bluuebunny/crossref_metadata_2025 huggingface dataset:
Occurrence of Ultramafic-Mafic Rocks of Komatiitic Affinity in the Abujhrnar Basin of Bastar Craton (ME), India
Authors: Parthasarathy T. N. , Rajasekharan P. , Manjunath Y. S. , Chaturvedi S. N. , Bose A.
Published: November 2024

Ultramafic-mafic rocks of komatiitic affinity are reported from the Kerali area of Abujhmar basin in Bastar Craton, Madhya Pradesh. These rocks, occurring below the Gundul sandstone member of the Middle Proterozoic Abujhmar group, are composed of peridotitic komatiites, pyroxenitic komatiites and basaltic komatiites, besides tholeiites and microgabbro emplaced into them as dykes. Petrographically, olivine and pyroxene occur both as major phenocrysts, and as microphenocrysts, with the groundmass made up of interstitial glass. Normatively, these rocks are both olivine and hypersthene normative. Petrochemical data plots on discriminant ternary diagrams such as AFM, Jensen Cation plot, MgO-CaO-AI2O3 diagram, indicate their close similarity to the komatiitic trends shown by the type area rocks from the Munro Township area, Canada and Yilgarn Block of West Australia very much paralleling the trend of Barbertonland komatiites. Trace element data involving Ti, Y, Zr and V plots also points out that these rocks fall in the kornatiitic field as against the tholeiitic field. Tectonic environment discriminant diagram involving the plots of these ultramafic-mafic rocks indicates the possibility of deep passive or 'failed' (?) rift in the region through which these ultramatic-mafic rocks of komatiitic affinity might have been emplaced.
Palaeoenvironment of Bist College Member in Krol Formation Nainital, Lesser Himalaya
Authors: Shukla U. K.
Published: November 2024

The Bist College member of Krol Formation, a locally developed arenaceous succession within the dominantly carbonate sequence is comprised of five major lithofacies, viz. (A) Thickly bedded fine to medium grained sandstone, (B) Cross-bedded sandstone, (C) lnterbedded sandstone-siltstone, (D) Rippled-parallel laminated fine-grained sandstone, and (E) Quartzarenite. The Bist College Member is characterised by repetition of lithofacies, and its deposition took place in subtidal-intertidal complex, in subtidal channels, tidalflat and tidal creeks. The clastic sedimentation of Bist College Member started as a result of increased influx of sediment from land and repetitive facies sequences were formed due to lateral shifting of depositional domains coupled with gradual subsidence. This terrigenous clastic sedimentation terminated with the reduced sediment supply from land, switching over to carbonate sedimentation of upper part of Krol Formation.
Remote Sensing Delineation of Zones Susceptible to Seismically Induced Liquefaction in the Ganga Plains
Authors: Gupta R. P. , Chander R. , Tewari A. K. , Saraf A. K.
Published: November 2024

Liquefaction in saturated sandy soils as a result of earthquake-induced shaking, poses a major threat to men and materials. Many parts of the Indo-Gangetic plains have experienced such catastrophes repeatedly. The border region of southern Nepal-northern Bihar (India) is a typical existing setting prone to soil liquefaction in the Indo-Gangetic Plains. The Bihar-Nepal earthquake of 1934 (Ms>8) and the earthquake of 1988 (Mb = 6.7) induced extensive liquefaction in the terrain in living memory. Characteristics of soil in this area of nothern Bihar have been determined from field samples. Various parameters (e.g. clay content, D50 - and C-values) indicate high susceptibility to liquefaction among soils in the area.

A close study of remote sensing data (Landsat TM and MSS) products reveals that the boundaries of liquefaction zone in the Bihar-Nepal region during the 1934 earthquake are identifiable on the remote sensing images. This is due to a combination of several inter-related factors, such as landform, soil type, soil moisture and vegetation. These clues have been applied as guides on the adjoining remote sensing images for delineating areas on a regional scale, where liquefaction might possibly occur in the Ganga plains, in the event of future Himalayan earthquakes.
Upper Pleistocene Soricidae and Muridae from Bhimtal-Bilaspur Deposits, Kumaun Himalaya, India
Authors: Kotlia B. S.
Published: November 2024

The first Upper Pleistocene micromammalian assemblage consisting of Soricidae and Muridae in the Indian sub-continent is described from the fluvio-lacustrine sediments of Bhimtal-Bilaspur area of the Kumaun region. North India. Two new species, Sorex reumeri sp. nov. and Mus dhailai sp. nov. are proposed. Considering nearly all the soricid characters, Sorex reumeri sp. nov. is found to be more derived than the Lower Pleistocene Sorex. It is suggested that Mus dhailai sp. nov. does not have any phylogenetic connection with the Plio-Pleistocene Mus so far reported from the subcontinent. The age of the fossil horizon is 730-40 ka.
Seismicity Impact in Patan Taluka, District Satara, Maharashtra
Authors: Patwardhan A. M. , Karmalkar N. R. , Panaskar D. B. , Meshram D. C.
Published: November 2024

