bluuebunny/crossref_metadata_2025 huggingface dataset:
Trace and REE Geochemistry of Pelites from the Sargur High-Grade Terrain, Southern Karnataka
Authors: Janardhan A. S. , Shadakshara Swamy N. , Capdevila R.
Published: November 2024

Metapelites form one of the important supracrustal lithounits of the quartzite-pelite-carbonate association in the Sargur high-grade terrain of Southern Karnataka. These pelites have low ferromagnesium trace elemental concentrations, common to the pelites of the Archaean high-grade terrains elsewhere. Though concentration of Sc and U are comparable with the Archaean rocks, the Th concentration and majority of the trace and rare earth elemental ratios are more akin to post-Archaean levels. The REE pattern indicates a mixed provenance dominated by acid igneous rocks. Significant variability in the REB pattern advocates a lithologically complex but definitely a bimodal provenance and also inefficient mixing of source rocks.
Hydrogeology of the Jharia Coal Field, India
Authors: Choubey V. D. , Sankaranarayana I.
Published: November 2024

The Jharia Coal field is a part of an east-west trending intracratonic Gondwana basin in eastern India. This paper presents the results of a comprehensive research programme to understand the hydrogeological setting and the aquifer characteristics. Water table in weathered zone is observed to fluctuate cyclically with seasons and suggests shallow ground water flow system. Aquifer parameters obtained by pumping tests are relatively low and these formations are classified as poor aquifers. The small volumes of water in coal mines is directly related to poor hydraulic conductivity of the rocks associated with coal.
Distribution and Textural Characteristics of the Heavy Minerals in the Beach and Dune Sands of Cox's Bazar, Bangladesh
Authors: Mitra Sachinath , Ahmed Syed Samsuddin
Published: November 2024

The beach and coastal dune sands of Cox's Bazar constitute the most important source of metallic minerals in Bangladesh. The sands are fine, well-sorted, negatively skewed and leptokurtic in their grain-size distributions. Plots of different size parameters suggest that (a) the finer the grain-size the better is the sorting; (b) the sediments are more negatively skewed as the grain-size decreases; and (c) sorting improves as the skewness changes from nearly symmetrical to negative. The dune sands are finer, better sorted and more negatively skewed than beach sands. The percentage of heavy minerals increases from 2 f (250 μ m) to 3.5 f (88 μ m) fraction. The light fraction consists predominantly of quartz (about 90 %), while amphibole, ilmenite, garnet, epidote, mica, pyroxene, magnetite. kyanite, tourmaline, staurolite, zircon, rutile and monazite constitute the heavy minerals. The distribution of the heavies in the dunes and beaches depend on their respective shape. The equant ones are predominant in the former than in the latter. The predominance of unstable minerals and their shapes suggest that the major source of the sediment may be in the easterly highlands of Chittagong-Arakan hills.
Ediacaran Medusoids from the Krol formation, Naini Tal Syncline, Lesser Himalaya
Authors: Mathur V. K. , Shanker Ravi
Published: November 2024

Late Precambrian Ediacaran medusoid coelenterates, viz., Tirasiana sp., Medusinites sp, and Beltanella sp. are reported from the upper part of the Krol Formation in the Naini Tal Syncline, Lesser Himalaya in association with other Ediacaran fossils, viz., Beltanelliformis sp., Pteridinium sp, and Ichnogenus Gordia sp.
Significance of Fayalite (+Quartz) Assemblage in Gokanakonda Syenite, Prakasam District, Andhra Pradesh
Authors: Srinivasan T. P. , Natarajan R.
Published: November 2024

The Fayalite syenites of Gokanakonda in Andhra Pradesh, India, are mineralogically divided into two types: (1) fayalite-clinopyroxene syenites (FC-syenites) and (2) fayalite-quartz syenites (FQ-syenites). The olivine composition ranges from Fa90-95 and the petrochemistry suggests their successive evolution in that order. The assemblage (fayalite+magnetite+quartz) in these syenites suggests a pressure of 11.5 kb and a temperature of 900°C under constant fo2.
A Rapid Method of Ferromanganese Nodule Mounting
Authors: Mukhopadhyay S. , Banerjee R.
Published: November 2024

A rapid method of sample preparation for ferromanganese nodules and crusts mounting is presented here, by using laminated polyester resin, cobalt napthanate and methyl ethyl ketone peroxide. With this technique vacuum impregnation is not required. Any naturally soft and brittle material can be successfully mounted by this procedure.
Lithofacies and Environments of Deposition of a Part of Talchir Group, Talchir Gondwana Basin, Orissa
Authors: Pandya K. L.
Published: November 2024

The Talchir sequence is divisible into three units named informally as 'Unit A', 'Unit B' and 'Unit C' from the base to the top. Eleven lithofacies have been recognised. The lithofacies associations and their inter-relationships suggest deposition of Unit A in a network of alluvial braided stream environment merging into a lake. Unit B represents three phases of delta advance into a lake basin with the development of prodelta, delta slope, subaqueous delta platform and deltaic distributary sediments. The sediments of Unit C were laid down in a quiet lake basin of moderate depth with the sedimentation being from suspension and chemical precipitation followed by intermittent clastic density underflows.
Deformation Microstructures and Geochemistry of the Mylonitic Augen Gneisses in the Chail Thrust Zone in Satluj Valley of Himachal Pradesh
Authors: Gururajan N. S.
Published: November 2024

Microstructural and geochemical analysis have been carried out on the mylonitic augen gneisses of the Chail thrust zone, in the Satluj valley of Himachal Pradesh. The microstructural features of K-feldspar, plagioclase, quartz and mica indicate that these gneisses have undergone an early deep level ductile deformation followed by a high level brittle deformation. The mylonites and blastomylonites represent ductile deformation products and the cataclasite represents brittle deformation product. The mylonitization is related to thrusting events during the Himalayan Orogeny.

