Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

Debashish Ghosh ¹

Affiliations
1 Department of Geology, Presidency College, Calcutta, IN

Abstract

The abundance of myrmekite within the granite gneisses of Doranda is strongly correlated to the proportion of K-feldspar within the granite gneiss. The proportion of quartz in myrmekite is independent of the anorthite content of the myrmekitic plagioclase. These myrmekites have originated due to crystallization of residual liquid within some strain features developed within the plagioclases at their contact with K-feldspar. The strain features resulted due to lateral Stress exerted on the plagioclase by the growing adjacent K-feldspar.

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Abhinaba Roy ¹, Debashish Ghosh ²

Affiliations
1 Jayanagar, Bangalore-560011, IN
2 Cement Research Institute of India, New Delhi-110048, IN

Abstract

The deformed pebbles of the conglomerate horizon occurring to the SE of Hospet have their longest and the intermediate axis lying on the schistosity plane. The long axis shows a strong preferred orientation. The intermediate axis is parallel or subparallel to the regional fold axis. The strain is plane strain type with slight elongation parallel to the intermediate axis or the regional fold axis.

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Dhruba Mukhopadhyay ¹, Mohan Chand Baral ¹, Debashish Ghosh ¹

Affiliations
1 Department of Geology, Presidency College, Calcutta 700 001, IN

Abstract

The regional structure within the Chitradurga schist belt consists of a central antiform flanked by two synclines on either side. The central antiform is a second generation struc:ture which has refolded an earlier syncline whose axial trace is now exposed on either side of the central antiform. The second generation antiform shows regional plunge culminations and depressions along its axis. The earlier syncline had originally curved fold axis and was a canoe shaped fold. In the southern part of the schist belt a tectonic slide has cut off the lower limb of the early syncline. This came into existence before the second phase of folding. The stratigraphic sequence within the schist belt has been worked out taking into account this structural framework.

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