Authors: Ramakrishnan M. , Moorbath S. , Taylor P. N. , Anantha Iyer G. V. , Viswanatha M. N.
Published: November 2024

Rb-Sr and Pb-Pb whole rock isotopic systematics and petrochemical data for two suites of Peninsular Gneiss immediately underlying the first order regional unconformity at the base of the main greenstone successions of Dharwar Supergroup in Bababudan and Chitradurga belts are presented.

The Chikmagalur granite (s.l.) and associated migmatite gneisses (CMG suite) underlying the Bababudan greenstones define an eleven point Rb-Sr isochron of 3080 ± 80 m.y. (MSWD4.5) with an initial 87Sr/8686 isotope ratio (I.R.) of 0.7016 ± 0004. Pb isotope data for the same samples yield a 3185 ± 60 m.y. isochron (MSWO 7.0) with single stage 238U/204Pb (μ1) ratio of 7.99. The crust-forming event in this area spans a range of 3000-3200 m.y. within the analytical error of the isochrons. The mantle-type I.R. and μ1 values preclude interaction with or reworking of earlier continental crust in their genesis. Petrological and chemical studies of the CMG suite show that the Chikmagalur 'granite' is a biotite granodiorite and the intruded gneisses are low alumina trondjhemites having a calc-alkaline trend. It is significant that the CMG suite is located within a low strain zone in Central Karnataka.

The gneisses and granitoids close to the western margin of the Chitradurga belt (CDG Suite) give a Rb-Sr age of 2970 ± 100 m.y. (MSWD 11) with I.R. of 0.7035 ± 0.0013. The corresponding Pb-Pb isochron defines a date of 3044 ± 150 m.y. with μ1 = 7.69. The μ1 and I.R. values suggest the possible involvement of previous sialic crust in their generation during the gneiss-forming event around 3000 m.y. ago. The CDG suite is heterogeneous, but all its components are regarded as a part of the Peninsular Gneiss. The composition of the CDG suite has a wide range from tonalite to granite, with a typical calcalkaline granitic trend.

Recent intensive geochronological studies in central Karnataka suggest a widespread crust-forming event around 3000 m.y. together with older gneissic components of Ca 3300 m.y. The present data bridge the time gap between 3000 and 3300 m.y. suggesting that continental crust was being generated in Karnataka craton from 3300 to 3000 m.y. semi-continuously. The unambiguous field relations in central Karnataka suggest that this event occurred prior to the deposition of main greenstone piles of Dharwar Supergroup.
Magnetic Polarity Stratigraphy of the Upper Siwalik Subgroup, East of Chandigarh, Punjab Sub-Himalaya, India
Authors: Tandon S. K. , Kumar Rohtash , Koyama M. , Niitsuma N.
Published: November 2024

An approximately 900m thick succession of pre-Pinjor (Tatrot) and Pinjor beds of the Upper Siwalik Subgroup is exposed in the Khetpurali section which lies to the east of Chandigarh. Samples collected from the mudstone interval from forty-nine fluvial cyclic units exhibit a stable detrital remanent magnetisation. The study of magnetic polarity of these samples reveals the presence of six normal and six reverse magnetozones. The Tatrot-Pinjor faunal boundary has been interpreted to approximately lie at the Gauss-Matuyama boundary. Based on this interpretation, the Olduvai Event in Matuyama reversed polarity epoch spans 160m of the middle part of the Pinjor Formation. The local Pliocene/Pleistocene boundary in this section is interpreted to lie 170m higher in the sequence with reference to the Tatrot-Pinjor faunal boundary.

Changes in the fluvial domain in the post-Gauss Epoch are interpreted to reflect changes from 'meander belt' deposits to 'braided stream' deposits. The first appearance of conglomerates in the section has been interpreted to occur in the post-Olduvai time.
Genetic features of Gold Ore Deposit at Kolar, Dharwar Craton, India
Authors: Safonov Yu. G. , Genkin A. D. , Vasudev V. N. , Krishna Rao B. , Anantha Iyer G. V.
Published: November 2024

Twenty-five ore minerals have been identified from a study of ore-bearing samples from different reefs of the Kolar Goldfields. The mineral association includes fifteen minerals being reported for the first time: altaite, hessite hedleyite, tzumoite, volynskyite gudmundite, ullmannite, brethauptite, tetrahedrite, hawleyite, cotunite, electrum and native bismuth. Besides, two new minerals, as yet unnamed, have been determined through electronprobe - Pb3Te9Cl4S2 and PbTeCI2 They occur along with cotunite (PbCI2) and altaite.