Available geochronological data with high initial strontium ratio suggests that the protoliths of the mylonitic augen gneisses (Svtype granitoid) intruded the Chait formation during Precambrian times. The major element chemistry, with the absense of normative corundum values and low Al-index values indicate a mantle origin.
Appraisal of Environmental Impact of the Construction of Jamrani Dam in Nainital District, Kumaun Himalaya, India
Authors: Anbalagan R.
Published: November 2024

Construction of big dams lead to modification of existing fluvial conditions, in addition to affecting the socio-economic conditions of the people of the area. Analysis of the environmental impact on river-bed morphology, hydrogeological regime, stability of hill-slopes around reservoir, seismicity conditions, land-use and socio-economic conditions due to construction of the proposed 130m high dam across the Gaula River at Jamrani (29°16' : 79°36'36") in the Nainital District, Kumaun Himalaya, indicates that there may not be any adverse environmental impact in the area, but on the contrary the project is likely to bring economic benefits to the Bhabar belt of the Nainital District, by enhancing water availability for domestic, industrial and agricultural needs.
Geochemistry of the Alkaline Rocks of Sarnu-Dandali Area, District Barmer, Rajasthan, India
Authors: Chandrasekaran V. , Srivastava R. K. , Chawade M. P.
Published: November 2024

The alkaline suite of Sarnu-Dandali (comprising ultrabasic alkaline rocks, ijolite, foidal syenite, phonolite and carbonatite) is one of the few occurrences of carbonatite-nephelinite association reported in India. The suite is intrusive into the Lower Cretaceous sedimentaries. The rocks show a continuous gradation from alkali pyroxenite to feldspathic ijolite through micro-melteigite and ijolite, Foidal syenite and phonolite mark the end phase of ijolitic series and phonolites are the last to be emplaced. Carbonatites include sovitic alvikite and ferro-carbonatite varieties. The suite shows a progressive increase in Al2O3, Na2O and K2O and decrease in MgO, CaO, total Iron, MnO and TiO2 with increasing SiO2. Fractional crystallisation has played a dominant role in the evolution of the suite, the major fractional phases being pyroxene and iron oxide mineral.
The Albitite Line of Northern Rajasthan-A Fossil Intracontinental Rift Zone
Authors: Ray Sumit Kumar
Published: November 2024

A 170km long NNE-SSW lineament, extending from the Khetri Copper Belt to the Dudu-Kishangarh sector, is characterised by intrusives of albitite, composed predominantly of aventurine albite. Textural evidences suggest that the albitites, magnetite-albitites and pyroxenites, occurring along the Albitite Line, represent different cumulate fractions derived from the same source magma. The fractures, which tapped the magma chamber are related to an intracontinental rift system.
Cyanophyta (Girvanella) as Micrite Contributors to Permo-Triassic Limestones of Pirpanjal Range, Kashmir Himalaya
Authors: Bhat G. M.
Published: November 2024

Two species of Girvanella (G. ducii and G. wetheredii) have been observed during the course of microfacies analysis of limestones of Pirpanjal range. Observations made on three types of Girvanella clasts (tubules, rafts and oncolites) and the associated allochems have revealed calcified algal contribution to the sediments in the form of algal clasts and production of micrite by boring and perforating activities of the Girvanella. The preservation of porous and delicate Girvanella rafts indicates very little reworking prior to transport and deposition.
Paleochannels of the Palar River West of Madras City: Possible Implications for Vertical Movement
Authors: Narasimhan T. N.
Published: November 2024

Hydrogeological field observations indicatc that the river Palar, which now follows a south-easterly course in the vicinty of Kancheepuram, once flowed towards the north-east during quaternary times. The shift appears to have taken place in four stages. The shifts probably, suggest gently vertical movements to the north of the river. If such vertical movements have indeed occurred, It should be of interest to study their relation in regional vertical motions elsewhere along the east coast and their implications to regional hydrogeology of aquifers.
Silver Mineralisation in Ingaldhal Copper Deposit, Chitradurga Greenstone Belt, Karnataka
Authors: Raghu Nandan K. R. , Vidyadharan K. T. , Naik R. H. , Murthy V. S.
Published: November 2024

Native silver alloyed with gold in varying proportions occurs as tiny inclusions mostly in the sulphide ores of Ingaldhal, Chitradurga schist belt. The data presented establishes the copper deposit as a source of silver metal too and the appropriateness of terming the hill 'Belligudda' (Silver Hill) by the ancient miners is affirmed. The volcanic flows having a dominant tholeiitic character are the actual source of basemetals, as well as precious metals, while tectonism and metamorphism aided by the intrusion of Chitradurga granite pluton have probably caused variable amounts of redistribution and remobilisation.
Petrology and Problems of Dating Karal Rocks
Authors: Ghate Savita , Raghavan Hema , Rajagopalan G.
Published: November 2024

14C dates supplemented by micromorphological studies of Karal rocks are presented. 14C dates, micromorphological analysis and sedimentological processes reveal that the calcite cementation of Karal rock, drift-wood and lithounits have taken place in several phases and not in a single stage. This appears to be the main reason for the discrepancy of 14C dates of the Kara1 and wood samples occurring at the same stratigraphic position and depth.
Studies on the Distribution of Organic Matter and Carbonate Content of Sediments in Mahe Estuary, Northern Kerala
Authors: Sebastian Syriac , George Roy , Damodaran K. T.
Published: November 2024

