bluuebunny/crossref_metadata_2025 huggingface dataset:
Uraninite in the Uranium Deposits of Singhbhum Shear Zone, Bihar
Authors: Krishna Rao N. , Rao G. V. U.
Published: November 2024

Uraninite is the main uranium mineral in the uranium deposits of Singhbhum Shear Zone, Bihar. The uraninite from different deposits have compositions varying between UO2.30 to UO2.44 which is typical of vein uraninites. They contain < 1 % ThO2, but have appreciable rare earths C?5%). They also contain 12-15% PbO, which is all radiogenic. Among the rare earths the heavy lanthanides predominate. In addition uraninite from Narwapahar shows an enrichment in Eu. The unit cell edge of uraninite from different deposits varies between 5.420 Å and 5.453 Å. The uraninite from the copper deposits of Rakha and Surda, and Narwapahar have decidedly higher cell edge (5.45 Å) than those from Bhatin and Jaduguda (5.42 Å). On annealing at 1000°C in an inert atmosphere the cell edge decreased to a near constant value of 5.428 Å, the contraction varying between 0.01 Å to 0.03 Å.

D. T.A. and T.G.A. curves of Narwapahar and Bhatin uraninite indicate that these differ considerably from those of pure UO2. There are also significant differences between the two. These differences are attributed to crystallinity and degree of disorder in the uraninite lattice. The variations in the composition, cell edge, annealing and oxidation characteristics of uraninite from different uranium deposits reflect different temperature conditions during their formation.
Proboscidean Teeth from the Bokabil Formation of Tripura State, India
Authors: Trivedy A. N.
Published: November 2024

The paper describes two fossil teeth, a third upper left and a lower true molar, of Gomphotherium which were recovered by the author from the Bokabil Formation of Tripura State.

The characters of the teeth, specially the upper one (LM3), suggest that they belong to a form intermediate between the Indian species, Gomphotherium Cooperi Osborn and Gompholherium palaeindiscus (Lydekker) Osborn. This form is comparable to Gomphotherium anqustidens Cuvier. An Upper Aquitanian to Lower Helvetian age to the Bokabil Formation is favoured.
Pink Granites in the Highland Series of Sri Lanka-A Case Study
Authors: Munasinghe Tissa , Dissanayake C. B.
Published: November 2024

Pink granites in the Digana antiform area of the Precambrian of Sri Lanka occupy the marginal zone of migmatites and metasediments of granulite facies, and occur as isolated bodies within the migmatite terrains. Field evidence and petrography of these rocks are suggestive of an anatectic origin. The period of emplacement is interpreted as being correlative with the basement mobilization and migmatisation presumed to have occurred at 1250 Ma which affected the Highland Series metasediments of Sri Lanka.
Tectonic History of the Bijawar Rocks at the Barmhanghat Section of the Narmada Valley
Authors: Roday Prakash P. , Bhat Arun K.
Published: November 2024

The Bijawar rocks exposed at the Barmhanghat section of the Narmada Valley bear imprints of two folding episodes (D2 and D3) and a shearing movement (D1) that predates folding in the rocks. The first fold structures (Fl related to D2) evolved by a combination of tangential longitudinal strain and oblique flexural slip, the latter suggesting initial unsymmetrical disposition of rock layers in relation to principal stresses. Numerous slickensided fibres were produced as a result of this on layer surfaces, these are unrelated to any recognisable fault movements in the rocks examined. Cleavage contemporaneous with F1 folds shows slight transection in a few minor folds. Three geometric variations of transected folds are described. In submacroscopic fold chains, the geometry of single or paired folds suggests their initiation in the north and gradual propagation to the south along the layering, newer folds probably appellring with the advancing stress front. The youngest structures (F2, related to D3) are broad flexural slip warps, lying at high angle to early folds.

The shearing movernent was accompanied by the intrusion of basic dikes and quartz veins. The youngest event in the area was the intrusion of a second set of basic dikes, devoid of any traces of deformation or metamorphism.
Lithology and Conditions of Deposition of the Talchir Formation in North Karanpura Basin
Authors: De Ajay Kumar
Published: November 2024

In North Karanpura basin, the Talchir Formation ranges in thickness from about a metre to 130m and consists of tillite, sandstone-conglomerate, rhythmite and sandstone/siltstone members. Synthesising surface and sub-surface data, these are interpreted mainly as glacial (drift) sediments. Field relationship suggests that the tillites were deposited mainly as 'ablation tillite' or 'basal tillite' on erosional embryonic basin. Restricted occurrences of 'lodgement tillite' are noted along the margins of the basin. Till fabric data indicates that several lobes of glaciers flowed towards the basin in response to local palaeoslope from the various cappings of ice occurring on the northern Hazaribagh as well as the southern Ranchi Plateaus. Present study reveals advancement of two separate systems of ice-lobes from NW or west and south or sw in the northern and southern parts of the basin respectively. A radiating ice-flow direction from the Lurunga-Indratoli high is noted in the southeastern part of the basin. Oscillations of ice front are documented in the southern part of the basin. Synthesis of data indicates that melting of these ice-lobes gave rise to the deposition of glaciofluvial and glaciolacustrine sediments in ice-contact or proglacial environment in various parts of the basin. Based on surface and subsurface data, several disconnected ice-bound lakes are delineated in different parts of the basin. During latter part of the Talchir sedimentation, the basin came under the domain of alluviation.
Deep Crustal Structure at Koyna, Maharashtra, Indicated by Deep Seismic Soundings
Authors: Kaila K. L. , Reddy P. R. , Dixit M. M. , Lazarenko M. A.
Published: November 2024

