bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sapphirine, Kornerupine, and Sillimanite + Orthopyroxene in the Charnockitic Region of South India
Authors: Grew Edward S. 
Published: November 2024

Abstract
Sapphirine, kornerupine, and the associations sillimanite-orthopyroxene and sillimanite-gedrite are reported from 23 localities (or areas of closely spaced localities) in Fermor's (1936) charnockitic region and in transitional zones to Fermor's non-charnockitic region in south India (Andhra Pradesh, Tamil Nadu, and southern Karnataka). The rocks containing these minerals and mineral associations are believed to have a pelitic sedimentary precursor. They are in general closely associated with khondalite (garnet-sillimanite gneiss), quartzite, and calc-silicate rocks, and less commonly with metabasites of presumed metavolcanic origin. However, the sapphirine occurrences in the Sittampundi anorthosite complex, where sapphirine and sillimanite-gedrite are found in reaction zones between anorthosite and chromite layers, are an exception. Assemblages of sapphirine with garnet and sillimanite are not rare, but sapphirine in direct contact with quartz, which has not previously been reported from south India, was found at Paderu, Vishakhapatnam District, A. P. Kornerupine occurs with sillimanite at three localities but with orthopyroxene only at Ganguvarpatti, a new locality for kornerupine. Temperatures and pressures calculated from pyroxenes, garnets, and feldspars in associated rocks suggest that sapphirine, kornerupine, and sillimanite-orthopyroxene crystallized at 800-850°C and 6-10 kbar in the charnockitic region and sapphirine at 780°C in a transition zone between the granulite and amphibolite-facies near Sargur. Water partial pressure during the metamorphism was significantly less than total pressure. Regional differences in pressure are reflected in the distribution of mineral assemblages: sillimanite-orthopyroxene is found in Madras and Andhra Pradesh, but is conspicuously absent in the Palni Hills, where spinel-cordierite is an important assemblage. Sapphirine and sillimanite-orthopyroxene (and sillimanite-gedrite) are restricted to rocks relatively rich in Al2O3 with high Mg/Fe ratios relative to khondalite. Kornerupine appears to be confined to rocks containing boron. These special rock compositions (except Sittampundi) are believed to reflect unusual compositions of the precursor pelitic sediments rather than changes in chemistry during metamorphism.
Palaeogeographic Reconstruction of the Jaffna Peninsula, Sri Lanka
Authors: Senaratne A. , Dissanayake C. B. 
Published: November 2024

Abstract
The study of the tonal variations of aerial photographs showing the vegetational cover in the Jaffna Peninsula of the north of Sri Lanka clearly points to the progressive formation of spits and lagoons. The contrasting tonal variations of the vegetation found in the emerging lands of different ages can be used to some extent effectively in the delineation of lands in a chronological sequence as exemplified by studies in the Karativu island.
The Early Precambrian Crust with Reference to the Indian Shield: An Essay
Authors: Glikson A. Y. 
Published: November 2024

Abstract
The existence of several greenstone generations and of continuous transitions between gneiss-greenstone terrains and granulite terrains in the Indian Shield allow a unique insight into the structure and evolution of the Archaean crust. The long standing controversy on granite-greenstone relations reflects contrasting basic assumptions, methods and criteria. Many of the problems reflect the uncertain significance of Rb-Sr ages, which often represent thermal resetting events. Correlations between volcanic units in separate greenstone belts and between shallow and deep crustal zones should be soon enabled by U-Pb and Sm-Nd isotopes. The concept of greenstone belts as primary basins is not applicable to the oldest supracrustals whose remnant enclaves and xenoliths are distributed on all scales throughout the Peninsular Gneiss. The oldest directly identifiable rocks in south India consist of ultramafic-mafic-anorthosite-pelite-chert assemblages of the Sargur Group intruded by ca 3.3 Gyr gneiss. While sialic nuclei may have been present, a pre-existence of regional sialic crust is inconsistent with the petrological, geochemical and isotopic characteristics of the dominant tonalite-trondhjemite components of the Peninsular Gneiss. The gneisses are extensively imprinted by a ca 3.0 Gyr thermal event which reset Rb-Sr systematics, but left least-reset isotopic 'windows' such as around Hassan. The age of the discrete depositories in which the Dharwar Supergroup volcano-sedimentary successions accumulated remains to be clarified. These rocks were possibly deposited in rifted zones floored by Peninsular Gneiss blocks, older greenstones and simatic gaps. The formation of charnockites and the generation of K-rich adamellites about 2.7-2.6 Gyr ago may have been genetically linked and appears to have been essentially imprinted on the older gneiss-greenstone system. Repeated thermal rises at infracrustal levels during the Proterozoic resulted in isotopic resetting of Rb-Sr systems in the Eastern Ghats granulite-gneiss belt. The temporally unique nature of the Archaean Era and major unresolved questions are pointed out.
Carbonatite-Alkaline Complex of Mundwara
Authors: Narayan Das G. R. , Sharma C. V. , Navaneetham K. V. 
Published: November 2024