Sediment samples collected from selected stations in the Mahe estuary during the pre- and post-monsoon periods were analysed for their texture, organic matter and carbonate content. It is observed that finer sediments, mainly clayey silt, constitute the major part of the estuarine substratum. Organic matter in the bulk sediments generally follows the distribution pattern of the sediments, i.e., finer the texture greater the organic matter content, whereas the carbonate content shows an inverse relation with the texture. Studies on seasonal variations show that the post-monsoon sediments have higher proportions of organic matter (average: 4.12%) and carbonate (average: 5.23%) content more than those of pre-monsoon periods. No significant relationship between organic matter and carbonate content is observed during pre-monson (r = -0.35) and postmonsoon (r = -0.27) periods.
LANDSAT Image Enhalncement for Mapping Fluvial Palaeofeatures in parts of Middle Ganga Basin, Bihar
Authors: Philip G. , Gupta R. P. , Bhattacharya A.
Published: November 2024

An area in the Middle Ganga Basin, lying around Monghyr, Bihar, has been selected for delineation of fluvial palaeofeatures. The investigation is based on aerial photographs LANDSAT MSS and TM data products and ground data. Digital enhancement of LANDSAT MSS and TM data by linear contrast stretching and ratioing has been found to be highly powerful in identification and mapping of subtle fluvial palaeofeatures. Based on the above interpretation, a summary of the fluvial palaeo-history is presented.
An Unusual Evaporite Association from the Papaghni Group, Cuddapah Basin
Authors: Phansalkar V. G. , Kale Anand S. , Karmalkar Nitin R. , Kale Vivek S.
Published: November 2024

The hitherto unreported occurrence of halite and gypsum casts from the Vempalle Formation is reported. Implications in terms of the early depositional history of the Cuddapah Basin is discussed.
Silver-Bearing Sulphosalts from Rampura-Agucha Massive Sulphide Deposit of Rajasthan
Authors: Mukherjee A. D. , Glahiri Samhita , Bhattacharya H. N.
Published: November 2024

Occurrence of freibergite, argentian pearcitc and miargyrite, from the Rampura-Agucha sulphide deposit is reported.
A Textural and Mineralogical Study of the Beach Sands Between Talapady and Surathkal, Karnataka
Authors: Jayappa K. S. , Subramanya K. R.
Published: November 2024

The beach sediments are medium-sized sand, unimodal, well-sorted to mode-rately sorted, nearly symmetrical and mesokurtic to leptokurtic in terms of their grain size distribution. The sand-silt ratios are very high. The content of heavy minerals is very less compared to the content of light minerals and there is an appreciable percentage of shell fragments. The heavy minerals commonly found in these sediments in the decreasing order of abundance are opaques, garnet, zircon, hornblende, actinolitetremolite, sillimanite, enstatite, rutile, pyroxene, spinel, epidote and kyanite. The percentage of quartz in the light mineral fraction varies from 68 to 99. The provenance of these beach sands is the Netravati river basin of Western Ghats largely consisting of Precambrian granitic gneisses.
Occurrence of Ijolite with Veinlets of Carbonatite in the Deccan Trap at Murud-Janjira, Maharasbtra, India
Authors: Sethna S. F. , D'sa Christopher P. R.
Published: November 2024

Petrographic and petrochemical studies indicate the Ijolite to be somewhat magnesium-rich. The agpaitic index is very close to one and the magma is considered to be of an intermediate type (between miaskitic and agpaitic). The structural setting of the area is of the rift type, as the Panvel flexure occurs just a little to the west of the pluton.
Geochronology and Geochemistry of Granite Plutons from East Khasi Hills, Meghalaya
Authors: Ghosh Subhasish , Chakraborty S. , Bhalla J. K. , Paul D. K. , Sarkari Amitabha , Bishui P.K. , Gupta S. N.
Published: November 2024

Discordant granite plutons at Kyrdem, Nongpoh and South Khasi intrude the basement gneisses and the overlying Shillong Group of metasediments in the Meghalaya Plateau. Porphyritic granitoids ranging in composition from quartz monzonite to granite represent the dominant component in all the three plutons. Common characteristics of these granitoids arc spatial association with hornblende dioritic rocks, dominantly potassic and metaluminous nature. A positive correlation of SiO2, Na2O + K2O, Rb, Rb/Sr and negative correlation of CaO, MgO, FcO(T), Sr, TiO2 with Differentiation Index in the Kyrdcm pluton point to fractional crystallisation processes. Rb-Sr whole rock isochron data of the plutons yield ages in the range 480-690 Ma wiLh initia1 87Sr/86Sr ratios ranging from 0.70948 -0.71482. Absence of post emplacement tcctonolhennal event is suggested by near concordant K-Ar biotite ages.

A protracted thennal event during late Proterozoic-early Palaeozoic (500-700 Ma), possibly related to mantle upwelling, possibly triggered the generation of these granitoids.
Primary Silicate-Melt Inclusions in Olivine Phenocrysts from the Pavagad Igneous Suite, Gujarat
Authors: Hari K. R. , Santosh M. , Chatterjee A. C.
Published: November 2024

