bluuebunny/crossref_metadata_2025_split huggingface dataset:
Upper Gondwana Stratigraphy, North of the Pranhita-Godavari Confluence, Southern India
Authors: Bandyopadhyay Saswati , Rudra Dhiraj Kumar 
Published: November 2024

Abstract
A revised geological map showing the Upper Gondwana stratigraphy of the area north of the Pranhita-Godavari confluence is presented. The early Upper Triassic (Carnian) Maleri Formation, is overlain conformably by the Dharmaram Formation of late Upper Triassic (Norian-Rhaetian) age. The two local sandstones, viz., the Sironcha sandstone and the Anaram sandstone, earlier believed to be the lithological constituents of the Lower Gondwana Kamthi Formation and the Upper Gondwana Kota Formation, respectively, are found to be inter-related. The two sandstones have been mapped within the Dharmaram Formation. It is suggested that the plant remains described from the Anaram sandstone are of late Upper Triassic age.
A Note on the Metamorphic Conditions of Ultramafic Rocks from the Sargur Region, Karnataka, India
Authors: Srikantappa C. 
Published: November 2024

Abstract
Ultramafic rocks occurring within the high-grade schistose rocks from the Sargur region show evidences of recrystallization. A metamorphic temperature of the order of 700± 20°C is estimated based on coexisting olivine-spinel and orthopyroxene clinopyroxene mineral chemistry.
The Ahar River Granite, Its Stratigraphic and Structural Relations with the Early Proterozoic Rocks of South-Eastern Rajasthan
Authors: Roy A. B. , Golani P. R. , Bejarniya B. R. 
Published: November 2024

Abstract
The Ahar River granite near Udaipur city, considered by Heron as intrusive into the Aravalli rocks of early Proterozoic age, is a coarse-grained, massive, leucocratic rock except along the outcrop margins. The granite ranges in composition from alkali granite to granodiorite and tonalite, with about 5% ferromagnesian minerals. The enveloping Aravalli metasediments form a continuous sequence starting with greenschist (metavolcanics) and quartzite (locally conglomerate) along the granite contact. The stratigraphic position of the Ahar River granite in relation to the surrounding metasediments suggests that the granite is the basement rock. The granite characteristically shows post-crystalline deformation of the constituent grains, specially quartz and feldspar; and the granite-cover contacts are marked by ductile shear zones developed during the earliest deformation of the Aravalli rocks.
Root Beds and Palaeoenvironment in Daltonganj Coalfield-A Preliminary Study
Authors: Chaudhuri S. 
Published: November 2024

Abstract
In Daltonganj coalfield some root beds have been studied. The roots occur as root casts with caliche and as coalified ones. The host rocks represent a variety of facies like channel, abandoned channel-fill, sheet flood (?), levee and flood basin. Two types of roots are recognized. Roots of type I are laterally spreading and small, while those of type 2 are vertically extending and large compared to those of type I. These differences in root character have been attributed to response of plant to availability of water which depended on host-rock characteristics as well as fluctuation of level of ground water. It is further noted that coalification of root proceeded in areas of water accumulation of relatively perennial type, compared to those of accretion of caliche where there was a balance between supply and loss of water to and from the system. Moreover, pedogenic remobilization played a great role in localizing the caliche around the roots in preference to the host rock. Rainfall appears to have been poor and intermittent.
'Chail Series' of the Himachal Himalaya
Authors: Srikantia S. V. , Bhargava O. N. 
Published: November 2024

Abstract
A critical study brings out that the 'Chail Series' broadly occurs in two tectonic positions - the 'Lower Chail allochthon' as a thrust sheet over the Shali and the' Upper Chail allochthon' as an infra-Jutogh thrust sheet. The revision mapping of the Simla area has brought out that the' Lower Chail allochthon' includes (i) a sedimentary unit occurring as a cover over the Shali and designated as the Basantpur Formation of the Simla Group and (ii) a regional nappe tectonically overlying the Shali-Simla Groups and designated as the Salkhala thrust sheet. The' Upper Chail allochthon' has been found to be part of the Jaunsar Group. Thus, the' Chail ' was never an entity and has lost its validity as a stratigraphic term. This naturally precludes its adoption even as a tectonic term.
Trace Element Studies of the Zircon Separates and the Related Host Rock/Sediment Assemblage Along Manimala River, Kerala
Authors: Parthasarathy R. , Murali A. V. , Sankar Das M. , Nair A. M. , Narayanaswamy  
Published: November 2024

