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

A. Badarudeen ¹, D. Padmalal ¹, K. Sajan ²

Affiliations
1 Centre for Earth Science Studies, Thuruvikkal P.O., Akkulam,Trivandrum - 695 031, IN
2 Department of Marine Geology and Geophysics, School of Marine Sciences, Cochin University of Science and Technology, Kochi - 682 016, IN

Abstract

Distributions of organic carbon (OC) and total phosphorus (P) in the sediments of three mangrove ecosystems located at Veli, Kochi and Kannur areas, southwest coast of India are described. The mangrove sediments of Kannur contain comparatively high concentration of DC (4%) than that of Veli (2.6%) and Kochi (3.7%). Total P records the highest concentrations in Kochi (av. 0.395%) compared to Veli (0.055%) and Kannur (av. 0.323%) mangroves. However, their distribution does not yield any specific pattern with respect to landward, intermediate and shallow water profiles. Statistical analysis of OC and P contents against the various causative factors stresses the role of particle size in regulating their distributional pattern in mangrove environments.

Keywords

Sedimentology, Organic Carbon, Phosphorus, Mangrove Environments, Southwest Coast.

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P. Seralathan ¹, D. Padmalal ¹

Affiliations
1 Marine Geology Division, School of Marine Sciences, Cochin University of Science and Technology, Cochin 682 016, IN

Abstract

The Tertiary sequence begins with fossiliferous marl and is overlain by carbonaceous clay, china clay and laterite. The thin (3 cm thick), hard, compact duricrust layer, which is found interbedded within the carbonaceous clays, shows abnormal geochemical anomalies. Major elements such as Fe, Mn and Ca and the trace element Co show about 2-3 fold and 1-2 fold increase respectively in the duricrust than the upper and lower sections. However, the content of Na, K, Ni, Cu and organic carbon show an opposite trend. Cd does not show any marked variation along the profile. The CaCO₃ content is remarkably high in the duricrust and marl than the other layers. Fe and Mn contents are much higher in the laterite than china clay, other parameters do not show much variation. The high content of Fe, Mn, Ca and CaCO₃ and low Ni/Co ratio and organic carbon content in the duricrust layer indicate an oxidizing environmental condition which existed at the time of the formation of this layer, while the converse trend of these parameters in the carbonaceous clays indicate the prevalence of a reducing condition.

Keywords

Geochemistry, Pozhikkara Tertiary, Kerala Environment.

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D. Padmalal ¹, P. Seralathan ¹

Affiliations
1 Marine Geology Division, School of Marine Sciences, Cochin University of Science and Technology, Kochi 682 016, IN

Abstract

The tropical perennial muvattupuzha river and adjoining Vembanad estuary, Central Kerala, were surveyed for texture, organic carbon and heavy metals (Fe, Mn, Cu, Ni, Zn, and Cr) in suspended particulates and bed sediments. Sand is the dominant textural class in river, whereas mud, muddy sand and sand floor the estuarine substratum. Particulate organic carbon varies from 2.04-3.44% with a slight increase towards estuarine mouth. River sediments show low range of organic carbon (0.35 - 1.03%) while the estuarine sediments show 3-4 fold increase than that in the river. The concentration of Fe, Mn and Zn are in general higher in bed sediments than in suspended particulales. But Cu, Ni and Zn enrich in particulate phase. The overall variation of geochemical parameters is in general controlled by particle size as well as chemical desorption during estuarine mixing.

Keywords

Marine Geology, Muvattupuzha River, Vembanad Estuary, Kerala.

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P. Seralathan ¹, D. Padmalal ¹

Affiliations
1 Marine Geology Division, School of Marine Sciences, Cochin University of Science and Technology, Kochi - 682 016, IN

Abstract

The Muvattupuzha river and the Central Vembanad estuary have been studied mainly for grain size spectrum and textural parameters such as phi mean, standard deviation, skewness and kurtosis. In general, the grain size spectrum shows a marked gradation downstream. The observed variation is in consonance with the energy conditions controlled by the profile of the river as wellas the natural and man-made obstacles encountered in the river channel. In the estuary, the textural pattern is highly complicated owing to the fluctuation in the physico-chemical conditions prevailing in the system. Further, seasonal maintenance dredging activities by the Port authorities also have a considerable bearing on the sediment dispersal pattern of the estuary. The CM model worked out for the fluvial system perfectly agrees with the transportational and depositional regimes of the river and the estuary.

Keywords

Sedimentology, Muvattupuzha River, Vembanad Estuaty, Kerala.

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N. K. Babu ¹, D. Padmalal ¹, K. Maya ¹, R. Sreeja ¹, P. R. Arun ¹

Affiliations
1 Centre for Earth Science Studies, P.B. No. 7250, Thuruvikkal P.O., Akkulam, Thiruvananthapuram - 695 031, IN

Abstract

A study is conducted to assess the quality and seasonal variation of surface and ground water sources in and around Chalakudy basin, where intense clay mining activities for tile and brick manufacturing are taking place. The study reveals marked differences in most of the physical and chemical constituents of the ground and surface water sources. The pH, DO, BOD, conductivity, TDS, chloride, hardness and nutrient (N, P and Si) contents of ground water register high values than that of surface water. The conductivity, chloride, sutphate, hardness, calcium, magnesium and iron in the ground water samples fall within the BIS/WHO permissible limits of drinking water standards. Generally, the concentration of chemical components in ground water from clay mine areas is high compared to that from non-cIay ' mine areas. High incidence of bacterial contamination is observed in well waters which stresses the need for proper treatment prior to human consumption.

