bluuebunny/crossref_metadata_2025 huggingface dataset:
Stylolitic Origin of Chrysotile Asbestos Near Pulivendla, Cuddapah District, Andhra Pradesh
Authors: Ramam P. K. , Ananta Iyer G. V. , Narayanan Kutty T. R. , Murthy M. V. N.
Published: November 2024

The field observation that chrysotile asbestos near Pulivendla is localised along stylolites in the Proterozoic carbonate sediments of the Vempalli Formation (Cuddapah Supergroup) proved crucial and paved the way for a re-thinking on the origin of Pulivendla asbestos. The length of the fibre, nowhere, transgresses the amplitude of the stylolite. Further, the lateral termination of the chrysotile seams invariably coincides with that of the enclosing stylolite. The stylolite development and fibre growth appear to be a sequel to directional pressure. X-ray and infra-red studies of the massive serpentinous zones revealed dioctahedral dewelyite to be the main serpentine mineral. It is suggested that the chemical pre-requisites (e.g. magnesia, silica and hydroxyl molecules) necessary for serpentinisation and pari passu chrysotilisation, were present in the carbonate sediment itself at the loci of stylolitisation and that the intrusive dolerite merely provided the desired thermal energy. The emplacement took place, possibly, when the carbonate sediment was in a semi-consolidated stage. Stylolitisation and chrysotilisation appear to have ceased with the complete consolidation of the enclosing sediment.
U-Pb Isotopic Ages of Uraninites from Kulu, Himachal Pradesh and Berinag, Uttar Pradesh
Authors: Bhalla N. S. , Gupta J. N.
Published: November 2024

U-Pb Isotopic ages of a eight uranmites, occurring as veins and disseminations in quartzite in Kulu district of Himachal Pradesh and Berinag (Pithoragarh district) of Uttar Pradesh are reported. The ages are discordant and show the general pattern (207Pb/206Pb) age > (207Pb/235U) age > (206Pb/238U) age. An attempt has been made to find a convergent age related perhaps to the actual time of mineralizanon and to explain the discordancy in terms of episodic loss of lead/gain of uranium, Uraninites occurring as disseminations in quartzite in Kulu are estimated to have been formed at 1232±120 my., whereas those occuring as veins and fracture fillings appear to be younger Both the mineralizations show the effect of a recent episodic event (55 my.).
Gravity Surveys for Barytes Around Mangampeta, Cuddapah District, Andhra Pradesh
Authors: Bose R. N. , Vaidyanathan N. C.
Published: November 2024

The barytes deposit of Mangampeta (14°01'15" : 79°19'15") may now be classed as the largest single barytes deposit in the world. Though the occurrence of barytes in Mangampeta was known since mid-sixties, a multi-disciplinary approach including gravity surveys carried out during 1971-73 revealed the immense potentialities of the deposit. Exploratory drilling at the recommended points over the gravity' high' struck thick zones of barytes. As many as 61 boreholes have so far been drilled over the main gravity: anomaly zone, of which 53 intersected barytes ranging in thickness from 5 to 44 metres, indicating a reserve of about 60 million tonnes.
Observations on the Geomorphology of Goa
Authors: Sriram K. , Prasad K. N.
Published: November 2024

The area studied represents the coastal tract along the West Coast of Peninsular India. Remnants of planar surfaces showing deep lateritic weathering profiles are common in the northern part of Goa. The southern part, however, presents a rugged topography with hills ranging in altitude up to 600 m, especially near the coast. It is surmised that the present coast emerged during late Neogene and presumably before the onset of Pleistocene glaciation. Remnants of the emerged marine denudational surfaces are noticed at altitudes of 160m, inland near the ghats and at 60m along the coast. In general, most of the remnants are at 120 m above the present mean sea level. From the accordance of summit heights of hills and inselbergs rising above the remnants of planar surfaces, trace of the older erosional surface appears at 300 m above the mean sea level. This surface may be assigned to Mio-Pliocene. The remnants of the late Pliocene planar surface is marked by valley benches and terraces that are probably the result of oscillations of the sea level during Pleistocene. It is difficult to assess their specific relationship with the interglacials of the Quaternary period.
The Gariadih Rapakivi Granite of the Bihar Mica Belt Hazaribagh District, Bihar
Authors: Bhattacharya Udaybhanu
Published: November 2024

The rapakivi granite forms a large dyke-like body within a group of amphibolite facies Precambrian metamorphites and gneissose granite. The essential mineral constituents are orthoclase, microcline, plagioclase, quartz, biotite, hornblende (ferrohastingsite) and accessory minerals apatite and xenotime. Emplacement of a fresh surge of K-rich magma towards the closing stage of crystallisation of the gneissose granite body gave rise to the rapakivi granite.
Depositional History of Permo-Carboniferous Tillites and Associated Sediments in W. Bokaro Gondwana Basin, Bihar, India
Authors: Das S. N. , Sen D. P.
Published: November 2024

The Talchir Group of rocks in India form a very important stratigraphic horizon by their presence at the base of all the Gondwana basins. Talchirs have been recognised as glacial sediments. The present study suggests that the Talchir Group was deposited both as stratified drift and unstratified drift. The glaciers responsible for Talchir sedimentation in eastern India belong to piedmont glacier system. The number of times the glacial lobes advanced into different basins varies from basin to basin. In all the basins the bulk of the sediments was deposited during first deglaciation period as meltwater channel, esker, glaciolacustrine delta and lake deposits. The topography surrounding the basin during upper Talchir time provided infra-structure for Barakar sedimentation.
Mesozoic Sedimentary Model of Wagad Hills, Kutch, Western India
Authors: Deshpande S. V. , Merh S. S.
Published: November 2024

Wagad Hills in the eastern part of Kutch, Western India, mainly comprise of rocks ranging in age from middle Jurassic to lower Cretaceous encircled by a thin and narrow fringe of Tertiary sediments.