The continued seismicity in the Koyna region has had the maximum impact in the Patan Taluka of the Satara District in Maharashtra within 30 km radius from the epicentral region of earthquakes. The Government of Maharashtra has undertaken rehabilitation of the villages which have suffered the damage and are threatened also by the collapsing edges of the overhanging lateritic cliffs. On the M.M. intensity scale the damages suffered by the settlements and lateritic plateau would indicate an intensity between VII and VIII. A high acceleration, maximum of 0.1 g (100 cm/sec2), is inferred for the soil profiles and alluvial tracts, loose gravel colluvium, river terraces material and weathered basalts on which the settlements are located. The continued seismicity around Koyna reservoir is often referred to as "reservoir induced", but such a mechanism is considered valid only for earthquakes originating from very shallow depths. For earthquakes whose hypocenters lie far below in the basement rocks (depth >3 km), the magnitude frequency relationship (26 years period) is similar to that observed in any tectonically active regions. It seems that the seismicity is related more to the reactivation of basement faults, reflected also in the overall geomorphological features of the region.
Evidences for a Volcanic Province in the Central Indian Basin
Authors: Iyer S. D. , Sudhakar M.
Published: November 2024

Based on various lines of evidence such as the widespread occurrence of basalts. pumice. volcanic glass shards and their transformational products (zeolites, palagonites, and smectite-rich sediments), we suggest the presence of a volcanic province in the Central Indian Basin (CIB). In addition to the rocks studied, the occurrence of many morpho-tectonic features such as seamounts, abyssal hills and major fracture zones at 73°E, 75°45'E and 79°E, have helped in correlating and in deciphering the source of the rock types. Further, the large manganese nodule fields in the CIB are seen to occur in conj unction with the volcanic materials, since the latter forms nuclei and substrates for ferromanganese deposits. It is concluded that a spatial relation exists between the occurrence of the volcanic materials and the ferromanganese deposits in the CIB.
Depositional Environmental History of the Chhattisgarh Basin, M.P., Based On Stromatolites and Microbiota
Authors: Moitra A. K.
Published: November 2024

The Proterozoic Chhattisgarh basin, comprising 2000m thick sediments mainly limestonel/dolomite, sandstone and shale, shows prolific growth of stromatolites and presence of micro biota dominantly cyanobacteria. Added to these there are many sedimentary features and structures found in the rocks throughoutthe sequence. Depositional environment is thus well doculnented by physicochemical factors in general and biological features in particular.

Based on all these biogeological features, it has been deduced that the deposition is largely marine under tidal flat conditions, sources of sediments being both precipitation as well as terrigenous material. Sedimentation shows a distinct cyclic pattern commencing with arenaceous facies culminating into argillaceous facies with intervening calcareous facies. During the waning stage of sedimentary history of the Chhattisgarh basin, the cycles repeated rapidly, interpreted from the intercalatory sedimentation of the upper horizon, namely Raipur Limestone. Disposition of stromatolites ancLtheir morphologies reveal low as well as high-energy conditions of deposition, levels of deposition being both intertidal and subtidal ones. The sedimentological, mineralogical and petrological evidences point towards an alternating oxidising and reducing environments throughout the sequence irrespective of cycles or lithologies.

Overwhelming dominance of procaryotic algae and absence (7 or near absence) of eucaryotic algae have possibly the following implications, namely the temperature during deposition was raised above 40°C at least for major part during deposition and also the pH of the environment. was 7 or more.
Lithostratigraphy and Alluviation History of Quaternary Deposits of Southern Part Of Gangetic Plain, Uttar Pradesh
Authors: Bhartiya S. P. , Narayan Shyam , Nigam A. C.
Published: November 2024

The Quaternary sediments of a southern part of the Gangetic Plain in parts of Allahabad, Banda, Fatehpur, Hamirpur, Pratapgarh and Raebareli districts of Uttar Pradesh have been classified into the Banda Older Alluvium (BOA), the Varanasi Older Alluvium (YOA) and the Newer Alluvium, each representing different eycles of sedimentation in basins of different configuration during different periods. The Banda Older Alluvium resting over the Bundelkhand Gneissic Complex or the Vindhyan Supergroup, represents the first cycle of Quaternary sedimentation which has been sub-divided into the basal Variegated clays and an upper Chitrakoot Formation. These sediments had their provenance in the Peninsular terrain. The Varanasi Older Alluvium constituting the second cycle of sedimentation comprises polycyclic sequence of sand, silt and clay with or without calcrete bands. Its sediments di ffers in mineralogical assemblage from that of Banda Older Alluvium and have been derived from Extra Peninsular region. The Newer Alluvium, the third cycle of sedimentation, has been sub-divided into Terrace Alluvium and Recent Alluvium confined within the palaeobanks of the rivers.

The evidences in favour of neotectonic movements recorded in the area are displacement of beds, deformational structures in Newer Alluvium, unusual straightening and abrupt changes in the river courses and sudden widening of flood plains or entrenchment of the rivers. An attempt has been made to work out the alluviation history of the Quaternary sediments of the area on the basis of available palaeontological data and some close lithological similarities.
Morphology and Recession of Miyar Glacier Lahaul - Spiti District, Himachal Pradesh
Authors: Prashra K. C. , Dasgupta S.
Published: November 2024

The Miyar glacier is a 28 km. long valley-type galcier with a number of transverse tributary glaciers, encompassing an area of about 110 sq. km of ice and snow in its basin. It has retreated by about 325 m between 1963 and 1983 with an average annual retreat of about 16 m. This phenomenon is comparable with similar recessionery trends of other galciers of Lahaul, which indicates deglaciation period still prevalent in this part of the Himalaya.
Foraminifera from the Bagb Group, Narmada Basin, India
Authors: Rajshekhar C.
Published: November 2024

The sediments of the Bagh Group lack keeled Cretaceous index/zone foraminifera, and therefore, are not suitable for standard biostratigraphic zonation. However, abundance of certain foraminiferal taxa, viz. Gavelinella piummerae, Siphogenerinoides clarki, species of Hedbergella, Archaeoglobigerina and Heterohelix globulosaare noticed in Nimar Sandstone Formation, Nodular Limestone Formation, and Chirakhan Limestone Formation respectively.