Abstract
Zircon separates from a few whole rocks and sediments along with the parent sources have been analysed for Zr, Hf, Se, REE, Th and U concentrations by the neutron activation analysis technique. The major, minor and trace analyses of rock samples and their modal analyses are also presented. The chondritic normalised REE patterns of rock samples show positive Eu anomalies, while the zircon samples show negative Eu anomalies. The data have been used to explain the genetical relationship among the rocks under study. This study supports the hypothesis proposed from this laboratory that the detrital zircons of Kerala beach are time integrated cumulates from the whole-rocks of this region. The scandium data indicate the paragenetic sequence of crystallization of zircons in relation to cpx and magnetite.
Archaean Komatiites from Banasandra Area of Kibbanahalli Arm Of Chitradurga Supracrustal Belt in Karnataka
Authors: Srikantia S. V. , Bose S. S. 
Published: November 2024

Abstract
The Banasandra Komatiites occur within the Kibbanahalli arm of the Chitradurga supracrustal Belt in Karnataka. They apparently overlie the Bababudan Group and the Peninsular Gneiss and occur in two isolated exposures, (i) east of Birasandra, and (ii) near Kodihalli - Kunikenahalli. Ultramafic rock types include pillowed serpentinites, spinifex-textured komatiite, massive and schistose serpentinite and talc-tremolite-chlorite schist. Certain quartz-antigorite (birbirite ?), quartz-amphibole, and high-magnesian chlorite rocks are also closely associated with the ultramafics. The major element chemistry of the Banasandra komatiites compares with those of Barberton, S. Africa, Munro Township, Canada and of W. Australia. The exact relationship between these komatiites and the Bababudan volcanics is not clear for lack of continuous outcrops. Field evidences point to possible tectonic emplacement.
New Petrographic Data on the Metapelites of Almora Crystallines in Kumaun Himalaya
Authors: Karanth R. V. 
Published: November 2024

Abstract
Detailed structural and metamorphic study has revealed four tectonic episodes in the Almora Crystallines. The first two have brought major metamorphic changes. The earliest event (D1) belonging to the Late Precambrian/Early Palaeozoic orogeny produced the early cleavage (S1), parallel to the axial planes of isoclinal folds (F1) which now trend NNE-SSW. Almandine garnet and sporadically occurring staurolite generated during this pre-Himalayan orogenic event reveal a growth under static condition. D1 culminated with the intrusion of granitic lenses which granitised the adjacent metapelites. The second event (D2) belonging to the Early Tertiary Himalayan orogeny refolded this sequence into another set of isoclinal folds (F2) that are co-axial with F1 and produced widespread crenulation cleavage and snowball garnet. The continued action of D2 detached the crystallines from the root zone and pushed them over the less metamorphosed unit of the Lesser Himalaya as thrust sheet. Chlorite trails of the retrograded garnet in the intensely mylonitized zone indicate southeasterly movement of the thrust sheet. The early stage of thrusting of the nappe synchronized with the progressive metamorphism in the interior region. Third (D3) and fourth (D4) events merely folded and crinkled these rocks.
Multiple Deformation and Interference Structures in the Archaean Iron Ore Group Rocks Around Barda-Ulugutu Area, Singhbhum District, Bihar
Authors: Srivastava Deepak C. , Sarkar S. N. 
Published: November 2024

Abstract
Systematic structural analysis of the Archaean Iron Ore Group rocks around Barda and Ulugutu throws new light on the tectonic pattern and structural evolution of the area. The polyphase tectonics (D1-D3) is evident by the style and over-printing relationship between three types of s-planes (SO-S2), folds (F1-F3), and related lineations. Folds (F1) showing complex geometries, related lineations showing variable plunges and slaty cleavages (S1) have developed synchronously during the earliest tectonic phase (D1). The concomitant evolution of a new set of structures and deformation of preexisting D1 structures took place during the second phase (D2). The numerous smallscale culminations - depressions of F2 folds are attributed to the variable orientations of s-surfaces prior to F2 folding. Critical field evidences suggest the evolution of both F1 and F2 folds through similar deformational plans including buckling and post-buckle flattening. The concentric warps (F3) are envisaged to have developed under flexural conditions during D3 phase in local domains.
En-echelon arrangement of elliptical interference structures are ascribed to the nonorthogonal axial surfaces of F1 and F2 folds, and axial migrations during F2 folding. The co-existence of type-1 and type-2 patterns is due to F2-flexure of alternating tight and open folds (F1) within the same layer. That the bedding (sO) has been successively subjected to layer parallel compression is implied by buckling nature of repeated folding. Therefore, finite strain-ellipse of the whole area corresponds to constrictional field (1&gt;?1&gt;?2)
A Comparative Study of Tectonic Fabrics and Deformation Mechanisms in Dharwar Grits and Phyllites and Sargur Quartzites on the West of Chitradurga Supracrustal Belt, Karnataka
Authors: Chadwick B. , Ramakrishnan M. , Viswanatha M. N. 
Published: November 2024