Fluid inclusion studies in olivine phenocrysts from alkali olivine basalt, iddingsite basalt and three-phenocryst basalt of the Pavagad igneous suite, an outlier of the Deccan Trap, indicate the presence of highly evolved primary silicate-melt inclusions with various daughter crystals of olivine, pyroxene, plagioclase and opaques. High temperature experiments using a heating stage indicate homogenization in the range of 1040 to 1240 °C. The gas bubble within these inclusions show melting close to the triple point forpure carbon dioxide and homogenize into liquid phase between 25 and 31 °C, denoting densities of 0,70-0.50 g/cm3. Trapping pressure estimated from CO2 equation of state barometry is about 3.8 kbar, which translates to a depth of formation of ca. 10 km. This correlates well with an independent depth estimate of 10-14 km derived from combined melt and fluid homogenization data. The melt inclusion chardcteristics in the Pavagad suite suggesllhatlhe olivines equilibrated from a slow cooling system at high pressure conditions, the parental melt having a probable alkali olivine basalt composition.
Ostracoda in the Estuarine Sediments, Pulicat Lake Estuary, East Coast, India
Authors: Sreenivas K. , Raju B. N. , Honnappa  , Reddi K. R.
Published: November 2024

Thirteen Recent ostracode taxa belonging to 11 genera, 4 families and 1 suborder were identified and illustrated following the classification suggested by Morkhoven (1962-1963) with slight modifications. The species were studied for their distribution. percentage of total shells of species with reference to number of larva, juvenile, adult specimens, male, female ratios, colour pattern and to assess the nature of the estuary and its environs. An attempt has been made to calculate the percentage of biological factor, i.e., predation.
The Birth History of Two Granitic Plutons of the Bhilangna Valley of Garhwal Himalaya: A Geochemical Approach
Authors: Islam R. , Purohit K. K. , Thakur V. C.
Published: November 2024

On the basis of geochemical study, two granitic plutons are identified in the Bhilangna valley of the Garhwal Himalaya, viz. the Chaili porphyritic granite gneiss (CPGG) and the Ingedinala granite gneiss (IGG). Both, CPGG and IGG rocks fall in the quartz rich zone (QRZ) of chemical-mineralogical typology of Dcbon and Le Fort, 1982. CPGG and IGG are strongly peraluminous, S-type granites and enriched in Si and K and depleted in Ca and Sr. The unusually high K2O suggests introduction of LILE during metasomatic processes. Both, CPGG and IGG are crustally derived and produced due to the partial melting of psammo-pelitic sediments. Probably the source materials for CPGG and IGG are same, attested by the geochemical similarities. The Q-Ab-Or plots of CPGG and IGG revealed that the temperature higher than that of the 'minimum' melt was attained during anatexis. During the Himalayan orogeny, intracontinental subduction took place along MCT and provided channels for the metasomatic fluids which induced K and Rb metasomatism and subsequently modified the nature of CPGG and IGG.
Pellatispira-Bearing Upper Eocene Subcrops in Tanot-I Well, Northwest of Jaisalmer, Rajasthan and their Significance
Authors: Kalia Prabha , Banerjee Amit
Published: November 2024

Late Eocene strata bearing Pellatispira crassicolumnata, Silvestriella tetrahedra, Nummulites fabianii, Nummulites striatus and Asterocyclina stellata have been identified in the subsurface samples from Tanot-I well 145 km northwest of Jaisalmer Earlier in the Rajasthan region, the sea was considered to have finally withdrawn by the Late-Middle Eocene. The present record of strata of Late Eocene age supports the hypothesis of oceanic subduction followed by obduction of the Indus Basin. The presence of Late Eocene in Kirthar and Sulaiman Ranges, Pakistan, and Jaisalmer, India and their absence in Kutch can thus be explained.
Lithofacies Analysis, Benthic Foraminifera and Depositional Environments of the Chhasra Member: A Transgressive Tide and Storm Affected Early Miocene Sequence in Kachchh, India
Authors: Wahi Sanjay , Tandon S. K. , Sharma V.
Published: November 2024

A 40m thick Early Miocene sequence occurring near Naliya has been investigated for its sedimentary facies and benthic foraminiferal biofacies. The changing depositional environments of the sequence have been interpreted to represent (a) supratidal to (b) supratidal-intertidal and (c) subtidal (limited clastic influx) to ultimately subtidal (increased clastic influx) palaeoenvironments. The lowest part of the section shows evidence of emergence which together with benthic foraminiferal population dominated by Pararotalia nipponica - Loxostomwn lobatwn (water depths of 05-10m) suggests a supratidal environment.

The middle part of the stratigraphic interval has been subdivided into a lower and upper part on the basis of an intervening calcrete (calcretised shell limestone) horizon. The lower part of this interval represents lagoonal and high intertidal environments.

The upper part of this interval shows development of cross bedded and wave-rippled sandstones representing beach ridge-tidal inlet sequence. Other lithofacies include shell layers having predominance of one kind of organism. Some of these shell banks are wave sorted. Biofacies II -Hanzawaia nipponica - Cibicides lobatulus characterises this part of the section and indicates water depths of - 5Om.

The upper part of the sequence is composed of silt which contains Ammonia beccarii -Pseudorotalia gaimardi in abundance. This interval is frequently interspersed by oyster-Pecten beds and indicates subtidal environment with increased influx of siliciclastics.