Abstract
Two types of carbonatite dykes - alvikite and beforsite are associated with (the Mundwara alkaline igneous complex. Petrochemical and mineralogical studies indicate enrichment of alkalies and niobium. Pyrochlore is noted in beforsites along with dolomite, apatite, barite and flourite, whereas calcite, ankerite, heamatite, aegirine, apatite and barite are noted in the alvikites. The presence of both metasomatic as well as intrusive syenites are noticed. Higher content of Nb is noted in the syenites containing sphene, aegirine and magnetite.
The presence of annular fractures around the plutons and the arcuate shatter zone with breccia on the outer margins of the Mer pluton indicate upwarping and later intrusion of carbonatites through the Erinpura granite. High P2O5 and Nb content of the soil samples around Mer Pluton suggest possible existence of a carbonatite plug below.
Mantle Convection Pattern under India: Relevance to Lonar Crater, Girnar Node and Peri-Indian Volcanism
Authors: Crawford A. R. 
Published: November 2024

Abstract
The mantle convection pattern under India as calculated by H-S Liu shows only two points of upwelling, which correspond with the Lonar crater and the Girnar circular complex. This suggests that Lonar is more likely to be endogenic rather than of impact origin. The Ramgarh crater, having no such correspondence, is more likely to be an impact. The pattern also shows upwelling in the vicinity of the Taftan volcano of southeastern Iran.
Ree Geochemistry of Pink Granulites from North Arcot District, Tamil Nadu
Authors: Kutty T. R. N. , Anantha Iyer G. V. , De Poli E. 
Published: November 2024

Abstract
Petrography, mineral chemistry, major elements as well as Rb, Sr, Ba and REE geochemistry of pink granulites and the associated charnockites have been studied. Pink granulites are prograde rocks metamorphosed under granulite facies condition. There is no genetic relation between potassic pink granulites and tonalitic charnockites and their geochemical evolutionary trends are distinctly different. K/Rb ratios are in the same range, although abundance level of K and Rb in pink granulites is high. Charnockites have higher Sr and lower Rb/Sr. Pink granulites have variable Sr level, high Rb/Sr and variable Ba/Sr indicating heterogeneity in the parent rocks. REE abundance level in pink granulites shows wide variation; non-uniform but negative Eu anomaly, strong fractionation with respect to LREE, positive slope after Gd and lower ∑LREE/∑HREE ratio (5 to 26). Charnockites have coherent REE patterns, with strongly fractionated LREE and slight positive Eu anomaly and higher ∑LREE/∑HREE (30-70) ratios. Field relation, mineral paragenesis, whole rock chemistry, Sr-isotope ratios and REE geochemistry strongly support sedimentary parentage for the pink granulites. The highly fractionated REE patterns of the associated charnockites reflect not only igneous inheritance but also the effect of granulite grade metamorphism.
Gravity Field and Tectonics in Karanpura-Daltonganj Coalfields, Eastern India
Authors: Verma R. K. , Mukhopadhyay M. , Ashraf M. H. 
Published: November 2024

Abstract
Both coalfields are marked by significant gravity 'lows'. Maximum sedimentary thickness present is of the order of 1. 75km below the surface under the Karanpura and 0.8 km under the Daltonganj coalfields. The two coalfields, are characterized by prominent normal faults at their southern margin. The throw of the faults may be few hundred metres, Within the individual coalfields, basement faults appear to be associated with younger Gondwana sediments on the surface. The areas occupied by youngest Gondwanas do not necessarily represent the deepest part of the coalfields. This is noted, in general, for nearly all coalfields of the Damodar Valley. Differential movement appears to have occurred during Gondwana times under the coalfields resulting in either single-walled or double-walled grabens.
Deformation Structures in Pegmatite, Aplite and Quartz Veins in Delhi Group Rocks
Authors: Bhola A. M. , Varadarajan S. , Khosla Virender 
Published: November 2024

