INTRODUCTION

1.1 General Statement

The study of microorganisms more and more

neglected by geologists and paleontologists, was carried further

mainly by the brilliant efforts of Biologists. Outstanding

contributions were made to the knowledge of some of the more

complex foraminifera. The absolute pract~cal value of

micropaleontology gradually led to ~ t s application in all

countries where petroleum exploration 1s carried out.

Occasionally, mlcropaleontology LS applied to other problems of

economic geology, such as regional geological surveys. Thus

micropaleontology did not break away from the main line of

development of paleontological sciences but actually entered a

phase in which it appears to be about to take a leading part in

the exploration of the organic world of the past.

Micropaleontological studies have already opened a new fields of

research and have shed new light on groups of organisms of which

paleontologists had previously very little or no information.

The growth of micropaleontology in genc!ral, and

foraminifera in particular, to its present elite position, as one

of the most active and fascinating branches of natural sciences

is closely linked with its undisputed value in oil exploration.

From the eighteenth century onwards amateur microscopists

collected and studled the fauna or foramlnlfera purely out of

personal curiosity without expecting Ehelr results to be useful.

At the beginning of thls century wher! the exploratior~ for oil

began in earnest, exploration geologists discovered that fossil

foraminifera survived the process of bore hole driiling. Because

of the knowledge built up by the amateurs concerning their

stratigraphical distribution, it became obvious that they were

potentially useful for blostratlgraphlcal correlation of bore

hole successions. Indeed, this study of foraminifera 1s important

not only in petroleum exploration but also in geological surveys

of many different kinds and In addition, these microfosslls can

also be used to interpret the environment of accumulation of

strata. It 1s therefore, great important that studies on the

distribution and ecology of modern representatives should be

carriedout to provlde a basls of comparison for che fossil fauna.

The gratifying demand for petroleum products has necesslated the

foraminiferists to study extensively the stratigraphy, the

sedimentation, the paleoenvlronments, and other like aspects to

hold the key to explain the oil bearing formations. In addition,

a generalised picture of foraminlferal distribution, abundance

behaviour, and relationship with ecosystem has been studied from

coastal estuarine, shelf, and slope and deep sea sediments.

1.2 Locat ion

In thls connection, the author has taken the

opportunity for the exhaustive investigation of the recent

benthic foraminifera1 fauna, particularly from coastal sediments

of Kovalam-Kanniyakumari-Tuticorin including Manapad and

Tambaraparni Estuaries, of South India. The area is represented

in the Survey of India toposheet no. 58, D,H and L in the scale

of 1 inch to 4 miles jlcm = 2.52km) and is located between 8O

and 9' northern latitudes and 76O.45' and 78O.15' of the

eastern longitudes (Fig.l.1). The length of the coast. line of

the area is about 215kms. The present investigat.~on is

considered to be the first detailed study ever carriedout on

different aspects of recent benthic foraminifera, and

their implications pertaining to the study area. These

studies are exclusively confined to the sediments of coastal

and estuarine regions of the South India.

1.3 Geomorphology

The coast llne I n the present study area is

slightly projected at Cape-Comorln(Kanniyakumari) and laterally

compressed by bcth West and East Coasts. Development of sandbars

and crenulate appearence of coast line, may be due to constant

water currents which are typically seen through out the coast

line. The confluence of the Arabian Sea, the Indian ocean and

the Bay of Bengal at the southern most tip of Indian peninsula

(cape-~omorin)is an unique sight. The Manapad and the Tambaraparni

are the important rivers, that debouche into the Biiy of Bengal

and there 1s no major river which empties into Arabian Sea on the

West Coast of the study area. There is considerable admixture of

marlne and fresh flood waters at the mouths of the

different rlvers. The sedimentation along the coast line is

predominantly controlled by nature of coast line, parent

rock, rivers and estuaries. The huge rock masses in and along

the coast line are unceasingly acted ilp cn by marine current

actlon, resulting cavities on the rock masses and detaches

relatively less resistant mlneral grains from th~? rocks. The

Coastal scenery is interesting for its projection towdrds seas at

Cape-Comorin and geomorphological features such a:; a wide

Tambaraparni Estuary, shallow creeks in river Tambaraparnl and

sand mixed secondary low level deposits formed by residual

weathering of Archean schists and gneisses.