A sedimentary model of Wagad Hills is proposed comprising environments of deposition, basin geometry, lithic fill, lithic arrangement, directional structures and tectonic setting. The area experienced a prograding delta system with a gradual shift of strand line from east to west during the course of deposition.
Recent Foraminifera from the Pennar Estuary, Andhra Pradesh
Authors: Reddy K. R. , Jagadiswara Rao R.
Published: November 2024

45 foraminiferal species belonging to the suborders Textulariina, Miliolina and Rotaliina, identified from 180 bottom sediment samples from the Pennar estuary in the east coast of India are reported and illustrated.
Geochemistry of Spinifex-Textured Peridotitic Komatiites from Ghatti Hosahalli, Karnataka, Indi
Authors: Narayana B. L. , Naqvi S. M.
Published: November 2024

Spinifex-textured peridotitic komatiites (STPK) of Ghatti Hosahalli have low CaO/Al2O3 ratio (< 1), low TiO2, K2O and high MgO. These STPK have comparable Ni and Co contents with those of the Australian and Canadian shields. These characters support the view that the spinifex-texture observed in these rocks is primary and not the result of later metamorphism. The Al2O3/TiO2 ratios are comparable to those of Chondrites indicating that the STPK are products of partial melting of the Archaean mantle. The STPK of Ghatti Hosahalli arc overlain by exhalative chemical precipitates and argillaceous metamorphosed sediments like bedded-barytes, fuchsite-quartzites and kyanite-mica schists. It is suggested that Ghatti Hosahalli band is a relic of an early Archaean greenstone belt.
Some Observanons on the Sedimentology of the Krol Succession of Mussoorie Area, Uttar Pradesh
Authors: Singh Indra Bir , Bhargava Ajai Kumar , Rai Vikram
Published: November 2024

Study of sedimentary structures indicate that Krol succession of Mussoorie area represents deposits of a shallow tidal sea: Krol A-deposits of open sea tidal flats in intertidal-subtidal zone. Krol B - deposits of protected embayment Or lagoon, Krol C - open tidal flats to intertidal zone of restricted tidal flat, Krol D - algal mat facies of inner intertidal to supratidal zone with increased salinity, Krol E - intertidal zone. The algal mat facies of Krol E shows dominantly Loferite, fenestral dolomite or bird's eye dolomite, showing different types of shrinkage cracks e.g. sheet cracks, irregular fenestral fabric, shrinkage pores. The supratidal facies is quite abundant, represented by vuggy dolomite and bird's eye pisolitic dolomite.
New Foraminifera from the Neogene of Little Andaman Island, Bay of Bengal
Authors: Srinivasan M. S. , Singh D. N.
Published: November 2024

The following five new species of benthic foraminifera are described and illustrated from the Neogene sequence of Little Andaman Island, Bay of Bengal: Bulimina andamanica* , Cibicides hochstetteri* , Pararotalia geei, Fursenkoina indica, Ehrenhergina schwageri. Observed stratigraphic ranges are given for each species. All the new species described occur associated with deepwater assemblages characteristic of lower to middle bathyal depths. Those marked with an asterisk have proved useful, as zonal markers in the Andaman Sea region.
Rare Minerals from Rajpura-Dariba, Rajasthan, India 1: Owyheeite
Authors: Basu Kanika , Bortnykov N. , Mookherjee A. , Mozgova N.
Published: November 2024

Owyheeite is reported for the first time from an Indian ore deposit. Optical properties, microhardness and X-ray powder diffraction data of the mineral are furnished. Microprobe analysis yields the formula Pb4.76(Ag1.59CU0.11)h0.70Sb6.54Sl5.32. Comparison with other available microprobe data of samples from different localities indicates nonstoichiometric composition of the mineral phase. A small amount of copper seems necessary to stabilize the mineral, since it could not be synthesized in the system PbS-Ag2S-Sb2S3. Curved nature of lamellar grains and existence of spindle-shaped deformation (?) twins imply pre- or syn-tectonic crystallization of the mineral.
Some Aspects of Diagenesis of the Broach Group of Tertiary Sediments Around Jhagadia, District Broach, Gujarat
Authors: Gadekar D. R.
Published: November 2024

The supra-Trappean Broach Group of Tertiary sediments show evidences of a variety of diagenetic changes. The arenaceous sediments of the Vagalkhod Formation contain proofs of recrystallisation of sparry and micrite cement indicating pore-filling and shallow depth of burial. The calcareous sediments of the Bhilod Formation (Nummulitics) show limonitisation suggesting low temperature metasomatism and precipitation in shallow waters. The argillaceous rocks of the Tarakeshwar Formation reveal authigenic sparite, also indicative of shallow burial. Silica cementation, authigenesis and limonitisation are some of the important diagenetic changes discernible in the overlying rudaceous Babaguru Formation. These changes suggest redoxomorphic stage, precipitation from gel and epidiagenesis. The calcareous sediments of the Kand Formation reveal recrystallisation of spa rite from micrite, which may suggest diagenetic transformation. The arenaceous sediments of the Jhagadia Formation bear evidence of the activity of carbonate cementation ~nd replacement, which may perhaps indicate locomorphic stage of diagenesis.
Petrochemical Studies on Chromites from Sinduvalli, Karnataka, India
Authors: Srikantappa C. , Friend C. R. L. , Janardhan A. S.
Published: November 2024

Mineralogical and chemical studies of chromite deposits of Sinduvalli ultramafic body, Mysore District, show definite evidence of layering and other crystal settling processes. Stretching of occluded olivines, chain structures in chromite and rotation of chromite layers indicate their participation in the deformational episodes which affected the area. Structure and chemistry of chromites classify the host ultramafics as belonging to stratiform type. Presence of gabbroic anorthosites confirms this and indicates that they represent layered complexes characterizing the Sargur high-grade terrain.

