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Dey, R.
- Deformation Pattern in a Proterozoic Low Pressure Metamorphic Belt near Ramanujganj, Western Chhotanagpur Terrane
Authors
1 Department of Earth Sciences, Indian Institute of Technology, Powai, Mumbai - 400 076, IN
2 Intersight Consulting Pvt Ltd, 12th Main Road, Vasanthnagar, Bangalore - 560 052, IN
3 Geological Survey of India, Sector 33B, Chandigarh - 160 047, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 70, No 2 (2007), Pagination: 207-216Abstract
The Ramanujganj area in eastern India exposes a Proterozoic metasedimentary belt (-35 km x 18 km) which has been mapped in detail in terms of two pelitic and two psammitic lithounits. Dominant rock types in the belt include porphyroblastic argillite, phyllite and pelitic schist, feldspathic quartzite and orthoquartzite. The belt has an elongated oval shape with broadly NW-SE trend. Folds of three generations (F1, F2 and F3) have been recorded F1 folds are rarely preserved as small isoclinal folds on bedding(So)associated with an axial planar cleavage (S1) F2 folds involve transposed So+S1 surfaces and vary from open to isoclinal, with steeply inclined axial plane and moderate plunge. Several large scale F2 closures with NW to NNW striking axial planes are exposed F3 folds are steeply inclined to upright in nature with NE striking axial planes. Large scale F3 folds are usually broad warps. Interference patterns of dome and basin type and hook type are observed in the area F1 and F2 folds are broadly coaxial in nature, and their superposition has resulted in hook shaped pattern F2 and F3 folds have superposed to produce dome-and-basin structures on both outcrop scale and large scale. The regional structure of the area is an elongate basin resulting mainly from the interference of F3 folds on F2 structures.
The western and northern parts of the area are occupied by biotite quartzofeldspathic orthogneiss which intruded during or before F1 deformation. In the eastern part mesocratic granodiorite intruded after F1 deformation and before or during F2 deformation. The Ramanujganj pelites are commonly characterised by large porphyroblasts of andalusite (chiastolite), whereas biotite and garnet form relatively small porphyroblasts. Andalusite occurs in the southeastern and central parts of the area, and transforms to sillimanite as we go towards northwest. This indicates increasing grade of metamorphism from southeast towards northwest. The metamorphism is of low pressure type.
Keywords
Structral Analysis, Polyphase Deformation, Pelite, Chhotanagpur Gneissic Complex.- Metamorphism and Contrasting Corona Structures in Bolangir Anorthositic Rocks, Orissa
Authors
1 Department of Earth Sciences, Indian Institute of Technology, Bombay, Powai, Mumbai - 400076, IN
2 Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071, US
3 MR Division, R & C Directorate, ACC Ltd., LBS Marg, Thane - 400 604, IN
4 University Science Instrumentation Centre, University of Roorkee, Roorkee - 247667, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 57, No 1 (2001), Pagination: 31-38Abstract
Massif type anorthositic rocks in Bolangir area of the Eastern Ghats belt contain garnet porphyroblasts, which are surrounded by reaction coronas. The corona usually comprises a vermicular intergrowth, which in one instance consists of radial orthopyroxene and anorthite-rich plagioclase, and in another of radial chlorite and anorthite-rich plagioclase. Some of the anorthositic rocks are layered with thin discontinuous mafic layers of clinopyroxene and biotite. Notable is the presence of retrograde ferro-anthophyllite in the mafic layers of some of the rocks. Thermobarometric calculations using assemblage in the orthopyroxene corona indicate decompression from minimum peak P-T condition of 8 kbar and 700°C.Keywords
Anorthosite, Metamorphism, Corona, Decompression, Bolangir, Eastern Ghats.- Seasonal Reproduction in Fish:A Functional Interplay between the Pineal Organ and Photoperiods
Authors
1 Department of Zoology, Visva-Bharati University, Santiniketan-731 235, IN
2 Department of Zoology, University of Burdwan, Burdwan-713 104, IN
Source
Journal of Endocrinology and Reproduction, Vol 5, No 1&2 (2001), Pagination: 1-12Abstract
Reproduction in most fishes is discontinuous or seasonal. Rhythms with a periodicity of one year represent major components in the adaptation of concerned fish to their environment. Environmental factors, such as light and temperature, play an important role in the synchronization of this rhythmic activity of reproduction. In vertebrates, synchronization is mediated through the system which is composed of sensors and circadian oscillators like the pineal organ, the lateral eyes and the suprachiasmatic nuclei of the hypothalamus. The fish pineal seems to be involved in the timing and control of reproduction. On the basis of several experimental evidences, it is believed that the pineal is able to translate environmental information (photoperiod, temperature) into rhythmic messages. To date, two kinds of signals have been clearly identified, a nervous signal and a neurohormonal signal, i.e., melatonin. Whereas the functional significance of the nervous signal is not yet clearly understood, there is increasing evidence that in at least temperate zone vertebrates, melatonin is the chemical messenger of photoperiod (Zeitgeber). In contrast to the neuronal message, elaborated mainly (if not exclusively) by the pineal of ectotherms, melatonin appears to be a conservative signal in the vertebrate phylum. In all the species investigated so far, melatonin production is high during nighttime and low during daytime. Despite this apparent homogeneity, the involvement of the pineal in the temporal organization of reproduction, as well as the mechanisms by which the photic information is processed in the control of gonadal germ maturation in fish have been the matter of great interest. Molecular mechanism involved in photoreceptor-induced pathway in fish is yet to be known, without which benefit from such information remains unveiled.Keywords
Fish, Light, Pineal, Reproduction.- Quantification of Valuable Metals from E-Waste
Authors
1 Department of Metallurgical & Material Engineering, J U, IN
2 School of Materials Science & Nanotechnology, J U, IN
Source
Indian Science Cruiser, Vol 27, No 1 (2013), Pagination: 51-54Abstract
E-waste is a growing environmental concern for both developed and developing countries in recent times. Huge quantity of e-waste is generated world-wide each year. In the present work, authors have processed three different kinds of e-waste sources (SMPS, mobile phone & television remote), and while presenting a reproducible technique using chloride leaching to extract the valuable content (e.g. gold, silver) and other elements (e.g. Co, Ni), also presented the comparative study of their observed composition.