Overall foraminiferal assemblage which consists of more than 90% benthic and less than 10% planktonic elements is cosmopolitan and suggests a normal shallow marine environment of deposition. Frequency of foraminifera increases from the calc top ofNimar Sandstone to the uppermost marl and hence represents a transgressive phase.

The Bagh assemblage does not permit bed by bed correlation with the Cretaceous of Cauvery basin.
Geochemistry of the Phyllites of the Copper Mountain Region, Sandur Schist Belt, Karnataka
Authors: Krishna Rao B. , Hanuma Prasad M.
Published: November 2024

Chemical composition of the phyllites of the Copper Mountain region of the late Archaean Sandur Schist belt in the eastern block of the Dharwar craton indicates that the fine-grained clastic sediments from which they were formed, were derived from a provenance comprising -60% felsic, - 30% mafic and 10% ultramafic rocks. High Zr/Nb and Zr/Y ratios and lack of strong -ve Eu anomalies suggest that the felsic component of the provenance was dominantly made up of tonalites-trondhjemites; granites and granodiorites were very subordinate constituents. The sediments appear to have accumulated in a continental island are environment. Rarity of granitic constituents in the pre-Dharwar provenance of Sandur basin contrasts with the abundance of such constituents in the provenance for the fine-grained clastic sediments of basins in the western block of the Dharwar craton. The continental crust of the eastern block was apparently less evolved during the pre-Dharwar time as compared to that in the western block of the Dharwar craton.
Quaternary Stratigraphy and Sedimentation of the Indo-Gangetic Plains, Haryana
Authors: Thussu J. L.
Published: November 2024

Lithostratigraphy of the Indogangetic Plains in Haryana has been attempted on the basis of borehole data. Three geomorphic units have been identified. These show contrasting lithologies. Older sediments, represented by fans and piedmonts, essentially consist of a sequence of very coarse sediments. The Central Alluvial Plains (Ambala Older Alluvium) holds the bulk of the Quaternary sediments. Clay forms the dominant lithology in the southern part while alternate layers of sand and clay are predominant in the northern part. The main fluvial system seems to be in the northern part of the Central Alluvial Plain. Bulk of these sediments have been deposited under quiet condition with prolonged periods of semiarid type of climate. The occurrence of Quaternary sediments below the m.s.l. has been inferred due to faulting along WNW-ESE to E-W direction. Reactivation along north-south lineaments has also been inferred.
Mineral Matter in the Lrajmahal Coals: Study Through Incident Light Microscopy and Scanning Electron Micrography
Authors: Singh Mahendra P. , Singh Prakash K.
Published: November 2024

The Lower Gondwana coals of the Rajmahal group of coalfields have been studied, in detail, under the Petrological and the Scanning Electron Microscopes to elucidate the mode of occurrence of mineral matter and their microstructural relations with organic constituents. Observations of both the methods reveal the occurrence of mineral matter as massive impregnation, intimate inter growth, superficial mounting, superficial blanketting, pore filling and solution cavity filling. The absence of microstructures, when observed via incident light microscopy such as superficial blanketting and superficial mounting in the macerals and microlithotypes, in general. suggests their elimination during the course of grinding and polishing of the coal pellets. This suggests skewing of the mineral matter assessment through microscopic examination. The quantitative distribution of mineral matter in the coal lithotypes as observed in SEM is Durain> Clarain > Vitrain > Fusain while the ash analysis of different lithotypes shows the order of dominance of ash (equivalent to mineral matter) as Durain > Fusain> Vitrain > Clarain.
Petrogenesis of Quartz-Bearing Syenite Occurring Within Nepheline Syenite of the Elchuru Alkaline Complex, Prakasam Province, Andhra Pradesh
Authors: Ratnakar J. , Vijaya Kumar K.
Published: November 2024

A quartz-bearing syenite (QS) dyke cuts across the nepheline syenite (NS) in the Elchuru alkaline complex. The QS is leucocratic, medium grained and hypidiomorphic in texture. It is composed of K-feldspar, albite, amphibole, biotite and quartz. The QS has higher amounts of SiO2 Al2O3 and Na2O and, lower CaO and K2O than the average quartz syenite. The QS is metaluminous and oversaturated-in character. It has higher concentrations of Ga, Zr, Hf, Ta, V, Cr and U and, lower Ba, Rb, Sr, Y, Nb, Zn, Pb, Sc, Co, Ni and Th than fhe NS . The QS exhibits LREE-emiched and HREE-depleted pattern with a conspicuous negative Eu anomaly. The normalised incompatible trace element abundance pattern of the QS shows spikes for Ba, Ta and Y. A petrochemical comparison of the QS and NS suggests that they are derived from a feldspathic residual liquid by liquid immiscibility under variable PH2O and PCO2 conditions. This process mimics "branching differentiation" mechanism.
Occurrence of Sulphur Crystals in Sediments from Northwestern Part of Lower Bengal Fan
Authors: Sastry A. V. R. , Suresh K. V.
Published: November 2024

Sulphur crystals are identified in the silt size fraction of the deep-sea surface sediment samples collected from the northwestern part of the lower Bengal Fan opposite to the Krishna river.
Mineralo-Chemical Analysis of Ilmenites from the River Valliyar and the Manavalakurichi Beach, Tamil Nadu
Authors: Nair Ajith G. , Damodaran K. T. , Suresh Babu D. S.
Published: November 2024

