bluuebunny/crossref_metadata_2025 huggingface dataset:
Tectonic Framework of Sedimentation in the Western Part of the Palnad Basin, Andhra Pradesh
Authors: Vijayam B. E. , Reddy P. H.
Published: November 2024

The lithologic character of sediments, geometry and sedimentary characters of the formations belonging to the Palnad Basin have been taken into consideration in interpreting the probable tectonic framework of sedimentation and tectono-environmental classification of sedimentary formations in the western part of the Palnad basin. The Banganpalli quartzites were deposited in the littoral to infra-littoral environment under stable shelf conditions. The Narji limestones were deposited in infra-littoral to neritic environment under stable shelf conditions. Due to uplift the environment changed to infra-littoral and quiet water environment, when the Auk shales were deposited. The Paniam quartzites were deposited in the littoral to infra-littoral environment under stable shelf conditions with minor tectonic instability in certain local areas where positive elements were active during the uplift of the basin. The Kundair limestones and shales were deposited in neritic zones under reducing environment on stable shelf.
Know Thy Mother's Face - A Plea for Geomorphological Studies in India
Authors: Mukherjee S. K.
Published: November 2024

This paper has been put together from a series of notes written by Sri S. K. Mukherjee, Additional Secretary, Ministry of Mines & Steel and circulated among the participants of the seminar on Himalayan Geology. Sri Mukherjee is not a geologist but is one who is greatly interested in geology, especially the study of the face of the Earth. He is Widely travelled and is well informed about the topographic peculiarities of the Indian sub continent. The present note is a fervent plea to Earth Scientisits in India to take to the study of geomorphology or, as he puts it, 'to know the Mother's face '. The thoughts embodied in this note deserve the earliest consideration by Earth Scientists in India.
Provenance and Sedimentation of Pakhals
Authors: Venkateswara Rao M.
Published: November 2024

Thc Pakhals (Cuddapahs) comprise basal conglomerates at the base, followed by coarse and fine clastics and non-clastics. They rest unconformably over the Peninsular granites and gneisses (Archaeans). The statistical parameters of size and shape analyses and the heavy mineral analysis were computed from the coarse clastic sediments (quartzites and ferruginous sandstones). The data so obtained suggest that the sediments were deposited in a littoral environment.
Model Galena Ages from Karnataka and Surrounding Areas
Authors: Venkatasubramanian V. S. , Radhakrishna B. P. , Jayaram S.
Published: November 2024

Lead isotope ratios have been measured for selected samples from the Chitradurga and Kolar schist belts, the high-grade gneisses E of Karnataka (in Tamil Nadu) and Agnigundala of Cuddapahs. Most of the isotope data approximately fit a single-stage model and yield model ages at 3000 m.y., 2500 m.y., 1400 m.y. and 1100 m.y. The relations with other available age data are discussed.
Airborne Geophysical Survey - A Case Study from Central India
Authors: Mishra D. C. , Narain Hari
Published: November 2024

The airborne magnetic case history from Central India presented here provides indications regarding following concealed geological structures: (i) a deep-seated structure oblique to Narmada-Son lineament at a depth of nearly 4800 feet (below Vindhyan sediments). (ii) a subsurface basic intrusion similar to volcanic plug located at a depth of nearly 4900 feet (below Vindhyan sediments). (iii) extension of Bijawar rocks underneath Vindhyan sediments.
X-Ray Studies on the Structural State, Orthoclase Content and Al-Distribution in Tetrahedra of Potassium Feldspars from Southern India
Authors: Krishna Rao J. S. R. , Dhana Raju R.
Published: November 2024

Potassium feldspars from the granitic and related rocks occurring in Hyderabad, Salem, Mysore and Waltair areas were subjected to X-ray diffraction studies, both in their natural state and after heating to 1050°C for 8 hrs. The triclinicity (?) value in the natural samples varies from 0.98 to 0.74, indicating more or less complete ordered Al/Si distribution, whereas in the heated samples it varies from 0.76 to 0.0, showing increasing disorder with heating. The % Or for these samples as well as for the K-feldspars of Chipurupalle-Razam area was estimated using d-¯201 following different methods. The % Or obtained from the equations of Wright (1968) very closely agrees with the value obtained from reliable chemical analysis.

Quantitative estimation of the Al contents in the four tetrahedral sites (T1O, T1m, T2O and T2m), following the method of Stewart and Ribbe (1969), shows that in orthoclase the Al content is equally distributed between T1O and T1m sites, whereas in intermediate and maximum microcline A1 is concentrated more in T1O site than in T1m site. Based on the triclinicity values, the K-feldspars from the Chipurupalle-Razam area belong to the high structural state followed by those from Salem, Waltair, Hyderabad, and Mysore areas with low structural states, and the differences in the structural state may be related to the differences in the P-T conditions prevaling at the time of K-feldspar formation in these areas.
Synthesis of Abiogenic Graphite under Precambrian Conditions
Authors: Karkhanis Suresh Narayan
Published: November 2024

It has long been known that graphite can be formed by the carbonization of organic matter at temperatures greater than 2000°C. These experiments show that carbon from inorganic precursors-carbonate minerals-can form ordered layers at relatively low temperature of only 600°C at 1 Kb pressure. This relatively low temperature of graphitization might be due to other minerals acting as catalysts. The ordered layering of carbon at low temperature and pressure should have an important consideration in the study of ancient carbonaceous sediments.
'Peninsular Gneiss' in the Northern Parts of Andhra Pradesh
Authors: Perraju P. , Natarajan V.
Published: November 2024

The' Peninsular Gneiss' in the northern parts of Andhra Pradesh can be described briefly as a group of composite gneisses, mostly banded or layered, formed as a result of migmatisation of the older meta-pelites (predominantly biotite-schists), metapsammites, and meta-basics (predominantly amphibolites and hornblende schists), by a grey quartzo-feldspathic injection. The resultant migmatitic gneisses enclose inclusions of all shapes and sizes of the older rocks and exhibit different degrees of interaction and assimilation of them. This complex was later intruded by a 'Pink Granite' the effect of which is also seen as a ' second period of migmatisation '. The two major injections appear to be fairly well separated in time.