The presence of recrystallised orthopyroxenes and development of chrome amphibole indicate their formation under metamorphic conditions. Olivine-spinel geothermometry suggests re-equilibration at sub-solidus temperatures during high grade metamorphism. The formation of 'Ferritchromit' zones is connected to magnesite formation.
Geology of Part of Central Ladakh Himalaya with Particular Reference to Indus Tectonic Zone
Authors: Srikantia S. V. , Razdan M. L.
Published: November 2024

In the Central Ladakh Himalaya, the Ladakh Granitic Complex with Kharbu Group, the Indus Tectonic Zone and the Spiti-Zanskar and Kashmir Precambrian Phanerozoic belts constitute the chief geological units. The Ladakh Granitic Complex comprises a heterogeneous association of granitoids, gabbroids and basic rocks. The Spiti-Zanskar and Kashmir belts comprise Precambrian-Eocambrian crystallines and Late Palaeozoic-Mesozoic sediments.The Indus Tectonic Zone, a name adopted in preference to the Indus Suture Zone consists of two parallel and almost homotaxial sedimentary belts viz., the non-ophiolitic Indus Group in the north and the ophiolitic sedimentary volcanic belt of the Sangeluma Group in the south. The Indus Group unconformably overlies the Ladakh Granitic Complex, and the Sangeluma Group tectonically overlies the former. The Indus Group is divisible into the Skinding, the Kuksho, the Maklishun and the Karit Formations in the ascending order, and the Sangeluma into the Khalsi, the Dras Volcanic, the Nindam and the Shergol Formations with ophiolite association in all the formations excepting the Nindam.

The Indus Group cycle of sedimentation comprises, shallow diamictite, flyschoid, lagoonal and molassic stages, whereas the Sangeluma comprises the platform, submarine volcanic, flyschoid and unstable shelf type sedimentation.

Tectonically, the area can be divided into: Ladakh Granitic Complex-Indus Group autochthon, the Sangeluma parautochthon, the Kuling-Lilang schuppen belt, the parautochthon of Spiti-Zanskar and Kashmir Precambrian-Phaneroxoic belts and Shilakong ophiolite nappe.

The Indus Tectonic Zone was an original mega lineament which later became a site of opening of sea and sedimentation for the Indus and the Sangeluma. A sequence of stages of sea-floor spreading subduction and closing is envisaged.
The Occurrence of Heavy Mineral Sands along the Tanzanian Coast
Authors: Duyverman H. J.
Published: November 2024

Heavy mineral sands containing garnet, ilmenite, kyanite, zircon, rutile, magnetite and monazite occur along the eastern coastal belt of Tanzania. Concentrations of these heavy minerals vary along the coast from south to north, but the mineralogical assemblage is fairly constant, the average for the entire coast being garnet 39.2%, ilmenite 33.8%, kyanite+zircon 21.7%, rutile 3.8%, others 1.4%, total heavy minerals 23%.

The heavy mineral concentrations are restricted to the Mtoni Terrace, consisting of lagoons, swamps, raised coral reefs and beach ridges of Pleistocene to Recent age, the richer concentrations being found north of the mouths of the bigger rivers, e.g., the Msimbati Peninsula, north of the Ruvuma River. The source rocks are the Precambrian Basement rocks to the immediate west of the coastal belt and, to a lesser extent, the younger sedimentary rocks from Karroo to Recent in age.

A study of beach profiles and of heavy mineral concentrations at five selected localities along the coast has shown that higher concentrations occur during November to January and May to July, coinciding with the beginnings of the monsoonal periods, when the erosive action of the sea is greatest.
Cluster Analysis and Ecology of Living Benthonic Foraminiferids from Inner Shelf off Ratnagiri, West Coast, India
Authors: Nigam Rajiv , Sarupria J. S.
Published: November 2024

Q-mode cluster analysis explains the spatial distribution data of living benthonic foraminiferids from the inner shelf off Ratnagiri. Two main biotopes and two subbiotopes are recognised within the study area; biotope A, characterised by Trochammina inflata (Montagu), covers the inner shelf north of Ratnagiri and demarcates the influence of fresh-water from Shastri and Vashishti rivers. Biotope B characterised by Nonion and Ammonia covers the inner shelf south of Ratnagiri and represents less influence of fresh water from Rajapur and Vaghotan rivers. Two sub-biotopes in Bare represented by the additional occurrence of Ammobaculites agglutinans and Nonionella respectively. Relatively low and high rate of sedimentations were noted in areas of biotopes A and B respectively.
Some Recent Earthquakes in Peninsular India
Authors: Mohan Indra , Sitaram M. V. D. , Gupta Harsh K.
Published: November 2024

The Peninsular Shield of India, generally considered to be aseismic, has recently experienced significant activity al Koyna (1967), Bhadrachalam (1969) and Broach (1970). Besides, over two hundred tremors, with magnitudes ranging from 2 to 5, have also been identified mainly in Andhra Pradesh, Karnataka and Maharashtra during 1967 to 1977, and are catalogued. Low magnitude activity (M < 4) is observed to be prevalent in the Peninsular Shield.
Sulphur Isotope Abundance Variations in Sulfides of the Dharwar Craton - Part II: Ingaldhal
Authors: Venkatasubramanian V. S. , Menon A. G. , Ananta Iyer G. V.
Published: November 2024