Characterisation of ilmenite collected from the source to the mouth of the River Valliyar shows progressive alteration with the exception of a junction. where a major tributary joins the main stream. Mineralogical and compositional comparison between alluvial ilmenites and those collected from the beach sediments of adjoining area indicates that the River Valliyar partly contributes to the enrichment of the Manavalakurichi deposit. FeO/Fe2O3 and Ti/(Ti+Fe) ratios along with ore microscopic and XRD studies confirm the degree of alteration in the ilmenites of the study area.
Rutile Exsolution in Fe3+-chromites: A Case Study from Layered Granulitic Complex of Sittampundi, S. India
Authors: Mitra Sachinath , Samanta Asok Kumar
Published: November 2024

The presence of Fe3+ at both tetrahedral (A) and octahedral (B) sites (-45% of total iron). from Mossbauer spectroscopic data of Sittampundi chromite, strongly suggests that high fO2(10-7.30 to 10-7.34) conditions were prevalent during its formation. This Cr-spinel was formed with enough of Ti and Al (at its B-site) in its initial structure, attained while in the primary melt at high P-T field (>10.6 kbar, >950°C). The high fO2 in the crystallizing environment did not allow iron to remain as "free" Fe2+ ion to be stabilized into ilmenite structure. In chromite lattice, Ti4+ gets stabilized at Bsite only by coupled occupancy with bivalent cations, strongly with Fe2+. Inadequacy of Fe2+ content to charge-balance Ti4+ at B-site due to further oxidation of iron to Fe3+ caused an expulsion of Ti4+ from the chromite lattice. The released free Ti4+ ion readily combines with oxygen alone to form rutile (or its ilk) which comes out as acicular exsolution bodies within chromite, often following its crystallographic planes [along (111)].
Variation of Discharge and Solute Concentration in the Meltwaters of Dokriani (Bamak) Glacier, Garhwal Himalaya, India
Authors: Hasnain Syed I. , Thayyen Renoj J.
Published: November 2024

Electrical conductivity of proglacial and supraglacial channels of Dokriani (Bamak) glacier have been studied during August-September 1992 and October-November 1993. Specific conductance of meltwaters of proglacial stream varies inversely with discharge both on diurnal and temporal scale. Observed year to year variations in solute characteristics are probably due to the change in internal channel system of the glacier. The spatial and seasonal variations in solute enrichment of supraglacial meltwaters depend on contact time with surface moraines.
The Significance of the Genus Whiteinella in the Mid-Cretaceous of Cauvery Basin, India
Authors: Venkatachalapathy R. , Ragothaman V.
Published: November 2024

A study of 41 samples from the Karai-Kulakkanatham traverse revealed the presence of the genus Whiteinella which is recorded for the first time in this area. Three species of Whiteinella were identified. They are: Whiteinella archaeocretucea Pessagno, W. baltica Douglas and Rankin and W. brittonensis (Loeblich and Tappan). The position of Cenomanian - Turonian boundary event (CTBE) is placed between Rotalipora cushmani Zone and Whiteinella archaeacretacea Zone. The morphological description and stratigraphical importance of this species are discussed.
Potential Areas of Coal Seam Methane in India
Authors: Patra T. C. , Pandey A. K. , Datta H. C.
Published: November 2024

Coal-Seam-Methane (CSM) natural gas that has evolved from and is adsorbed by coal seams is a potential source of unconventional energy World over. In India, the major part of this resource is contained in five coal-bearing areas, broadly across the eastern quadrant, This paper presents the resutts of a detailed subsurface geological analysis of the potential Gondwana coal bearing areas such as Raniganj, Jharia, Bokaro, Karanpura and petroliferous basins of West Bengal for CSM exploration and exploitation.

The correlations of coal rank and depth with gas content were used along with coal volume to determine CSM in-place. More than 150 Tcf (Trillion cubic feet) of CSM has been estimated for Gondwana basins of India, of which 25 to 75% may be recovered depending on the number of seams completedin, the size of the stimulation, well spacing and pattern of alignment.
Event Stratigraphy and Physico-Chemical Characters of Banded Gneissic Complex and Associated Supracrustals in the South Mewar Plains of Rajasthan
Authors: Bose Utpal , Mathur A. K. , Sahoo K. C. , Bhattacharya S. , Dutt Krishan , Aneel Kumar V. , Sarkar S. S. , Chowdhury S. , Chowdhury I.
Published: November 2024

The oldest cratonic nucleus pf the Western Indian shield, familiarly known as the Banded Gneissic Complex (BGC), occupies a large tract in the Mcwar plains of South Rajasthan. It has essentially an old gneissic component (3.3 Ga) and a host of mafic bodies associated with detrital and chemogenic sediments which have been subjected to multiple phases of anatexis and granite intrusions (2.9 Ga and later events). The emplacement of Berach granite and succeeding dolerite dyke swarms mark the end-Archaean cratonization process. This also initiated intracratonic and cratonmarginal basin formation.