These two granitic injections and their corresponding migmatisation effects on the older group of diverse rocks has produced a heterogeneous complex of rock types which show wide variations in composition as well as in texture over the region. Both granites have their own groups of aplite, pegmatite and quartz veins. The white quartz and pegmatite veins traversing the grey porphyroblastic biotite gneisses in Karimnagar district carry molybdenite and sulphide mineralisation. All the rocks were later injected by quartz, epidote and at places by fluorite veins. Fluorite is also found as a component mineral of the' pink granites' in Karimnagar district. Dolerite dykes which cut across all the above, mark the last phase of igneous activity.
Charnockites from Hullahalli, Mysore District, Karnataka State
Authors: Janardhan A. S. , Ramachandra H. M.
Published: November 2024

Charnockites have been noticed in the canal sections near Hullahalli, south of Mysore city. From their field, petrographic and chemical character, it is argued that they were formed as a result of granulite grade metamorphism and migmatization of pelites and intercalated earlier basic igneous rocks and pelites of the Sargur schist complex.
Radioactive Carbonatites of Pakkanadu and Mulakkadu, Salem District, Tamil Nadu
Authors: Suryanarayana Rao C. , Narayan Das G. R. , Krishnaiah Setty B. , Perumal N. V. A. S.
Published: November 2024

Precambrian carbonatites associated with pyroxenites occur as discontinuous lenticular bodies intruding the syenites west of Pakkanadu (11°40'15'': 77°50'1'') and Mulakkadu (11°44'3'' : 77°50'2''). They strike northeast to southwest with easterly dips and have been emplaced along a major northeasterly trending deep crustal fault zone. Large outcrops of serpentinised dunites carrying accessory chromite, cut by asbestos and magnesite veins are also found along the same fault zone to the east and northeast of Pakkanadu.

The carbonatites are of the pure calcite-rich sovite type, with biotitic and ankeritic variants. Apatite, magnetite, allanite, barite, monazite, zircon and cerianite, are the accessory minerals.

Spectrographic analysis has revealed Ba, Sr, Ce and La in major amounts (more than 10,000 ppm) and Th, Nb, P, Zr, Y and Sc in minor amounts (< 10,000 ppm). Spectrographic data suggest that the carbonatite-pyroxenite complex is Ce-La rich.

Niobium is not found in economic concentrations. The general radioactivity recorded by the carbonatite-pyroxenites ranges from 5 to 20 x BG. Representative whole rock samples assay from 0.02% to 0.054% eU3O8 (Carbonatites) and 0.02% to 0.06% eU3O8 (pyroxenites). Allanites assay from 0.35% to 0.4% eU3O8 with chemical U3O8 values from 0.007% to 0.034%, thereby indicating the predominance of thorium over uranium. Monazite is mostly concentrated in the biotite-rich portions of the carbonatites to the west of Pakkanadu, whereas allanites predominate in the pyroxenites west of Mulakkadu.
Discovery of Early Jurassic Micromammals from Upper Gondwana Sequence of Pranhita Godavari Valley, India
Authors: Datta P. M. , Yadagiri P. , Jagannatha Rao B. R.
Published: November 2024

The occurrence of Early Jurassic mammalian parts which are microscopic consisting of teeth, mandibles with attached teeth, limb bones, vertibrae, pelvic and pectoral girdles and broken skull portions, have been found for the first time in the marly clay of the Kota Formation from Yamanpalli area in Pranhita Godavari Valley of Andhra Pradesh, India. Also occurring with these micromammalian remains are interesting microscopic eggs. The paper gives an account of the stratigraphic setting of the horizon yielding the micromammalian fossils and fossil evidences that support Early Jurassic age for the Kota Formation.
Narmada-Son Lineament of India Traced into Madagascar
Authors: Crawford A. R.
Published: November 2024

An extension of the Narmada-Son lineament of peninsular India can be traced across northern Madagascar, the lineament having been continuous in Gondwanaland. The Indian section, now a narrow seismicrift, appears to be a deep fault. It influenced Precambrian and Phanerozoic sedimentation and is the locus for post-Deccan Trap carbonatite and fluorite occurrences. The Malagasy section shows comparable unusual rocks. Postulated sinistral movement along the Indian section of about 450 km culminating at 750 Ma BP was associated with volcanism, plutonism and base metal mineralisation. The structure may not then have been in existence in Madagascar.
Some Observations on the Foraminifera from the Tertiary Rocks of the Vinjhan-Miani Area, Kutch
Authors: Jauhari A. K. , Vimal K. P.
Published: November 2024

Six biostratigraphic zones of local nature have been proposed in this section and correlated on regional as well as inter-continental scale. Possible palaeoecologic interpretations are briefly discussed with the help of recovered fossil fauna.
Occurrence of Camelus Sivalensis Falconer and Cautley from the Tatrot formation of Ambala, India
Authors: Nanda A. C.
Published: November 2024

The paper gives the first detailed morphological description of a partial mandibular ramus of Camelus sivalensis Falconer and Cautley from the Tatrot Formation of the Siwalik Hills of Ambala district and discusses in brief its stratigraphic occurrence.
Deformation and Metamorphism in the Western Part of Singhbhum Shear Belt Around Lapsa Buru and Kharsawan, Bihar
Authors: Sarkar A. N. , Bhattacharyya D. S.
Published: November 2024

