bluuebunny/crossref_metadata_2025_split huggingface dataset:
Occurrence and Origin of Water Well Methane Gas in Bangladesh
Authors: Ahmed K. M. , Hoque M. , Hasan M. K. , Ravenscroft P. , Chowdhury L. R. 
Published: November 2024

Abstract
Gas occurrences in irrigation wells have been reported from most parts of the country, and in some parts of the southeast region, gas occurrences have become a limiting factor for groundwater development. Methane is the main component of water well gases and is readily identified by its ignition characteristics. It has been found that conditions required for gas formation, such as the amount of total organic carbon and organic matter, depth of burial, hydrothermal gradient and degree of compaction, are all favourable for the generation of biogenic gases in the deltaic regions of the Bengal Basin. Biogenic gas from water wells contains only methane as the hydrocarbon gas and along with more than one per cent (by volume) of carbon dioxide. On the other hand thermogenic gas from deep wells contains methane and other higher hydrocarbon gases along with less than one per cent of carbon dioxide. Areas marked by high groundwater salinity generates more methane than other parts of the country and this is suggestive of estuarine environment of deposition of the aquifer materials in those areas.
Occurrence of Palladian Melonite in Jaduguda Uranium Deposit, Singhbhum Shear Zone, Bihar
Authors: Narasimhan D. , Sunilkumar T. S. , Babu E. V. S. S. K. , Krishna Rao N. 
Published: November 2024

Abstract
Palladian melonite, containing upto 7% palladium is reported for the first time from the uranium ores, Jaduguda Mines.
The Lead Isotope Geochemistry and the Uranium-Lead Apparent Ages of the Sandstone - Type Uraniferous Ore of Domiasiat, Meghalaya, India
Authors: Das Radha R. , Dwivedy K. K. , Mahalingam T. R. , Mathews C. K. 
Published: November 2024

Abstract
The relative abundance of radiogenic lead varies depending on the mineralogical characteristics of the ore. In high uranium containing coaly matter, radiogenic lead is &gt; 80% of the total, whereas in a composite ore, as much as 60% of the total is of the initial common lead. The uranium-lead 'apparent ages' are in the range of 25 Ma to 95 Ma and are related to the mineralogical assemblage in the ore. The most recent of the uranium mineralization, of 'apparent age'-25Ma is with the coaly matter separates that contain considerable amount of pyrite. The variations in the abundance and distribution of radiogenic lead isotopes and the resultant orderly changes in 'apparent ages' of uranium mineralizations in different type of mineral separates are attributed to the existing favourable conditions in the ore for movement of uranium from the rock and preferential concentration and retention in the coaly matter, leading to more than one stage uranium mineralization.
A Prognostic Assessment of the Environmental Impact due to Open Cast Mechanised Mining of the East Coast Bauxite Deposits in Andhra Pradesh
Authors: Ramam P. K. 
Published: November 2024

Abstract
The East Coast Bauxite (ECB) Province of India, extending into the neighbouring States of Andhra Pradesh and Orissa, has contributed to a substantial rise in the total bauxite resource of the Indian sub-continent. Bauxite is gibbsitic and in situ. Thickness of the bauxite profiles varies from 3 to 54 m and bauxite is confined to select geomorphic expressions viz., sloping, landforms, and are amenable to open cast mechanised mining.
There are chances of accelerated recharge of the groundwater table, through coursed run-off, of the meteoric precipitation in the mining areas. In fact, tiny reservoirs of surface water can be created in the mined out areas. There is no possibility of toxicity due to Al as it is insoluble. Other toxic elements like Cr, Mn, V etc. are in negligible amounts to impart toxicity to the water regime. Human settlements in the area are sparsely populated and widely scattered. It is logical to expect employment opportunities to some of the inhabitants. Infrastructural facilities created to facilitate mining and movement of are, would contribute to improved socia-economic conditions and a rise in the per capita income.
Extensive green belt development and other mitigative measures, being practiced as a part of Environmental Management at Panchpatmali bauxite mine in Orissa is a case study to demonstrate that it is possible to maintain the eco-system of the terrain even during the mining phase. The bauxite deposits in Andhra Pradesh can be mined without causing any adverse impact on the prevailing environment.
A Petrochemical Study of the Proterozoic Alkaline Complex of Uppalapadu, Prakasam Province, Andhra Pradesh, India
Authors: Krishna Reddy K. , Ratnakar J. , Leelanandam C. 
Published: November 2024