Keywords

Surface and ground water sources, Tile and brick clay mining, Water quality parameters, Chalakudy river basin, Southwest Coast of India.

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D. S. Suresh Babu ¹, D. Padmalal ¹, P. R. Arun ¹

Affiliations
1 Centre for Earth Science Studies, Akkulam, Thiruvananthapuram - 695 03 1, IN

Abstract

Estimation of water balance and sediment yield pertaining to two forest watersheds of southern India was carried out as part of the forest conservation program in Kerala State. The tropical watersheds namely Upper Peppara (-80km²) and Upper Neyyar (-140km²) of southern Kerala region host two important wildlife sanctuaries maintained in the Western Ghats of Indian subcontinent, which have high biodiversity values. The watershed evaluation conducted during the period 1995-2000 reveals that Peppara reservoir catchment yields an average of 1600 tons of suspended sediment and 126Mm³ of run off water every year. On the other hand, Neyyar reservoir at Full Reservoir Level (FRL) carries a suspended sediment load of 1400 tons during the peak monsoon month of June and it receives 207Mm³ of run off from its catchment annually. Unit plot measurements for soil loss indicate that grassland yields substantially high sand-Silt material, of the order of one ton per hectare annually. A management plan map for the Upper Neyyar watershed has been prepared taking into consideration of landscape features. One micro watershed, Panampara (6.73km²) falling within Peppara sanctuary was closely monitored to check its physical health. A number of locally feasible conservation strategies have been proposed to improve the water holding capacity as well as to minimise soil erosion in this subwatershed area. Periodic and manual silt removal from reservoirs during summer periods is recommended to maintain the storage capacity rather than constructing an upper dam or increasing the height of existing dam, as actively being considered.

Keywords

Forest Watershed, Water Balance, Sediment Yield, Conservation Structures, Siltation, Western Ghats, Kerala.

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K. M. Nair ¹, D. Padmalal ², K. P. N. Kumaran ³

Affiliations
1 LBS Centre for Science and Technology, Thiruvananthapuram - 695 033, IN
2 Centre for Earth Science Studies, Thuruvikkal PO, Thiruvananthapuram - 695 03 1, IN
3 Agarkar Research Institute, G G Agarkar Road, Pune - 41 1004, IN

Abstract

The South Kerala Sedimentary Basin(SKSB) extending along the coast between Kollam and Kodungallur, is the landward extension of the offshore Kerala-Konkan Basin (KKB). The SKSB has a fill of about 700 m of sediments, of which > 80 m are made up of Quaternary sediments, the rest being Miocene formations. Data from over 120 bore holes drilled for groundwater extraction from Tertiary aquifers, geotechnical investigations and stratigraphic studies form the basis of this paper. Based on sediment characteristics and tectonic setting, the SKSB can be divided into three separate blocks (a) Southern Block (uplifted during Pleistocene end), (b) Central Depression (undergoing subsidence from Early Miocene to Present) and (c) Northern Block (uplifted during Pleistocene-Holocene transition but undergoing subsidence during Holocene).

The Late Pleistocene sedimentary sections indicate continental environments at the bottom. The marine influence during Pleistocene predates 42 ky BP. Ecology and environment deduced from sedimentology, palynology micropalaentology and geochemistry suggest climatic variations from higher-Than-Present to low rainfall rates during deposition of Pleistocene sediments.

Holocene sedimentation also started in continental environments. The marine transgression giving rise to littoral-Lagoonal environments dates back to 7-6 ky BP. The high precipitation in Holocene gradually got reduced and by ca 3 5 ky BP the area witnessed prolonged exposure and development of ferruginous palaeosols.

Within the constraints imposed by insufficient samples and inadequate geochronological data, the paper gives a broad picture of the structural framework, stratigraphy, palynology and depositional environments of SKSB. From these, inferences on sea level oscillations, palaeoclimatic variations and depositional environments are made.

Keywords

Quaternary Sedimentation, Sea Level Oscillations, Palaeoclimate, South Kerala Sedimentary Basin.

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D. Padmalal ¹

Affiliations
1 Environmental Sciences Division, Centre for Earth Science Studies, Trivandrum - 695 031, IN

Abstract

The Quarry at Cherunniyoor, 3 km east of the Varkala town exposes a section of Warkalli beds of Mio-Pliocence age. The Sedimentary structures like channel fills, cross bedding, lenticular bedding, convolute lamination, clay galls, water escape structure and trace fossils are noticed in the section. The Warkalli sandstone at Cherunniyoor is composed mainly of coarse to medium grained, poorly to moderately sorted, angular to subangular grains with platy-to-mcso-kurtosis and nearly symmetrical skewness. The sedimentary structures together with the textural characteristics as well as the fining upward nature of lithological units point to a fluvial (meandering river) origin for the sandstone and hence for the Warkalli beds at Cherunniyoor.

Keywords

Sedimentology, Tertiary Sediments, Warkalli Sandstones, Kerala.

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