Deep Seismic Soundings (DSS) were carried out by the National Geophysical Research Institute, Hyderabad, during December 1975-April 1976, along a profile across Koyna. The studies of the data reveal a number of reflection horizons below the Deccan Traps up to the Moho discontinuity. Below the Deccan Traps, the crustal section along this profile is cut into two blocks by a deep fault west of Koyna. The eastern block is further cut by another deep fault which affects only the deeper horizons including Moho. Recent movements along the first of these deep faults, west of Koyna, appear to be responsible for the major Koyna earthquake of 1967 and subsequent seismicity in this region. The Moho depth in the western block is around 40 km in the vicinity of the deep fault and is of about 30 km at the west coast of India. In the eastern block the Moho boundary lies at an average depth of 36 to 38 km.

The thickness of the Deccan Traps along Koyna profile varies from o.4 km in the east to about 1.5 km near the west coast. The velocity in Deccan Traps is found to vary between 4.7 to 4.9 km/sec, and in the Pre-Trap basement it varies between 5.9 to 6.1 km/sec.
Fracture Pattern Study from Landsat Imagery and Aerial Photos of a Part of the Eastern Ghats in Indian Peninsula
Authors: Prudhvi Raju K. N. , Vaidyanadhan R.
Published: November 2024

The terrain between the Godavari river in the south and the Mahanadi river in the north, comprising about 50,000 sq. km area forms the study region. LANDSAT imagery and aerial photographs were studied with a view to delineate the fracture patterns and analyse their possible significance. The frequency azimuth rose diagrams of fractures indicate two sets of preferred orientations in ENW-WSW and E-W directions. The possibility of some of these fractures/fracture traces being relatively very much younger to the main Eastern Ghat orogeny is a tentative surmise made from this study. These younger fractures may be related to a cymatogenic upwarp during mid-Tertiary.
Micropalaeontology of Marine Miocene Subsurface Sequence of Galsi Area, Bengal Basin
Authors: Banerji Ranjit K. , Baruah R. M. , Gupta S. C.
Published: November 2024

The exploration for hydrocarbons in the Bengal Basin has revealed the development of nearly 100m of a highly fossiliferous subsurface sequence near Galsi in West Bengal. This sequence has yielded a large number of planktonic and benthonic foraminiferal species. In all, twenty-two species belonging to seven genera and three families of planktonic foraminifera are identified and described. Based on their stratigraphical distribution, four assemblage Zones are distinguished which range in age from Zone N.4 to N.14 (Aquitanian to Langhian, Early to Middle Miocene). The microfaunal study suggests an oscillatory nature of the depositional basin varying from coastal marginal facies to short intervals of open marine inter-tongues within overall shallow marginal basin.
Geochemistry of Anorthositic Dyke from Nuggihalu Schist Belt of Dharwar Craton, Karnataka, India
Authors: Jafri S. H. , Saxena Ramavati
Published: November 2024

Geochemical data is presented of an anorthosite dyke from Nuggihalli made of calcic plagioclase (An70-80), amphibole, pyroxene and accessories like magnetite, sphene and apatite. The chemical data shows high Mg/Mg+Fe++ ratio (Avg.=0.48) and CaO/Na2O ratio (Avg.=8.70) with, <5 ppm Rb and 56-90 ppm Sr., indicating a substantial fractionation of ferromagnesium phase from a highly calcic ultrabasic parent magma.
Determination of Weathered Granite Resistivity from Electrical Resistivity Profiling Data using Empirical Relations
Authors: Srisailanath A. , Patangay N. S. , Bhimasankaram V. L. S.
Published: November 2024

Methodology of groundwater prospecting in granitic terrains using electrical resistivity method sequentially consists of conducting profiling survey, selection of low apparent resistivity zones indicative of probable saturated regions, and estimating the resistivity and thickness of the weathered layer to determine its hydrogeological characteristics employing VES method.

In Musi Ayacut region, where a detailed survey was carried out for groundwater, one of the current electrodes (AB/2) separation used for profiling survey was 10 m. The apparent resistivity values obtained using the above separation were found to be indicative of the hydrogeological nature of the weathered granite layer in the area. It was observed that the apparent resistivity values obtained by the above separation ?a (AB/2= 10m) are linearly related to the true resistivity (?2) value of the weathered granite.

Using the above obtained statistical empirical relations, the weathered granite layer resistivity can be estimated from the profiling survey results even without conducting a large number of vertical electrical soundings in the area.
Minor Element Geochemistry of Pyrite and Sphalerite in the Polymetallic Sulphide Deposit of Deri, Sirohi District, Rajasthan - A Preliminary Study
Authors: Aggarwal Pradeep K. , Nair N. G. K.
Published: November 2024

Data on the distribution of Cd, Mn, Cu, Ag, Ni and Co in four monomineralic fractions each of sphalerite and pyrite from five ore samples of the Precambrian stratiform zinc-lead-copper deposit of Deri, Rajasthan are presented. The minor element geochemistry of the sulphides suggests possible volcanic exhalative origin.
Geological Effects of Storm Associated Tidal Wave on the Krishna Delta Area, East Coast of India
Authors: Durga Prasada Rao N. V. N.
Published: November 2024