The changing depositional environments show that these Early Miocene rocks represent a transgressive, tide-dominated, storm affected sequence.
Pliocene Soricidae (Insectivora, Mammalia) from Kashmir Intermontane Basin, Northwestern Himalaya
Authors: Kotlia B. S.
Published: November 2024

The earliest as well as the first Episoriculus (Tribe Soriculini; Subfamily, Soricinae) in Asia is described from the Pliocene sediments of the Karewas of Kashmir, India. Based on the examination of nearly all lower and upper dental elements, a new species, Episoriculusrepenningi sp. nov. is proposed. In addition; the only record of tribe Beremendiini in Southern Asia is discussed based on limited material. The presence ofhoih tribes in India offers evidence of faunal similarity between Europe and Southern Asia during Late Cenozoic. The age of the sediments yielding fossil shrews is about 2.4 Ma.
Sediment Transport Direction Derived from Grain-Size Statistics on the Continental Shelf Off Mangalore, West Coast of India
Authors: Narayana A. C. , Pandarinath K.
Published: November 2024

Grain-size statistics are employed in sediment transport studies. The alongshore transport of sediment in shallow regions (30-50m depth) and deeper regions (>l50m depth) is in north and south directions, whereas in the depth range of 50-75m, the sediment transport direction is towards the south. The onshore-offshore sediment transport study reveals that the sediment transport direction is towards onshore where fluvial influence is absent and the direction is towards both onshore and offshore where the fluvial influence is prevalent. The studies further reveal the different energy regimes of transportation.
The Origin of Myrmekites in the Granitic Rocks of Ambagaspitiya, Sri Lanka
Authors: Mathavan V.
Published: November 2024

Myrmekite occurs in four distinct modes in the granitic rocks of Ambagaspitiya. Intragranular myrmekite (1) occurs completely within microcline grains, while marginal myrmekite (2) is confined to the rims of microcline grains and these two types of myrmekites are abundantly developed in the studied rocks. They invariably show corrosion features and the myrmekitic quartz may either protrude into or lie entirely in the adjacent microcline grain. Rim myrmekite (3) and intergranular myrmekite (4) occupy pJagioclase-microcline, and microcline-rnicrocline interfaces respectively. The four modes of occurrence of myrmekites described here are interpreted on the basis of exsolution and Becke's metasomatic exchange models in the light of the inferred geological history of the granitic rocks of Ambagaspitiya.

The study supports the view that myrmekite is polygenetic and different types of myrmekites in a suite of rocks may be formed by more than one unrelated process.
Tectonic Slices of High-Grade Rocks in the Delhi Fold Belt of North-Central Rajasthan
Authors: Fareedduddin  , Sharma A. K. , Bose U.
Published: November 2024

The occurrence of tectonic slices of high-grade rocks in Pilwa-Chinwali-Arath area, about 25 km NNW of Ajmer is described. They occur in discontinuous strips Over a distance of 25 km within the Alwar metasediments of middle amphibolite facies. The high-grade sequence comprises charnockite-enderbite, two pyroxene granulite, pelitic granulite, leptynite, garnetiferous augen gneiss and garnetiferous amphibolite. Their tectonically-controlled occurrence and comparable mineral parageneses, the highgrade granulite facies rocks of the study area show striking similarity to those of Sandmata metamorphites emplaced in the Archaean Banded Gneissic Complex.
Source Rock Characteristics of the Late Proterozoic Nagthat Formation, NW Kumaun Lesser Himalaya, India
Authors: Ghosh Sumit K.
Published: November 2024

The Nagthat siliciclastics consist of sublithic-arenite and subarkose with subordinate proportion of quartz wacke,lithic graywacke, quartzarenite,lithic arenite and arkosic wacke. Triangular plot of lithic fragments, variable diagrams of quartz types and heavy mineral assemblage collectively suggest their derivation mainly from low to high grade metamorphic terrain with minor contribution from sedimentary and plutonic igneous rocks. This is further supported by the dominance of brown luminescing quartz and blue to non-luminescent feldspars. The palaeoflow analysis reveal three prominent modes NE. NW, ESE and suggests that the source areas for the Nagthat sediments was towards the SW. SE and WNW directions.

Taking all these points into consideration, it can be inferred that the major part of the detrital framework materials for the Nagthat siliciclastics were possibly supplied due to uplift and subsequent erosion of Aravalli-Delhi mountain chain and Bundelkhand granite-gneiss massif sometime during Aravalli and Delhi orogenic events.
Illite Crystallinity Indices and Their Significance in Anchimetamorphism and Mineralisation in the Cumbum Formation (Cuddapah Supergroup), Andhra Pradesh
Authors: Rao C. N. , Srinivasan K. , Roychowdhuri Amit
Published: November 2024

Phyllites from the Cumbum Formation are exclusively made up of 2 M polymorph of illite. The 2 M polymorph, the most stable phase in the temperature range of 200-300°C, is comidered to be due to its heritage from the source area, having been derived from high-grade metamorphic Eastern Ghat and Dharwarian provenances. The Illite Crystallinity Jndex shows progressive improvement with depth as well as nearness to the Pb-Zn mineralised zone. The crystallinity Index averaging 0.4°2? is consistent with anchizone of metamorphism. The progressive increase in the crystallinity and size with depth and in the proximity of the mineralized zone suggest that the mineral suffered post-depositional recrystallisation effected by the depth of burial, uplift and folding in the eastern margin of the Cuddapah basin and subsequent hydrothermal activity concomitant with the Pb-Zn mineralisation at Bandlamotu.
Zircons from the Granitic Rocks of the Malani Igneous Suite : Morphological and Chemical Studies
Authors: Kochhar Naresh , Vallinayagam G. , Gupta L. N.
Published: November 2024

Zircons are hydrothennal or late-magmatic. The high UO2 contents of the Tosham zircons reflect the high UO2 of the host rocks. The Siwana granites, though high in Zr values, have very poor zircon yield. This is probably due to the pcralkalinity of the Si wana magma.
Characterisation of a Clay Deposit at Malti, Purulia District, West Bengal
Authors: Fentaw Haile Michael , Rao C. N. , Sengupta D. K.
Published: November 2024

The clay deposits at Malti in Purulia District, West Bengal have formed on phyllites of probable Precambrian age.