Abstract
The Proterozoic Uppalapadu alkaIine complex (1348±41 Ma) in the Prakasam province of Andhra Pradesh is predominantly composed of nepheline syenite, hornblende syenite and quartz syenite, all of which represent an alkaline series. The pluton is closely associated with tholeiitic gabbro and ferrosyenite representing a sub-alkaline series. Geochemical characters suggest that the rocks of the alkaline series were formed by the differentiation of the hydrous alkaline basaltic magma under high PH2O, whereas those of the sub-alkaline series were formed by differentiation of an anhydrous olivine tholeiitic magma under low fO2 (reducing) conditions. Quartz syenite (an offshoot in the alkaline series) is formed either by fractionation of K-feldspar, ferrohastingsite and/or biotite under high PH2O conditions or by crustal contamination of critically saturated syenitic liquids.
Facies, Petrology and Depositional Environment of the Tertiary Sedimentary Rocks, Around Port Blair, South Andaman
Authors: Bandopadhyay P. C. , Ghosh M. 
Published: November 2024

Abstract
The Tertiary sedimentary rocks around Port Blair, South Andaman are classified into several facies and constraints on their formational environments are established.
The Oceanic Pelagic Sediments ( OPS ) are made up of bedded chert and variegated shale facies. Radiolarian tests and microcrystalline quartz are major constituents of the chert. The variable mixture of silt-size quartz, feldspar, clay minerals, pyroclacstic fragments and outosized terrigenous clasts constitute the variegated shale. The OPS were formed in continental-margin orogenic basin through suspension settling and fine grained sandy debris flow in deep water.
Paraconglomerate, tuff and mudstone constitute three major facies of the Mithakhari Group. Pebble size subrounded to rounded, disorganised and polylithologic clasts, in matrix support characterize the conglomerate facies. Pyroclastic facies are coarse grained and unstratified tuff and fine grained and well stratified tuff. They are crystal-rich tuffs of basic to intermediate composition. Massive mudstones interbedded with conglomerate and tuff are geochemically similar to sedimentary mudrocks. Conglomerates represent debris flow deposit formed in submarine channel. The tuffs are interpreted as pyroclastic debris flow deposit and primary air-fall ash turbidites. Mudstones indicate deposition of pelagic mud from basinal water.
The Andaman Flysch comprises quartzwacke sandstone and dark shale facies. Bouma sequences are conspicuous in sandstone-shale rhythmites. Angular and assorted detrital grains that constitute the framework components and also contributed to the formation of matrix, exhibit diffuse and corroded grain outlines and other textures indicative of burial diagenesis. The Andaman Aysch is interpreted as proximal turbidites formed in mid-fan environment by a combination of sandy debris flow deposition and pelagic sedimentation adjacent to an uplifted source terrane.
Depositional Environments: Inferred from Grain Size Along the Coast of Tamil Nadu
Authors: Mohan P. M. , Victor Rajamanickam G. 
Published: November 2024

Abstract
Between north of Pondicherry and Ennore (12°03' to 13°12' N - 79° 53' to 80° 15' E) two geomorphic units such as beach and beach ridges and their associated units (Low Water Mark (LWM). Foreshore (FS). Berm (BM). Backshore (BS), Dune (DU) and Beach Ridge (SL) are selected for the present study to understand the micro level variation in the depositional environment. The samples mostly show medium to fine size, well sorted to moderately sorted, very coarse skewed to fine skewed and platykurtic to leptokurtic nature. Graphic mean, standard deviation, skewness and kurtosis confirm that the sediments are of typical beach origin. Frequency curves indicate that the dune samples represent unimodal and others show bimodal to poly modal source of influence. Based on bivariant plots the samples of dune, berm, backshore, foreshore and low water mark with strandline deposits are classified.
Nagaur-Jhalawar Geotransect Across the Delhi/Aravalli Fold Belt in Northwest India
Authors: Tewari H. C. , Divakar Rao V. , Narayana B. L. , Dixit M. M. , Madhav Rao N. , Murty A. S. N. , Rajendraprasad B. , Reddy P. R. , Venkateswarlu N. , Vuaya Rao V. , Mishra D. C. , Gupta S. B. 
Published: November 2024