The effect of storm associated tidal wave, that struck the Andhra Coast, on the sediments of the Krishna Delta is investigated. Granulometric analysis of the pre- and post-tidal wave estuanne sediments of the Krishna River revealed a remarkable increase in the silt content of the post-tidal wave sediments. Enormous quantity of silt was transported from the shelf and deposited io the estuarine environment by the tidal wave. A slight difference is noticed in the chemical composition of the pre- and post-tidal wave estuarine sediments. Deposition of silt-sized sediments is also observed in the interdistributary area during the field survey. Stabilisation of coastal dunes with proper vegetation is suggested to minimise the effects of tidal waves and storm surges on the coastal region.
Coexisting Humite-Chondrodite-Spinel-Magnesian Calcite Assemblage from the Calc-Silicate Rocks of Ambasamudram, Tamil Nadu, India
Authors: Krishnanath R.
Published: November 2024

A humite-chondrodite-spinel-magnesian calcite assemblage occurs in the calcsilicate rocks of the Ambasamudram area and is associated with the high-grade metamorphic rocks of Peninsular India. This assemblage was stabilised under high-grade metamorphic conditions followed by partial reequilibration under dominant fluorine influence. A coexisting humite-chondrodite assemblage in textural equilibrium does not appear to have been reported from elsewhere.
Effect of Separation of Sri Lanka and India on High Level Landforms and Coastal Sedimentation
Authors: Subramanian K. S. , Gopalakrishnan L. S.
Published: November 2024

The high level plateau landforms characterised by lateritic bauxite cappings and traced at altitudes of about 2,000m in the Nilgiri and the Palni hills in the Western Ghats and in the Central Highlands of Sri Lanka, are correlatable.

The presence of Talchir sediments (Lower Gondwana) below Upper Gondwana sediments in the Palar Basin suggests that the initiation of NE-SW trending tectonic basins on the east coast was in Pre-Jurassic times. The Palar Basin evolved even before the break-up and fragmentation of the Gondwanaland, determining the configuration of the east coast of the Indian Peninsula. The Cauvery Basin, where the oldest sediments are of Upper Jurassic age, came into being in Jurassic times, consequent on the impetus provided by the rifting and fragmentation of Antarctica from the east coast of India.
Sedimentation and Deformation Analysis of Gurusiddapura Conglomerate, Chitradurga Schist Belt
Authors: Bhasker Appah Amrit , Fareeduddin
Published: November 2024

The Gurusiddapura and Hoskere conglomerates of Chitradurga schist belt belong to one continllolls stratigraphic unit. Deformational analysis indicates that the pebbles in both the conglomerates belong to one single population. Graded bedding and occurrence of pebbly and non-pebbly zones indicate turbidite environment of deposition in an unstable geosyncline. Since the conglomerates are interbedded with chlorite schist they do not mark any unconformity.
Surficial Sediments of the Continental Shelf off Karnataka
Authors: Hashimi N. H. , Nair R. R.
Published: November 2024

The continental shelf in this area is about 80 km wide and the edge of the shelf varies between 90 and 120m water depth. Geologically modern fine-grained clastic sediments occur between the water depths of 15 to 50m corresponding to a distance of about 40 km from the coast. Beyond 50 m to the shelf edge are calcareous sands. Noncarbonate components of these deep water sands are essentially quartz, many of which are heavily iron-stained and are attributed to the presence of rich iron formation on the land. The carbonate components in the outer shelf sediments are mainly foraminifers, pelecypods, gastropods, pteropods, and ooids, while ooids and pteropods are absent on the inner shelf. X-ray mineralogy of the silt fraction of the sediments shows the presence of quartz, calcite, aragonite and orthoclase as major minerals. Some of the sedimentary processes effecting the distribution of these sediments are discussed.
Groundwater Chemistry and Formation of Carbonate Concretions in Alluvial Soils
Authors: Chaturvedi A. K. , Raymahashay B. C.
Published: November 2024

Gangetic alluvial soils of Uttar Pradesh typically contain carbonate concretions (kankar) of different morphology at various depths. The concretion mineralogy has been correlated with local groundwater chemistry by calculating mineral solubility products from available thermodynamic data. It is concluded that carbonate minerals are precipitated from supersaturated groundwater in pore space leading to formation of concretions.
Fenitized Sandstones in Amba Dongar Carbonatites, Gujarat, India
Authors: Sukheswala R. N. , Viladkar S. G.
Published: November 2024

Potash fenitization of sandstones of Amba Dongar carbonatite-complex was described earlier by Deans et al. in 1972. The present work mainly deals with newly found soda-fenites in carbonatites, rich in aegirine-augite, aegirine, albite and orthoclase. The chemistry of potash fenites and soda fenites (new analyses) reveals two trends in Amba Dongar fenites; (i) 'normal fenitization' in which both soda and potash have been added and (ii) predominantly potash fenitization leading to the development of potash fenites. The fenitlzing solutions were supplied by the carbonatite magmas (both sovite and ankeritic carbonatite).
Geochemistry of Archaean Metavolcanic Rocks from the Kudremukh Area, Karnataka
Authors: Drury S. A.
Published: November 2024

Major and trace element data for metabasaits and metaperidotites from the littleknown Archaean volcanic-sedimentary belt at Kudremukh are presented. The dominant rocks are low K tholeiites showing evidence of partial melting from a Zr, Y and Nb enriched, P and Ta depleted mantle source, at depths where garnet was stable in peridotitic compositions. The action of olivine, pyroxene and possible spinel fractionation from a high MgO parent magma can account for many of the chemical variations within the suite. Clasts and matrix from an associated agglomerate prove to be the most evolved rocks of the suite and evidence strong plagioclase feldspar fractionation. No precise tectonic setting for the volcanics is attempted; this must await more information on age, structure and volcanic geochemistry for the rest of the Karnataka craton.
Petrology of the Carbonatites and Associated Alkaline Rocks of Siriwasan, Cahota Udaipur
Authors: Sethna S. F. , Borges S. M.
Published: November 2024