1.4 Geology

The study area comprises the area

belonging to both Kerala and Tamil Nadu states. Tnis area

consists of Archean gneisses, schists and charnockites.

Mesozoic and Tertiary sediments are also found along some parts

of the East Coast. The Western Ghats form a well-marked features

along the West Coast from Tapati Valley down to Cape-Comorin.

Recent sediments resting on Precambrian basement gneisses

and schists are alluvial deposits along riter banks,

estuarine deposits, littoral deposits all along the coast line

with black, red and white sands including silty and muddy sands.

1. An Unique sight of Sun rise at Kanniyakumari at 6.11 AM

2. A Panoramic view of the famous !<ovalam beach, West

Coast of India.

3 . A view of the Sand bar near Manapad River, East Coast

of India.

1. A vlew of the Southern most tip of India - The unique confluence of three seas where devotees are taking the

d l p .

2. A close view of an admixture of tricolour sand

patches, near Kanniyakumari, East Coast of India.

3 . A vlew of the country boat aloncj with the candidate

(second from Ki l t ) and his team leaving for sampling.

PLATE - .- .~.-. - . .

Fig. L

Fig. 3

PLATE - I11

1. A close view of an organic l i f e on a l a r y e charnockite

boulder, West Coast of India.

2. A view of an intensive wave action during high tide

near Kanniyakumari, West Coast of India.

3. A close view of the wave action during low tide, near

~anniyakumari, East Coast of India.

4- --

Fig. 3

PLATE - IV

1. A Panoramic view of the river Tambaraparni joining the

Bay of Bengal.

2. A view of the fractured charnockite boulders, near

Kovalam beach, West Coast of India.

3. A close view of the Coast line erosion, near Kovalam

beach, West Coast of India.

1.5 Climate

The study area en~oys 3 troplcal subhumid type of

climate with an annual mean temperature of 2 5 O ~ . Usually, summers

are long and hot shooting mercury at 3 3 O ~ to 3e0c, winters

are short and mild with a temperature range of 23'~ to 2z0c.

Relative humidity varies from 73% to 76% during summer months

and 65% to 90% during winter months. The raln fall is very

scanty during the early months of South-West monsoon, and brings

appreciable rainfall ln the latter months of South-West monsoon.

The Maximum amount of rainfall during South-West monsoon is 380

cms/annum and minimum of 230 cns/annum. The North-East monsoon,

which brings rain ir, the fag-end months of the year resblts

scanty rainfall that may account to 25% of total rainfall.

1.6 Previous Work

k surT.iey of the literature ilvallable with the

author shows that extensive work has been done on the

exceedingly rich and essential fauna(foramin1fera) of the shore,

shelf, slope estuarine and lagoonal sediments of South India are,

Carter (1880) , the first who studied the foraminif era from

Indian subcontinent, of the recent sediments which have dredged

from Gulf of Mannar, East Coast, India. Later, Brady

(1884) gave an excellent account of the foramlnlfera from the

collections made by HMS "Challenger" during her voyage in the

Indian Ocean. Murray (1889) published a list of 37 foraminifera1

species at a depth of about 1,300 fathoms from the Bay of

Benga 1.

The studies on the West Coast have been started

by Chapman ( 1895) , who reported 274 foraminif era1 species from the Arabean Ocean, near Laccadive Islands. Later in 1927230,

Hofker published a monograph of foraminifera collected from the

Arabian Sea, followed by Stubbings (1939), who reported about

300 species and varieties from the same area. Kurien (1953)

reported 22 species from bottom sediments, of Travancore Coast

within 15 fathom line. Later about 46 species and varieties were

observed by Bhatia (1956), from Chowpathy and Juhu beaches

near Bombay and Shore sands near Bhogat in Saurastra. Ganapati

and Satyavati (1958) gave an illustrated account of 103 species

from the bottom sediments collected from Visakhapatnam area. In

1959, Bhatia and Bhalla described 14 species fror the beach

sands at Puri, Orissa. Rocha and Ubaldo (1964, studied and

recorded 52 foraminifera1 species from the dune and beach

sands of Diu, Gogoia and Shi~~bor, Gujarat Coast. Bhalla ( 1 9 6 8 )