In this sequel to the previous note, we describe the results of d34S measurements on sulphides of the Ingaldhal deposit. A component with near-zero permit values is superposed on a possibly larger component with positive d34S values ~+10‰. The spread can be explained in terms of change in the solution parameters (T, pH and fO2) of the source-fluid, these being represented by fs2-fO2 diagrams. An area on this diagram, sets constraints on the solution parameters during deposition, as indicated.
A Statistical Study on Reliability of Different Scale of Cross-Beds as Paleocurrent Indicator in the Late Paleozoic Fluviatile Rocks of Jharia Basin, India
Authors: Khan Zahid A. , Casshyap Satyendra M.
Published: November 2024

Three scales of cross-beds were recognised and investigated for the Barakar strata of the Jharia basin, attributed to deposition largely by streams of low to moderate channel Sinuosity. Following the recent modifications in statistical methods of crossbedding azimuthal data, sample resultant instead of mean was compared between three scales of cross beds. Sample resultant so computed was tested for 16 sample pairs in 6 sectors and 3 sample, pairs at formation level by applying a modified 'P' statistics. Results are found to be non-significant at 95% level of confidence in 16 out of 19 sample pairs.

Synthesis of paleocurrent data reveals With high degree of probability that all scales of cross beds in fluviatile deposits may be regarded as reliable indicators, provided a proper interpretation is made in respect of the environment of deposition of the host bed form and associated sediments.
Rapakivi Granite of Ezhimala Complex and its Significance
Authors: Nair M. M. , Vidyadharan K. T.
Published: November 2024

The field characters, chemistry and the spatial association of the 678 m.y. old Rapakivi granite with gabbros and anorthosites suggest that these litho-units have developed through bimodal magmatic processes whereby heat derived from basic magma parental to the anorthositic rocks caused partial melting at or near the base of the crust to produce granitic magma with Rapakivi characteristics.
A Plate Tectonic Model for the Geologic Evolution of Sri Lanka
Authors: Munasinghe Tissa , Dissanayake C. B.
Published: November 2024

A new model is put forward to explain the geologic evolution of Sri Lanka. The Highland Group is a highly metamorphosed assemblage of a marine deposited volcanic, volcano-clastic and sedimentary rocks. The origin of the Highland Group dates back to 3000 Ma during a permobile phase in the evolution of the earths crust. Archaean tectonics suggest a downfolding of a thin crust forming the Highland Basin and subsequent filling with marine sediments and volcanics. The tectonic characteristics of the Archean suggest that its evolution possibly passed through a transitional phase (during which the crust thickened) to a plate tectonic phase. Plate tectonic processes analogous to those of the present were active from 2000 Ma. The material in the Highland Basin was metamorphosed and deformed repeatedly, in a collisional tectonic environment, to form the present configuration in the Precambrian of Sri Lanka.
A Note on the 'Volcanic Conglomerate'/Pyroclast Horizon near Palkanmaradi in the Hutti Schist Belt, Karnataka
Authors: Roy Abhinaba , Biswas S. K.
Published: November 2024

Palkanmaradi 'Conglomerate' occurs as a conformable bed within the volcano-sedimentary sequence of the Hutti schist belt. Well-rounded pebbles of granodiorite/tonalite gneiss, microgranite/acid volcanic rock, angular to subangular fragments of amphibolite, are found embedded in a matrix having unusual chemistry representing probably an admixture of volcanic and sedimentary material. Along with the other rocks tbe conglomerate bed has suffered from three distinct phases of deformation and attained amphibolite facies of metamorphism.
Deformation Structures in the Delhi Group of Rocks around Nibhor, Rajasthan
Authors: Bhola A. M. , Saberwal K. K.
Published: November 2024

The metamorphic rocks occurring around Nibhor, northwestern part of the Alwar district, Rajasthan, bear evidence of three phases of folding and one period of regional metamorphism of green-schist facies. The first deformation phase, F1 produced the principal, foliation S1 and the later deformation phases, F2 and F3, produced crenulation cleavages, S2 and S3 respectively. Kinking by the rotation mechanism emerges as the dominant structure supported by kinks with tabular dilatant zones between parted laminae. Some kinks may also have developed by simple shear mechanism.
Ooids in the Trikuta Limestones of Jammu, J & K State, India
Authors: Chadha S. K.
Published: November 2024

The ooids and peloids show diverse morphological characters, and diverse nature of their nuclei and rims. The growth, shape and size of ooids depend upon the method of sorting, formative environments and degree of sphericity they attain during rolling. The compound ooids, on the contrary, are the product of a complex method of aggregation, cementation, reworking of the grains, recementation, and finally their packing under a common envelope. The ooid bearing rocks appear to have been formed in ephemeral lagoons or playas under fluctuating conditions of formative environments with fairly high values of pH, Eh, CO3 ionic concentration and a widely ranging hydrodynamic energy conditions of the basin.
Early Miocene Planktonic Foraminiferal and Radiolarian Zonation, Colebrook Island, Andaman Sea
Authors: Srinivasan M. S. , Lombari Gail , Dave Alok
Published: November 2024