The upper portions of the Bagh sandstones of Siriwasan have been penetrated and soaked by a sill-like intrusive of carbonatite which has also penetrated the overlying Deccan Trap basalts at a few places. The carbonatite is intimately associated with tinguaite which shows the same form and occurs as discrete dykes as well. The carbonatite mainly forms the matrix of the brecciated sandstone but in places, where it collected as pools, large pockets of sovite are found. Pools of sovite are also found within tinguaite which shows brecciation at places. Thirty-four samples have been analysed for Sr, Rb, Zr, Nb, Zn, Mn, P, Ce, La, Y and Th. Thirteen of these have also been analysed for U. Analytical data show a consanguinity of the carbonatites and the tinguaites. Immiscible liquid fractions of a carbonatite-alkalic magma are considered to have produced the different rock types.
On the Genesis of Lapsa Buru Kyanite, Singhbhum District, Bihar
Authors: Banerji A. K.
Published: November 2024

A number of massive pegmatoid kyanite veins occur along shear planes at Lapsa Buru, in the western part of the Singhbhum shear zone, Bihar. The host rocks are Precambrian metatuff and metachert, now represented by muscovite-biotite-chlorite schist and quartzite, which have been affected by four phases of deformation and metamorphism. During the first two phases granitic rocks were emplaced within the shear zone at temperature between 650°-700°C and pressure around 2 Kbar. During the 3rd phase albite metasomatism took place within the shear zone under pressure of about 5 Kbar. At the same time, kyanite veins were emplaced along the northern boundary of the shear zone under slightly higher pressure ranging between 5-6 Kbar. A review of experimental data indicates that temperature around 450°-500°C prevailed during kyanite segregation. It has been suggested that under these P-T conditions alumina and silica were mobilised from the alumina rich volcanogenic rocks of the shear zone. Presence of tourmaline, topaz, and dumortierite in the kyanite veins indicates that boron and flourine may have aided the mobilisation process. The resulting kyanite was affected by minor shearing and local retrogressive metamorphism during the fourth phase of deformation in the region.
Large Scale Basin and Dome Structures in the High Grade Metamorphics, Near Visakhapatnam, South India
Authors: Natarajan V. , Nanda J. K.
Published: November 2024

Large scale basin and dome structures with intense buckling in some layers are recorded in the Archaean high grade metamorphic-migmatitc complex of the Eastern Ghats near Visakhapatnam, South India. Two major phases of deformation have been deciphered. The earlier phase was regionally continuous, and resulted in nonplunging, tight and isoclinal (overturned) folds, as well as gently plunging elongate structures. The axial trends of these folds vary from NE-SW to ENE-WSW. Gneissic layering of rocks, development of axial plane schistosity and tight isoclinal angular parasitic minor folds, and large scale shearing and faulting in the axial regions, are correlated to this event.

The later phase of deformation was discontinuous and variable in nature. Southerly/southeasterly plunging, open to tight, normal, similar folds belong to this event and they were superposed on the earlier structures. They modified the pattern and plunges of the latter, and also produced intense buckling or gentle warping locally at several places. Development of warp-like open minor folds, and groove and mineral lineations are correlated to this deformation.

On the basis of critical synthesis of the available structural data, the evolution of the Balacheruvu basin and Madhuravada dome has been attributed to a single deformation of the earlier phase of folding.
Bolaspidella from the Cambrian of Kashmir and its Stratigraphic Significance
Authors: Shah S. K. , Sudan C. S.
Published: November 2024

New species of the trilobite genus Bolaspidella viz., B. himalayensis, B. costalus, B. magamensis and Bolaspidella sp. have been recorded from the top part of the Middle Cambrian of Kashmir. Bolaspidella bearing beds constitute a well marked zone which may be extending into the base of Upper Cambrian. This is the first record of Bolaspidella from Asia and the stratigraphic position of this genus corresponds exactly to that known from North America.
Mesozoic Ammonites from the Spong Valley, Zanskar, N. W. India
Authors: Brookfield M. E. , Westermann G. E. G.
Published: November 2024

A Callovian-Oxfordian sphaeroceratid, (?) Prograyiceras, proves for the first time, the presence of Jurassic flysch in the allochthonous Spongtang Klippe. A berriasellid, Kilianella, similarly proves the presence of probable Valanginian in the autochthonous shelf sequence of the Zanskar range, and supports the presence of the (upper) Spiti Shale hitherto recognized in the area on lithological grounds.
40Ar-39Ar Incremental Heating Studies on a Suite of 'Disturbed' Rocks from Cape Breton Island, Canada; Detection of a Deformational Episode
Authors: Baksi Ajoy K.
Published: November 2024

40Ar_39Ar incremental heating studies have been carried out on a set of Middle Cambrian (age) whole-rock samples, which, in an earlier study (Hayatsu and Carmichael, 1970), yielded a K-Ar isochron age of ~400 Ma and an initial 40Ar_39Ar ratio of ~500. Age spectrum plots reveal that almost all of the argon originates from fine-grained K-feldspar and plagioclase in these rocks; the argon clock in these minerals was almost totally reset by a deformational event (part of the Acadian Orogeny) which occurred ~400 Ma ago. Plotting the results on an Isochron diagram suggests that the high initial argon ratios noted earlier are not due to isotopic homogenisation on a grainsize scale. Since feldspars are known to be susceptible to argon loss at temperatures of >250°C, mild deformation and/or metamorphism in suitable rocks can now be identified and dated by careful 40Ar_39Ar incremental heating work.
Mineralogy and Origin of Jammu Bauxite
Authors: Chadha S. K.
Published: November 2024

The bauxites of Jammu comprise extensive surface spreads of generally hard dense varieties with a typical knobby appearance. The bauxite unconformably overlies Upper Pre-Cambrian limestones and underlies the Nummulitic series of Eocene age. Thickness varies from 1.5 m to 9 m. Three distinct facies are recognised: pisolitic. semi-pisolitic and non-pisolitic.