X-ray diffraction, differential thermal and Infra-red spectral studies suggest that these clay deposits contain kaolinite as the predominant clay mineral. The kaolinite shows two distinct varieties of crystal perfection-one the highly crystalline with Hinckley Indices of well over 0.8 (8 samples) and the other of comparatively low crystallinity with Hinckley Indices of less than 0.8.

The poorly crystalline samples show strong low temperature endothermic peaks at 200°C in DTA curves suggesting the presence of some inter-layer water. The presence of hydrated halloysite has, however, not been conclusively established.
Influence of Precursor Sediments on Coal Distribution and Quality, Barakar Formation, Sohagpur Coalfield, Madhya Pradesh
Authors: Chakrabarti Utpal
Published: November 2024

The Barakar Formation of Sohagpur Coalfield is an alluvial succession consisting principally of channel sandstones with subordinate amounts of overbank deposits comprising finer clastics and coal. The major factor controlling peat accumulation is the physical characteristic of sub-peat sediments. Coal is thin and high in ash in sand-rich areas which compacted least and produced elevated surfaces where peat was sub-aerially exposed and oxidised. Two modes of accumulation of thicker and relatively low-ash peat operated in the study area. First, relatively sand-deficient areas compacted easily and yielded morphologically low surfaces where peat could accumulate in greater quantity and the water table was sufficiently maintained to prevent peat destruction. Secondly, an optimal sand concentration in the substrate created intermediate topographic sites where a delicate balance between the water table and the depositional interface favoured concentration of thicker and better quality coals.
Measurement of Natural Recharge in India
Authors: Athavale R. N. , Rangarajan R. , Muralidharan D.
Published: November 2024

The broad pattern, emerging from recharge measurements in various basins ranging in area from few tens to few thousands of square km indicates an annual input of about 16% (or 100 mm) of the precipitation in the Indo-Gangetic alluvial tract and about 8% (or 60 mm) ofthe precipitation in the Peninsular hard-rock areas. The Tritium recharge measurements are compared with those obtained by using hydro-meteorological and hydrogeological methods. The relation between recharge values and water level fluctuations in open wells is studied and regression plots showing dependence of recharge rate on rainfall over granitic, basaltic, sedimentary and alluvial provinces are presented. Data on temporal variation in recharge due to variation in rainfall over three hydrological cycles in a granitic watershed in the semi-arid area is presented. The utility of such studies in prediction of recharge from rainfall data is illustrated.
The Assam Basin: Tectonic Relation to the Surrounding Structural Features and Shillong Plateau
Authors: Das J. D.
Published: November 2024

The Assam basin is surrounded by hills and plateau. Structurally the basin is mainly bounded by thrust belts in the north, northeast and southeast. Bulk of the Precambrian landmass of Shillong plateau lies to the south of the river Brahmaputra between longitude 90° and 94°E and controls the whole lower part of the river course. Compressional tectonism in northeast India is responsible for the present configuration of the Assam basin which compressed gradually. Structures developed along the foothills of the Himalaya and Naga hills show migration of rock masses towards the basin. Besides, recent earthquakes have changed the basin morphology as well as river courses. It seems the basin is gradually becoming narrower and shallower under the influence of the present tectonism.
Fluid Inclusion Studies on Molybdenite Mineralization of Yegawakote, Kolar District, Karnataka, India
Authors: Ahmed Syed Ashfaq , Pathan A. M. , Srikantappa C.
Published: November 2024

Developments in stable oxygen and carbon isotope studies of the sediments from oceanic realm has established their potential use as stratigraphic markers. Whereas, other schemes of stratigraphic classifications for the Cenozoic sediments of Kutch are available, this paper attempts to establish the stable isotope stratigraphy of a part of the sequence. It is observed that the δ180 and δ13C variation significantly correspond to the chronostratigraphic units of this area. The negative δ13C of the Kakdian Stage (Berwali Series) shifts characteristically to positive values in the Babian Stage (Berwali Series) and then swings back to negative values in the Bermoti Series. The Kakdian Stage and the Bermoti Series, both having negative δ13C, can be differentiated by their respective δ18O range.
Earth Science Museums in India
Authors: Prasad K. N.
Published: November 2024

Earth Science Museums playa vital role in imparting knowledge to students and scholars by providing basic information on the natural resources. The Geological Survey of India has the largest number of ESMs in the country. Universities with a Geology Department have ESMs though not on such a large scale like the G.S.I. Within the last four years, two modern ESMs have been established at Neyveli and Ranchi. The importance of museums and national parks in educating the common man is stressed. The history of the ESMs in India is outlined and the two modern museums at Neyveli and Ranchi are described in detail. The technique of modelling prehistoric animals like the dinosaurs which form part of a museum by dynamic and animated movements with acoustic background is stressed. New Innovations change of display material occasionally adds a new dimension to the quality and attractiveness to the museum. A list of national parks with museums and life-sized fibreglass models of prehistoric animals is given. The two ESMs established at Neyveli and Ranchi are to a limited extent based on the lines of some of the famous museums such as Smithsonian, the American Museum, the Field Museum, the Carnegie Museum, Yale Peabody Museum, and the British Museum of Natural History. The need for more ESMs in India using latest techniques in museology for better display is stressed.
The Possible Causes of Variation in Water Quality of Mahi River, Gujarat, India
Authors: Barodawala S. F. , Patel P. K. , Patel C. D.
Published: November 2024

The damming of the Mahi has retarded the natural cleansing processes of the river, making it incapable of flushing away effluents. This problem is further compounded by the large-scale tidal ingress in the Mahi, which impedes the already sluggish flow of the water, thereby concentrating the pollutants in the downstream portion. This is critical, since nearly half of Baroda city's drinking water is obtained from French-wells dug in the Mahi river bed at Vasad which is under the influence of the tidal ingress.
Benthic foraminifera and Deep-Sea Water Masses in the Tropical Indian Ocean
Authors: Gupta Anil K.
Published: November 2024