This contribution is the first of the series of investigations on integrated radiolarian and planktonic foraminiferal biostratigraphy of the Andaman-Nicobar region. Fifty species of radiolaria and thirty-one species of planktonic foraminifera have been recorded from the Early Miocene sequence exposed at Piu Bay, Colebrook Island, Andaman Sea (Northern Indian Ocean). The planktonic foraminiferal assemblage is referable to the Upper Catapsydrax dissimilis Zone and Lower Catapsydrax stainforthi Zone representing the interval from the Upper Andamanian to Lower Jarawaian Stages (Lower Archipelago Series). The radiolarian assemblage is referable to the Stichocorys wolffii Zone which corresponds with Paleomagnetic Epoch 18 with an estimated age of 18.5 to 19.5 Ma. Comparison of radiolarian and planktonic foraminiferal assemblage in the Piu Bay section with Deep Sea Drilling Project data indicate an Early Miocene age of 18.5 to 19.5 Ma.
Studies of Depositional Environment of Therria Sandstone in the Sheelveta Area, Karbi Anglong District, Assam
Authors: Kataki T.
Published: November 2024

The Therria Sandstone of Eocene age includes sandstones, shale, carbonaceous shale, coal seam and clay. Petrographically Therria Sandstone is mainly a micaceous quartizite, whose constituents were derived from an igneous terrain. A slight admixture of clastic material transported from low rank metamorphic and older sedimentary rocks is found. The provenance area was not far from the depositional site. Environmental interpretation based on bivariate grain size parameter plottings is not an effective tool since conflicting results are obtained. The deposition took place mainly by tractive current possibly in fluvial channel, The clastic materials were cemented by calcite, iron and silica of which calcite dominates over the others.
Efficacy of Some Chemical Extractions in the Recognition of True and False Anomalies in Geochemical Exploration
Authors: Ramanamurthy M. V.
Published: November 2024

Various chemical extraction techniques are being employed in exploration geochemistry to identify true and false nature of soil anomalies. The efficacy of hydroxylamine hydrochloride, sodium dithonite and ammonium acetate selective extractions have been evaluated through model experiments on a series of Pb, Zn, Mn and Fe near pure mineral forms. The results obtained suggest that these extractions are not as specific as claimed in literature. Due to its complexing tendency, ammonium acetate extractant cannot be employed to extract ion-exchangeable trace metals either in the selective or sequential extractions. Selective and differential chemical quantities arc useful in designing an interpretative methodology for recognising true and false anomalies. Selective chemical quantities of Zn have provided greater insight into the distribution characteristics. Computation of background, anomalous and highly anomalous components has been accomplished from the Zn selective quantities, which are usable directly in exploration. Evaluation of this nature can assist in taking a decision. whether to carry out detailed exploration or not. Hence practicing of such an approach is strongly recommended.
The Position of Indian Tin Occurrences in the Tin-Belts of Gondwana
Authors: Schuiling R. D.
Published: November 2024

Tin deposits and occurrences show an inhomogeneous distribution in elongate belts on all the continents. When the continents are fitted together in pre-drift position, these belts form a coherent pattern. The delineation of tin-belts in Gondwana is difficult due to the inaccessibility of Antarctica and to the fact that most continents belonging to Gondwana seem to have a relatively deep average level of erosion. This may have caused the removal of pre-existing tin-deposits to a large extent. Still it appears that most of the Indian tin occurrences including the recently discovered tin province of Bastar, M.P., fall on a continuation of the tin-belt in Western Australia. The association of cassiterite with Nb-Ta minerals and with Li-minerals is a characteristic of most of the eastern Indian occurrences as well as of most of the Western Australian deposits.
Clay Mineralogy of the Siwalik Group of Simla Hills, Northwestern Himalaya
Authors: Chaudhri R. S. , Gill G. T. S.
Published: November 2024

Clay mineralogy of the Siwalik Group of Simla Hills was worked out by X-ray diffraction technique. The mineral assemblage comprises kaolinite, illite, chlorite, vermiculite, montmorillonite and mixed-layers. The source rocks bearing feldspars, micas and ferrornagnesian minerals suffered chemical decomposition and mechanical fragmentation in temperate climate. The sediments were deposited in rapidly subsiding fresh-water basins. Terrestrial and (or diagenetic origin has been assigned to the various clay minerals.
Comparative Petrology of Pedogenic Carbonates from Quaternary Deposits of Kashmir and Rajasthan
Authors: Sharma Rajiv , Tandon S. K.
Published: November 2024

The purpose of this study is to compare pedogenic carbonates which have accumulated in varying climatic conditions in Quaternary deposits of North India. The pedogenic horizons sampled for the purpose are from the dunal/interdunal tract of parts of Rajasthan and from the Upper Karewa sub-Group of Kashmir valley. These pedogenic carbonates reveal an overall preponderance of micrite in both the situations. Similarity in the form of presence of voids and floating textures is also observed. The pedogenic carbonates of the Upper Karewa SUb-Group show a greater degree of corrosion and replacement indicating a more reactive microchemical environment. The presence of ferroan calcite in the pedogenic carbonates of Kashmir and its absence in those of Rajasthan further bears out the reducing character of the palaeoenvironment of the carbonate layer underlying the loess in the Kashmir valley.
Mineral Chemistry and P-T Conditions of Formation of A Basic Scapolite-Garnet-Pyroxene Granulite from Doddakanya, Mysore District
Authors: Devaraju T. C. , Coolen J. J. M. M. M.
Published: November 2024

Electron microprobe analyses of coexisting phases in a basic scapolite-garnet-hornblende-two-pyroxene granulite from a Sargur supracrustal enclave near Doddakanya are presented. The results of various mineral geothermometers and geobarometers indicate temperature and pressure conditions of 810±20°C and 9.5 ± 0.5 kbar during metamorphic reequilibration. A comparison with other data from granulites of southern India shows that granulite-facies metamorphism of relatively high pressure is a common feature of the granulite region of the Archaean shield.
Petrochemistry and Tectonic Significance of the Peralimala Alkali Granite, Cannanore District, Kerala
Authors: Nair N. G. K. , Santosh M.
Published: November 2024