The bauxites have been analysed for their mineralogical composition adopting X-ray, D.T.A., heavy mineral analyses and optical study. The pisolitic bauxites mostly contain diaspore (A12O3 H2O) and boehmite (AI2O3. 2H2O), the semi-pisolitic bauxites contain, boehmite, limonite, and quartz. The non-pisolitic varieties contain kaolinite. Heavy mineral studies have shown the presence of magnetite, limonite, anatase and corundum. The source rocks appear to be limestones which weathered mitially into clay. The desilicification of the clays under tropical and sub-tropical climatic conditions gave rise to bauxite.
Dehydroxylation and Dehydration as Parameters For Characterisation of Clays - Part II: Kaolinites, Pyrophyllite and Talc
Authors: Venugopal J. S. , Hirannaiah B. V. , Majumder S. K.
Published: November 2024

A sophisticated technique of modified TG, DTG has been described which can detect clay species of kandite, pyrophyllite and talc groups by employing a simple home-made TG Instrument. Many new parameters like half weight loss, differential phase lag and half weight loss temperature are obtained along with other thermal parameters and their rationale are discussed in relation to species level characterisation. The parameteral derivation and its relationship to surface morphology of clays has been described. This highly sensitive method has special application in developing countries and could be adopted in clay based industries for material quality control.
Grain Characteristics of Zircons of Beach Sands from Southwest Coast of India
Authors: Sinha-Roy S.
Published: November 2024

The mineral beach sands of the southwest coast of India, particularly of Chavara and Manavalakurichi areas, contain 4-6% zircon. Although the general setting of the zircon-bearing sands in these two areas is similar, the zircon grain characteristics show some differences. The Manavalakurichi zircon is coarser than the Chavara zircon and in the former, the grain-size has in general a positive correlation with the aspect ratio, whilst in the latter, the correlation is not straightforward. Zoning is more prominent in the Chavara zircon than in the Manavalakurichi zircon. In contrast to the Chavara zircon, the Manavalakurichi zircon shows statistically significant preferred association of idiomorphic grains with microfractures. The level of inclusions (ilmenite, rutile, monazite, quartz, apatite and fluid), either in single phase or in polyphase, is higher in the Manavalakurichi zircon than in the Chavara zircon. The source rock (s) of these zircons may not have been much dissimilar.
Aspects of the Syntectonic Extension and Shear Veins from the Barwaha Region, Dhar forest, Central India
Authors: Roday Prakash P.
Published: November 2024

Extension veins with sigmoidal crystal fibres affected by post-crystallization deformation and synkinematic with the F2 deformational event are developed in the metamorphic rocks east of Barwaha in western Madhya Pradesh. Though the original vein textures have been modified by the effects of post-crystallization deformation such as bending, rupture and shearing, they are sufficiently well-preserved to conclude that the growth process was essentially of the' stretched crystal' or 'crack-seal' type.

The vein origin can be ascribed to a period of low grade metamorphism and associated deformation. Post-vein modifications in the matrix are not associated with any retrogressive metamorphic assemblages, suggesting that the modification process occurred under more or less the same conditions which prevailed during vein growth but under the greater influence of ductile deformation within the veins.

The veins cross-cut the regional schistosity or a statically recrystallised hornfelsic fabric and therefore they postdate the F1 movement and the post F1 dyke, but predate the end of regional ductile deformation F2. Extension veins are themselves cross-cut by shear veins or the shearing is restricted to the walls of extension veins suggesting significant change in orientation of the maximum principal compressive stress towards the late stages of vein dilation. The drusy fabrics of quartz crystals in nontectonic veins developed in the Lameta sandstones are also deformed, as are those of secondary calcite in basalt flow cavities in the area to the east of Sanavad, presumably related to the rifting and volcanism of late Mesozoic-early Cenozoic period. The effect of this later tectonic activity was found in the older syntectonic veins, this being the infilling of zeolite in the late' saddle-reef' type dilation sites between the bent crystal fibres.
Age Of Basic Magmatism in Kerala
Authors: Sinha-Roy S.
Published: November 2024

The Kerala basic dykes that cross-cut the crystalline rocks are quartz or olivinenormative tholeiites. In Trivandrum district. south Kerala, two of these dykes have yielded K-Ar whole-rock dates of 127±2 m.y. and 104±5m.y., whilst the third, 476± 11 m.y. The 104-127 m.y. group age dates the thermal response of the western continental margin distension, and it relates also to the early phase of the Deccan Trap volcanism. The 476 m.y. date is either obtained via crustal contamination or more likely, it represents an older and unrelated thermal event. This event has analog in South Africa, including Madagascar.
Trace Fossils from the Cambrian of Kashmir and their Stratigraphic Significance
Authors: Shah S. K. , Sudan C. S.
Published: November 2024