Abstract
Late Archaean t ectonic LS fabrics in quartz-pebble conglomerates and grits in the lower part of the Dharwar Supergroup are defined by micas and the preferred planar orientation of long (X) and intermediate (Y) axes of ellipsoidal clasts of vein quartz. Long axes of clasts define the linear component ofthe fabric. With increasing strain the grits become L tectonites. Pressure solution and intragranular processes were important at lower strains, but dislocation creep was dominant at higher strains related to the LS fabric development.
Dharwar phyllites and polymict conglomerates have a bedding-parallel S fabric of phyllosilicates and detrital grains of quartz. This fabric is attributed to neocrystallization and recrystallization of phyllosilicates coplanar with a primary bedding-parallel fabric during diagenesis and subsequent burial and regional heating deep within the Dharwar volcanosedimentary pile. Coeval, domainal and penetrative tectonic LS fabrics, with transitions from domainal to penetrative types, which formed contemporaneously with LS fabrics in the grits were superimposed on the bedding-parallel fabrics. Microbuckling and pressure solution dominated early stages of the cleavage development, but they were overtaken by coplanar growth of biotite in the later stages. Discordant prisms of tourmaline and blue-green amphibole, radiating intergrowths of chlorite and quartz and octahedra of magnetite and their pseudomorphs of quartz indicate that grain growth took place during the low-grade metamorphism that outlasted the late Archaean deformation.
Transitional crenulation to penetrative S fabrics, locally with a linear component coaxial with folds, were superimposed on an older tectonic S fabric broadly parallel to bedding in the Sargur quartzites which form part of the basement immediately below the Dharwar Supergroup. The younger fabrics are correlated with the late Archaean tectonic fabrics in the Dharwar grits and phyllites. The older fabric, which includes prisms of kyanite, is believed to be related to pre-Dharwar deformation and medium- to high-grade metamorphism. Whilst microbuckling, pressure solution and dislocation deformation processes were important in the development of the younger fabric, their role in the development of the older fabric is not clear because of the superimposed effects of the later processes. Discordant chloritoid grown across pre-Dharwar garnet. staurolite and kyanite and their low-grade alteration products in the Sargur quartzites suggests grain growth took place during low-grade metamorphism that outlasted the development of the younger fabric, a relation identical to that in the Dharwar grits and phyllites.
Stratigraphic Status of Javanahalli Belt in the Archaean Geology of Karnataka
Authors: Ghosh Roy A. K. , Ramakrishnan M. 
Published: November 2024

Abstract
Javanahalli belt situated at the eastern margin of Chitradurga superbelt is either juxtaposed against the latter or separated from it by linear stripe of granite. The rocks of Chitradurga and Javanahalli belts and the associated enclaves are part of the Chitradurga Group. The primary lithologies of both the belts as well as the enclaves are comparable despite differences in metamorphic grade. These are ortho- and para-amphibolites, calc-silicate rocks, limestones, fuchsite quartzites, mica schists, cordierite-anthophyllite rocks and banded iron formation which is locally manganiferous. The meta-arkose/paragneiss, is mylonitic, potash-rich ortho-gneiss, and constitutes the deformed and partly remobilised basement. Preliminary structural studies have shown that Javanahalli belt is affected by early recumbent folds (F1) followed by the major second phase of nearly co-axial upright N-S folds (F2) which control the present map pattern. The ENE trending third phase open folds (F3) have caused local fold interference patterns. There is a progressive increase in metamorphism from west to east towards the gneissic contact, ranging from greenschist facies in Chitradurga belt to middle amphibolite facies in Javanahalli belt and enclaves, culminating in extensive granitic veining and migmatisation. Javanahalli belt represents a classic case of wide-spread basement reactivation associated with a boundary thrust in an ideal, ensialic, Archaean orogen.
Early Life in the Chitradurga Schist Belt
Authors: Suresh R. 
Published: November 2024

