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Varadarajan, S.
- Chromian Antigorite from the Chromite Deposit near Byrapur, Mysore State, India
Authors
1 Department of Geology, Central College, Bangalore, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 2, No 0 (1961), Pagination: 98-103Abstract
Scaly aggregates of purple or lavender coloured chromian antigorite occur interlaced with carbonates, in small veins, cutting across the chromite deposit near Byrapllr chromite mines, Mysore State. The physical, optical and chemical characters of the mineral are determined. The axial angle, refractive indices and birefringence of the mineral are higher than those of the normal antigorite, due to the presencc of chromium in the mineral. X-ray and electron microscopy studies of the mineral were made by Dr. G. W. Brindley and C. R. F. De Kimpe, in the Department of Ceramic Technology, Pennsylvania State University, U.S.A. X-ray powder diagram shows that it belongs to serpentine group; electron diffraction proves that the mineral is antigorite. It contains 3.86% of Cr2O3.Keywords
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- Mineralogy and Petrochemistry of the Differentiated Sill Around Gwalior City, Madhya Pradesh
Authors
1 Department of Geology, University of Delhi, Delhi, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 14, No 4 (1973), Pagination: 384-393Abstract
Mineralogical and petrochemical characteristics of the differentiated sill, occurring at the highest horizon of Morar Stage, Gwalior System (Cuddapah age), around the city of Gwalior, Madhya Pradesh, are detailed. Petrographically the sill, composed of dolerite which is sparsly porphyritic, tends to be quartz dolerite in higher levels. The occurrence of micropegmatitic texture is proportional to the amount of hornblende present in the rock. Chemical nature of the chilled margin reveals that the undifferentiated magma was tholeiitic. Differentiation in the sill is of limited extent and is considered to be the result of the combined processes of fractional crystallisation, crystal settling and mild convectional currents.- Potassium - Argon Ages of the Amritpur Granite, District Nainital, Kumaun Himalaya and its Stratigraphic Position
Authors
1 Department of Geology, University of Delhi, Delhi 110007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 19, No 8 (1978), Pagination: 380-382Abstract
Potassium - Argon ages of muscovite and biotite, separated from the Amritpur Granite, District Nainital, Kumaun Himalaya, determined in the 'Geochronology Laboratory' of the IGEM Institute of the USSR Academy of Sciences, Moscow, are 1880 ± 40 m.y. and 1330 ± 40 respectively. The granitic body apparently shows intrusive relationship with quartzite-metavolcanic association of the Bhimtal-Bhowali area of which the latter has given a whole rock K-Ar age of 228 ± 10. These reveal that the Amritpur Granite is composite in nature intruded in Middle Proterozoic Period (1880 ± 40 m.y.) and later remobilised at different periods with the development of tourmaline granite in the peripheral parts, as the latest phase.Full Text
- Polyphase Deformation of Ajabgarh Stage Rocks, Delhi Group, Around Narnaul, Mohindergarh District, Haryana, India
Authors
1 Department of Geology, University of Delhi, Delhi 110007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 22, No 4 (1981), Pagination: 153-163Abstract
A detailed study and analysis of all the planar and linear elements in the lithic units of the area, in both meso and macro scale reveal that they bear the impress of three phases of folding, F1 F2 and F3. The most dominant phase is the second phase resulting in open asymmetric folding with high wave length/amplitude which express in mesoscale crenulations on the planar surface of F1 folding. The F1 phase is responsible for the regional foliation S1 which is parallel to lithic banding S0. The tight isoclinal folds develop appressed surface which act as form-surface of F2. The F1 and F2 are generally co-axial. The last phase of folding F3appear as broad open cross-folds broadly warping the pre-existing foliation. This phase can distinctly be observed on map scale.Distinction between each phase and the associated structures is based on the overprinting relations, in particular the bending of axial surface foliation and other interference patterns between the existing phases. Structural analysis of the area indicates operation of a predominantly sub-horizontal NW-SE oriented stress.
- Deformation Structures in Pegmatite, Aplite and Quartz Veins in Delhi Group Rocks
Authors
1 Department of Geology, University of Delhi, Delhi 110007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 24, No 6 (1983), Pagination: 269-280Abstract
Pegmatite. aplite and quartz veins of varying dimensions occur in association with pelitic schists, calcareous rocks, quartzites, amphibolites belonging to Ajabgarh Formation, Delhi Group in the Narnaul area and act as important structural markers.
The polyphase nature of deformation of the rocks with which these veins occur, is shown by rotation of boudins, presence of overturned tight isoclinal folds resembling F1, presence of F2 folds and refolded folds shown by quartz veins, refolding of limbs of folded pegmatites by folds resembling F3. Features like boudins, pinch and swell structures shown by quartz veins and pegmatites at the limbs and along the axial planes of F1 folds with S1 development in the host rock and attenuation and disruption of limbs of tight folds resembling F1 shown by these veins also point to significant amount of flattening during F1 folding phase and longitudinal stretching in the late stage of their development. Slippage in the later stages of deformation phase (F3) is also distinctly borne dy displaced aplite veins.
- Deformational and Crystallization History of the Delhi Group Rocks, Around Narnaul, Haryana, India
Authors
1 Department of Geology, University of Delhi, Delhi 110007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 26, No 6 (1985), Pagination: 380-389Abstract
The regional metamorphic rocks of Precambrian age belonging to the Delhi Group, around Narnaul, show complex deformational-crystallization history. The first deformation phase, F1 of Delhi orogeny produced isoclinal folds overturned towards southeast plunging in NNE-SSW directions associated with most pervasive foliation S1. The later deformation phases, F2, tight to open folds, and F3, open folds produced crenulation cleavages S2 and S3 (rare). These three deformational events have been correlated with the crystallization periods of the more important minerals in pelitic schists and amphibolites.
The study reveals that mineral assemblages were identical during the first and second deformation phases. The index minerals garnet, staurolite, kyanite, hornblende started forming either during F1 folding or immediately after F1 and continued till the close of F2 folding with incipient crystallization of micas during F3 phase. Mineral assemblages in the pelitic schists display a single staurolite-kyanite zone. Mineralogical reactions ,indicate metamorphism under amphibolite condition below 650°C with minimum temperature 540°C and pressure 5.5 kb (PL =Ptotal) in this part of the Aravalli belt.
- Himalayan Geology: Proceedings of the Seminar Held at Delhi, 28th-30th December, 1984
Authors
1 Delhi University, Delhi, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 26, No 9 (1985), Pagination: 677-681Abstract
No Abstract.Full Text
- Metallogeny of Basic and Ultrabasic Rocks
Authors
1 Delhi University, Delhi, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 27, No 4 (1986), Pagination: 397-399Abstract
No Abstract.Full Text