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K. S. Shukla , S. B. Gupta

Abstract

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V. P. Jaitly , B. C. Pant , S. B. Gupta

Abstract

Working qualities and finish adaptability of two Eucalyptus species have been studied with a view to promote their utilization in the timber industry. The results obtained under six wood worklng operations viz., planing, sanding, shaping, turning, bolring, mortising and five polishing operations with different surface treatments, are reported in to this note. Both the species can be worked to smooth surface fairly easy and high gloss as compared to teak can be developed on the surface after polishing.

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D. C. Mishra ¹, S. B. Gupta ¹, M. B. S. V. Rao ¹, M. Venkatarayudu ¹, G. Laxman ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad 500007, IN

Abstract

Detailed gravity and magnetic surveys in and around the Godavari basin have helped in delineating the subsurface structures which, in turn, facilitated reconstructing its evolution. The general NW-SE trend of the magnetic and the gravity anomalies towards north takes a swift turn along an E-W line south of Bhadrachalam. This may be attributed to a deep-seated fault dividing the basin into Godavari and Chintalapudi sub-basins. The same fault may be responsible for limiting the southern extent of Pakhal sediments. A similar deep-seated fault north of Bhadrachalam along the Mailaram 'high' is also indicated. Modelling of some critical gravity and magnetic anomalies indicates the maximum thicknesses for Gondwana and Sullavai sediments as 4.5-5 km and 1.5-2 km respectively. A large gradient in the Bouguer anomaly on the eastern side of the Gondwana basin suggests the existence of a long continuous normal fault which is the master fault of the Gor.dwana rift valley. The other side of the basin is characterised by variations in the gradient of the Bouguer anomaly suggesting enechelon faulting.

The Gondwana basin is flanked on either side by heavy rocks of density 2.95 g/cm³ between the depths of 6km to 13 km which might be due to the block uplift of the lower crust forming the 'shoulders' of the rift valley or large sub-basic intrusions in the region. The definite magnetic anomalies in this region providing a high susceptibility of 0.1-0.2 emu almost at the same depth as obtained from the Bouguer anomaly further substantiate them. The subsequent uplifts of the basin is apparent from 'highs' in Bouguer anomaly inside the basin such as around Chinnur which shows sharp gradients on either side suggesting faulted margins. The Regional Bouguer anomaly separated from the observed field along a few representative profiles suggests the presence of a high density (3.1 g/cm3) material along the Moho between the depths of 30km to 38km.

The magnetic data reveals several basement ridges and intrusions as far west as. Manthani and Sirpur-Kagaznagar which are transverse to the general trend of the Gondwana basin and almost parallel to the eastern ghat trends suggesting that they may be the subsurface reflections of eastern ghat orogeny. A well-defined magnetic anomaly in the Chintalapudi sub-basin suggests the depth to the basic intrusion in the basement as 3.1 kilometres. There are high magnetic anomalies along the Precambrian faults defining the Purana basin suggesting basic intrusions along them. The basin as a whole depicts a high heat flow specially its southern part which might be due to several intrusive bodies as inferred from the magnetic and the gravity studies. The Godavari basin is a typical rift structure formed during the Gondwana period. The high density material along the Moho and in the upper crust suggests the diapiric upwelling of the asthenosphere as the main cause for the development of a typical continental graben in this region and subsequent uplifts along the shoulders.

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H. C. Tewari ¹, V. Divakar Rao ¹, B. L. Narayana ¹, M. M. Dixit ¹, N. Madhav Rao ¹, A. S. N. Murty ¹, B. Rajendraprasad ², P. R. Reddy ¹, N. Venkateswarlu ¹, V. Vuaya Rao ¹, D. C. Mishra ¹, S. B. Gupta ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad-500007, IN
2 National Geophysical Research Institute, Hyderabad-500007

Abstract

Lithological, gravity, magnetic, and seismic data within 100 Km corridor of the 400 km long seismic reflection profile are compiled to constitute the NW-SE Nagaur-Jhalawar Geotransect. The transect sequentially cuts across the Neo-Proterozoic Marwar Basin (MB) on the northwest, the Palaeo/Mesoproterozoic Delhi Fold Belt (DFB), the middle/late Archaean Bhilwara Gneissic Complex (BGC) and the MesolNeoproterozoic to early Palaeozoic Vindhyan Basin (VB) at the southeast. The BGC and DFB belts show polyphase deformation and metamorphism.