The rocks record four phases of deformation, of which the imprints of the first two are not readily recognisable. The deformation during the third phase was the most intense and is manifested in the northern part of the area by a set of E-W folds on an earlier schistosity and its transposition into a later schistosity. Towards the south, the transposition increases and culminates in the formation of the shear zone. The fourth deformation, restricted within the shear zone, indicates a relative downsliding movement of the northern block over the southern block. Two phases of regional metamorphism are recognised: (i) a progressive cycle, synchronous with the first deformation, and (ii) a progressive-retrogressive cycle, syn-to post-kinematic with respect to the third deformation. The later cycle shows a general increase of grade towards tbe north. The study records two highly contrasting, but grossly simultaneous, tectonometamorphic environments during the third deformation: (i) low stresses, low strain-rates, more of grain rotation and progressive metamorphism in the areas of folding in the north, and (ii) high stresses, high strain-rates, more of flowage and slip and retrogressive metamorphism in the shear zone in the south.
On the Stratigraphy and Sedimentation of the Vindhyan Sediments in the Chitrakut Area, Banda District (U.P.)-Satna District (M.P.)
Authors: Singh I. B. , Kumar S.
Published: November 2024

The lower Vindhyan sediments of Chitrakut area (Chitrakut Formation-Semri Group of Son Valley) are deposits of a tidal swept shallow sea, mainly in tidal flats under extremely stable conditions. They represent a special case of condensation horizons (condensed deposit) under conditions of exceptionally low rates of deposition and negligible sinking of the basin. The stromatolite assemblage suggests lower Riphean age and can be correlated to the Kajrahat limestone of Son Valley area. A marked depositional hiatus is established at the base of Kaimur at Sangrampur hill. Variation in the facies and absence of time plane index-horizons makes the correlation in the Chitrakut area very difficult. It is too early to suggest a generalized lithostratigraphy for the Chitrakut Formation.
Ganges Versus Indus Cone-A Comparative Study
Authors: Mallik Tapas Kumar
Published: November 2024

The Ganges and the Indus cones represent two of the most important sediment inputs in the Bay of Bengal and Arabian sea respectively. The different aspects of these cones have been presented here giving mainly the Deep Sea Drilling Project Data and results of smear slide examinations and other sedimentalogical studies of samples from the DSDP sites on these cones and from the river mouths.
Structural Studies in the Archaean Sargur and Dharwar Supracrustal Rocks of the Karnataka Craton
Authors: Chadwick Brian , Ramakrishnan M. , Viswanatha M. N. , Srinivasa Murthy V.
Published: November 2024

Structural studies in the linear supracrustal belts and adjacent Peninsular Gneiss in the areas of Sargur, Holenarsipur and Chitradurga have revealed Land S tectonites and related structures, which are attributed to phases of deformation SgDl, SgD2 and SgD3 in the older Sargur Group and DhDI, DhD2 and DhD3 in the younger Dharwar Supergroup. These phases gave rise to comparable patterns of strain in each group, the deformation taking place with similar timing relative to metamorphism. Metamorphic grade is higher (middle to upper amphibolite facies) in the Sargur Group and lower (upper greenschist to lower amphibolite facies) in the Dharwar Supergroup: the higher grade assemblages in the Sargur Group show some degree of retrogression. The structures and fabrics in both groups may either be of approximately the same age (SgD1=DhDl, SgD2=DhD2, SgD3=DhD3) or more probably, the SgDI, SgD2 and SgD3 structures and fabrics in the Sargur Group may be older and were rotated into parallelism with younger structures formed in the Dharwar Supergroup during phases of deformation DhD1 and DhD2 that gave rise to the present form of the linear belts of supracrustal rocks extending from Sargur to Chitradurga. Some aspects of the Archaean tectonometamorphic evolution of the Karnataka Craton are discussed in the light of these alternatives.
Rare Earth Minerals of Carbonatites of Tamil Nadu
Authors: Semenov E. I. , Upendran R. , Subramanian V.
Published: November 2024

Uranium-titanium pyrochlore, fergusonite (cubic), eschynite, Fe-Nb rutile, allanite, chevkinite, thorite and bastnaesite are some of the rare earth minerals identified and described.
Fossil Sea Cow from the Tertiary of Kutch
Authors: Satsangi P. P. , Trivedy A. N.
Published: November 2024

The paper records the occurrence of Sea Cow from the Tertiary sediments of Kutch. The mandibular fragment recovered from the ferruginous marl.beds of Chattian resembles Halitherlum reported from Europe, Africa and North America. In certain respects it is comparable to Dugong, the living genus, and it may represent a transitional form between the two. With overall consideration it is assigned Halitherium sp.
Nature of Fluorspar Mineralisation at Chowkri-Chhapoli, Sikar-Jhunjhunu Districts, Rajasthan
Authors: Ranawat P. S.
Published: November 2024

Fluorite mineralisation is localised in post-Delhi intrusives of tonalite, hornblendite and vein quartz at Chowkri. Fluorite occurs in Ajabgarh feldspathic quartzites at Chhapoli and also aplites of younger age. The mineralisation is attributed to hydrothermal solutions genetically related to the post-Delhi intrusive granite, tonalite and aplites of the area.
Structural History of Sargur Supracrustals and Associated Gneisses, Southwest of Mysore, Karnataka
Authors: Janardhan A. S. , Ramachandra H. M. , Ravindra Kumar G. R.
Published: November 2024

Results of structural investigations in Sargur schist complex around Sargur, Dodkanya and Gundlupet indicate four major fold episodes and associated fault movements. These episodes have resulted in the formation of antiform-synform structures(F2), extensive interleaving and dome-basin patterns (F2 and F3). Tectono-metamorphic studies have brought out the polymetamorphic (with late retrogressive) and polydeformational nature of the terrain. At least two migmatization events and (anatectic) granitic intrusions (associated with F2 and F3) have been recognised. A classification of gneisses of the area has been made and reasons and criteria for the recognition of 'Kabini gneiss' are given.

