Informatics Publishing Limited

S. Basumallick ¹, P. C. Mukherjee ²

Affiliations
1 Department of Applied Geology, Indian School of Mines, Dhanbad 826004, IN
2 CCL, Darbhanga House, Ranchi, IN

Abstract

The sediment mixing pattern of the Ajay with the Bhagirathi-Hooghly river system has been worked out utilizing three different kinds of data viz. grain size, grain shape and heavy mineral composition. The near concurrence of the results of sediment mixing pattern worked out by three different techniques demonstrates the usefulness of each of the properties as tracer. The bed load contribution of the Ajay to the Bhagirathi during freshet appears to be 25% which can not be regarded as an insignificant contribution. Assuming the conventional bed load content of 5 to 15 percent of the total load, it can be presumed that the suspended load contribution of the Ajay to the Bhagirathi-Hooghly system couId also be quite significant and may be an important factor in the silting of the Hooghly in its lower reaches.

Keywords

Sedimentology, Sediment Mixing, Fourier Analysis, Bhagirathi-Hooghly River System, West Bengal.

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S. Basumallick ¹, B. C. Sarkar ¹, S. Banerjee ²

Affiliations
1 Department of Applied Geology, Indian School of Mines, Dhanbad - 826 004, IN
2 Department of Geology, University of Oklahoma, Norman, US

Abstract

The Upper Proterozoic Lower Bhander Sandstone, occupying a major part of the Tamasa valley at Maihar, has been thought to be deposited in a tidal flat-lagoon complex,in an intertidal to supratidal environment, dominated by ebb and flood tides. A tidal bundle (a medium grained thicker sandstone unit and a thinner siltstone bed) is thought to bear the imprint of velocity and discharge associated with each tidal current as reflected in the thickness of the layers. Thickness data pertaining to 155 tidal bundles recognized in the exposures have been analysed using techniques of Smoothing, Autocorrelation and Fourier filtering, to reveal whether or not any tidal cyclicity existed. The results amply support not only the presence of alternating high spring-neap-low spring semi-lunar cycles, but a dominant periodicity of 32 bundles corresponding to 16 semi-lunar days.

Keywords

Tidal Cyclicity, Sedimentology, Fourier Analysis, Vindhyans, Madhya Pradesh.

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