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

M. S. Gandhi ¹, J. Seetharamaiah ¹, P. Bhanu Murty ¹

Affiliations
1 Delta Studies Institute, Andhra University, Visakhapatnam - 530 003, IN

Abstract

A simple but very effective and inexpensive indigenous method of vibracoring has been developed for acquisition of continuous cores in subaqueous environments at water depths of below 2m. The principal components are the following: 3.5 HP concrete vibrator, irrigation PVC tube, tripod and pulley. The entire system weighs 50 kg. and approximately costs about Rs.25,000/-. This system was operated successfully in the transitional sedimentary environments of the East Coast deltas by collecting around 100 cores averaging to 2 m in length. Sediments ranging from clay to coarse sand have been recovered using this system. Percentage of recovery was usually 60 to 100 and distortion of delicate sedimentary structures was generally minor.

Keywords

Vibracoring, Deltaic Environments, Andhra Pradesh.

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J. Seetharamaiah ¹, A. S. R. Swamy ¹

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

Abstract

Organic matter and calcium carbonate in the shelf sediments off Penner river are mainly controlled by the texture of the sediments. The outer shelf (30-50 m depth) sediments of the southern and northern parts have a higher content of organic matter (1.2 to 2.22%). The sharp differences in organic matter content (varies from 0.8-1.6%) and fine nature of the sediments at the river mouth reveals detrital contribution. A calcium carbonate rich zone (30-40%) associated with coarse sands occurs opposite to Penner river mouth (20-50 m depth). The source for high concentration of calcium carbonate in the coarse sands (relict) are molluscan shells, shell fragments and foraminifera indicative of the in situ origin . It is inferred that the calcium carbonate supports that the coarse sands are stillstand deposits admixtured with present conditions.

Keywords

Sedimentology, Calcium Carbonate, Penner River, East Coast, Andhra Pradesh.

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