The tectonic relations between the Sargurs, Dharwars and 'Khondalite-Char- nockites', point to structural continuity of the Sargur terrain with the 'Khondalite-Charnockite' terrain to its south.
Geology, Structure and Uranium Mineralisation in Kulu, Himachal Himalaya
Authors: Narayan Das G. R. , Parthasarathy T. N. , Taneja P. C. , Perumal N. V. A. S.
Published: November 2024

Uranium mineralisation as Uraninite vein filling is seen in joints and fractures in the quartzites exposed within an eroded cover of crystallines, tectonically thrust from east and NE in Kulu-Banjar area of Himachal Pradesh. Analysis of the joints suggests a tensional origin and can be related to the three main folding events identified from the fold structure in the quartzites. It is believed that the mineralisation is essentially under low temperature-pressure conditions as there is a remarkable absence of large scale wallrock alteration.

U-Pb dating of six Uraninite samples reveals two distinct episodes of mineralisation at 1200 m.y. and 700 m.y. confirming the Precambrian age of Uranium mineralisation, and associated metasediments.
Environment and Age of the Tal formation of Mussorie and Nilkanth Areas of Garhwal Himalaya
Authors: Singh Indra Bir
Published: November 2024

The Tal Formation in Mussorie area represents deposits of a shallow tidal sea. The basal black shale succession-with phosphorite, chert, and minor amounts of sandy layers and limestone bands is the deposit of a protected lagoon or embayment, followed by streaky siltstone facies, representing deposits of a protected tidal flat. Streaky siltstone shows characteristic features of mixed flat and mud flat of intertidal zone. The topmost thick quartzite succession is a deposit of a shoal complex of a tidal sea with rather high energy. Thus, from bottom towards top of the Tal succession, there is a gradual improvement in the circulation system, as well as increase in the energy of deposition. The fossiliferous shell limestone (Nilkanth Formation) is not a part of the Tal Formation, but represents deposits of a high-energy sand bar-shoal complex of a shallow tidal sea.

The Tal succession is devoid of any well defined body fossils and a Precambrian age is proposed. The fossil-bearing horizons occurring in association with the Tal Formation (hitherto considered to be part of Tal Formation) may belong to different age, namely, Carboniferous-Permian and Jurassic-Cretaceous; however, and these horizons do not appear to form part of the Tal succession.
Fossil Plants from the Sub-Recent Clay in Sirmur District, Himachal Pradesh
Authors: Tewari A. P. , Swain P. K. , Awasthi N.
Published: November 2024

This note records some Prunus sp., Mallotus philippinensis Muell, and Celtis sp. from Kalidhang in district Sirmur, Himachal Pradesh. These plant fossils were found embedded in varve like clay around Kalidhang during the course of the field investigation in 1975-76. The geological set-up and the plant assemblage indicate a sub-Recent age for the clay beds.
Migrations of the Indus River, Pakistan, in Response to Plate Tectonic Motions
Authors: Snelgrove Alfred K.
Published: November 2024

It is contended that the westerly shift of the Indus River, up to about 160km, much of which occurred during historic times and is attested to by a network of abandoned channels and associated structures (and the corresponding easterly trend of the Ganges) is a side-effect of the northward drift of the Indian tectonic plate.

In the extremely fiat alluvial Indus Plain, located in a mobile belt near the boundary of the Indian and Afghanistan plates, instrumental documentation of tilting is lacking but is strongly indicated by systematic and progressive river migrations in stages recognized by Pithawalla as Prehistoric, Greek, Arab, Middle Ages, Eighteenth Century, and British.

Speculations are ventured on how future differential motions of the Indus and Afghanistan plates might further affect the Indus drainage; engineering applications of such motions focus on the Tarbela Dam.
Palaeomagnetism of the Dykes from Kolar Gold Mines, India
Authors: Damodara Reddy V. , Prasad C. V. R. K.
Published: November 2024

Results of the palaeomagnetic studies on five dykes intruding the Archaean schists from the Nundydroog mine (lat. 12°57', long. 78°15") of the Kolar Gold Fields are reported. Three dykes have given consistent and stable directions after cleaning in an alternating field of 150-200 oe. The virtual geomagnetic poles (VGP's) of these dykes are 47°N, 163°W; 50°N 36°W; and 45°N, 30°W. A Precambrian polar wandering curve for India is drawn taking into consideration radiometric ages and the palaeomagnetic data, available from the formations other than the dykes. Based on this polar wandering curve the ages of the dykes are interpreted. It is suggested that these dykes occupy the fractures which were probably formed during Precambrian times, due to an East-West compressive stress. Continental drift in Precambrian era is indicated.
Welded Tuffs from Mangampeta, Cuddapah District Andhra Pradesh
Authors: Sastry A. V. R. , Viswanath K.
Published: November 2024

Close association of peralkaline vitric crystal tuffs (welded) with the massive dark grey stratified barytes deposit is reported. Megascopic and microscopic description of the rocks reveal that these rocks are of eruptive origin.

