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M. Jagannadha Rao ¹, J. Venkata Ramana ¹, R. Venugopal ¹, M. Chandra Rao ¹, N. Avataram ¹

Affiliations
1 Department of Geology, Andhra University, Visakhapatnam - 530 003, IN

Abstract

The so-called beach rock along the Visakhapatnam coast is exposed where the overlying placer deposit (sand dunes and red sediments) is eroded or removed. The morphology of samples reveals a well preserved density stratification, layering, grain size variation and alternate layering of light and heavy mineral fractions Textural characteristics confirm their derivation from beach environment. The mineral composition is similar to the present day beach sands and includes quartz, sillimanite, ilmenite and other opaques, monazite and zircon, with conspicuous absence of garnet X-ray diffraction analysis of the cementing matenal revealed the presence of siderite and himonite Study of polished beach rock specimens under the reflected light revealed exsolution features in ilmenite grains, similar to present day ilmenite Carbonate cementing matenal is replaced by secondary iron oxide. The associated flat pebbles are of quartzite and khondalite. The in situ occurrence of the beach rock along this part of the coast forms the physical evidence supportmg the coastal submergence during the Holocene transgression. The formation of beach rock is resultant of a combined marine and groundwater activity m the intertidal zone.

Keywords

Beach Rock, Holocene Transgression, Inter Tidal Zone, Placer Sand, Visakhapatnam Coast, Andhra Pradesh.

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M. Jagannadha Rao ¹, J. Venkata Ramana ¹, R. Venu Gopal ², M. Chandra Rao ¹

Affiliations
1 Department of Geology, Andhra University, Visakhapatnam - 530 003, IN
2 Department of Mineral Engineering, Indian School of Mines, Dhanbad - 826 004, IN

Abstract

Ilmenite from the beach and dune environments of the Visakhapatnam-Bhimunipatnam placer sand deposit has less TiO₂ and more total iron contents, as compared to its stoichiometric composition. Its trace elemental concentrations indicate its basic percentage. It has exsolution features and four types of intergrowths, viz. ilmenite-Hematite, hematite-Ilmenite, graphic intergrowth and ilmenite-Rutile. Hematite phase in ilmenite incorporate excess iron in the structure of ilmenite. Based on the geochemical and ore mineralogical aspects, ilmenite of present study area is more suitable for pigment-Manufacturing than to synthetic rutile preparation.

Keywords

Ilmenite, Beach Placers, Mineragraphy, Geochemistry, Visakhapatnam Coast, Andhra Pradesh.

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