Abstract
Lithological, gravity, magnetic, and seismic data within 100 Km corridor of the 400 km long seismic reflection profile are compiled to constitute the NW-SE Nagaur-Jhalawar Geotransect. The transect sequentially cuts across the Neo-Proterozoic Marwar Basin (MB) on the northwest, the Palaeo/Mesoproterozoic Delhi Fold Belt (DFB), the middle/late Archaean Bhilwara Gneissic Complex (BGC) and the MesolNeoproterozoic to early Palaeozoic Vindhyan Basin (VB) at the southeast. The BGC and DFB belts show polyphase deformation and metamorphism.
The BGC within the transect, consists of Sandmata Granulite Complex, followed by amphibolite facies Mangalwar Complex and Greenschist facies Hindoli/Sawar groups. The BGC show evidence of crustal reworking at c.3.0 Ga. The DFB is represented by amphibolite facies metavolcanic-metasedimentary shallow marine sequences and is tectonically highly disturbed. The DFB deposits (c. 2.0 - 1.5 Ga.) were subjected to tectonic deformation during Delhi orogeny (c. 1.5 Ga.), which is marked by syntectonic granitic plutonism. Both, the BGC and OFB also appear to have been affected by Neoproterozoic thermal events and granitic plutonism. The Neoproterozoic MB consists of clayevaporite sequences of shallow oscillatory basin deposits.
Seismic, gravitylmagnetic and magneto-telluric techniques could delineate a number of shallow to deep faults, intrusive bodies and a high conductivity zone. The total magnetic intensity shows a regional increase towards southeast. The Bouguer anomaly values show a steep rise of upto 80 mGal towards the boundary of OFB and BGC. Based on the seismic studies, doubling of the crust under the OFB and vertical intrusion of high density material under the BGC are inferred. The upper crust is, in general, transparent in its reflectivity while the lower crustal reflectivity is high in the transect area, except in the BGC and the VB. A thrust boundary, dipping NW, is present at the eastern margin of the BGC and could be traced up to 30 km depth. The Moho is at a depth of 36-38 km under the MB. Multiple Moho reflections are identified in the DFB crust, the deepest being at 45-50 km depth. In some part of the BGC the Moho can not be identified but in parts it is traced at about 50 km depth, with southeast up dip, before becoming subhorizontal at depth of 41-42 km. It becomes shallower to about 30 km depth at the SE end under the VB.
Driving Forces of Indian Summer Monsoon on Milankovitch and Sub-Milankovitch Time Scales: A Review
Authors: Naidu Pothuri Divakar 
Published: November 2024

Abstract
A scientific consensus exists that tectonic evolution of Himalaya is the main cause of monsoon initiation and evolution in southeast Asia. Several forcing factors such as tectonic, solar insolation, latent heat transport, albedo of the earth surface and deep water circulation changes drive the variability of southwest (SW) monsoon in the Indian subcontinent. Different forcing factors act on different time scales. Arabian Sea sediments consist of distinct fauna that are endemic to areas of upwelling. The SW monsoon wind strength, upwelling in the Arabian Sea and precipitation in the subcontinent are inter linked. Thus Arabian Sea sediments provide a record of past monsoon variability covering a time span of a few million years.
Detailed analysis of numerous monsoon indices and General Circulation Models (GeM) show that SW monsoon was strong during interglacials (warm periods) and weak during glacials (cold periods). Spectral analysis of detailed time series of monsoon indices reveal that the intensity of the SW monsoon fluctuates with periodicities of 100 ka and 23 ka. These periodicities of SW monsoon were attributed to the orbitally induced changes in solar radiation and surface boundary conditions (Milankovitch Theory). Recent high-resolution studies from the Oman Margin provide new evidences on the SW monsoon variability on century time scale and a Sub-Milankovitch Periodicity in the range of 2,200 to 2,400 years. The SW monsoon variability on century scale and high frequency periodicities might be forced by the deep water circulation changes in high latitudes. The present review discusses the atmospheric 14C changes and recent onset of aridity in the tropics, which is also linked to the SW monsoon variability in one way or other.
Cluster Analysis and Nickel Thermometry of Garnet Xenocrysts from Majhgawan Diamondiferous Pipe, Panna District, Madhya Pradesh
Authors: Mukherjee Abhijeet , Rao K. S. , Roy Gautam , Babu E. V. S. S. K. 
Published: November 2024