The E-W elongated pluton of Peralimala, Cannanore district, Kerala, which is classified here as an alkali granite, occurs along the Bavali lineament, spatially associated with the late Proterozoic anorthosite-gabbro-granite-granophyre suite of the Ezhimala Igneous Complex. Perthitic K-feldspar, plagioclase of albite-oligoclase composition, quartz alkali amphibole, aegirine and sphene constitute the main mineralogy of the alkali granite. Chemically, the rock shows high content of alkalies with K2O values ranging up to 10.96 wt. percent. The extremely high levels of K, AI, Ba and Ba/Sr suggest the existence of a phlogopite-rich pocket in the mantle beneath the Bavali lineament from where the melt equilibrated. As peralkaline plutonism is a keynote of pre-rift tectonics, the occurrence of the alkali granite along the Bavali lineament is a manifestation of rift-related alkaline magmatism in this part of the western continental margin of India.
Structure and Metamorphic Characteristics of Cordierite-Bearing Gneiss of South Kerala
Authors: Sinha-Roy S. , Mathai John , Narayanaswamy
Published: November 2024

Cordierite-bearing gneiss of the Quilon district, Kerala, occurs in a 8-10km wide zone within quartzo-feldspathic gneiss, being bordered on the north by a charnockite massif. These gneisses are deformed and are polymetamorphic in character. The cordierite-forming metamorphism is the second in metamorphic chronology. The reaction producing the bulk of cordierite was: biotite + sillimanite + quartz ? cordierite + garnet + K-fetdspar + H2O. The KD (Mg-Fe) values of coexisting garnet-cordierite and garnet-biotite pairs indicate that the PT conditions of metamorphism (~ 7 kb, ~ 720°C) were those of granulite facies. Under these conditions cordierite was produced from Fe-Mg enriched melt restite, being trapped at the fringe of the charnockite massif.
Heavy Mineral Zones in the Fluvial Environment - Ghaggar River, Haryana
Authors: Chaudhri R. S. , Gill G. T. S.
Published: November 2024

The heavy mineral assemblage of modern sediments of the Ghaggar River comprises such nonopaque minerals like zircon, tourmaline, rutile, garnet, epidote, chloritoid/chlorite, biotite, staurolite, kyanite and sillimanite. Opaque minerals include ilmenite, magnetite, hematite and limonite. Percentage frequency of the various minerals in channel, levee and flood-plain microenvironments has been worked out. It is concluded that the distribution and size of the minerals are functions of the physical conditions prevailing in the microenvironments and the heavy mineral assemblage can safely be used to decipher the provenance and evironments of sedimentation of older deposits.
A Computer Based Factor Model to Elucidate Secondary Trace-Element Distribution Patterns around the Sargipalli Lead-Zinc Sulphide Deposit, Sundergarh District, Orissa (India)
Authors: Roy A.
Published: November 2024

The paper examines the results of computer based factor analysis performed on multi-element data from detailed soil geochemical survey over the lead-zinc mine at Sargipalli. Eleven elements (Pb. Cu, Zn, Ni, Co, So, Zr, Ag, Sr, Bi and Ga), measured on each of 216 soil samples by spectrographic and atomic absorption spectrophotometric methods were considered. The results from the factor analysis (R-mode) indicated that the multi-element soil geochemical distribution patterns around the Sargipalli deposit could be explained by a six-factor model. The proper evaluation of this model in relation to sound geological/geomorphological facts known from the area of study, would provide a significant insight into the probable nature of dominant underlying factors influencing the areal distribution of trace elements in soils around the ore body, and hence may serve as an indirect aid in locating further potential prospecting targets in the area.
Volcanic Associations in Tertiary Formations in Meghalaya
Authors: Narasimha S.
Published: November 2024

This paper records the occurrence of volcanic rocks associated with the Tertiary sediments in Meghalaya. They are acidic in composition and can be classed as 'Ash falls and Ash flows,' indicative of explosive volcanic activity during early Tertiary times.
Stromatolites from Middle-Riphean Gangolihat Dolomites (Deoban), Berinag-Gangolihat Area, Pithoragarh District, Kumaun Lesser Himalaya
Authors: Pant Charu C.
Published: November 2024

Gangolihat Dolomite (= Deoban) of eastern Kumaun Himalaya, predominantly made up of micrite, dolomicrite) pelmicrite, dolomitic limestone and talc-associated magnesite, has preserved a variety of stromatolites, of Colonnella group, in its uppermost horizons, best developed soulh of Berinag near Rain Agar, Bora Agar and near the township of Gangolihat. The paper describes four forms of stromatolites which are compared with similar forms described by earlier workers from different parts of Himalaya and the depositional environment has been deduced.