Trace fossil assemblages studied from the known stratigraphic horizons of Cambrian with a view to establishing their ranges in Himalayan succession have indicated that trilobite tracks and trails are stratigraphically significant. These include the ichnogenera Monomorphichnus, Rusophycus and a new genus and species, Kupwaria fusiformis, together with varieties of claw scratchings. As against this, the various species of ichnogenus Phycodes have stratigraphic ranges which do not exactly, correspond to their reported distribution from other parts of the world. A range chart based on associated trilobite fossils has been built for stratigraphically significant ichnofossil assemblages.
Metamorphism and Development of Morphometric Parameters: An Illustration from Bino Basin-Almora Crystalline
Authors: Joshi S. C. , Rawat J. S.
Published: November 2024

Composition of drainage net in the Almora crystalline is considerably controlled by tectonics. The open synformal structure of Almora Nappe 1, composed of highly puckered granetiferous mica schist with stretched quartz lenses of High Grade Metamorphic rocks are demarcated by relatively higher values of drainage density (1.81 km/km2), stream frequency (6.22 channels/km2) and ruggedness number (1.26); and lower values of the length of first (2.05 krn), second (.85 km) and third (0.51 km) order streams, basin area (2.24 km), basin perimeter (6.68) and basin length (1.63 km) than that of the Low Grade Metamorphic rocks of the Almora Nappe II, composed of quartzite. phyllite, orthogneiss, granite, schist and amphibolite.
Pellatispira (Foraminiferida) From the Upper Eocene of Surat-Broach, Gujarat
Authors: Samanta Bjmal K.
Published: November 2024

The foraminiferal genus Pellatispira Boussac is represented by P. crassicolumnata Umbgrove in the Upper Eocene succession of Surat-Broach, Gujarat. The morphology of the species is described and illustrated. The specimens from Surat-Broach originally identified by Rao as Pellatispira inflata Umbgrove var. minor var. nov., P. madaraszi (Hantken) var. indica var. nov. and P. orbitoidea (Provale) are considered to fall within the range of variation of P. crassicolumnata Umbgrove. An analysis of the external and internal structures indicates that the genus Pellatispira is distinct from the typical members of the Calcarinidae, Miscellaneidae and Nummulitidae. It is best retained in the family Pellatispiridae Hanzawa.
A New Phanerozoic Basin in Kinnaur, Himachal Himalaya
Authors: Bassi U. K. , Chopra Suresh , Datta B. M.
Published: November 2024

A Phanerozoic sequence except Carboniferous, has been identified in the eastern part of the Kinnaur district. The strata have yielded a rich invertebrate fauna and ichnofossil assemblage besides plant fossils of Lower Permian age. Four sedimentary cycles punctuated by the Cambrian, Caledonian, Hercynian and Upper Callovian disruptions are identifiable, The rocks of this area have suffered from at least two phases of folding, as reflected in both major and minor structures.
Petrochemistry of the Chengannoor Granite, Alleppey District, Kerala
Authors: Santosh M. , Nair N. G. K.
Published: November 2024

The granite of Chengannoor, Alleppey district, Kerala, having an intrusive relationship with Precambrian charnockite-cordierite gneiss sequence is inferred to be a post-kinematic granite of magmatic origin. The major mineral constituents are mesoperthitic K-feldspar with quartz and two generations of plagioclase. A late/post intrusive potash metasomatism caused changes in the mineralogy and chemical composition of the granite.

Recent K-Ar dating of hornblende from the Chengannoor granite assigns an age of 550 m.y. for the granite (Soman, Golubyev and Santosh. Ind. Jour, Earth Science) (in press).
Significance and Genesis of Early Diagenetic Glauconite-Pyrite Assemblage in the Quilon Limestone, Kerala
Authors: Thrivikramji K. P. , Ghosh Swapan K.
Published: November 2024

Pyrite and glauconite are the only lauthigenic iron minerals present in Quilon Limestone. Pyrite occurs as fossil infiIlings and as disseminated grains having shapes like cubes and framboids. Four morphologically distinct types of glauconite have been identified, viz., capsulated pellets, globular pellets, microfossil casts and moulds. Glauconite occurs as fine sand sized aggregate of clay particles. The colour varies between different shades of green to greyish green.

The XRD pattern of glauconite pellets shows the presence of a mixed layer clay mineral assemblage of chlorite and montrnorillonite. The pyrite-, glauconite- and micrite-fabrics of the limestone show evidence of their formation in early diagenetic stages. Pyrite has formed in a neutral to alkaline pH condition in a localised reducing condition; glauconite also formed in a similar environment. However, overall environment was oxidising in a shallow and quiet inner shelf area.
On the Occurrence of Scheelite in Almora and Chamoli Districts, Uttar Pradesh
Authors: Shukla B. D. , Singh A. K. , Swarup Prem
Published: November 2024

Presence of scheelite is reported in the panned concentrates prepared from stream sediments collected from certain tributaries of Pindar river in Chamoli district. Studies carried out so far show that scheelite mineralisation is strata-controlled occurring within a garnetiferous-mica schist member. The host rocks are (i) green coloured epidote-amphibole rich rock (amphibolite?) and (ii) light coloured quartz-epidotecalcite bodies (boudins ?). Associated minerals are calc-silicates namely, actinolite, diopside, garnet and epidote; calcite is also present mainly in boudins, The garnetiferous schist member has been traced in both the limbs of Almora-Dudatoli syncline, along with the mineralised host rocks. The study indicates possibility of tracing extensive scheelite deposits in the crystalline nappe rocks of Himalayas. The deposits are believed to be of volcano-sedimentary origin, where tungsten is derived from submarine volcanic processes that took place during the deposition of limy argillaceous sediments.
Palaeoenvironment and Stratigraphic Position of Green Sandstone (Lameta: Late Cretaceous) Jabalpur Area
Authors: Singh Indra Bir , Shekhar Shashi , Agarwal Shrish Chandra
Published: November 2024