Later magmatism, especially along the basement-cover interface. is due to local remobilisation of the basement at the time of Proterozoic orogeny.
Titanium-Rich Phlogopites from the Zangamarajupalle Kimberlitic Rock, Andhra Pradesh, India
Authors: Chalapathi Rao N. V. , Madhavan V.
Published: November 2024

Electron probe studies on the phlogopites from the Zangamarajupalle kimberlitic rock (14°76'7" : 78°88'3" E) in the Proterozoic Cuddapah basin, Andhra Pradesh, reveal their titanium rich (6 wt%) nature - a character typical of lamproite micas. The compositions and their systematic variation in the phlogopite micas of the Zangamarajupalle-kimberlitic rock are compared and contrasted with those of other kimberlitic and lamproitic rocks including pipe-2 Wajrakarur, pipeS (Muligiripalle) and Maddur (Mahbubnagar) - all of which have an ambiguous identity. The utility of phlogopite compositions in discriminating between kimberlites and lamproites is emphasised and an attempt is made to classify the studied rock types accordingly and the implications are discussed.
Some Observations on the Geochemistry of Ramannapeta-Ustapalle Lamproitic Body, Krishna District, Andhra Pradesh
Authors: Chalapati Rao N. V. , Madhavan V.
Published: November 2024

Detailed petological and geochemical studies pertaining to the lamproitic body recorded by the Geological Survey of India at Ramannapeta-Ustapalle, Krishna district, Andhra Pradesh, are presented. Unmistakable lamproite signatures like the presence of Ti-rich potassic richterite, abundance of Ti-rich, Al-poor phlogopite and Ca-rich, Al-poor clinopyroxene, absence of primary calcite, paucity of typical kimberlite indicator minerals and the ultra potassic nature are recognised. Major oxide as well as the trace elemental abundances of the body are observed to be similar to those of the Chelima lamproites occurring within the intra-cratonic Cuddapah basin. The available radiometric ages of all the known Indian lamproites and kimberlites are taken into consideration and a mid-Proterozoic lamproite event in the Indian sub-continent is postulated.
Sediments of the Bharathapuzha, Kerala: Implications of Downstream Trends of Texture and Grain Shape
Authors: Anirudhan S. , Thrivikramaji K. P.
Published: November 2024

The results of analysis of textural parameters of channel sediment samples of the Bharathapuzha system using the scheme of McLaren and Bowles (1985) reveal the existence of Case B trend in the direction of transport for mainstream (Bharathapuzha) and two high gradient tributaries viz., Gayathcipuzha and Thuthapuzha. Further, Fourier amplitude spectra estimated from digitized data of grain boundaries of the sand grade sediment from selected samples and the Waddell's sphericity and roundness indices demonstrate that influx of sediment from tributaries does not alter the size or shape distribution trends of the mainstream sands to any extent.
Structural Geometry of the Rocks of the Southern Part of the Nallamalai Fold Belt, Cuddapah Basin, Andhra Pradesh
Authors: Matin Abdul , Guha Jaydip
Published: November 2024

A sequence of quartzite, banded phyllite and slate in the southern part of the Nallamalai fold belt shows a series of macroscopic gently plunging folds (DI) with NW-SE striking axial plane and a pervasively developed axial planar slaty cleavage. A weak later deformation has produced sporadic gentle folds (D2) with axial planes at high angle to the D1 fold axial planes.

The rocks along the eastern contact of the belt are mylonitized and the intensity of deformation gradually dies away towards west. A zone of tectonic dislocation is envisaged between the basement granite gneiss towards the east and the supracrustal Nallamalai rocks.
Ostracode Fauna of the Niniyur Formation (Palaeocene), Cauvery Basin, Tamil Nadu, Southern India
Authors: Mallikarjuna U. B.
Published: November 2024

A rich and interesting ostracode assemblage comprising 29 taxa, are recorded from the Niniyur Formation of the Cauvery Basin, Tamilnadu, Southern India. Of these, 6 species are new, 19 species are already reported and 4 species are left under open nomenclature. The new species are Hemicyprideis oertlii, Cyamocytheridea? niniyurensis, Costa niniyurensis, Stigmatocythere gowdai, Protobuntonia Jaini and Ponlocyprella niniyurensis. The present paper gives distribution, age and affinity of the fauna with systematic descriptions of six new species and four indeterminate species. The assemblage shows affinity to Palaeocene and Eocene forms of Western Europe, Saudi Arabia, Pakistan and other areas in India. The overall palaeontological evidences suggest a Palaeocene age for the Niniyur Formation.
Sr, Pb and Nd Isotope Studies and their Bearing on the Petrogenesis of the Jalor and Siwana Complexes, Rajasthan, India
Authors: Dhar Sunil , Frei Robert , Kramers Jan D. , Nagler Thomas F. , Kochhar Naresh
Published: November 2024

The Jalor and Siwana complexes belong to the Malani igneous suite, Rajasthan, India and are characterised by within - plate, A - type granites associated with coeval felsic and mafic volcanism. Sr, Pb and Nd isotopic compostions of the two complexes have been determined. Sr isotopic studies reveal an isochron age of 725±7 Ma for the felsic rocks of the Jalor Complex, with an initial 87Sr/86Sr ratio of 0.7062±0.0020. Three highly differentiated granites from Siwana plot on the same near-isochron, indicating that the complexes are coeval. The Pb and Nd isotopic ratios range between (206Pb/204Pb = 18.52-21.28, 207Pb208Pb = 15.58-15.98, 204Pb/204Pb/206Pb = 38.53-40.8) and (143Nd/144Nd = 0.5122-0.5127, 147Sm/144Nd = 1.1260-0.157) respectively. Pb and Nd isotopic compositions of the Siwana samples show that the magma is mantle derived; for the Jalor complex the combined Sr, Nd and Ph data indicate primary mantle derivation with a variable degree of crustal contamination. with the assimilated crust being most likely of Archaean age.The petrogenesis of the two complexes is interpreted as an effect of fractionation of a primary mantle derived magma, simultaneous with assimilation of rocks from the lower crust. The data further document the presence of Archaean crust in the area.
Distribution of Organic Matter, Iron and Manganese in the Estuarine Clay of Mangrove Sediments, Tellicherry, Kerala
Authors: Thamban M. , Reghunadh K. , Sajan K.
Published: November 2024