Chemical analyses of three representative rock samples are given. Peculiar chemical characteristics are discussed.
Factors of Concentration of Chalcophile Elements in the Evolution of Plateau-Basaltic Magmas
Authors: Al' Mukhamedov A. I.
Published: November 2024

The geochemical evolution of ore-bearing trappean intrusions particularly from the Siberian platform is discussed. Analysis of empirical geochemical and experimental data shows, on the one hand, that it is reasonable to suggest that chalcophile elements were concentrated together with the sulfide melt in the lower horizons of the bedded bodies due to gravitational accumulation of the sulfide melt and, on the other hand, that the mechanism of sulfurization of basic magmas is the most possible one to explain the formation of sulfide liquid in sufficient quantities to concentrate ore components in economic amounts.

Within the framework of the hypothesis of magmatic sulphurization, the source of ore elements is the parental magma. The source of sulfur seems to be of crustal nature. Since the sulfide melt formed after the sulfurization mechanism is in equilibrium with the silicate part of the system, it does not differ from the sulfide melt formed due to liquation of the sulfur dissolved in the magma. There are as yet no data enough for a quantitative estimation of the contribution from the sulfide-silicate liquation which is, undoubtedly, manifested steadily. However, it may be stated that the role of sulfide-liquid liquation in the ore genesis is negligible.

In terms of the above mechanism, the conditions necessary for chalcophile elements to be concentrated at the magmatic stage in ore amounts are estimated: 1. Primary enrichment of ore elements in magma at the pre-chamber stage effected by the formation of magnesian melts. 2. The contact of the intruding melt with sulfur-containing sequences. 3. Deep differentiation of the intruding melt to facilitate gravitational accumulation of sulfide liquid.
Geochemistry and Origin of Acidic Rocks of Shimoga, Karnataka, India
Authors: Ali Syed , Divakara Rao V.
Published: November 2024

Acid igneous rocks of Shimoga which were earlier mapped as single granite unit actually consist of two distinct lithological units: an older tonalite and a younger granodiorite. Tonalite is highly disturbed, migmatised and appears to have been derived by partial melting of a basic crust. Younger granodiorite is coarse grained to often porphyritic with higher concentration of K, Ni, Cr and V. Its field relationship with tonalite suggests a different late stage intrusive mode of origin.
On the Workings of Some Crabs on the Sandy Beach of Western Sundarban, Bengal Delta, India
Authors: Baksi Subhendu Kumar , Ray Tapan Kumar , De Chirananda
Published: November 2024

The present study includes the nature of burrowing and grazing activities of different types of Crabs on the beach floor of a part of shore line delta complex of Western Sundarbans, West Bengal, India (Fig. 1) along with their geological significance. Two species of the crab Ocypoda are seen forming contrasting burrows, pellets and grazing marks. One crab species with its products of burrowing activities significantly reflects microenvironment in its spatial extent with respect to the shoreline region. Such features might enable us to determine the orientation of shoreline and the basin marginal configuration of the past. Two species of the hermit crab Diogenes are located on the wave washed part of the foreshore and they form contrasting trails of grazing marks from which the orientation of the shoreline, foreshore slope and outer extremities of foreshore may be confidently indicated.
Geomorphological and Sedimentological Study of a Part of the Lower Ganga Basin, District Begusarai, Bihar
Authors: Sinha S. N. , Dayal N.
Published: November 2024

The present day geomorphological features of the area have been evolved through the combined influence of neotectonism and interfluvial processes of the rivers Burhi Gandak, Baghmati, Bainti and Balan. The various geomorphological units have been classified into three major groups: (i) levees, (ii) stream channels and (iii) flood plains. A review of the borehole data and the size analysis of sediments from different geomorphic facies suggests that sedimentation in the eastern part is exclusively fluviatile, whereas the western portion has also experienced a lacustrine environment in the later part of its geological history.
Sedimentology of Limestones in Niniyur Formation, Paleocene, Cauvery Basin, South India
Authors: Madhavan Nair K. , Vijayam B. E.
Published: November 2024

Niniyur Formation, composed essentially of limestones, of Paleocene age, is exposed along a narrow stretch in the Ariyalur outcrop area. The maximum exposed thickness of 15 m constitutes but a part of the Formation, the rest being concealed by the Cuddalore Sandstone. Three shallow boreholes ENE of Sendurai and 2 stratigraphic information wells in Tanjore area indicate that the Formation extends subsurface over a large area.

Exposed sections show sandy and clayey limestone of wackestone texture, deposited in shelf lagoon environments. But eastward in the subsurface, the formation becomes pure limestone (algal lime boundstone-packstone-grainstone) deposited in algal banks. In the Tanjore area the formation is composed of foraminiferal and algal lime packstone-wackestone, probably deposited in quiet to slightly agitated inner to middle shelf environments. In the deeper parts of the basin, under favourable conditions of tectonics and clastics dispersal, transgressive carbonates of similar age and lithology could be expected.
Evidences of Multiple Deformations Near Amaidegri in the Western Part of the Gangpur Group
Authors: Chaudhuri A. K. , Pal A. B. , Roy A.
Published: November 2024

Three phases of folding have been detected in a large exposure along the Sapai lladi near Amaidegri (22°01': 84°08') in the Ghoriajhor manganese belt in the western part of the Gangpur Group. Reclined to inclined folds (F1) plunging SSE have been coaxially refolded by open upright F2 folds, and finally, upright folds with ENE-trending axial planes (F3) cause culmination and depression of axes of open-folded reclined folds. The multiple deformations cause characteristic outcrop patterns and they are reflected in two distinct S-pole girdles around a plane of symmetry which is the axial trend of F3 folds.
The Uppalapadu Alkaline Pluton, Prakasam District Andhra Pradesh
Authors: Leelanandam C. , Krishna Reddy K.
Published: November 2024