illustrated 16 species from Visakhapatnam beach sands. In 1359,

Ramanathan made an interesting discussion on the relation of

the substrate to foraminiferal population sampled from the

Vellar Estuary, Tamil Nadu. About 15 species were recorded by

Bhalla (1970) from the Marina beach sands, Madras. The first

biocoenoses study of foraminifera based on constant volume

sediment samples in the Bay of Bengal was studied by Rao and Rao

(1972) from the Kakinada Channel. They recognised about 53

species. Reddy (1973) studied and illustrated 45 species from the

Pennar Estuary. Thereafter Seibcld (1975), described and listed

69 species including one new specles from the lagoon of Cochln

Harbour, down to 35 m of water depth. In 1978, Jaln and Bhatla

errccted 37 foraminifera1 taxa including one new species from

beach sediments from Mandavi, Kutch. Rasheed and Raghothaman

(1978) listed 70 species and gave a voluminous account on

ecology and distribution from Bay of Bengal off Porto Novo. In

1979, Bhalla and Nigam studied the Calangute beach sand and

reported 36 foraminiferaltaxa. Later Bhalla and Raghav

(1980) reported 25 species from the beach sands of Malabar

Narappa (1980) studied the livlng foramlnlfera of the Godavari

and Krishna River Estuaries. In 1981, Kaladhar recognlsed 75

species from Pudimadaka stream. Raja Sekhar (1981) identified

and described 59 species from the Inner shelf of Tuticorin.

Reddy (1981) reported 46 species from Araniar Estuary, Tamil

Nadu. Chandrasekhar Rao (1982) identified and reported a

quantum number of about 284 species from Vizag Harbour complex.

In (1982) ~ a s i m recorded 30 taxa from the shore sands of

Rameswaram. Naidu (1983) identified about 101 taxa from

Sanidaniqadda and Bendilagoon, Andhra Pradesh. Bhalla and

La1 (1984) reported about 28 taxa from Okhs beach sand, Gujarat

state wherein Miliolidae are found to be dominant. They added a

note on the distribution of the species and relative abundance.

Manivanan (1985) identified, described and listed 56 species

from off Mandapam. Raqothaman and Kumar (1985) recorded 52

taxa from off the Coast of Rameswaram. Kumar (1989) identified,

listed and illustrated 108 taxa from PalkBay, off Rameswaram.

Thereafter Suryakumar (1990) reported 50 species from Pullcat

Lake.

1.7 Objectives

The prime objectives of the present

investigation are:

ji) to ascertain distribution, density and

diversity of the living and total (living + dead) foraminiferal

population and to assess the seasonal changes in the faunal

distribution, abundance and diversity,

(ii) to relate the foraminifera1 population to the

Ecosystem and Sedimentology,

(iii) to process the foraminifera1 census data

utilising statistical technique and to relate their

applicability in the sedimentalogical and ecological

interpretations,

(iv) to compare the foramlniferal fauna of present

study area with those reported from beach, coastal, estuarine,

lagoonal and shelf sediments of Indian Peninsula,

(v) to report the f oraminiferal taxon occurring

in the present area with a speclal interest to new species,

(vi) to advance the existing knowledge of

the recent benthic foraminifera from the coastal and

estuarine sediments of India.

Methodology

1.8 The Sampling

A total of 180 bottom water and sediment samples

were collected for two different seasons viz., Monsoon(0ctober

- December) 1990 and Premonsoon(Ju1y - September) 1991 from

the coastal and estuarine environments of the study area.

Ten and twenty bottom water and sediment samples in both seasons

were collected from Manapad and Tambaraparni River Estuaries

repsectively, by fixing the sampling stations with a permanent

land bearings (Fig. 1.2, Tab. 1.1) . The bottom waters were

collected by making use of shallow water sampler, and

Sarnpl~ng E a s t North 1 Sarnpllng Z a s t Nortb S t a t l o n s i S t a t l c i n s

Table 1.1

Co-ordinates of sampling stations

sediments by Mud Grab. Sail and Mechanlsed boats were used

according to the need. The water samples were collected and

stored in polyethylene bottles fitted with tight stoppers and

screw caps and indexed accordingly.

The sediment samples for graln size alstributlon,

organic matter and heavy mineral crop were collected in

polyethylene bags (size 5" x 8") and preserved in cloth bags

(size 6" x 9'') and duly indexed for laboratory investigations.