Abstract
The Archean Chitradurga schist belt (&gt;2600 m.y.) is ideal for the investigation of morphological and chemical remnants of early life because of the presence of distinct sedimentary units. Available data so far, has not indicated the presence of undoubted microfossils from the Chitradurga belt. Possible microfossils from the Dodguni area are the only reliable evidences of early life from the Chitradurga schist belt.
Chemical and Magnetic Stratigraphy of Parts of Narmada Region, Deccan Basalt Province
Authors: Sreenivasa Rao M. , Ramasubba Reddy N. , Subbarao K. V. , Prasad C. V. R. K. , Radhakrishnamurty C. 
Published: November 2024

Abstract
Field investigations of a 666 m thick Deccan volcanic sequence north of the River Narmada (Khalghat-Mhow traverse; 60 km) showed the presence of 21 flows, while a 549 m thick southern section comprises of 28 flows (Mandaleswar-Pipaljopa traverse: 110 km). The lava sequences essentially consist of PI and/or Pyx phyric to aphyric basalts with glassy vesicular - amygdular tops/flow breccia.
On the basis of selected major and trace elements (Si, K, Ti, P, Ba, Sr, Zr), the Khalghat section is divided into three formations. The lowermost Narmada Formation is characterized by lower K, Ba, Sr, Ba/Ti, Ba/Sr and Ba/Zr than the succeeding Manpur Formation. The uppermost Mhow Formation is highly depleted in K, Ba, Sr compared to the two lower formations. Chemically, a four-unit informal stratigraphy has been adopted for the Mandaleswar section. The lower three may be correlated with the Narmada, Manpur and Mhow Fms of the Khalghat section and the upper one is labelled the Satpura Formation. Each formation is defined as a set of flows characterized by one or more chemical types such as 'primitive' and' evolved' ones.
The palaeomagnetic results of the Khalghat section demonstrate that the lower 254m pile of flows belongs to normal polarity (N) ('Narmada Normal Epoch') overlain by 412 m thick flows with reversed polarity (R) ('Malwa Reversed Epoch'). Interestingly, on the southern side of the river, about 21 m thick N flows are overlain by 476 m R flows, which in turn are capped by 52m thick N flows ('Satpura Normal Epoch') resulting in an unambiguous NRN sequence in the Deccan basalt province. It appears that the northern side of the Narmada River has been thrown up relative to the southern side. Based on the correlation of the magnetic reversals in the Deccan as well as marine magnetic anomalies, it seems likely that the normally magnetized older Rajmahal traps (about 100 MA) of eastern India form the base of the Deccan basalts.
On the Formation of K-Feldspar Augens - An Example from the Central Crystallines of the Bhutan Himalaya
Authors: Roy A. 
Published: November 2024

Abstract
Mesoscopic and microscopic studies on the K-feldspar augens of Thimphu augengneiss of Bhutan suggests microshearing followed by a rotational mechanism. Megacrysts of K-feldspar are often broken into smaller segments by ductile shear faulting, followed by a combination of simple shear and flattening deformation giving rise to the augens.
Reaction Textures in Silica-Deficient Granulites of Ganguvarpatti, Madurai District, Tamil Nadu
Authors: Mohan Anand 
Published: November 2024

Abstract
The silica-deficient granulites of Ganguvarpatti display textural evidences of metamorphic reactions, involved in the formation of diverse mineral assernblagest documented by different types of reaction coronas and symplectitic intergrowths. The symplectitic intergrowths, viz., orthopyroxene-spinel-cordierite and orthopyroxene-spinel-cordierite-sapphirine rimming corroded garnet have been attributed to reactions:
Gt + H2O⇋Opx + Sp + Cd
Gt + O2 + H2O⇋Opx + Sp + Cd + Sa
The textural relation of orthopyroxene isolated from sapphirine by a reaction corona of cordierite + spinet is related to reaction: Opx +Sa + H2O⇋Cd + Sp.
Gravity Bases Established by the Centre for Earth Science Studies in and Around Palghat Region, South India - Part I
Authors: Singh H. N. , Panchanathan P. V. , Unnikrishnan K. R. 
Published: November 2024

Abstract
Forty-one gravity bases were established with a Worden gravimeter in parts of Palghat gap area bordering Kerala and Tamil Nadu. The description of these base stations and the observed gravity values are presented. The observed gravity values at these stations are with reference to a value of 978.0715 gals at the Coimbatore Airport, established by the National Geophysical Research Institute, Hyderabad. The accuracy of the observed gravity values is estimated to be 0.07 mgal. The new base stations are being used for regional gravity surveys.
Occurrence and Significance of Algal Stromatolites from the Choral Valley, Near Barwah, Khargoan District, M.P.
Authors: Kale Vivek S. 
Published: November 2024