The surficial mangrove sediments in the estuarine course of Eranholi river were sampled at 21 locations and analysed for the determination of organic matter, iron and manganese in 2 mm size fraction of the sediments. The study indicated that the these constituents are apparently controlled by the spatial variation of the physico - chemical factors of the estuary such as pH and Eh, base exchange and adsorption characteristics and the texture of the sediments, tidal influence and proximity to the mangrove vegetation in the prevailing estuarine environment.
Ostracodes from the Ariyalur Group (Late Cretaceous), Cauvery Basin, Southern India
Authors: Mallikarjuna U. B. , Nagaraja H. M.
Published: November 2024

Fifty-two ostracode taxa are recorded from the Ariyalur Group (Late Cretaceous), Cauvery Basin, Southern India. Of these, seven are new, thirty-nine already reported and six left under open nomenclature. The new species are Cytherelloidea jaini, Curfsina Sastryi, Limburgina gowdai, L. mannikerii, L. guhai, L. khoslai and Pontocyprella ariyalurensis. The paper gives systematic description of seven species and revised/synonymised list of ostracode species reported earlier.
Carbonatite Dykes from Kudangulam Area, Near Cape Comorin, Tamil Nadu
Authors: Ramasamy R.
Published: November 2024

Occurrence of dyke rocks of carbonatites in charnockites and granite gneisses near Kudangulam village situated 20 km NE of Cape Comorin, Tamil Nadu is reported. Petrography and Chemical composition of these rocks reveal that coarse grained curbonatites were formed under subvolcanic miarolitic crystallization from a degassed carbonatitic melt.
Colour-Coded Compositional Mapping of Reaction Textures in a Calc-Silicate-Charnockite Interface at Nuliyam, Kerala
Authors: Satish Kumar M. , Santosh M. , Yoshikura S. , Yoshida M.
Published: November 2024

Colour-coded compositional mapping under an electron microprobe provides useful information on chemical gradients within the domain of individual minerals. Here we apply this technique to granulite facies reaction textures from a calc-silicate-charnockite interface at Nuliyam, southern Kerala, to understand the element mobility patterns and mass balance related to fluid-induced metasomatism during deep crustal metamorphism. The contact zone assemblage at Nuliyam is characterized by plagioclase + quartz symplectites after K-feldspar. From element mapping of this reaction interface on micron - scale, and from quantitative analyses of the individal mineral phases under an electron microprobe, we trace the diffusion of K, and addition of Na and Ca, through an open system migration dUling the influx of externally-derived CO2-rich fluids. Our study provides the first direct evidence for microscale chemical diffusion associated with CO2-induced charnockite formation in southern Kerala, and illustrates the potential of colour-coded compositional mapping in tracing element mobility patterns.
Mundwara Alkali Igneous Complex, Rajasthan, India: Chronology and Sr Isotope Systematics
Authors: Rathore S. S. , Venkatesan T. R. , Srivastava R. K.
Published: November 2024

Six whole rock samples have been dated by 40Ar/39Ar method to ascertain the emplacement time of the Mundwara Alkali Igneous Complex, Rajasthan, India. The dated samples include four from the Musala hill and one each from Mer and Toa hills of the complex. Out of these, only two syenite samples. viz. MR 86/4 and MR 86/7 from the Musala and Mer hills, respectively, have given plateaus at 64 Ma, while the remaining samples have exhibited saddle shaped spectra owing to the presence of excess argon. However, similar isochron ages of about 70 Ma obtained from a basalt (Musala hill) and a gabbro (Toa hill) by linear regression of all the data points might suggest initiation of igneolls activity at Mundwara around 70 Ma ago.

87Sr/86Sr ratios of this suite range from 0.70385 to 0.70551 indicating its derivation from a mantle source.
Contrasting Precambrian Mafic Dykes of the Bastar Craton, Central India: Petrological and Geochemical Characteristics
Authors: Srivastava Rajesh K. , Hall R. P. , Verma R. , Singh R. K.
Published: November 2024

Numerous mafic dykes occur within the Archacan-granite-gneisses of the Bastar (Bhandara) craton of central India. Width of these dykes varies from about 20 to 200 metres and are 1 to 20 kilometers long. The dykes trend mainly NW-SE, following the foliation of the granite gneiss and major regional structural trend. They mainly comprise two different types, one, amphibolitic and the other doleritic. The amphibolite dykes have a granoblastic texture whereas the unaltered dolerite dykes are ophitic or sub-ophitic. All of the dykes are sub-alkaline Fe-rich tholeiites. However, variations in the incompatible elements such as Nb, P, Ti, Zr, Y and the light rare earth elements (LREE), suggest that the Bastar dykes infact comprise two different sets. The amphibolite dykes were derived from an earlier relatively high-Mg, low-Ti olivine tholeiite magma. These dykes have high field strength element (HFSE) values only around six times higher than those of primordial mantle. In contrast, the doleritic dykes have fractionated HFSE levels 10 to 30 times higher than primitive mantle values; they are also characterised by a marked negative Sr anomaly not present in the older dykes. One subset of amphibolitic dykes corresponds geochemically to the predominantly doleritic swarm. These latcr dykes are derived from a low-Mg, high-Ti quartz-tholeiitic magma. The two different Bastar dyke sets are recognized here as the older, BD1 amphibolitic dykes and younger, BD2 doleritic dykes. Age constraints for these dykes are set by the ages of the enveloping host gneisses and discordant granitoids and hence they are placed at or near the end-Archaean.
Structural Patterns in the Sausar Group Around Mansar, Nagpur District, Maharashtra
Authors: Mohanty A. K. , Mohanty S.
Published: November 2024