The study of time relations of different ore and vein mineral assemblages in the Kolar gold-quartz reefs has revealed six stages of mineralization: 1) Early quartz, 2) quartz-feldspar (Pegmatite), 3) scheelite, 4) early sulphides with gold, 5) sulphide-gold-tellurides (with quartz) and 6) quartz-carbonate. Fluid inclusions indicate that the mineral association of quartz-feldspar stage has developed under high TP-conditions of 250-300°C and 1.8 and 3.5 kb. Isotope composition of sulphur in the sulphides indicate the juvenile nature of sulphur. Available data suggest that the quartz of first stage is of metasomatic origin, derived possibly from host amphibolites; gold-sulphide and gold-telluride mineralization took place through hydrothermal processes.
On the Anatectic Migmatites of Panchet Dam Area, Bihar
Authors: Pareek H. S.
Published: November 2024

Petrological and geochemical studies on a representative set of specimens of the basement gneissic rocks of Panchet dam area, district Dhanbad, Bihar, and district Purulia, West Bengal, have indicated that these rocks are derived from an anatectic migmatitic suite of granitic composition, formed at a possible temperature range ca 650°-700° C under 5 Kb. PH20.
Lithomarges from Goa - A Study Based on Infrared Spectroscopy and Differential Thermal Analysis
Authors: Dessai A. G.
Published: November 2024

The DTA and IR studies of the lithomarges (saprolites) from Goa have shown that they are predominantly made up of kaolinite, chlorite group minerals, goethite and quartz, with minor amounts of gibbsite and talc.

The lithomarges have resulted from weathering of rocks of varying lithologies under subtropical climatic conditions. Depending upon the microenvironments different alteration products may be derived from the same starting material. Absolute and relative accumulation of iron gives rise to the ferricretes while relative enrichment of aluminium as silicates leads to the formation of lithomarges at depth.
American Research in the Geochemical Modeling of Groundwater
Authors: Runnells Donald D.
Published: November 2024

The advent of digital computers has allowed the development of sophisticated geochemical models for describing and predicting the chemical behavior of complex natural waters. More than 50 such models have been developed and published in the North American literature. Much of the impetus for the development of geochemical computer models comes from the need to protect the chemical quality of groundwater, and from a search for safe methods of geologic disposal of nuclear wastes.

The geochemical computer codes can be broken down into three main categories, in order of increasing complexity: (1) equilibrium codes, (2) mass-transfer codes, and (3) mass-transport codes.

Much research still remains to be done in this area. Additional effort must be devoted to the complication and critical evaluation of the thermodynamic data which form the basis of all geochemical models, as well as to the determination of the kinetics of heterogeneous and homogeneous relations. A critical need exists for the investigation of the behavior of natural and synthetic organics in aqueous systems. Fundamental research must also continue on improving the mathematical and computational aspects of the increasingly complex models.
Spatial Analysis of Hydrogeological Subsystems
Authors: Seyhan E. , Nienhuis P. R. , Simmers I.
Published: November 2024

Regionalization based on multivariate statistical analyses of hydrochemical data proved successful in differentiating distinct groups of groundwater types and hence of varying hydrogeological origins within the Sasso Lungo dolomitic mountain stock, Northern Italy, and the Luz de Tavira area, Portugal.

Further studies have now indicated that universal kriging, cokriging and block kriging are not always suited for delineation and classification of groundwater systems, since the basic assumption that subsystems are internally homogeneous does not comply with reality. The shallow groundwater level which is mainly controlled by gravity drainage in Luz de Tavira area yielded satisfactory results using universal kriging technique. But the kriged maps of EC of either the Sasso Lungo (because of multi-layer aquifer system) or the Luz de Tavira (because of more than one controlling factor) were not error free. Therefore, for interpolation to unknown localities one cannot rely on kriging; additional information concerning the groundwater subsystems under study is needed.
Coastal Geomorphology and Beach Erosion and Accretion in the Northern Kerala Coast
Authors: Suchindan G. K. , Samsuddin M. , Thrivikramji K. P.
Published: November 2024

The coastal Zone of Kerala is characterised by typical broad strand plains and cliffed shoreline with or without a beach. A facsimile of such coastal settings have been identified between Mahe and Talapadi in northern Kerala. The strand plain consists of a series of sub parallel ridges formed by successive accretion of low narrow beach ridges parallel to the shoreline. The erosional and accretional behaviour of the beaches were monitored during a programme of field observation and survey during November 1980 to November 1981. In addition to the beach profiling at 64 survey locations, the breaker parameters and longshore currents were also monitored. It is estimated that 96.84m3/ linear meter of the beach has been eroded during the survey period.
Morphology of Sagar Island, A Part of Ganga Delta
Authors: Paul Ashis Kumar , Bandyopadhyay M. K.
Published: November 2024

The deltaic morphology of Sagar island is controlled by the river Hugli to the north and the Bay of Bengal to the south. The seasonal (summer and winter) and diurnal (two high tides and two low tides) fluctuations of sea level and the Hugli discharge with a large amount of silt contribute to the formation of the largest island in Ganga delta. Deposition of sand, silt, clay and mud from south to north is also characteristic of this deltaic island. The 12 km shoreline and its sand ridges are deformed by wind and waves. Mangroves in the swamp, some halophytic plants on the sand dunes and different marine organisms on the sea beaches and mud flats are responsible for the development of some micro-morphological features in this westernmost island of Sundarban. At present the nature of human settlement, reclamation of low land, indiscriminate resource utilisation and finally the mangrove destruction cause deterioration of the deltaic environment. Land erosion is severe in south, east and west of the island. The deposition in old creeks such as Phuldubi, Ganga Sagar etc. and the predominance of new creeks in the southwest of the island are the result of tidal scouring and deposition.