Green Sandstone (Green Sand) of Lameta sediments, in Jabalpur area, makes a conspicuous basal lithounit of the succession. It is made up of clean sand without any shale intercalations, and ranges in grain size from medium to fine sand. Largescale cross-bedding in the form of large festoons is the most dominant structure, showing mostly a bipolar current pattern, where one direction is more prominent. The sandstone also exhibits branched Thalassinoides-type burrows. The Green Sandstone represents deposit of an estuarine channel with tidal influences exclusively by marine processes. The prominent southerly palaeocurrent direction at Chui Hill is interpreted as local ebb-current direction.
Nannoplankton from Rc9-156 in the Southeastern Arabian Sea
Authors: Shankaranarayana Guptha M. V.
Published: November 2024

A deep sea core RC9-156 collected in the Arabian Sea at a water depth of 4583m was analysed for calcareous nannoplankton and dissolution studies. Twelve species of nannoplankton were identified and based on the assemblage, it is suggested that the age of the sediment is late Quaternary. The alternate fossiliferous and un-fossiliferous bands encountered in the core is attributed to the fluctuations in the rate of sedimentation by the river Indus during glacial and interglacial periods.
Clay Mineral Distribution on the Kerala Continental Shelf and Slope
Authors: Purnachandra Rao V. , Nair R. R. , Hashimi N. H.
Published: November 2024

Seventy-five sediment samples collected from the Kerala continental shelf and slope during the 17th and 71st Cruises of RV Gaveshani were analysed by X-ray diffraction for clay mineral content. The distribution of total clay < 4μ fraction) indicates low percentages < 10%) on the outer shelf and high percentages on the inner shelf (20 to 50%) and upper continental slope (11 to 47%). The clay minerals are composed of montmorillonite (smectite), kaolinite, illite and gibbsite and the nonclay minerals are quartz and feldspar. Kaolinite and gibbsite have low values on the outer shelf and high values on the inner shelf and slope, while illite increases in the offshore direction. However, montmorillonite behaves differently from others in having high values on the outer shelf and low values on the inner shelf and slope. These variations in the clay mineral distribution have been attributed to differences in the energy of the various environments and due to size segregation of the minerals.
Petrology of Quartzo-Feldspathic Schists/Phyllites Associated With Manganese Formations of North Kanara and Kumsi, Karnataka
Authors: Sivaprakash C.
Published: November 2024

Rocks associated with manganese formations in Supa, Dandeli and Bisgod (North Kanara district), and Kumsi (Shimoga district) areas consist of quartz ± muscovite± biotite ± plagioclase ± chlorite ± calcite ± ankerite ± ilmenite ± pyrite ± pyrrhotite ± K feldspars ± epidote ± rutile ± apatite. Whole-rock compositions correspond to greywacke, clay/shale and suggest deposition in reducing environments. Muscovite is phengitic, Chlorite is mainly ripidolite variety. Plagioclase is dominantly albite. Ilmenite in some rocks is manganoan. Phase relations between coexisting minerals suggest that they have formed with a close aporoach to equilibrium. Compositions of coexisting pyrite and pyrrhotite, and of phengite suggest temperatures of formation of 300-400°C and pressures 2-4 kb corresponding to greenschist facies conditions.
Diversity and Dominance of Living and Total Foraminiferal Assemblages, Pennar Estuary, Andhra Pradesh
Authors: Reddy K. R. , Jagadiswara Rao R.
Published: November 2024

A quantitative study has been made of the distribution of recent foraminifera in 180 samples of bottom sediments collected from 15 stations in the Pennar estuary. The diversiiy and dominance of the living and total foraminiferal assemblages have been studied by calculating diversity indices and by relating the number of species with the per cent dominance and the average number of species with the average cumulative percentage of genera.
On the Interrelationship Between Two Granitic Units of the Singhbhum Granite Near Karanjia, Mayurbhanj District, Orissa
Authors: Chattopadhyay Basab K.
Published: November 2024

Two magmatic units of the Singhbhum Granite complex intersect near Karanjia (85°88'E, 21°45'N), Mayurbhanj district, Orissa; these are (i) Bhaunra porphyritic biotite granite and (ii) Karanjia leucocratic fine to medium-grained granodiorite. Presence of xenoliths of porphyritic granite within the leucocratic granodiorite as well as dykes of leucocratic granodiorite cutting across the porphyritic granite indicate the distinctly younger age of the granodiorite.

Statistical studies indicate that significant compositional difference exists between the two granitic bodies in respect of important mineralogical variables. Field evidences along with structural analysis and statistical analysis of the compositional data suggest a magmatic origin for both the units of granitic rocks with a large proportion of liquid at the time of emplacement.