A middle Riphean age (1260 - 1000 m.y.) is assigned to these dolomites because of the presence of Colonnella and Baicalia baicalica. In the present structural superposition, the Gangolihat Dolomites are discordantly succeeded by quartzites and chlorite schist of Berinag Formation which have given a radiometric age of 725 m.y., thus confirming a structural break between the two formations.
Kinematics of the Transverse Lineaments, Regional Tectonics and Holocene Stress Field in the Garhwal Himalaya
Authors: Jain A. K.
Published: November 2024

Lineament and fracture trace analyses of the Indo-Gangetic Plain and different tectonic units of the Garhwal Himalaya reveal four important sets with strike-slip sense of movements. Horizontally-displaced lithologic and tectonic boundaries clearly depict the sense of displacement along certain lineaments, e.g. the Ganga and Yamuna. Also, small-scale straight fracture traces generally are associated with major fracture traces of lineaments in the sense of Riedel (R), Conjugate Riedel (R'). Displacement (D) and Thrust shears (P). L1 lineaments trend N5°-N10° and show dextral sense of displacement, while its conjugate sinistral set (L3) trends N50°. The other strike-slip fracture traces and lineaments trend N25° (L1) and N90° (L3) with a dextral and sinistral sense of displacement respectively. Kinematically. it seems that the orientation of maximum principal horizontal stressU 1. deduced from lineament and fracture trace analysis, has changed anticlockwise from N60° to N24° in space and time by an amount of 35°. Interplay of some important faults along some lineaments with the Krol Thrust in frontal parts of the Krol Thrust Sheet has produced the Dehradun Re-entrant as a lateral ramp unlike the other re-entrants in the Himalaya. Furthermore, present-day seismicity in the Garhwal Himalaya is controlled by certain transverse lineaments besides being associated with major thrusts.
Arculacythereis indoarabica, A New Species of Ostracoda from the Miani Creek, Saurashtra Coast
Authors: Khosla S. C.
Published: November 2024

A new species of the Ostracoda genus Arculacythereis is described and iIIustrated from the Miani Creek, in Saurashtra. The present record, thus, extends the geographic distribution of the genus from the east coast of Australia to the west coast of India.
Lithospheric Subduction Beneath the Arakan-Yoma Fold Belt: Quantitative Estimates Using Gravimetric and Seismic Data
Authors: Gupta Harsh K. , Fleitout Luce , Froidevaux Claude
Published: November 2024

A set of consistent geophysical data show the presence of cold material at depth, east of the mountain chain, in the Arakan-Yoma fold belt region. There are intermediate focus earthquakes to a depth of 150 km or so and longitudinal seismic waves are faster under the chain than west of it. The pronounced gravity low, east of the chain, is well explained by cold high density material at depth in the seismic area, compensated by crustal thickening under the mountain chain and a sediment filled depression under the eastern basin. The gravity low flanking other collisional chains might also be due to compensation of cold material at depth rather than the usually invoked flexural effect.
Graphical Solution to the Drawdown Due to Pumping of the Limited Confined Aquifers in Unsteady State Flow
Authors: Mohapatra P. C. , Anjaneyulu B.
Published: November 2024

At the initial stage of pumping, the discharge-drawdown relationship in a limited confined aquifer is identical to that of an extensive aquifer followed by a transition-period during which the zero-drawdown contour moves from the nearest to the farthest boundary. After that the time-rate of increase in drawdown assumes a constant value. A graphical method is proposed in this paper to calculate the drawdown at a place due to unsteady flow in a limited confined aquifer.
Metamorphism and Magnetic Susceptibilities in South Indian Granulite Terrain
Authors: Ramachandran C.
Published: November 2024

The magnetic susceptibilities measured in 220 metamorphic rocks collected over a traverse distance of about 2500 km, from South Indian granulite terrain, varied over a wide range. The wide variation in the susceptibilities, 6-4420×10-6 emu/cc is explained in terms of changes in magnetic mineralogy during prograde and retrograde metamorphic processes.
Clay Mineralogy of the Soils of Indrayani River Basin, Western Maharashtra, India
Authors: Patil D. N. , Bhosale V. N. , Kulkarni A. V.
Published: November 2024

Clay mineralogy of the soils of Indrayani river basin of western Maharashtra, has been investigated with the help of DTA, XRD and IR spectroscopic techniques. On the basis of clay mineral assemblage of the soils, trends of chemical weathering of basalt and formation and evolution of the soils have been visualised. It has been observed that the chemical weathering of basalt of nearly uniform chemical and mineralogical composition, has led to the development of two contrasting soil types. Red to reddish-brown coloured lateritic to semi-lateritic soils of the western part of the basin are predominated by the presence of kaolinite group of clay minerals. Formation of these soils has been attributed to free drainage and high rainfall conditions. On the other hand, grayish-black coloured margalithic or black cotton soils showing predominance of the minerals of smectite group, have been formed under poor or restricted drainage and low rainfall conditions in the eastern part of the Indrayani river basin. An attempt has been made to discuss the formation and evolution of soils in the light of clay mineralogical data.
A Geochemical and Pb, Sr Isotopic Study of the Evolution of Granite-Gneisses from the Bastar Craton, Central India
Authors: Sarkari G. , Pauli D. K. , De Laeter J. R. , Mcnaughton N. J. , Misra V. P.
Published: November 2024

Preliminary Pb-Pb and Rb-Sr geochronology of granitic and gneissic rocks from the Sukma area of the Bastar craton, Central India, provides important constraints on crustal evolution, Much of the craton is made up of felsic orthogneisses and younger granitic intrusives, compositionally ranging from tonalite to granite. Pb-Pb isotopic data suggest the presence of ca. 3.0 Ga old gneisses. Younger granitic intrusives have been dated at ca. 2.6 Ga which represents a widespread resetting and/or emplacement event. Comparison of the Pb-Pb and Rb-Sr whole rock ages suggests that the latter were more perturbed after the gneiss-forming or emplacement events. All rock suites show significant geological scatter of isotopic data probably because of sampling on a regional scale, and reflect multi-stage isotopic evolution in a complex terrain.

