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

M. M. Nair ¹

Affiliations
1 Hyderabad, IN

Abstract

No Abstract.

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K. T. Vidyadharan ¹, P. V. Sukamaran ¹, M. M. Nair ¹

Affiliations
1 Madhav Mandir, Theatre Road, Pettah, Trivandrum 24, IN

Abstract

An anorthosite occurrence is recorded from the granulite terrain of Kerala. The anorthosite is massive, coarse and dark grey coloured showing variation from anorthosite to gabbroic anorthosite and extends over an area of 50 Sq. km as an elliptical body. The An content of plagioclase ranges from 58 to 75%.

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M. M. Nair ¹, K. T. Vidyadharan ¹

Affiliations
1 Geological Survey of India, Southern Region, Hyderabad, IN

Abstract

The field characters, chemistry and the spatial association of the 678 m.y. old Rapakivi granite with gabbros and anorthosites suggest that these litho-units have developed through bimodal magmatic processes whereby heat derived from basic magma parental to the anorthositic rocks caused partial melting at or near the base of the crust to produce granitic magma with Rapakivi characteristics.

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M. M. Nair ¹

Affiliations
1 Geological Survey of India, Hyderabad 500001, IN

Abstract

Coastal geomorphological map of Kerala was prepared on a scale of 1 : 500,000 using LANDSAT imagery. Aerial photographs were used wherever necessary, followed by field checking. The coastal features identified include beaches, beach cliffs. stacks. islands, shore platforms, spits, bars, beach ridges, estuaries, lagoons, mudflats, tidal flats and deltaic plains.

Of the various lineaments identified over the Kerala region. the fault lineaments parallel to the coast as well as those at right angles to it are found to be neotectonically active and control the configuaration of the shoreline primarily.

Of the 560 km shoreline of Kerala, a cumulative 360 km length of shoreline is vulnerable and shows wide fluctuations in its stability. Based on their vulnerability and dynamism, the shoreline is divided into (1) permeable, gently sloping, sandy shoreline (2) semi-permeable, cliffed, sedimentary shoreline and (3) impermeable, crystalline shoreline, arranged in order of intensity of erosion. Apart from the known factors of slope morphometry, lithology and storm-wave generation, the non-parametric factors responsible for coastal erosion include presence or absence of mud banks near-shore and instability of off-shore regions.

The Kerala coast is described as a submergent coast, falling under the 'Terrigenous coast of primary morphologic disequilibrium '. Accordingly, the long-term tendency of coastal evolution is to increase the linear extent of erosional coastal segments at the expense of intervening depositional areas and, when the process goes to completion, a coast of equilibrium results.

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M. M. Nair ¹

Affiliations
1 Geological Survey of India, Kerala Circle, Trivandrum 695014, IN

Abstract

Lithological boundaries and co-parallel axial planar fabric of the earliest isoclinal folds have contributed the treodline features observed. Based on the nature and style of folding, persistence, frequency and discontinuity of trendlines, eight distinct structural domains have been identified.

Keywords

Geomorphology, Western Ghats, Structural Geology, Kerala.

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K. T. Vidyadharan , M. M. Nair , R. S. Nair , K. R. Pillay

Abstract

No Abstract.

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