The Uppalapadu alkaline pluton is predominantly composed of hypersolvus nepheline syenites containing biotite as the sole ferromagnesian mineral. Hornblendesyenites and orthopyroxene-bearing hornblende-syenites are the associated rock types. The pluton is enveloped by a variety of rock types such as amphibolites, gabbros, and granitic rocks.
Uranium Distribution in Siwalik Vertebrates using Fission Track Technique
Authors: Sharma Kewal K. , Chousey Vinay M. , Sharma O. P. , Nagpaul K. K.
Published: November 2024

Uranium distribution in Vertebrate Fossils from the Siwaliks of NW-Himalaya has been worked out using Fission Track Method. Uranium is found to be uniformly distributed in collophane and ferruginous material of the bone and a sympathetic relationship between uranium and collophane content has been observed. Percolating waters which leached uranium and phosphorus from the granitic matrix (80 to 90%) of the Siwalik sandstones appear to have brought about diagenesis, uranium mineralization and fossilisation of the organic remains in the Siwalik sediments.
Cenozoic Marine Sediments of Long Island, Andaman Sea
Authors: Srinivasan M. S. , Dave Alok
Published: November 2024

The paper briefly describes the sequence of Cenozoic marine sediments that occur on Long Island, Middle Andaman, northeastern Indian Ocean. The stratigraphic sequence recognized is based mainly on the study of smaller foraminifera from measured sections in the western, and eastern parts of the island. The occurrence of Neogene strata on Long Island has been known for some time but until now Paleogene rocks have not been reported from Long Island or any of the other islands east of the main Andaman ridge. The Paleogene strata represented by the Conglomerate and Grit Formation (Port Blair Series) occur only in the northern part of the island, forming the basement upon which the Neogene sediments were deposited. The Neogene strata of Long Island are represented by Inglis Formation (Early Miocene), Long Formation (Late Miocene) and Guitar Formation (Pliocene). The Long Formation yielded rich foraminiferal assemblages, while the recovery from the other two formations was poor.
The Narmada-Son Lineament and the Structure of the Narmada Rift System
Authors: Murty T. V. V. G. R. K. , Mishra Sharad K.
Published: November 2024

Geological, geomorphological, geophysical, petrological and mineralisation evidences have been presented to show that the Narmada-Son line is a line of dislocation from Precambrian to Recent times. Maps have been drawn on the basis of available evidence showing the location of the faults. It has also been shown that the Narmada fault system is interconnected with the Tapti and Purna fault systems. The main faults in the system are east northeast-west southwest traversed by a large number of generally north-south trending cross faults. At places the continuity of the ENE-WSW trending main faults is obscure.
Design of Dug Wells in Hard Rock Areas, Case Study in Karnataka State
Authors: Sharma S. K. , Seetharam A. N.
Published: November 2024

The average transmissivity value arrived at from analyses of pump test data for granitic rocks is 27.32 m2/d and basalts is 49.68 m2/d. The designed specific capacity in order to get an annual draft of 12000 m3 is 561pm/metre drawdown. An optimum diameter of wells in granitic and basaltic rocks for an annual draft of 12000m3 are 8.6 and 6.0m respectively with 2 m of saturated material. These are true only for wells located in groundwater worthy areas of significant transmissivity values.
Shilakong Ophiolite Nappe of Zanskar Mountains, Ladakh Himalaya
Authors: Srikantia S. V. , Razdan M. L.
Published: November 2024

The Shilakong ophiolite nappe occurs along the crest of the Zanskar Mountains in Ladakh, tectonically resting over the Mesozoic-Cenozoic sediments of the Spiti-Zanskar basin. It comprises two sub-nappe units. The lower Photang sub-nappe is made of pillow lava, basalt, volcanogenic sediments, purple chert and carbonate rocks with slivers of serpentinite. The Spong sub-nappe comprises mainly harzburgite, dunite and lherzolite in different stages of serpentinisation. The Shilakong ophiolite nappe is comparable with the Kiogar-Amlang La ophiolite nappe complex south of Kailas in South Tibet-North Kumaun region. These ophiolite nappes represent squeezed up material from the deep sea regime along the Inclus Tectonic Zone and are now obducted onto the continental zone as the highest allochthon in the Himalaya.
Sulphur Isotopic Composition of Ingaldhal Sulphides, Karnataka State, India
Authors: Seccombe P. K. , Subbarao K. V. , Pawar J. N.
Published: November 2024

Mineralisation at Ingaldhal, Kamataka State, comprises massive vein and disseminated sulphides within deformed Archaean metasedimentary rocks and metabasaltic rocks of tholeiitic affinity. Seven sulphur isotope ratio determinations on sulphide minerals separated from ore samples yield a narrow distribution of d34S values around the meteoritic mean (range -0.9 to +0.4 per mil; mean -0.2 per mil) values which arc similar to Archaean volcanogenic ores elsewhere.