The distribution patterns of important benthic foraminifera from surface sediment samples of 9 DSDP sites from the tropical Indian Ocean were examined. The faunal patterns reveal two major assemblages and one intermediate assemblage. The first assemblage is dominated by Uvigerina proboscidea and Globocassidulina pacifica and confined to a water depth ranging from 1800-2800m. This assemblage is associated with North Indian Deep Water (NIDW). The second assemblage, confined to waters deeper than 3800m, is dominated by Epislomineila umbonifera and is associated with Antarctic Bottom Water (AABW). The third assemblage occurs between 2800 and 3800m and is dominated by Uvigerina hispido-costata, Cibicides wuellerstorfi, Epistominella exigua, Pullenia bulloides, and Oridorsalis umbonatus. This assemblage is associated with a water mass intermediate between NIDW and AABW. A minor assemblage has also been observed at depths shallower than 1800m, dominated by Bulimina aculeata and Astrononion umbilicatulum. This assemblage appears to be associated with a water mass influenced by Antarctic Intermediate Water (AAIW).
Trace Fossils from the Muth Quartzite of Malia Johar Area, Tethys Kumaon Himalaya, India
Authors: Srivastava Ashok K. , Kumar S.
Published: November 2024

Trace fossils namely, Arenicolites, Monocraterion, Planolites,lchnogenus A, and trails are recorded from the Muth Quartzite of the Malla Johar area of the Kumaon Himalaya. The trace fossils are recorded dominantly from the middle unit i.e., Muth B Member. On the basis of ethology and preservational conditions it has been interpreted that during the deposition of the Muth B Member, the benthonic community was dominated by molluscs and polychaetes. The organisms producing trace fossils are dominated by feeding or feeding-dwelling habitat.
Role of Mantle Carbon in Archaean Gold Genesis in South India : Evidence from Carbon Stable Isotopic Composition of Fluid Inclusions
Authors: Santosh M.
Published: November 2024

Ore fluids in the gold-quartz veins in Kolar (Champion Reef) and Wynad (Nilambur) are characterized by CO2-bearing systems of low salinity and moderate density. Step-wise heating of auriferous quartz, and the isotopic analyses of CO2 extracted from fluid inclusions yield a tightly constrained d13C range of -5.9 to -9.4%0, providing the first direct evidence for the involvement of mantle carbon in the genesis ofthese Archaean gold deposits. The similarity in the range of carbon isotopic compositions of CO2 trapped within the Archaean granulites and gold deposits suggests a common source for the fluids. The isotope data are consistent with the derivation of CO2 from an outgassing sub-lithospheric mantle.
Fluid Inclusion Study of Vinjamuru Precambrian Stratiform Baryte Deposit, Nellore Schist Belt, A.P., India
Authors: Moeen S.
Published: November 2024

The fluid inclusions in Vinjamuru baryte can be broadly classified into primary and pseudo-secondary types. Primary inclusions are represented by monophase carbonic and mixed carbonic-aqueous types. CO2 densities lie in the range of 0.78-0.88 g/cm3. The pseudo-secondary inclusions are represented by aqueous bi-phase type, coexisting with vapor-rich inclusions. Their Th overlaps in the range of 220-230°C suggestive of entrapment from boiling fluids. The primary carbonic inclusions appear to be volcanic entrapments and the fluids in pseudo-secondary inclusions were entrapped from hydrothermal solutions.
A Reappraisal of an Archaean Carbonatite of Nellore Schist Belt, South India
Authors: Kumar Anil , Srinivasan R. , Gopalan K. , Patil D. J.
Published: November 2024

Field observations, trace element and isotopic results are reported for rocks classified as carbonatites from Vinjamur area in the Nellore schist belt. These carbonate rocks occur either inter-bedded with metasedimentary quartzites and pelites or in association with calc-alkaline rather than alkaline volcanic rocks. No fenitised contacts are seen. Their Nb and REE contents are too low for carbonatites. Samples free from baryte veins have less than 150 ppm of Sr with an isotopic ratio greater than 0.7100 d13CPDB range from -1.58 to - 0.56 ‰ and d18OSMOW from +14.00 to +16‰ , All these features, individually and collectively, show that the carbonate rocks of Vinjamur are most probably sedimentary and not igneous in origin.
Streamlined Landforms in the Inactive Zone of the Chhota Shigri Glacier, Labaul District (H.P.)
Authors: Chaujar Ravinder Kumar
Published: November 2024

Streamlined and superimposed streamlined landforms in the inactive zone formed by first deglaciation activity are fiutes which are characterised by low relief and very elongate form reflected by cigar shaped image. They are mostly present in clusters in the zone between the end moraines and second stage of glacier advance and retreat. It is suggested that the formation of these flutes is related to pre-existing forms of ground moraine which have been heavily dissected by preglacial melt water streams before reglaciation and deposition of upper till. Superimposed streamlined landforms suggest that the glacial ice, which formed them had insufficient power and energy to destroy tbe existing landforms, but could only modify them.
Geotechnical Properties and Processes of Marine Sedimentation
Authors: Krishnamohan R.
Published: November 2024

Marine sediments differ from terrestrial sediments in a number of ways and hence it becomes important to analyze their geotechnical properties and processes in a detailed manner. A brief summary of the nature of marine sedimentary environment, types and distribution of marine sediments, consolidation behavior, static shear strength and response under dynamic loading is presented in this paper. A knowledge of these aspects would greatly help the civil engineer/geologist to better understand the sedimentological and environmental conditions under which submarine slopes experience phenomena like long-term downslope displacements, slumps. slides, and other mass wasting processes.
Yttrium-Europium-Erbium Geochemistry of Granitic Soils of Kunkuri Area, Raigarh District, Madhya Pradesh, India
Authors: Singh Yamuna , Rai S. D.
Published: November 2024