Abstract
Pegmatite. aplite and quartz veins of varying dimensions occur in association with pelitic schists, calcareous rocks, quartzites, amphibolites belonging to Ajabgarh Formation, Delhi Group in the Narnaul area and act as important structural markers.
The polyphase nature of deformation of the rocks with which these veins occur, is shown by rotation of boudins, presence of overturned tight isoclinal folds resembling F1, presence of F2 folds and refolded folds shown by quartz veins, refolding of limbs of folded pegmatites by folds resembling F3. Features like boudins, pinch and swell structures shown by quartz veins and pegmatites at the limbs and along the axial planes of F1 folds with S1 development in the host rock and attenuation and disruption of limbs of tight folds resembling F1 shown by these veins also point to significant amount of flattening during F1 folding phase and longitudinal stretching in the late stage of their development. Slippage in the later stages of deformation phase (F3) is also distinctly borne dy displaced aplite veins.
A New Approach to the Lithostratigraphy of the Cenozoic Sequence of Kerala
Authors: Raha P. K. , Sinha Roy S. , Rajendran C. P. 
Published: November 2024

Abstract
A lithostratigraphic classification of the Cenozoic sedimentary sequence of the coastal plains of Kerala has been developed through an analysis of the exposed and subcrop litho-facies and their interrelationship based on sedimentologic parameters. The entire Cenozoic sequence is designated as the Malabar Supergroup comprising the Vembanad Formation (Quaternary-Holocene) and the Warkalli Group (Tertiary) separated by an unconformity marked by laterite. The Warkalli Group comprises the Ambalapuzha, the Quilon and the Mayyanad Formations from top to bottom. The Ambalapuzha and the Mayyanad Formations are basin margin fluvial and deltaic facies comprising sandstones, clays and lignites, and having a wedge of calcareous platform facies of the Quilon Formation. With the thinning out of the Quilon Formation (calcareous facies) in the eastern margin of the basin, the distinction between the constituent formations of the Warkalli Group disappears. Thus the purely terrigenous sediments in the eastern and southern margins of the basin form a single non-classifiable unit, the Warkalli Formation.
Deccan Trap Intrusion: Magma Mixing in the Chakhla-Delakhari Sill, Chhindwara District, Madhya Pradesh
Authors: Sen Gautam 
Published: November 2024

Abstract
Strong variations exist in compositions of olivine, plagioclase and pyroxenes within individual hand specimens of this differentiated sill. Such intergrain variations and zoning features were studied with the electron microprobe. These compositional variations can be explained by mixing between liquids that have undergone different degrees of differentiation at different parts of the sill. The mixing effect is illustrated with respect to phase equilibria in the anorthite-saturated surface forsterite-fayalitesilica in the system CaAl2Si2O8-Mg2SiO4-Pe2SiO4-SiO2. It appears that the mixing of these differentiated liquids has occurred along the surface pl + o1 + Ca-poor px + 1 in the natural multicomponent equivalent of the simple system.
Computer-Assisted Trend Surface Mapping-An Aid to Geochemical Exploration in the Sargipalli Lead-Zinc Mine Area, Sundergarh District, Orissa (India)
Authors: Roy A. 
Published: November 2024

Abstract
Computer-aided trend surface mapping of the Pb values from the Sargipalli Pb-Zn mineralized belt (Orissa) revealed that the fourth-degree surface (trends and residuals) is of utmost significance for prediction of further promising pay zones of the unexplored extension areas.
Uranium Mineralization in Singhbhum Shear Zone, Bihar II. Occurrence of 'Brannerite'
Authors: Krishna Rao N. , Rao G. V. U. 
Published: November 2024

Abstract
Composite grain-aggregates of titanium and uranium oxide phases resemble, both in texture and composition, those described as 'brannerite' grains occurring in quartz-pebble conglomerate-type uranium deposits such as those of Witwatersrand in South Africa and Blind River in Canada. The grain-aggregates contain variable amounts of quartz, rutile, anatase, uraninite, brannerite (s.s), pyrite, galena and hematite. Intimate inter-growths of uranium-rich and titanium-rich phases are observed. 'Brannerite' grains are secondary in origin, both detrital and metamorphic ilmenite being the antecedent mineral. They have been formed by the action of uranium-bearing solutions on ilmenite under conditions which favoured (i) alteration of ilmenite to titania by removal of iron (ii) simultaneous precipitation of uranium from solutions as uraninite and (iii) adsorption of uranium by titania. This can take place under both reducing and oxidizing conditions.
Erosion Intensity in a Mountain Watershed in the Himalayan Region
Authors: Narayan Devendra , Tandon S. K. , Joshi D. D. 
Published: November 2024