The source of sulphur is considered to be magmatic, with possible contribution from Archaean seawater. The stockwork and massive nature of the Ingaldhal ores, their Cu-Fe content, poorly developed metal zoning and basic volcanic association in a submarine setting point strongly to subsurface and sea-floor sulphide accumulation from sulphur- and metal-bearing fluids of volcanic origin. The sulphur isotope data support this view.
Gabbro-Anorthosite-Granophyre-Leucogranite Relationship Around Gorumahisani Hill, Mayurbhanj District, Orissa
Authors: Chakraborty K. L. , Bhattacharyya A. , Roy B.
Published: November 2024

Study on the field-relations, petrography and chemical composition of gabbroanorthosite-granophyre-leucogranite suite supports a co-magmatic origin of these rocks.
Depositional Environment Of The Late Precambrian Fossil-bearing Rocks of Southeastern Newfoundland, Canada
Authors: Misra S. B.
Published: November 2024

Thin bedded cherts and siliceous argillites of the Drook and Fresh Water Point Formations of the Conception Group were deposited above the wave base in most parts, as evident from the nature of bedding, large, scale ripple marks, penecontemporaneous deformation and calcareous nodules. The overlying Cape cove Formation of the same group is characterized by graded greywackes presumably deposited by turbidity currents. The animals that lived in the Conception sea during deposition of the Cape Cove Formation include pelagic as well as bottom dwellers. The presence of large-scale slump structures in the St. John's Formation (new group) indicate a gently sloping surface of he depositional basin. The depositional environment of the St. John's Formation had become shallower than that of the underlying Conception Group.
The Oldest Supracrustals of the Dharwar Craton, India
Authors: Naqvi S. M.
Published: November 2024

The metamorphosed supracrustal rocks of Holenarasipur, Nuggihalli, Krishnarajpet, Hadnur and Ghattihosahalli belts appear to represent the oldest (3.5 b.y.) greenstones of the Dharwar Craton. Detailed geological mapping of these belts and surrounding gneisses shows no evidence of a sialic basement for these predominently ultramafic belts. The sediments of these belts are mostly chemogenic-volcanogenic-volcaniclastic and fine-grained argillites. Fuchsite-quartzite, which is found at the top of the succession is the only siliceous rock unit. Its dO 18 value at+ 12.5, suggests that it is a metachert and not of detrital origin. REE pattern of the sediments of HNSB (Holenarasipur Schist Belt) is distinct from the sediments derived from acid plutons. The ultramafic schists of these belts, interbedded with the sediments, are generally komatiitic in composition and although metamorphosed under amphibolite facies conditions, locally exhibit relict pillow-structure and spinifex-texture.

The development of these greenstone belts was followed by at least three episodes of intrusion by sodic plutons. Erosion of these bodies and of the greenstone belts provided the sediment for the younger schist belts. The first evidence of detrital sedimentation derived from acid plutonic rocks is preserved in the form of current-bedded arkoses and quartzites in the younger greenstone belts. An interfingering sequence of the various successive greenstone belts and acid plutons, precursors of the Peninsular gneisses, can be recognised on the basis of available data.
Basin Configuration and Sedimentary Stratigraphy of Western Rajasthan
Authors: Pareek H. S.
Published: November 2024

The region west of the Aravalli Range in Rajasthan witnessed Palaeozoic, Mesozoic and Palaeogene sedimentation, with the Delhi Supergroup and the Malani igneous suite of rocks forming the basement. Cambrian sedimentation was confined to the Marwar Basins-Nagaur and Birmania; the Nagaur Basin being extensive, trending north and northwestwards to Salt Range (Upper Indus Basin). The Upper Palaeozoic remnants appear as Bap Boulder Bed (Upper Carboniferous) and Badhaura Sandstone (marine Permain) along the northwestern fringe of the Nagaur Basin; the Permians are fluviatile in the deeper parts of Jaisalmer area. The Lathi Basin (Liassic) had an extensive spread of fluviatile sediments. The Jaisalmer Basin (Callovian-Lutetian) formed part of the Indus geosyncline, Pakistan. The Palana-Ganganagar shelf (Paleocene-Eocene) had two embayments at Palana and Ganganagar, and extended up to Salt Range. The Barmer Basin (Cretaceous-Eocene) was sloping northwards and tectonically controlled by Cambay graben, Gujarat. Facies variations are exhibited by these Basins.
Stratigraphy and Depositional Environments of Neogene Limestones of Andaman-Nicobar Islands, Northern Indian Ocean
Authors: Srinivasan M. S. , Chatterjee B. K.
Published: November 2024

Carbonate rocks are widespread on the Andaman-Nicobar Islands, northern Indian ocean, ranging in age from Early Miocene to Pleistocene. Lithologically they range from deep water to shallow watcr calcarenites.

Thin section analysis of the limestones has revealed the following major lithofacies: lithic foraminiferal-algal grainstone-packstone; lithic foraminiferal-algal wackstone-mudstone; volcanoclastic packstone-wackstone/radiolarian cherts; foraminiferal packstone; coralgal boundstone and coarse lithic foraminiferal-algal-molluscan packstone grainstone. They exhibit sequential changes in their fabrics, biogenic and clastic constituents. Depths of deposition ranged from high energy, shallow neritic (lithic foraminiferal- algal grainstone-packstone facies) at the begnining of Early Miocene to progressively lower bathyal marked successively by lithic foraminiferal-algal wackstone-mudstone, volcanoclastic packstone-wackstone and radiolarian chert facies. The sudden influx of glass shards and tephras in thc later Early Miocene suggests that progressive deepening of the basin occurred contemporaneously with explosive volcanism in neighboring areas. During this interval of basinal subsidence, the limestones received abundant argillaceous material from subaerial erosion of nearby volcanic terrain. Gradual reduction in the frequency of glass shards and pumice from Middle Miocene (Ongeian Stage) onwards indicates culmination of volcanic eruptions and basinal stability. Gradual shallowing to subtidal and patch reef (Coralgal facies) environments began to form from the Middle Miocene onwards at Little Andaman, Havelock, Nicholson and other islands. However, deep basinal conditions prevailed during the Late Miocene to Early Pliocene at Neill, Sir Hugh Rose and Car Nicobar Islands. These different conditions may be attributed to tectonism in the Andaman sea region which occurred during the close of Middle Miocene. Thereafter, younger limestone facies of Plio-Pleistocene age, reflect a shoaling upwards to probable intertidal conditions due to rapid infilling and vertical uplift of the basin floor.