Study of the areal variations of several modal attributes of the two granites using moving average isopleth maps indicates systematic areal variation in composition. The compositional isopleths in the porphyritic granite body are clearly truncated by contact with the younger granodiorite.
Minerals Used in Indian Medicine
Authors: Murthy S. R. N.
Published: November 2024

The paper points out the various minerals used in Indian medicine. Difficulties in standardisation of various mineral substances used in Hindu medicine are noted. The more important therapeutic values claimed for the Ayurvedic medicine are mentioned. Attention is drawn to the need for research in the field of mineral medicine.
Clay Mineral Diagenesis in Parts of the Western Indian Ocean
Authors: Dilli Kailas , Rao C. N.
Published: November 2024

Drill core samples of DSDP sites 241 and 250 in the Somali and Mozambique Basins respectively have been examined to understand the nature and extent of burial diagenesis in the deep-sea pelitic sediments of the western Indian Ocean based on X-ray diffractometry and partial chemical analysis. The clay mineral suite is almost identical in both the basins with montmorillonite being the dominant mineral. Illite and kaolinite are present in minor amounts white chlorite is present only in traces. The sediments are in early diagenetic stage. The apparent breakdown of kaolinite and illite and the adsorption of K by the clay minerals has resulted in montmorilloniteillite mixed layers being the only phase present at depth. The mineral trends observed suggest that diagenesis is indeed initiated at much shallower depths as proposed by Matter.
The Jutogh Klippe of the Simla Area of the Himachal Himalaya: Its Geology and Structural Evolution
Authors: Srikantia S. V. , Bhargava O. N.
Published: November 2024

The Jutogh klippe near simla is the highest allochthon in the Himachal Himalaya. Its base is defined by the Jutogh Thrust. Five mappable lithostratigraphic formations are recognised. These are variously represented, in the ascending order, by carbonaceous phyllite and schist of Panjerli Formation; quartzite unit of Manal Formation; phyllite, schist and quartzite of Bhotli Formation; quartzite unit of Khirki Formation and carbonaceous schist, crystalline limestone of Taradevi Formation.

S0 and S1 are the prominent planar surfaces with local development of S2 and S3. F1, F2 and F3 are the three generations of folds. F1 is in minor scale as appressed and reclined folds related to tectonic transport and F2 and F3 having formed after the emplacement of the thrust sheet. F2 is the most pervasive structure along NW-SE, folding the klippe into an open synform. F3 is a larger cross-fold along WSW-ENE and is responsible for culminations and depressions of F2 folds.

The direction of tectonic transport is from ENE to WSW and F2 folds indicate a compression along the same direction.
Nature of the Narmada-Son Lineament
Authors: Das Bhagwan , Patel N. P.
Published: November 2024

Critical examination of the several sections along the lineament from Handia to Barwaha have led to the identification of ten major and several minor faults in the area. They constitute a wrench system. The largest Badel-Dhasar-Ajnaskhurd fault is a primary first order right lateral wrench fault typically associated with the second order right-handed and the third order right lateral wrench faults. The Barjar-Bhadlipura fault is interpreted as a complementary first order left lateral wrench fault. The Badel-Dhasar-Ajnaskhurd and Barjar-Bhadlipura faults represent a first order set of conjugate shears. This would mean that the first order regional stress direction had WNW-ESE orientation. Folds related to the wrench faults have developed in the Precambrian rocks of the area. The most important Badel-Dhasar-Ajnaskhurd fault of the area around Chandgarh forms part of the Narmada-Son lineament. The Narmada-Son normal wrench fault steeply dipping towards south and Pachmarhi-JabaJpur normal fault dipping towards north constitute a graben structure.

The Narmada-Son lineament has existed since late Archaean and has got rejuvenated from time to time.
A New Classification of Bauxite-Bearing Lateritic Plateaux
Authors: Szabo E.
Published: November 2024

The paper presents a classfication of bauxite-bearing lateritic plateaux, on the basis of the author's experiences on laterites and lateritic bauxites in West Africa, Southeast Asia and Central America. The criteria of classification are, surface area of the plateau, shape or the plateau (both vertical and horizontal view), altitude, parent rock(s), index of dissectedness, morphology, and ore tonnage per unit area. The classification is computer-compatible and is recommended for practical investment decisions.
Parallel Scarp Retreat and Drainage Evolution, Pachmarhi Area, Madhya Pradesh, Central India
Authors: Venkatakrishnan Ramesh
Published: November 2024

This study is the outcome of field and topographic map interpretations to evaluate the relationship between scarp retreat and associated drainage pattern evolution. The area under study is composed of gently north-dipping series of Gondwana (Triassic) sediments overlam by Deccan Trap basalts (Cenozoic). These sediments have been exhumed within an elliptical iniler, the Central India Gondwana Basin, due to domal uplift parallel with the Narmada river rift valley which lies to the north of the study area.

The near east-west trending Pachmarhi Scarp developed within the Pachmarhi Sandstones is about 160 kilometers long and as much as 280 meters 10 height along the north-south minor axis of the dome. Outliers of the Pachmarhi Plateau (Upland Landscape) aligned parallel to the present scarp and some distance from it suggests parallel scarp retreat to the north.

Numerous drainage lines on the Lowland Landscape south of the Pachmarhi Plateau are aligned parallel to the Pachmarhi Scarp and are interspaced with sandstone outilers astride the interfluves. The resulting rectangular drainage pattern also suggests former scarp positions. Continuing scarp retreat exhumes the underlying Bijori Shales on which evolves the Lowland Landscape.

Scarp recession is believed to have been initiated by strike-streams developed along the feather edge of the northerly-tilted Pachmarhi Sandstones. Post-Deccan Trap uplift parallel to the Narmada rift valley lead to the entrenchment of major drainage lines that maintained their course across the axis of uplift and are hence considered antecedent. Minor streams that were defeated by the uplift occupied litho-tectonicc 'weak zones' both parallel to the scarp and at large angles with it, creating the rectangular and barbed drainage patterns. The Narmada river rift valley has acted as a recurrently active local base level at least since the post-Deccan Trap uplift and has had a major influence on 'stepped landform' evolution in the study area.