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V. S. Venkatasubramanian ¹, B. P. Radhakrishna ², S. Jayaram ³

Affiliations
1 Dept. of Physics, Indian Institute of Science, Bangalore 560012, IN
2 Geological Society of India, Bangalore 560052, IN
3 Dept. of Mines & Geology, Race Course Road, Bangalore 560052, IN

Abstract

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.

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P. T. Rajagopalan ¹, S. Jayaram ², V. S. Venkatasubramanian ³

Affiliations
1 CISL, Indian Institute of Science, Bangalore 560012, IN
2 Department of Mines and Geology, Bangalore 560001, IN
3 Department of Physics, Indian Institute of Science, B'lore 560012, IN

Abstract

No Abstract.

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V. N. Vasudev ¹, S. Jayaram ²

Affiliations
1 Chitradurga Copper Company Limited, 16/1, Ali Asker Road, Bangalore 560052, IN
2 Department of Mines & Geology, Race Course Road, Bangalore 1, IN

Abstract

No Abstract.

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G. V. Ananta Iyer ¹, V. N. Vasudev ², S. Jayaram ²

Affiliations
1 Inorganic & Physical Chemistry Dept., Indian Institute of Science, Bangalore 560012, IN
2 Department of Mines & Geology, Bangalore 560001, IN

Abstract

No Abstract.

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V. S. Venkatasubramanian ¹, S. Jayaram ¹, V. Subramanian ¹

Affiliations
1 Department of Physics, Indian Institute of Science, Bangalore 560 012, IN

Abstract

Measurements of lead isotope ratios on some Indian galenas and calculation of single-stage model ages were presented in a previous paper. Techniques have been improved since then, and more samples from some of these areas and several new samples have been measured. The present measurements cover a wide age-span, Eocene to Archaean (∼3300 m.y.) and the Pb-isotope abundances are not inconsistent with a 2-stage evolution of lead which show an episodic change in μ-value at ∼ 3000m.y. Model ages and μ-values have been calculated using single and double-stage models and an attempt made to interpret these values.

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S. Jayaram ¹, V. S. Venkatasubramanian ², P. T. Rajagopalan ³

Affiliations
1 Department of Mines & Geology, Bellary 583101, IN
2 Department of Physics, Indian Institute of Science, Bangalore 560012, IN
3 DMS RDE, P.B. 320, Kanpur 208013, IN

Abstract

Systematic measurement of the abundances of major, trace and rare earth elements has been carried out on a number of samples of the Peninsular gneisses. The data suggests that the Peninsular gneisses could be broadly differentiated into Western tonalitic group and an Eastern granodioritic group. The dividing line roughly corresponds to the western margin of the Chitradurga greenstone belt. The Geochemical data also suggests that bulk of the Peninsular gneisses are magmatic. Critical differences in trace and rare earth element abundances are observed between the western tonalites and the eastern granodiorites.

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B. Chadwick ¹, V. N. Vasudev ², S. Jayaram ³

Affiliations
1 Department of Geology, University, Exeter EX4 4QE, GB
2 Department of Mines and Geology, Government of Karnataka, Gandhinagar, Bellary 583 101, IN
3 Department of Mines and Geology, Government of Karnataka, Bangalore 560 001, IN

Abstract

The Dharwar Supergroup in the Shimoga basin east of Bhadravathi has been subdivided into seven formations on the basis of sedimentary structures and facies. The lowest is dominated by metabasites including metalavas and tuffs, metagabbros with seams of titaniferous magnetite, serpentinites and talc schists. A range of sedimentary rocks including phyllitic greywackes, quartzites, dolomitic limestones, conglomerates and local banded ferruginous cherts characterise the formations overlying the metabasites. These formations include local metabasites, and the youngest formation contains a thick suite of metarhyolites. The Dharwar lithostratigraphy is characterised by rapid lateral variations in thickness and facies which are the consequence of its original unstable alluvial and relatively shallow marine depositional environments. The instability is marked by slump structures in the phyllitic greywackes and by debris flows at many levels in the stratigraphy. The Dharwar rocks were deposited on a basement of homogeneous granodiorite s.l. and foliated multiphase quartzo-feldspathic orthogneisses. Erosion of elevated parts of the basement and the Dharwar cover provided detritus for alluvial fans, shallow marine quartzites and more distal phyllitic greywackes. Correlation of the lowest formations in tbe Bababudan basin immediately to the south shows that the Dharwar Supergroup becomes progressively younger from south to north in this part of Karnataka.

The structure is characterised by large upright synclines in the Dharwar cover with intervening domal areas of basement. Many of the cover-basement contacts are faults, but some are interpreted as rotated and steepened unconformities. Flushing of water and CO₂ through much of the basement and cover took place during deformation. Buoyancy forces related to heating at deep crustal levels and concomitant compressional forces, generated perhaps in a transpressive oblique-slip regime, may account for the structure of the cover and its basement. Comparable tectonothermal instability, but with trans-tensile components, may have characterised the Dharwar volcanic and depositional phases.

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S. Jayaram ¹, V. S. Venkatasubramanian ¹, B. P. Radhakrishna ²

Affiliations
1 Indian Institute of Science, Bangalore, IN
2 Geological Society of India, Bangalore, IN

Abstract

The cordierite-gneisses of southern Karnataka give Rb-Sr ages of 3010±90 rn.y. indicating jheir relationship to 3000 m.y. event in the Dharwar craton, for which evidence is available in a number of areas.

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K. Sivaprasad , S. Jayaram , C. G. Nandakumar

Abstract

Main characteristic of ship recycling is the interdisciplinary nature of the engineering processes associated with it. These processes are multidimensional and have certain shortcomings, which make ship recycling a complex industry. The product design and life cycle stage management of naval fleet differ from that of merchant ships, still they also reach the same destination for dismantling. This demands implementation of new methodologies being implemented in merchant ship recycling, in naval ship recycling field as well. This paper presents two important ship recycling design and development tools, viz., Design for Ship Recycling and Recyclability Analysis which would add to the effectiveness of clean and safe recycling of naval fleet. Application of Design for Ship Recycling concept in naval ship design has been discussed. The concept of Recyclability Analysis of products and equipment with respect to ship recycling is presented as a guideline.

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