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

Rabindra Nath Hota ¹, Waturu Maejima ², Banabehari Mishra ³

Affiliations
1 P.G. Department of Geology, Utkal University, Vani Vihar, Bhubaneswar- 751 004, IN
2 Department of Geosciences, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, JP
3 PG Department of Geology, Khallikote Autonomous College, Berhampur-760001, IN

Abstract

The Karharbari, Barakar and Barren Measures Formations of the Damuda Group of Talchir Gondwana Basin show noticeable differences in their lithic fill. The Karharbari Formation represents syntectonic phase of sedimentation where as, the Barakar and Barren Measures Formations represent post-tectonic stable phases. The stream parameters of these three formations were determined objectively employing empirical equations worked out from modern streams. Stream parameters like depth, width, meander wavelength, annual discharge, normal and clast flow velocities decrease from Karharbari to Barakar sedimentation and increase from Barakar to Barren Measures sedimentation. Sediment load parameter, channel slope, flood stage velocity and Froude number, on the other hand, record alternatively increasing and decreasing trend while channel sinuosity show a steady increasing trend with advancement of Damuda sedimentation. Results suggest that during Damuda sedimentation the streams underwent metamorphosis, which may be attributed to tectonism in the source area and gradual denudation of the depositional surface coupled with possible changes in climatic condition.

Keywords

River metamorphosis, Sedimentation, Palaeocurrent, Palaeoflow, Gondwana, Talchir basin, Damuda Group, Orissa.

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Rabindra Nath Hota ¹, Wataru Maejima ²

Affiliations
1 P.G. Department of Geology, Utkal University, Vani Vihar, Bhubaneswar-751 004, IN
2 Department of Geosciences, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, JP

Abstract

Heavy mineral analysis has been carried out in the Barakar Formation of the Talchir Gondwana Bbasin, Orissa. The characteristic heavy minerals are garnet, zircon, tourmaline, rutile, biotite, chlorite, pyroxenes, hornblende, staurolite, sillimanite, apatite, epidote, sphene, spinel and siderite including opaques and leucoxene. These heavy minerals are divisible into four groups on the basis of principal component analysis and suggest derivation of Barakar sediments from pegmatite, acid and basic igneous as well as low- and high-rank metamorphic rocks lying to the south of the Talchir Gondwana Basin. Though the heavy mineral suites of all the sandstone samples are by and large similar, differences have been noticed in the frequencies of many heavy minerals in vertical succession. Cyclic nature and vertical fluctuation of heavy mineral frequencies can be ascribed to variation of the relief of the source area, sudden release of some of the minerals in the source region and/or existence of favourable geochemical condition to escape partial dissolution.

Keywords

Heavy Mineral, Principal Component Analysis, Barakar Formation, Talchir Gondwana Basin, Orissa.

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Rabindra Nath Hota ¹, Madhusmita Sahoo ¹

Affiliations
1 P.G. Department of Geology, Utkal University, Bhubaneswar - 751 004, IN

Abstract

The cyclic arrangement of lithofacies of the Karharbari Formation of the Damuda Group from a part of the Talchir Gondwana basin has been examined by statistical techniques. The lithologies have been condensed into five facies states viz. coarse-, medium-, fine-grained sandstones, shale and coal for the convenience of statistical analyses. Markov chain analysis indicates the arrangement of Karharbari lithofacies in form of fining upward cycles. A complete cycle consists of conglomerate or coarse-grained sandstone at the base sequentially succeeded by medium-and finegrained sandstones, shale and coal at the top. The entropy analysis categorizes the Karharbari cycles into the C-type cyclicity, which is essentially a random sequence of lithologic states. Regression analysis undertaken in the present study indicates the existence of sympathetic relationship between total thickness of strata (net subsidence) and number and average thickness of sedimentary cycle and antipathic relationship between number and average thickness of sedimentary cycle. These observations suggest that cyclic sedimentation of the Karharbari Formation was controlled by autocyclic process by means of lateral migration of streams activated by intrabasinal differential subsidence, which operated within the depositional basin and the channels carrying coarse grade clastic sediments, which make the cycles thicker, tend to be more common in the areas of maximum subsidence. Clastic sediments issued from the laterally migrating rivers interrupted the cyclic sedimentation of the Karharbari Formation in many instances.

Keywords

Cyclic Sedimentation, Markov Chain Analysis, Entropy Analysis, Regression Analysis, Karharbari Formation, Talchir Gondwana Basin, Orissa.

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Rabindra Nath Hota ¹

Affiliations
1 P. G. Department of Geology, Utkal University, Vani Vihar, Bhubaneswar - 751 004, IN

Abstract

In case of autocyclic sedimentation, direct relationship exists between net thickness of strata and number of coal cycles. Many of the coal basins including coal bearing Gondwana basins of India are good examples of autocyclic sedimentation, in which the cyclicity is attributed to intrabasinal differential subsidence of the basin floor. In the present work an attempt has been made to quantify the intrabasinal subsidence in a part of the Barakar Formation of the Talchir Gondwana basin. Eight undisturbed intervals were delineated in the Barakar stratigraphy. During different phases of sedimentation, different parts of the study area subsided with varying magnitudes. The areas of maximum subsidence accommodated thicker sediment column in comparison to the areas of slow subsidence rate.

Keywords

Coal Correlation, Differential Subsidence, Barakar Formation, Talchir Gondwana Basin, Orissa.

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Rabindra Nath Hota ¹, Bijay Kumar Das ¹

Affiliations
1 P.G. Department of Geology, Utkal University, Bhubaneswar - 751 004, IN

Abstract

The succession of lithofacies of a part of the Barren Measures Formation of the Talchir Gondwana basin has been studied by statistical techniques. The lithologies have been grouped under five facies states viz coarse-, medium-, and fine-grained sandstones, shale and coal for statistical analyses. Markov chain analysis indicates the arrangement of Barren Measures lithofacies in the form of fining upward cycles. A complete cycle consists of conglomerate or coarsegrained sandstone at the base sequentially succeeded by medium-and fine-grained sandstones, shales and coal at the top. The entropy analysis puts the Barren Measures cycles into A-4 type cyclicity, which consists of different proportions of lower, upper and side truncated cycles of lithologic states. Regression analysis indicates a sympathetic relationship between total thickness of strata (net subsidence) and number of cycles and an antipathic relationship between average thickness and number of sedimentary cycles. The cyclic sedimentation of the Barren Measures Formation was controlled by autocyclic process which occurred due to the lateral migration of streams triggered by intrabasinal differential subsidence. In many instances, the clastic sediments from the laterally migrating rivers interrupted the cyclic sedimentation resulting in thinner cycles in areas where the number of cycles are more. Principal component and multivariate regression analyses suggest that the net subsidence of the basin is mostly controlled by the thickness of sandstones, shale beds and coal stringers.

Keywords

Cyclic Sedimentation, Markov Chain Analysis, Entropy Analysis, Regression Analysis, Principal Component Analysis, Barren Measures Formation, Talchir Gondwana Basin.

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