Abstract
Based on the Q-Cluster analysis of 536 garnet grains, the garnets of Majhgawan are classified as Group 1, Group 2, Group 9, Group 10 and Group 11. Group 10 garnets have very high MgO (21.2%) and moderate to high Cr2O3 (9.5%), combined with low CaO. MgO shows negative correlation with CaO and FeO and this cluster contains a large number of garnet inclusions in diamonds. The major element chemistry of these garnets confirm that they are moderately subcalcic and have high Crcontent with a well-defined Ca-Cr trend. Around twenty percent of garnets show harzburgitic trend indicating low to moderate grade of the pipe. Nickel thermometry has indicated a well-defined geotherm between 1150° - 1400°C and corresponds approximately to a slightly elevated 42 m W/m2 conductive model. Garnets with temperature &gt; 1150°C probably were derived from diamond stability field. Based on Ni-thennometry (using only lower cut-off) omega value is calculated (&lt;30) which suggests an average grade upto 15 ctpht for Majhgawan pipe.
Natural Fresh-Water Ridge as Barrier Against Sea-Water Intrusion in Chennai City
Authors: Ballukraya P. N. , Ravi R. 
Published: November 2024

Abstract
Hydrogeological investigations along the Chennai (Madras) coast showed that groundwater levels are lower than mean sea level, often as much as -3 to -6m. However, the quality of groundwater in the near-surface unconfined aquifer, tapped by shallow wells, is reasonably fresh, though deeper wells show distinct signs of sea-water intrusion. Presence of fresh water below mean sea level in the absence of positive fresh water head is not possible in a coast line having hydraulic continuity with the marine environment. Detailed studies show that a narrow fresh water ridge, created by the beach dune complex, exists along the coast. Along most of the beach ridge groundwater abstraction is relatively less and also there is regular recharge into the aquifers from monsoon rains, and thus the static water level remains slightly above mean sea level along a narrow zone for most of the coastline. This fresh water ridge prevents contamination of the shallow aquifer to the west of the ridge, even though the water levels fall below mean sea level in the aquifer. Where the beach area has been urbanized or where there is large-scale abstraction from beach zone, groundwater has been contaminated with saline water as there is no fresh water barrier in such locations. Thus, the beach area has, to a large extent, safeguarded the shallow aquifers from serious saline water intrusion in Chennai city. This is a fortuitous situation which also selVes as a warning not to urbanise beach zones in coastal cities.
Early-Middle Miocene Planktic Foraminifera from the Quilon Formation, Kerala
Authors: Singh A. D. 
Published: November 2024

Abstract
Praeorbulina glomerosa (Blow), Praeorbulina sicana (de Stefani), Globigerinoides diminutus Bolli are recorded for the first time from the Quilon Formation in a subsurface section at Quilon. These planktic foraminifera are considered as diagnostic forms of the Early-Middle Miocene. Two biostratigraphic subdivisions were established based on the detailed qualitative analysis of planktic foraminiferal assemblages. The co-occurrence of Gs. diminutus and Gs. alttapertura Bolli and the absence of Praeorbulina Olsson in the assemblages of the lower portion of the section suggest this part to be referable to Globigerinatella insueta Zone of Bolli (1966), which is of late Early Miocene age. The assemblages from the upper part of the section are characterised by the presence of Praeorbulina glomerosa, P. Sicana and Gs. diminutus, representing early Middle Miocene Praeorbulina glomerosa Zone of Srinivasan (1989). The Praeorbulina glomerosa Zone (=Zone N8) lies within the European Langhian Stage, whereas the Globigerinatella insueta Zone (=Zone N7) corresponds to the upper part of the Burdigalian Stage. Thus, the stratigraphic age of the Quilon Formation is late Early Miocene to the earliest Middle Miocene (upper Burdigalian to lower Langhian) and not Burdigalian as previously inferred by many workers.
Stable Carbon and Oxygen Isotope Analysis of Natural Calcite and Dolomite Mixtures using Selective Acid Extraction
Authors: Ray Jyotiranjan S. , Ramesh R. 
Published: November 2024