Abstract
Conophytoll cylindricus, Collenia columnaris, Collenia symmetrica and Collenia undosa are reported from the dolomitic intercalations within the Mehdikhera Chertbreccia Formation, exposed in the Choral river valley near Barwah, in Khargoan District, Madhya Pradesh. There is a lack of consensus regarding the origin of this Formation and it has been considered to be equivalent of Bijawars. The present report of stromatolites conclusively points to its sedimentary origin and suggests a need for a reappraisal of the age.
Progressive Charnockitization of a Leptynite-Khondalite Suite in Southern Kerala, India- Evidence for Formation of Charnockites Through Decrease in Fluid Pressure?
Authors: Srikantappa C. , Raith M. , Spiering B. 
Published: November 2024

Abstract
The crustal segment south of the Achankovil zone in southern Kerala is built up by two litho-tectonic units: The Nagerkoil unit is represented by a series of acid to intermediate magmatogenic gneisses and charnockites associated with layered anorthositic to noritic complexes. The Pon Mudi unit consists of interlayered garnet-biotite gneisses (leptynites), garnet-biotite-sil1imanite gneisses (khondalites) and garnet-biotite-sillimanite-cordierite metatexites which represent a series of intensely deformed psammitic and pelitic sediments metamorphosed to upper amphibolite grade (700-750°C; 6-8 k bars). Subsequent to regional metamorphism in the POD Mudi unit, the leptynites have been partly transformed to massive orthopyroxene-garnet-bearing charnockites along a conjugate set of fractures (s1: N30E ilDd s2: S70E) and the foliation planes of the rocks (N30-60W).
The geochemical data and the results of geothermobarometry show that charnockitization was essentialJy isochemical and occurred at 750 ± 50°C and 6 ± 1 kbars lithostatic pressure. A complex but conformable development of tbe fluid phase composition during metamorphism is indicated by the occurrence of at least four generations of fluid inclusions (almost pure H2O and CO2 inclusions, mixed CO2-H2O inclusions and CH4-N2 inclusions) in both the leptynites and the charnockites. The common presence of graphite+pyrrhotite+ilmenite furthermore suggests internal buffering of the fluid composition at oxygen fugacities below those defined by the quartz-magnetite-ferrohypersthene assemblage and XCO2&gt;0.5.
The results of tbe present study indicate that charnockitization probably was not caused by the influx of CO2-rich fluids of deep-seated origin, tbe presently favoured model of granulite genesis (Newton, 1984), but rather was induced by an isothermal decrease of fluid pressure relative to lithostatic pressure, due to migration of the pore fluid into the network of fractures and ascent into higher crustal levels.
Trilobite and Other Trace Fossils from the Kunzam La Formation, Eastern Lahaul Valley, Himachal Himalaya
Authors: Bhargava O. N. , Srikantia S. V. 
Published: November 2024

Abstract
Trilobite locomotion trail Isopodichnus sp., swimming grazing trace Monomorphichnus sp. and resting trace Rusophycusdidymus are recorded from the siltstone-shale-quartzarenite sequence of the Kunzam La Formation (Cambrian) from the eastern Lahaul Valley, Himachal Himalaya. Besides these, a ringed conical ichnocoenosis is also reported.
The trilobite traces belong to Cruziana 'facies' which is characteristic of stable infra-littoral to circa-littoral zones. The presence of Rusophycus suggests a rather low energy environment.
40Ar-39Ar Darting of Deccan Basalts
Authors: Venkatesan T. R. , Pande K. , Gopalan K. 
Published: November 2024

Abstract
The feasibility of dating igneous rocks by the 40Ar-39Ar method in India using the Apsara nuclear reactor at BARC, Bombay is reported, based on measurements on two tholeiitic basalts and one alkali basalt associated with the Deccan volcanism. The ages of the tholeiitic basalts are 71±4 Ma and 65±4 Ma, respectively and that of the alkali basalt is 682 Ma. Apart from the low neutron flux requiring long irradiation times, the neutron fluence within the sample irradiation volume is somewhat anisotropic. The latter needs to be minimised to achieve the higher precision the method is capable of.
Chemical Ages of Zircons: New Results
Authors: Parthasarathy R. , Palrecha M. M. , Sankar Das M. 
Published: November 2024

Abstract
Seven zircon separates from different geological environments have been analysed for U, Th and Pb contents. U and Th are determined by Neutron Activation Analysis (NAA) and Pb by Differential Pulse Anodic Stripping Analysis (DPASV). The.elemental abundances have been utilised to calculate the chemical ages of zircons,