The Precambrian rocks of the Mansar area, Nagpur district, Maharashtra, belong to the Sausar Group and the Tirodi Gneiss. Both these lithological units show an unconformable relation in the area, marked by a conglomerate at the base of the Sausar Group. The metasediments of the Sausar Group bear imprints of polyphase deformation. The folds of the first generation (F1) are isoclinal with high amplitude to wavelength ratios and pervasive axial planar cleavage (S1). The structures of the second generation are represented by WNW-ESE trending upright isoclinal folds (F2) and axial planar crenulation cleavage (S2). Gentle upright folds with NE-SW striking axial planes represent structures of the third generation (F3) Superposition of F2 folds on F1 folds is marked by mushroom shaped interference pattern in small-scale. Because of upright isoclinal nature of F2 folds on WNW-ESE striking axial planes, the metasedimentary bands extend in E-W direction. Slight arcuate geometry of the metasedimentary bands is the result of superposition of F3 folds on F1/F2 folds.
Significance of Peat on the Western Continental Shelf of India
Authors: Mascarenhas Antonio
Published: November 2024

Peat layers 2 to 30 cm in thickness, 22 to 46 m below present sea level, are found along the inner shelf of India, up to 27 km from the coast. They are rich in plant debris, organic carbon and sulfur. These organic-rich layers are not sedimentary deposits. Lack of favourable substrates, absence of sheltered habitats, high energy physical environments, and a very rapid sea level rise during early Holocene indicate an unfavourable paleogeography and adverse oceanographic conditions for mangrove development and in situ peat formation. On the contrary, significant siliciclastic minerals, lithogenous elements and type III kerogen suggest a continental origin of peat. Restricted thickness, limited lateral distribution, absence of matted structures and laminated deposition imply transport of organics. Anomalous ages of wood with respect to present sea level are evidences of sediment reworking. Hence, peats on the continental shelf are not transgressive deposits.
Diversity of Planktonic Foraminiferal Assemblages From Quaternary Sequences at DSDP Sites 219, 220 and 241 in Northern Indian Ocean
Authors: Sarkar Ashish , Guha Asit K.
Published: November 2024

The Quaternary planktonic foraminiferal assemblages from DSDP Sites 219,220 and 241 in Northern Indian Ocean have been analysed in terms of diversity changes along the depth of each core. For an understanding of the population dynamics in the region and its relation to the paleoclimatic events (Ericson zones), relative abundance at family and species levels have been studied. Different indices of diversity viz., S, D, Hand E have been worked out and correlated with that of the oscillation in paleoclimatic record, which is based on the fluctuation in abundance of Globorotalia menardii along the depth of the core. It has been noted that during the Quaternary, relative abundance of different species and changes in diversity indices match well with that of the Ericson paleoclimatic zonation, enabling recognition of different stages of glacial and interglacial episodes in Northern Indian Ocean.
Clay Mineralogy of Argillites of the Precambrian Iron Ore Group, Noamundi Basin, Eastern India
Authors: Sambasiva Rao V. V. , Dasgupta H. C.
Published: November 2024

Clay mineralogy of the Precambrian argillaceous rocks of the Iron Ore Group from the Noamundi basin, is represented mainly by kaolinite and illite. In general. the kaolinite/illite ratio, the illite crystallinity and the (060) peak position and (002)/(001) peak height ratio of illite change systematically from the stratigraphically higher upper shales to lower shales and suggest diagenetic neoformation of illite in these rocks. Dominance of 2M1 polytype of illite in both the upper and lower shales, the range of illite crystallinity values and the absence of pyrophyllite in the assemblage indicate a maximum of epizone condition of metamorphism (-360°C/2kb) for these sediments. Growth of illite during diagenesis and paucity of chlorite indicate that the detrital sediments which accumulated in the basin were rich in kaolinite but poor in smectite group of minerals. The overwhelming dominance of kaolinite in the initial detrital physil input to the basin. its prolonged persistence and the non-opaque heavy mineral assemblage comprising mainly tourmaline, hornblende and zircon in the sand fraction suggest a granitic provenance and a non-marine condition of deposition for the sediments.
Ferromanganese Encrustation from Laksbadweep Area, Arabian Sea
Authors: Charlu T. K. , Kalluraya V. K. K.
Published: November 2024

Ferromanganese encrustation is reported from the central Lakshadweep area along the northern flank of Chetlat Island. It has comparatively high contents of Co, Ni, Ag and Pt and a MnlFe ratio of <1. This hydrogenous encrustation is similar in composition to those from the equatorial Mid-Atlantic Ridge.
Carbon, Oxygen and Uranium Isotopic Study of Uraniferous Dolostone from Cuddapah Basin, Southern India : Implications to Depositonal Environment and Uranium Alteration
Authors: Bhattacharya S. K. , Sarin M. M. , Roy Minati , Dhana Raju R.
Published: November 2024

The dolostones show a narrOw range of d13C values but a large range of d13O values. The small spread of d13C from 0.1‰ to -0.9‰ is typical of marine carbonates, whereas the large range of d13O from -7‰ to -14‰ represents characteristic Proterozoic marine carbonates some of which were exposed to alteration by fresh continental waters. A diagenetic environment of mixed marine and fresh water for the dolostone alteration is also supported by earlier studies in sedimentary structures and petrography. The 234U/238U activity ratio of 0.7 in some of the mineralised samples shows the effect of ongoing chemical leaching of uranium from discrete uranium minerals like pitchblende and coffinite.
Fluid Inclusions in Migmatites from Hunsur, Karnataka
Authors: Srikantappa C. , Venugopal L.
Published: November 2024

Fluid inclusion studies in migmatites around Hunsur document the presence of a) CO2-CH4, CO2 and CO2-H2O inclusions in paleosome, b) predominantly CO2 inclusions in leucosome and c) CO2 and low salinity aqueous inclusions in late pink granite.