Abstract
Accurate analysis of coexisting calcite and dolomite for d13C and d18O is generally hindered by the difficulty in the physical separation of these minerals. The difference in the reaction rates of calcite and dolomite with phosphoric acid, has been used to chemically separate these carbonates. Previously established procedures are only suitable for samples containing 1:1 calcite-dolomite pairs. However, these are sometimes tedious and time-consuming. Using mixtures of calcite and dolomite, two different selective acid extraction procedures (for reactions at 25°C), one for calcite-rich and the other for dolomite-rich carbonates, have been developed. Reduction of grain size (to 37μm - 45μm) increased the reaction rate and hence decreased the total reaction time to a reasonable interval (=72 hours for dolomite). Applying these procedures, d13C and d18O of calcite and dolomite/ankerite of carbonatites from Amba Dongar and Sung Valley carbonatite complexes of India were measured and their temperatures of crystallization determined. Accurate isotopic compositions of individual carbonates of calcite-dolomite mixtures can be determined for geological interpretations by these procedures.
Inferences on Rhodoids from Neogene Carbonates of Kudankulam, Tamil Nadu
Authors: Ramasamy S. , Armstrong Altrin Sam J. 
Published: November 2024

Abstract
Rhodoids are laminated algal nodules generally found in shallow marine environment. Algal crusts and nodules are poorly exposed between Kudankulam and Sattankulam in the coastal area near Cape Comorin. The thickness of the bed of algal limestone varies from 0.5 to 1.5 m. The occurrence of abraded rhodoids with lack of terrigenous material suggests moderate to high energy depositional condition. The present study of the rhodoids, points out that the Neogene tectonic activity has played a significant role for the development of algal limestone and rhodoids in the study area.
A Mineralogical Analysis of Karst Sediments and its Implications to the Middle-Late Pleistocene Climatic Changes on the Tibetan Plateau
Authors: Zhang David Dian 
Published: November 2024

Abstract
The minerals in various categories of Tibetan karst sediments were divided into three groups: carbonate, iron and silicate. The carbonate minerals, including calcite, aragonite and dolomite, consist mainly of speleothem, tufa and sinter. Most of the speleothems indicates wetter and warmer periods in early and middle Pleistocene, the youngest being 194,000 years old. The second formation of carbonate mineral, tufa, implies an arid period starting 91,000 years BP. The iron minerals, goethite and hematite, are often mixed up with cave alluvial sediments that are interbedded with flowstones, and the depression sediments. They indicate strong oxidizing environments during their deposition, which is absent at present. The clay minerals, specially kaolinite, were contained in cave alluvial, flowstone and the depression sediments as well. Combined with stratigraphic study and U-series dating, the mineral analysis shows that warmer and wetter climates, which were suitable for speleothem development, probably disappeared 200 ka ago, and drier and colder climates dominated this plateau since then.
Isotopic Composition of Middle Old Red Sandstone Carbonates: Implications for the Palaeoenvironment
Authors: Das Nachiketa 
Published: November 2024

Abstract
The carbonates occurring within the sandstones of the Middle Old Red Sandstone of the Orcadian basin (Middle Devonian) in Caithness, N.E. Scotland are of minor abundance, predominantly calcite and may be petrographically ascribed to early diagenetic origin.
Isotopic analyses (C, O, Sr) have been undertaken to elucidate the depositional mileu of these carbonates at two localities, Wick and Reay. Calcite and dolomite coexist in carbonate facies rocks and their similarity in d13CPDB (-4.57 ± 0.64 and -4.56 ± 0.53‰ respectively at Wick and -2.39 ± 0.30 and -2.00 ± 0.48 respectively at Reay) suggest a cogenetic origin at each locality. The d13C values also suggest deposition from lighter, freshwater.
Mean calcite d18OPDB values of -7.76 ± 1.92‰ and -8.76 ± 2.23‰ for Wick and Reay samples respectively also support this contention. Dolomite d18OPDB values are consistently heavier which is not inconsistent with a generally cogenetic origin. The oxygen isotope data reflects a lighter pore fluid composition either because of diagenetic modification by carbonate recrystallization or a greater contribution of freshwater via river supply during sandstone deposition in an ephemerally evaporative lacustrine environment. Mean Sr87/86 value of 0.711167 for the carbonates of Wick confinn a nonmarine origin.