The duricrust and the soils derived from the Precambrian granitic rocks of Kunkuri area in Raigarh district, Madhya Pradesh, contain anomalous concentratioIis of rare earth and yttrium minerals. The polymineral table concentrates obtained from the granitic soil contain xenotime, monazite, zircon, Hmenite and rutile. Chemical analyses of table concentrate indicate values up to 3.08% Y 203.0.30% Er203 and 0.0286% EU203 in the ratio of 10 : 1 : 0.1. Corresponding data on table concentrates from the source granitic rocks also demonstrate a similar form in Y 203 : Er203 : EU203' Y/Er ratio is 10. which is similar to the average granites, while Er/Eu ratio of 10 is anomalously high, being 4 times the average for granitic rocks. Since the REE and Y bearing minerals are radioactive and contribute to a major part of the radioactivity in soHI alluvial deposits of the areas investigated, aeroradiometric surveys fonowed by ground radiometric checkings, preferably along 2nd to 5th order streams in the adjoining areas, are recommended.
Stratigraphy and Sedimentation of Bombay Offshore Basin
Authors: Nair K. M. , Singh N. K. , Ram Jokhan , Gavarshetty C. P. , Muraleekrishanan B.
Published: November 2024

Correlation of seven chronostratigraphic sequences in over 300 wells drilled in the six structural blocks constituting the Bombay Offshore Basin has helped in defining the stratigraphy, paleogeography and facies distribution and suggesting a model for shelf carbonate deposition. The sequences correlated are: Paleocene-Early Eocene, Middle-Upper Eocene, Lower Oligocene, Upper Oligocene, Lower Miocene, Middle Miocene and Middle Miocene-Holocene.

The most significant observations arc 1) Surat depression and its southward extension through other grabens up to Ratnagiri block contain a restricted marine, paralic and continental shale, sand and coal facies of 500-3000 m. thickness, deposited during syn-rift. Paleocene-Early Eocene phase. This is the principal source rock in the basin. 2) The main reservoirs are the Miocene limestones in Bombay High and Middle Eocene and Lower Oligocene limestones in other areas. 3) The main sandstone reservoirs are in the Oligocene sequences in Daman-Tapti area of Surat depression and in the Paleocene-Lower Eocene sequence in Heera-Bassein and Ratnagiri blocks. 4) By tracing the clastic dispersal.pattern, it is shown that Saurashtra basin and Shelf Margin basin with their excessive Upper Oligocene-Holoccne fill are less favourable than the rest of the basin in hydrocarbon potential.

A homoclinal ramp model is suggested for the shallow shelf carbonate deposition. The suggested carbonate depositional model indicates that the platfonn areas are susceptible to shale incursions from the east which could affect the reservoir properties of limestone in many areas. Almost all the major carbonate pay zones are associated with unconformities and diastems and the principal porosity is telogenetic.
Morphology of the Sea Floor within the EEZ off Visakhapatnam - Kakinada Coast, Bay of Bengal
Authors: Murty P. S. N. , Mohapatra G. P. , Reddy D. R. S. , Hariprasad M.
Published: November 2024

The bathymetry contours show that the morphological features of shelf and slope off Visakhapatnam coast are mainly due to erosion and local deposition, while those of Godavari delta are due to high rate of deposition. Features such as terraces, pinnacles and ridges on the continental shelf at different depths are inferred to be vestiges of palaeostrand lines caused by sea level changes during the Pleistocene/Holocene period. The mass wasting near the shelf break off Godavari River could have led to the levelling up of the rise area with the slope giving rise to a smooth and cancave surface. The dissected topography of the northeastern part of the continental slope is inferred to be the effect of erosion and mass movement due to turbidity currents. The abyssal plain is influenced both by the peninsular rivers draining into the area as also by the Bengal Fan. The bathymetric surveys in abyssal plain delineated the boundary between western sedimentary basin influenced by peninsular river sediment and the eastern sedimentary basin having Bengal Fan sediment. The channels and valleys observed on the eastern side of this boundary are the continuation of Bengal Fan channels.
A Geostatistical Study of Alumina Content in Ores of an Indian Iron Ore Deposit
Authors: Kannan S. , Patel K. B. , Pandalai H. S.
Published: November 2024

Mining and blending operations in the high grade iron ore deposit under study are performed to optimize recovery with minimal alumina content while maintaining required levels of other chemical component and a proper mix of ore types. In the present work the regionalisation of alumina in the ores has been studied independently and its effects on global and local recoverable tonnage as well as on alternatives of mining operations have been evaluated.

The global tonnage recovery curves for blocks (20m x 20m x 12m) obtained by simulation closely approximated the curves obtained theoretically using a change of support under the discretised gaussian model. Variations in block size up to 80m x 20m x 12m did not affect the recovery as the horizontal dimensions of the blocks are small in relation to the range of the variogram. A comparison of the local tonnage recovery curves obtained through multiple conditional simulations made with that obtained by the method of unifonn conditioning of block grades on an estimate of panel 100m x 100m x 12m panel grade reveals comparable results only in panels which have been well conditioned and possesing an ensemble simulation mean close to the ordinary kriged value for the panel. Study of simple alternative sequence of mining on the conditionally simulated deposit shows that concentration of mining operations simultaneously on a single bench enhances the fluctuation in alumina values of ore mined.