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

S. Anirudhan ¹, K. P. Thiuvikramji ¹, P. T. Roy Chacko ¹

Affiliations
1 Department of Geology, University of Kerala, Kariavattom 695 581, IN

Abstract

Channel sediments of Bharathapuzha (BP) basin provide an unique opportunity to examine the relative roles of climate and relief on the character of first cycle detritus derived from a source area of high grade metamorphic rocks, as the major tributaries of the river are set in diverse climatic domains. For e.g., Gayathripuzha (GP) and Thuthapuzha (TP) are in a tropical setting, while Kalpathipuzha (KP) enjoys a semi-arid climate. Sediments of a tropical-, low relief stream, the Tirur river (TR) lying adjacent to Bharathapuzha (BP) in the north, have also been examined.

The average mineralogical maturity of sands expressed as Q:F:R ratio, for the mainstream of BP varies from 72:19:9 for coarse to 53:38:9 for medium sand and to 49:44:7 for fine sand, implying an arkosic composition. The Q:F:R ratios of GP and TP, the two high relief tributaries on the one hand and of KP, the low relief trib utai) on the other are similar to that of mainstream of BP basin. However, quartz arenite (Q:F:R = 93:5:2) is under transport in the tropical-low relief, Tirur river (TR).

The chemical maturity index (CMI), i.e. the ratio of SiO₂/Al₂O₃, for the sediments of main stream (7.27) and for the tributaries, amply demonstrates the immaturity of the channel sediments. Nevertheless a value 120, for Tirur river sands indicates their super maturity.

Keywords

Detrital Sediments, Sedimentology, Bharathapuzha, Kerala.

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S. Anirudhan ¹, K. P. Thrivikramaji ¹

Affiliations
1 University of Kerala, Kariavattom Campus-695 581, IN

Abstract

The results of analysis of textural parameters of channel sediment samples of the Bharathapuzha system using the scheme of McLaren and Bowles (1985) reveal the existence of Case B trend in the direction of transport for mainstream (Bharathapuzha) and two high gradient tributaries viz., Gayathcipuzha and Thuthapuzha. Further, Fourier amplitude spectra estimated from digitized data of grain boundaries of the sand grade sediment from selected samples and the Waddell's sphericity and roundness indices demonstrate that influx of sediment from tributaries does not alter the size or shape distribution trends of the mainstream sands to any extent.

Keywords

Sedimentology, Statistical Study, Bharathapuzha Basin, Kerala.

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Sabu Joseph ¹, K. P. Thrivikramaji ¹, S. Anirudhan ¹

Affiliations
1 Department of Geology, University of Kerala, Kariavattom - 695 581, IN

Abstract

Results of analysis of size data by frequency curves and multi-group discriminat analysis (MGDA) indicate that inland Teri Deposits (ITDs) are very much similar to colluvium, formed by mass-wasting and fluvial processes, whereas Coastal Teri Deposits (CTDs) Very likely originated in mixed environments i.e., beach and dune. further, it is proposed that the ancestral sediments of present day CTDs would have originated from the vast reservoir of shelf sand that remained subaerially exposed during the low sea leval stands which coincided with Late Pleistocene glaciation.

Keywords

Sedimentology, Teri sands, Tamil Nadu.

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M. S. Manu ¹, S. Anirudhan ¹

Affiliations
1 Department of Geology, University of Kerala, Kanavattom P. O., Thiruvananthapuram- 695 581, IN

Abstract

Achankovil River sets in one of the major shear zones of Southern India which separates the Kerala Khondahte Belt (KKB) and Charnockite terrain. In this paper morphometnc characteristics of the river basin developed in a shear zone is reported. Major basin parameters like linear, aerial and relief parameters of the basin indicate that the basin architecture is much influenced by this prominent shear zone. Development of rectangular, parallel and trellis drainage patterns and parameters like bifurcation ratio, elongation ratio, are clear evidences for the structural control. Further, main river course is oriented m WNW-ESE direction, which follow the trend of the Achankovil shear zone and most of the lower order streams are developed roughly at right angles to the main river course.

Keywords

Morphometry, Achankovil Shear Zone, Kerala Khondahte Belt (KKB), Drainage Characteristics.

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S. Anirudhan ¹, R. M. Frincy ¹, J. Udayakumar ²

Affiliations
1 Department of Geology, University of Kerala, Kariavattom - 695 581, IN
2 T.K.M. Engineering College, Kollam, IN

Abstract

The Quartz pebble conglomerate (QPC) markings the base of Bababudan Group of Dharwar Supergroup is well exposed in southern margin of Bababudan schist belt and is known as the Kalasapura conglomerate. The matrix of conglomerate has been studied in this paper for its petrography and chemistry. The matrix is siliceous or sometimes ferruginous in nature and rich in heavy minerals. It contains A1₂0₃, Fe₂0₃ and TiO₂, and there exists considerable difference between the matrix and whole rock chemistry. The variation diagrams suggest that: (i) all the oxides other than SiO₂ come from the matrix. (ii) geochemically it has arkose-subarkose affinity and (iii) deposited under humid climatic conditions in a cratonic basin.

Keywords

Bababudan Group, Quartz Pebble Conglomerate, Unconformity, Quartz arenite, Kalasapura, Karnataka.

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