Abstract
A simple method for mapping of erosion intensity in a mountain watershed based on assignment of qualitative indices to various categories of geomorphic features, mean ground slopes and lithological cum structural state of the bedrock is proposed.
A preliminary case study has been conducted in a part of the Ravi drainage basin in the Himalayan region. The major geomorphic features observed are fill-cut and strath terraces, alluvial fans, landslides, small talus cones and debris-flow deposits. The slopes range from 4° to 41° and have been divided into seven classes consisting of 6° intervals each. Lithologically, the area consists of phyllite, quartzite, slate, limestone, conglomerate and granite. An erosion intensity map of this region indicates that most of the high erosion areas lie close to the main river and their distribution is controlled mainly by the recent drift material and the valleyside slopes.
Although this method is qualitative, it can be useful for a preliminary evaluation of erosion intensity. and for delimiting high erosion areas for environmental planning.
Geochemistry and Petrogenesis of Basic Dykes of Agali Area, Palghat District, Kerala
Authors: Sinha-Roy S. , Radhakrishna T. 
Published: November 2024

Abstract
A basic dyke swarm trending ENE-WSW traverses the Agali area of north-central Kerala. The geochemistry of these dykes suggests that they are transitional in character between continental and oceanic basalts. and are akin to one of the magmatic phases of the Deccan volcanics. They have been derived from a tholeiitic magma generated by partial melting of a heterogeneous mantle containing minor amounts of phlogopite and apatite. Fractionation of clinopyroxene. magnetite and plagioclase is indicated. The present study supports one of the earlier suggestions that these dykes are related to the rifting of the western continental margin of India.
Opaline Silica in Tertiary Sediments of Kerala
Authors: Ghosh Swapan K. , Raha Pulak K. 
Published: November 2024

Abstract
Smooth and well rounded grains of opal are recorded in the Tertiary sediments exposed in Trivandrum and Quilon districts and from deeper levels in the subsurface sediments near Ambalapuzha, in Alleppey district of Kerala. The clear to translucent opal grains vary in size from 0.05mm to about 3mm. Opaline casts of fossil tests with characteristic shapes and organic structures on their surfaces suggest organic activity in selective precipitation of opal inside fossil tests. Silica infillings in partly broken shells of gastropods were also observed. Difference of pH level in porewaters and inside the fossil tests favoured by organic decay in them is considered to be the main controlling factor for their formation.
Micro-Lineament Analysis and the Palaeostress Environment in Ishwarakuppam Dome Area, Cuddapah Basin, Andhra Pradesh
Authors: Ramasamy S. M. , Sinha Manohar , Devaprasad C. 
Published: November 2024

Abstract
Stress environment of Ishwarakuppam dome area, Cuddapah Basin, has been interpreted through micro-lineament analysis. The strain history suggests deformation under horizontally disposed maximum and least principal stress axes having WNW-ESE and NNE-SSW orientations.
Algal Genus Aethesolithon from Neogene of Little Andaman Island
Authors: Venkatachalapathy V. , Gururaja M. N. 
Published: November 2024

Abstract
The paper records the occurrence of the red alga Aethesolithon from the Neogene limestone of LittIe Andaman Island in the Bay of Bengal. Two species of the genus are described. The new find is significant, for it is the first of its kind from Andaman area and is suggestive of its common occurrence between Andaman and Pacific regions in Miocene.
The Origins of the Closepet Granites and the Implications for the Crustal Evolution of Southern Karnataka
Authors: Friend C. R. L. 
Published: November 2024

Abstract
The origin of the late Archaean Closepet granites by in situ anatexis of amphibolite facies Peninsular gneisses is discussed.
The Closepet granites which are essentially post-tectonic, cut the high-grade metamorphic fabrics found in the Peninsular gneisses. They show no effects of the regional deformation and of the foliation, forming events found in the Peninsular gneisses. Additionally, the granites have escaped metamorphism except in the south where they are statically overprinted by charnockite. Since the charnockite may be shown to be syn- and post-Closepet granite it follows that there may be two granulite facies events: (1) belonging to the evolution of the Peninsular gneiss; and (2) the late-stage formation of charnockite, which is in some places static whilst in others may be accompanied by deformation.
The Closepet granites may thus be used to clearly separate the charnockite from the early evolution of the Peninsular gneisses.
Experimental studies on Magnesite Genesis - Application to the Magnesite Deposits Associated with Ultramafic Rocks
Authors: Venkataramana P. , Kutty T. R. N. , Anantha Iyer G. V. 
Published: November 2024