The BGC within the transect, consists of Sandmata Granulite Complex, followed by amphibolite facies Mangalwar Complex and Greenschist facies Hindoli/Sawar groups. The BGC show evidence of crustal reworking at c.3.0 Ga. The DFB is represented by amphibolite facies metavolcanic-metasedimentary shallow marine sequences and is tectonically highly disturbed. The DFB deposits (c. 2.0 - 1.5 Ga.) were subjected to tectonic deformation during Delhi orogeny (c. 1.5 Ga.), which is marked by syntectonic granitic plutonism. Both, the BGC and OFB also appear to have been affected by Neoproterozoic thermal events and granitic plutonism. The Neoproterozoic MB consists of clayevaporite sequences of shallow oscillatory basin deposits.

Seismic, gravitylmagnetic and magneto-telluric techniques could delineate a number of shallow to deep faults, intrusive bodies and a high conductivity zone. The total magnetic intensity shows a regional increase towards southeast. The Bouguer anomaly values show a steep rise of upto 80 mGal towards the boundary of OFB and BGC. Based on the seismic studies, doubling of the crust under the OFB and vertical intrusion of high density material under the BGC are inferred. The upper crust is, in general, transparent in its reflectivity while the lower crustal reflectivity is high in the transect area, except in the BGC and the VB. A thrust boundary, dipping NW, is present at the eastern margin of the BGC and could be traced up to 30 km depth. The Moho is at a depth of 36-38 km under the MB. Multiple Moho reflections are identified in the DFB crust, the deepest being at 45-50 km depth. In some part of the BGC the Moho can not be identified but in parts it is traced at about 50 km depth, with southeast up dip, before becoming subhorizontal at depth of 41-42 km. It becomes shallower to about 30 km depth at the SE end under the VB.

Keywords

Delhil Aravalli Fold Belt, Geotransect, Northwest India.

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D. C. Mishra ¹, S. B. Gupta ¹, M. R. K. Prabhakar Rao ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad-500007, IN

Abstract

Airborne total intensity magnetic survey flown at a height of approximately 152 m in central India has delineated several linear magnetic anomalies of 200-400 nT aligned together to form a large magnetic lineament approximately 1 km wide and 100 km long. The nature of magnetic anomalies suggest the lineament to be a fracture zone with basic intrusives at places. Magnetic and resistivity surveys on ground provide large magnetic (600-800 nT) and low resistivity anomalies along this lineament suggesting a fracture zone with basic intrusive rocks at places and very good groundwater potentiality along it.. Existing wells close to the lineament yield good amount of water, while those away from it show poor yield. Water table contour map of the area shows contours parallel to the lineament indicating pumping of more water from this zone causing lateral flow of groundwater.

This lineament does not find reflection in the ground gravity survey; instead it delineated some second order small dome and basin structures around Damoh and Jabera which are not recorded in the airborne total intensity map referred to above. This suggests that while linear features are better reflected in the airborne magnetic surveys small-scale three-dimensional basement structures are better reflected in the ground gravity surveys. This indicates the need for an integrated airborne and ground exploration programme for delineating subsurface structures/tectonics and to quickly assess the groundwater resources of a region.

Keywords

Geophysics, Groundwater, Linear Structures, Magnetic Anomaly, Electrical Resistivity, Vindhyan Basin.

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S. B. Gupta ¹, A. K. Dubey ², P. K. Sinha ¹, L. Singh ¹, G. N. Trivedi ¹

Affiliations
1 Reprod. Physiol. & Biochem. Lab, PG Dept. of Zoology (H.D. Jain College Campus) VKSU, Ara-802301, IN
2 Department of Zoology, GNM College, Parasathuan-821109, IN

Abstract

Natural selection has provided the mammal with a rich variety of signaling systems, each of which couples environmental variation with appropriate neuroendocrine responses. Therefore the complicated processed of mammalian reproduction occurs in harmony with exhisting dietary factors and different aspects of physical environmental. In recent years the study of low nutrients and their metabolism as well as various environmental factors effect reproductive processes has gained a great momentum., several research articles reveal that environmental factors and nutritional status directly or indirectly modulate reproduction in mammals. In general the male reproductive system show much more resistance to malnutrition and photoperiodic length of environmental factors alone influences the seasonal changes in testicular volume in sheep as earlier reported by Martin (1984).

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