The present isotopic data indicate the presence of Archaean rocks in the Bastar craton and suggest temporal similarity with the oldest crustal rocks in the Singhbhum and Dharwar cratons.
Geocbemistry and Magnetic Susceptibility of Surficial Sediments of the New Mangalore Port
Authors: Shankar R. , Karbassi A. R.
Published: November 2024

A geochemical study of surficial sediments of the New Mangalore Port has shown that there is no anthropogenic input of base metals (Cu, Zn, Pb, Mn and Fe). In comparison with the adjoining inner shelf sediments, Port sediments seem to have a higher proportion of detrital particles and hence relatively less organic matter. Manganese is found predominantly as adsorbed species. Other base metals are present in the lithogenous fraction. Organo-metallic association, reported by several workers for sediments, is not found in the Port sediments. Magnetic susceptibility of the sediments (Xm = 16.6 x 10-6 emu/g) is higher than that for shelf sediments. This is because of deposition of detrital particles of magnetic minerals in the nearshore area. The susceptibility values are not high enough to suggest any particulate pollution due to the Kudremukh iron ore loading operations at the New Mangalore Port.
Stratigraphy of the Upper Gondwana Sediments in the Krishna-Godavari Coastal Tract, Andhra Pradesh
Authors: Lakshminarayana G. , Murti K. S. , Rama Rao M.
Published: November 2024

The Raghavapuram Formation, as demarcated now, consists of shale and micaceous sandstone and contains Early Cretaceous (Neocomian-Aptian age) palynofossil assemblage-represented by Microcachryidites antarcticus, Contignisporites sp., Callialasporites sp, Lycopodiumsporites sp, Impardecispora sp, and Concavissimisporiles sp. The Tirupati Formation consists of conglomerate, ferruginous sandstone and sandstone. The hitherto considered 'Gollapalli sandstone' in Adamilli-Gopalapuram area of West Godavari district forms part of the continental Gondwana sequence (Kota Formation). Therefore, the present study has revealed that there is no stratigraphic unit called Gollapalli Formation in the Upper Gondwana of the Krishna-Godavari coastal tract and the revised stratigraphic succession consists of only two units, namely, the Raghavapuram and Tirupati Formations.
Origin of the Calcrete Deposits of Saswad-Nira Area, Western Maharashtra, India
Authors: Patil Dnyan N. , Surana Arati P.
Published: November 2024

Extensive development of calcrete deposits is observed in the Saswad-Nira area of western Maharashtra. Calcrete occurs in a variety of forms, the most common being powder, nodular, laminar, platy, tubular and hardpan calcretes. The DTA, XRD and IR spectroscopic studies show that the calcretes are composed chiefly of micrite - a microcrystalline calcite. Dolomite and opaline silica occur in subordinate amounts. The clay fraction of calcretes is dominated by attapulgite (palygorskite) and sepiolite, which along with other interlayer clay minerals like chlorite-montmorillonite and illite-montmorillonite, indicate extreme alkaline conditions for the precipitation of calcretes. The chemical data reveal that apart from calcium carbonate, silica and magnesium carbonate constitute an appreciable portion of some calcrete samples. From the textural, mineralogical and chemical characters of calcretes, it is evident that the precipitation of calcium carbonate in vadose zone and its progressive accumulation in the soils has ultimately resulted in the development of extensive calcrete deposits.
Petrographic and Geochemical Characteristics of the Kamthi and Lower Maleri Formations Adilabad and Karimnagar Dts (A.P.)
Authors: Sayyed M. R. G. , Patwardhan A. M.
Published: November 2024

Upper Kamthi sandstones are distinct being unimodal, less feldspathic, texturally more mature with a dominant ferruginous cement when compared with the Lower and Middle Kamthi sandstones which are bimodal, feldspathic with abundant carbonate cement. The bimodality and textural inversion in the latter is attributed to their derivation from both metasedimentary and plutonic sources. This is also reflected in the erratic distribution of Al2O3 total iron and Na2O contents. The Yerrapalli sandstones are petrographically not very different from the Lower and Middle Kamthi sandstones, but show finer grained feldspar, abundant carbonate cement and lime pellets. The Bhimaram sand'stones, however, show lesser carbonate content and are characterized by the presence of pyrite and ferruginous cement. In general, the Yerrapalli and Bhimaram sandstones show a greater mineralogical and textural maturity than the Lower and Middle Kamthi units. The distribution of CaO shows a maxima in. the middle portion of the Lower Maleri sequence, other major elements donot show any systematic variation.
Almandine-Rich Garnets from Payalite-Perrosilite- Quartz-Bearing Ferrosyenites in the Prakasam District of Andhra Pradesh, India
Authors: Leelanandam C.
Published: November 2024

The fayalite-bearing ferrosyenites in the Prakasam district of Andhra Pradesh are distinctly unique as they strangely contain not only the ferrosilitic orthopyroxene but also Iate aIrnandine-rich garnet, the two minerals which are totally alien to similar rocks occurring elsewhere in the world. Symplectic, vermicular, granular and coronal garnet (with intergrowth of quartz) occurs in insignificant amounts with sporadic distribution around ore, orthopyroxene, clinopyroxene, hornblende and fayalitic olivine when they are in contact with feldspar (occasionally with intervening and incomplete rim of quartz), All the garnet-forming reactions might have resulted due to falling temperature. High and variable silica activity, local variations in f02 and rate of cooling may explain many of the observed textural features.

The electron microprobe analyses of almandine-rich garnets suggest two independent substitutions have taken place, one involving Ca and Mn, and the other involving (Ca+Mn) and Fe. The minor chemical variations in garnet are significantly controlled by its habit. Textural features, and inter- and intra-granular compositional variations in garnet even within a single specimen reflect its disequilibrium formation.