Abstract
Previous experimental studies on magnesite formation which are confined to temperatures greater than 250°C, do not explain all the field and petrographic observations in natural situations where magnesite is associated with ultramafic complexes, as at Dodkanya, Mysore district, Karnataka.
A series of experiments were conducted using natural samples (rock and mineral powders) as starting materials. The experimental temperatures were varied from 35° to 300°C at intervals of approximately 50°C and normal and elevated pressures (500 and 1000 bars). At higher pressures, the XCO2 in the fluid phase was also varied.
These studies have shown that magnesite and quartz can be formed directly by the interaction of CO2-bearing water vapour and ferromagnesian minerals (olivine, orthopyroxene) without passing through the intermediate serpentine stage. The temperature conditions at which these reactions take place is between 150 and 250 °C at 500 bars total pressure with XCO2 in the fluid phase greater than 0.015. The presence of Na+ salts enhances these reactions.
The presence of calcite-aragonite-quartz-aluminous hydroxide gel-limonite (birbirite) cap rock intersected by a network of magnesite veins in Dodkanya and surrounding areas has been explained on the basis of experiments with natural hornblende, the major Ca2+-bearing mineral in hornblende-peridotites. Hornblende, under hydrothermal conditions, breaks down to calcium silicate hydrate (CSH). CSH, being unstable in the presence of CO2, inverts to CaCO3 (calcite/aragonite) and quartz. Mg2+ in trace quantities stabilises aragonite.
Carbonates of Chiknayakanhalli Schist Belt, Karnataka
Authors: Devaraju T. C. , Anantha Murthy K. S. 
Published: November 2024

Abstract
Carbonates of the Chiknayakanhalli (CN halli) area include (i) dolomite, (ii) limestone, (iii) ankerite and (iv) calc-schist. Of these, dolomite is the most widely developed rock. chemically the CN halli carbonates cover a wide range from almost pure calcite and dolomite-ankerite to Mg-limestone, shaly limestone and cherty limestone/dolomite/ankerite. In their trace element content, the rocks are typically much depleted in comparison with carbonatites. Available evidence indicates overall primary chemical sedimentary deposition of the carbonates in a barred basin with a gradual rise in salinity, pH, temperature and Mg:Ca ratio of the environment. Evidence of dolomitization is limited to the border zones between limestone and dolomite and there is no recognizable indication of organic activity.
Inter-Relationship of Tectonism and Sedimentation in the Jharia Basin
Authors: Mukhopadhyay Abhijit 
Published: November 2024

Abstract
The Jharia Coal Basin is composed of 2900 m of fresh-water Gondwana sediments deposited on the mature pediplained Archaean basement. The consistent fresh water features of the sediments indicate that the sedimentation kept pace with general subsidence. From the analysis of lithological attributes it can be postulated that there were longer intervals of rapid subsidence when fluviatile sediments were deposited; these alternated with shorter intervals of relative tectonic quiescence or slower rate of subsidence, favourable for the development of the regional coal seams. The subsidence was maximum during the Upper Barakar and Barren Measure times.
Geology of Karara Volcanic Vent, Rajasthan
Authors: Ranawat P. S. , Dashora R. S. 
Published: November 2024

Abstract
Fluorspar veins in Karara area occur in a variety of pyroclastic and flow rocks. represented by volcanic breccias, lapilli tuffs, and welded tuffs including ignimbrite. Lavas produced are of the nature of basalt. andesite, trachyte, dacite, and rhyolite along with their border line varieties.
Tertiary Fishes and Molluscs from the Kuksho Formation of the Indus Group, Near Nyoma, Ladakh
Authors: Sahni A. , Srikantia S. V. , Ganesan T. M. , Wangdus C. 
Published: November 2024

Abstract
A collection of Tertiary fishes and molluscs from the Kuksho Formation of the Indus Group near Nyoma, Ladakh are described, The fish families represented are: Siluridae, Channidae and Cyprinidae. The fishes are associated with dextrally coiled gastropods and unionid pelecypods.