No hydrocarbons have been observed in the limestone sequences. However, the regional stratigraphic and petrographic studies reveal the presence of potential reservoir rocks in the Ongeian-Havelockian limestones of Middle Miocene age on the Andaman-Nicobar Islands.
Structural and Metamorphic Relatioms Between Sargur and Dharwar Supracrustal Rocks and Peninsular Gneiss in Central Karnataka
Authors: Chadwick Brian , Ramakrishnan M. , Viswanatha M. N.
Published: November 2024

The Dharwar Supergroup and its basement of Peninsular Gneiss and Sargur supracrustal rocks in the areas of Ghatti Hosahalli and southeast Bababudan display certain textural, structural and unconformable relations which have important implications for the Archaean chronology of the Karnataka craton. In the first. instance these relations show that certain tonalitic-granitic parental rocks of the Peninsular Gneiss basement to the Dharwar supracrustal rocks were formed as a series beginning with polyphase gneisses and ending with discordant plutons such as the Chikmagalur granite s.l. The Sargur rocks were deformed and metamorphosed to medium-high grade during intrusion of the polyphase gneisses. After cooling, uplift and erosion of the Peninsular Gneiss and the tracts and enclaves of Sargur rocks, the Dharwar supracrustal association was deposited unconformably on the medium-high grade basement. The pre-Dharwar metamorphic minerals in the Sargur rocks were partly retrogressed and then overprinted by a second major metamorphism, mainly low grade, whose climax was attained after the main deformation of the belts and basins of the Dharwar supracrustal rocks. This major low grade metamorphism in central Karnataka is correlated with the later Archaean high grade terrane (ca. 2600 Ma) in southern Karnataka and elsewhere in Peninsular India.
Comparison of the Tarikere Valley Gneiss and the Gneiss Pebbles in the Kaldurga Conglomerate -A Study in the Dharwar Basement Problem
Authors: Ranganna M. , Shashidhara H. , Raghu Prakash T. R.
Published: November 2024

Kaldurga conglomerate of the Precambrian Dharwar Group contains 3250±150 m.y. old gneiss pebbles. Controversy exists as to whether the 'Peninsular gneiss' adjoining the conglomerate in the Tarikere valley contributed the pebbles or whether the gneiss is a remobilised product of the precursor gneiss that contributed to the pebbles.

A comparative petrographic study of the Kaldurga pebble gneiss (KPG) and the Tarikere valtey gneiss (TVG) shows that, although both have a tonalitic composition, the TVG are enriched in Ca and Ti, reflected in the abundance of sphene and apatite. Texturally, the Kaldurga pebbles are catac1astically deformed. TVG are comparatively free from such structures, and are characterised by syntectonic recrystallization textures.

TVG have greater Ti abundance than the KPG, and the latter are comparable to the Ti abundance levels of Archaean gneisses. The higher Ti abundance levels in the TVG suggests their evolution through remobilisation and supracrustal contamination.
Igneous Complex of Mount Girnar, Saurashtra, Gujarat - A Reappraisal
Authors: Sukheswala R. N.
Published: November 2024

Mount Girnar is a major igneous plutonic complex which intruded into the basalts towards the close of the Deccan Trap period. The rock types identified in this complex are gabbros (tholeiitic and alkalic), diorites, lamprophyres, alkali-syenites and rhyolites. The parent gabbroic magma is shown to have given rise in sequence to diorites, lamprophyres and alkali-syenites. The rhyolite, though earlier considered a product of differentiation, is now believed to be an independent magma without any genetic link with the gabbro and its variants.

On scanning through available literature, however, it became apparent that the chemical/petrographic data were at variance with the crystallization differentiation hypothesis proposed by earlier workers to account for the varying rock types. To overcome these difficulties it is thought that the 'fenitization' model proposed here can better explain the formation of the different rock types. During the geological history of Mount Girnar, at least three different types of genetically unrelated gabbroic, rhyolitic and syenitic magmas erupted independently at different periods. The highly volatile-charged alkali-syenite magma which came last, was responsible in bringing about metasomatic changes (Na-fenitization) in the earlier formed rocks. It was the process of fenitization that gave rise to rock types such as alkali-gabbro, diorites and lamprophyres. The rhyolitic rocks developed out of an independent rhyolite magma.
Quaternary Lacustrine Deposit of Kalidhang, District Sirmur, Himachal Pradesh
Authors: Swain P. K.
Published: November 2024

The Kalidhang clays were deposited in an elongated lake covering 0.17 km2 area formed due to a landslide in the Milkan drainage basin. The deposition took place mainly by fluvial agencies under humid climate during the late Quaternary period. The presence of 145 distinct couplets indicates that sedimentation continued for about 150 years.
Notopahar Granitic Complex: An Example of Magmatic Differentiation from Mayurbhanj District, Orissa
Authors: Sarkar S. S.
Published: November 2024

The area around Sarat and Notopahar, Mayurbhanj District, Orissa, is characterised by a suite of Precambrian granitic rocks ranging in composition from quartz diorite through tonalite, granodiorite, granite to alkali feldspar granite. Field, petrological and petrochemical evidences indicate that the rocks of the Notopahar Granitic Complex (N.G.C.) are essentially comagmatic, representing a wide range of magmatic differentiates and can be correlated with the Mayurbhanj Granite (ca. 2084 Ma.). It is also noted that, the N.G.C. rocks are intrusive into the adjacent sheet-like body of gabbronorite.