Chronological studies of CO2 inclusions in quartz grains from migmatites and their densities corresponding to Th maxima plus mineral P-T data for the regional metamorphism indicate that they are syn-migmatitic fluids. An internal origin of CO2 inclusions during the process of migmatization is envisaged.
Chemostratigraphy of Sedimentary Sequences: A Review of the State of the Art
Authors: Das Nachiketa
Published: November 2024

Chemostratigraphy of sedimentary sequences involves the application of major- and trace-element geochemistry for the characterisation and subdivision of sedimentary sequences into geochemically distinct units and correlation of strata in sedimentary basins. Chemostratigraphic correlation is particularly applicable to sequences that have very poor biostratigraphic control or to thick. rapidly deposited sequences that cannot be subdivided further by biostratigraphic data.

In order to maximise the number of geochemical characteristics of a given sediment, it is important to determine as many elements as possible. Such characterisation now routinely involves the analytical determination of concentrations of approximately 50 elements. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS) enable the rapid acquisition of major- and trace-element data for a large number of elements. Elements of simple mineralogical affinity, limited or no involvement in diagenetic activity and high concentration in refractory minerals are most suitable for chemostratigraphic correlation purposes.

Chemostratigraphic correlation is carried out on a reservoir scale as well as on a basin-wide basis for inter well correlation. The major- and trace-element data generated for chemostratigraphic correlation purposes could also be applied to studies of provenance and basin evaluation, diagenesis, reservoir characterisation and interpretation of wireline logs. In this review article, five case studies are also discussed in brief to demonstrate the applicability of chemostratigraphic correlation.
Diagenetic Effects on Sandstone Reservoirs of Nannilam Field, Cauvery Basin
Authors: Lahiri G. , Hardas M. G.
Published: November 2024

The Cretaceous Sandstones in Nannilam Field of Cauvery Basin, have a few significant hydrocarbon reservoirs. In general, Upper Creataceous Sandstones are good quality reservoirs with mostly intergranular and interconnected dissolution pores while Lower Cretaceous Sandstones are low-quality reservoirs with mostlymicropores and a few interconnected pores.
Evolution of Inter-Montane Kargil Basin (Oligo-Miocene), Ladakh Himalaya: A Sedimentological Approach
Authors: Kumar Rohtash , Virdi N. S.
Published: November 2024

Sedimentation pattern, palaeocurrent data and architectural elements indicate that deposition took place in three stages. The first stage (Kargil Formation) was dominated by alluvial fan to distal braided streams flowing over northeast and east directed palaeoslopes. The second stage (the Tharumsa Formation) involved deposition initially by gravelly braided to sandy braided and finally by distributary channels flowing due SW and south. The third stage (the Pashkyum Formation) showing an upward coarsening sequence occurred initially by braided channels followed by prograding alluvial fans in the north and portheast directions. Sedimentation during the Kargil and Tharumsa formations was accompanied by episodic tectonic upheavals along the western and eastern margin, while the Pashkyum indicates a gradual uplift towards the southern margin of the basin.
Dugwell Inflows from Shallow Deccan Basalt Aquifers
Authors: Kulkarni Himanshu , Deolankar S. B.
Published: November 2024

Inflow conditions represent an important aspect of dugwell drawdown and recuperation in shallow Deccan basalt aquifers. "Inner" boundary conditions like well storage, connection between the well and aquifer and distribution of inflow zones representing the hydraulic conductiviy around dugwells can be deciphered from drawdown and recovery data of dugwells tapping a typical shallow phreatic aquifer from the Deccan basalts. It is possible to calculate the aquifer response of a dugwell during drawdown and recovery phases. The inflow conditions in dugwells and their effect on the drawdown and recovery can be well illustrated by plotting well logs alongside single logarithmic graphs of drawdown and recovery against time. Diagnosis of such graphs reveals how the hydraulic conductivity around the dugwell influences segments of the drawdown and recovery of dugwells.
Analyses of Ground Magnetic Anomalies Over a Part of Vindhyan Basin around Damoh and Jabalpur Districts, Madhya Pradesh
Authors: Singh V. P. , Singh O. P. , Singh C. L.
Published: November 2024

Detailed ground magnetic survey over a part of the Vindhyan basin around Damoh and Jabalpur (40 km either sides of Hirapur-Mandala DSS profile) has been carried out. The magnetic field anomaly map is characterised by dense contours in trap covered areas near Jabalpur where as the Vindhyans show sparsely distributed contours with several lows. Spectrum analysis of total ground magnetic field anomalies reveals the average thickness of Vindhyans to be 3.9 km and depth of Conrod to be 15km. The average thickness of Vindhyans is in conformity with the Deep Seismic Sounding results of the region. The thickness of Vindhyan sediments along four profiles ranges from 1.5km to 5km. The maximum thickness of Vindhyan sediments at Jabera has been derived to be 4.8km which is close to the results of Oil and Natural Gas Corporation Ltd., Dehradun.