Care has been taken so that there was no loss of finer

particles and no damage to the bags during transit. In order to

preserve the living foraminiferal specimens, the samples for

foraminifera1 studies were treated with a iO% solution of

neutralised formaldehyde buffered with an excess of sodium

carbonate and stored in wide-mouthed polyethylene bottles and

duly indexed.

A field Geochemical kit was used to determine air

and bottom water temperature, dissolved oxygen, hydrogen ion

concentration, specific conductance(Ec), chloride, and caicium

for water samples in the fleld ~tself. Sallnlty, was calculated

from specific conductance and organic matter and phosphate were

estimated in the laboratory. Sedlment samples were analysed for

thelr grain size distribution, organlc matter, heavy minerals and

foraminiferal assemblages.

1.9 The Laboratory Procedure

The bottom water and sedinent samples

collected from the study area were brought to the

laboratory and recorded the details such as colour, nature of the

sediment, associated materials like shell fragments of

gastropods, pelecypods, wood pieces, laterite/limonite

fragments, coal fragments etc., apart from sample location,

depth and environment were also noted before taking up for

analysis. The samples of each locality were indexed and stored in

the micropaleontology laboratory, Department of Geology, Sri

Venkateswara University, Tirupati.

In order to determine the size distribution of the

sediment, about 30 gm of air dried sediment sample was

treated'with 30% Hydrogen peroxide and 2N hydrochloric acid, as

suggested by Van Andel and Postma (1954) to remove organic

matter and carbonates. The sample was thoroughly washed,

airdried and weighed. Sodium hexametaphosphate solution of 0.025

normality was used to disintegrate the flocculated clay particles

and to dissolve any minor salt that might have been locked up

in between the finer grains (Shepard and iaore, i555;

Barnes, 1959). The dispersion of the fine grained particles was

further aided by the use of an ultrasonic shaker similar to the

one recommended by Xravitz (1966). The dispersed sediment was

washed by the same solution lnto a sedimentation cylinder

through a screen having 0.0625 mm diameter openings for

separating sand from silt and clay. Further separation of

these fractions based on grain-slze was done by sieving and

pipette analysis (Krumbein and Pettijohn, 1938). The results

obtained by both these methods were comblned into a single

size-frequency distribution for calculating their percentage

in terms of the iqent Worth's grade-scales.

For extracting foraminifera, the sediment

sample was washed over an ASTM 230 sieve (opening of 0.0625 mm)

for the removal of finer particles. The sample was then

airdried and about 100 gns of material was obtained by

coning and quartering. A mixture of Bromoform (Specific

Gravity 2.9) and Acetone (Speclflc Gravity 2.4) was used

(Gibson and Walker, 19G7), as the foraminifera1 crop

could not be separated fron quantitatively by just using

Carbontetrachloride (CCLq) alone. As a check, the residue

was observed under a stereobinocular microscope fcr left

out fauna. Such tests were hand picked by using "00" Windsor-

Newton sable hair brush. The total and living fauna was

picked under a stereobinocular microscope using low and

medium power Carlzeiss-Zena objectives in reflected light. All

the picked out specimens of each sample were transferred to a

single chambered card board microfaunal slide and thus duly

indexed on one side of the slide. The typical specimens of all

the species picked out from the slide are kept in a

multichambered slide to prepare an assemblage slide. From

these, every species is identified, and selected as type

specimen, mounted on a slide, named and numbered.

1.10 The Identification

Geographic isolation of various researchers

and problems of communication appear to be obvious reasons for

the correct identification of the special problems, but the

author considering the main factor involved is the very great

inherent morphological variations within the foraminifera1 taxon

(Buzas et a1 . , 1985) . The identification of the species was done with the help of original literature and photocopies available

at Micropaleontological laboratory, Department of Geology, Sri

Venkateswara university and Department of Geology, University of

Madras, Madras. A detailed examination of the test morphologies

of the specimens was studied under stereobinocular microscope

using medium to high magnification (6.3 x 2.5; 6.3 x 4.0).

Biometry measurements were made using micrometer scale

attatched to the eye piece of stereobinocular microscope. The

individual tests were counted for tabulation o f both

relative and absolute abundances of the forammiferal crop

from each sample.

The well preserved specimens nominated as type

specimens were preferred for SEM mlcrophotography.