In dian Journal of Marine Sciences Vol. 29, December 2000, pp. 283-294

Beach lTIQr12hgtogy and the inferences from heav min~~al assemblage of \ -Mandapam to Kanyakumari,coast, southeast coast of India ~ -

- J:YAngusarny / G ictol" R-;j;n-;-nickam (oepartment of Earth Sciences, Tamil University, Th anj avur-6 13 ooy XI*,-trrcL E=Mai l: hemaanguehi @hotmail.com [email protected]

Received 21 .Iulle 1999. revised 16 Auglls/ 2000 On the basis of heavy mineral di stribution, th e southern coast o' Tamil ~ \ h as been divided into live blocks namely Mandapam, Yalinokkam, Tuticorin, Manappad, Kanyakumari blocks. The heavYrll ineral concentration by wt % va ri es from 2 to 87%. Zircon , co lourless ga rnet , pink garnet , ch lorite and biotite are th e predominant minerals. The abundance of these minerals vane;;- in each block. -C hlorit ~~i llim ;n- it ~, mic;1 , few hornblendes and kyanite are characteristic of while biotite and glaucophane for block, euhedral zircon, hypersthene, tourmaline for Tuticorin block, broken zircon, andalu site and topaz for Manappad block and rounded zircon, rutile and monazit e for KanyakunlJri block. Chlorite, mica and other !laky minerals are dominant in Mandapam and Manappad blocks , whereas in Kanyakumari and Valinockam block, minerals like zircon, ga rn et and other denser heavy min erals are abundant. Granular minerals li ke zircon and ga rnet , 0 'J)

Heavy mineral studies are usefuy n infe rring the unde rstanding the provena nce of sedime nts between prove nance and maturity of the sedtJne nts, and e ne rgy Mandapam and Kanyakumari. conditions prevai le d during / the d epositio n and subsequent environment confined in the depositional Materials and Methods basi n . The re lative abundances of heavy mine ra ls The study a rea extends from Mandapam to have been used to diffe rentiate the different d epo­ Ka nyakumari 111 the southern coastal trac t of sitiona l e nvironme nts I , the stratigraphical boun- Tamilnadu covering a bo ut 360 km (Fig. I ). It is bound d anes. 2-4 , t he source roc k s"5 6 ,s horewar d tran sportatIon. in the northeast by R a m eshwaram Is la nd, in the east 7 of minerals and marine tra nsgression , dispe rsal by B ay of Bengal, in the west by Eastern and W estern patte rnS, a nd economic viability of the d eposits? Ghats and in the south by Kanyakumari being the Moreover, heavy mineral distribution has also been southe rn most tip of India, c haracte rised by the used to deduce the additional incre me nt of heavy confluence of India n Ocean, Arabian Sea a nd Bay of mine ra ls from offshore 10. AloIlg southeastern coast of Bengal. The drainage pa tte rn of the a rea is m a inly India from Mandapa m to Kanyakumari, barring controlled by perennial rive rs like Vaigai, de tailed geomorpho log ical s tudies of Loveson II a nd Tamirabarani and minor rive rs like Vaippar, Gundar, I2 the occurrence of beach placers .\." little work has Virusuliar and Vembar. been done to understand the morpho logy of beaches The study region is c hiefly underlain by the and the assemblage of heavy mine ra ls. This paper c rysta lline rocks of Archean age consisting of a ims to highlig ht beach morphology, assemblage g neisses, charnockite, granites and Quate rnary ll of heavy minerals and their significance for sedime nts (Table I) . 284 INDIAN J. MAR SCI. , VOL. 29, DECEMBER 2000

Muttup.tt-...... u~_ s.t1Uc1loroi ~ l KiiaIcIroroi 1/embGf' Valinokkam P.S.pUrom K.R. PLrom Sippikulam Voippor Kollar tNot", GULF OF MANNAR N 8o - - ...... / 45 ~OKm

I 0001 Co/crete BAY OF 11:>1:> 1:>1 Coral/ine BENGAL 10001 Sheet Rocks 1---ISample Location 7830'

Fi g. I- Locati on Ill ap and classifi cati on or beaches by nature or rocks

Since, no standard classification is made available th e samples were sieved at 1/4 n; interv al in ASTM for the beaches of thi s region , an attempt was made to sieve sets by Ro-Tap sieve shaker for 15 minutes. group th e beaches on the bas is of the nature of From the sieved fractions +80, + 140, +230 mes h sizes lithology, sediment compositi on and gradi ent. To have been taken for heavy mineral separati on understand the heavy min eral di stribution in thi s part foll owing Milner'4. Th separated heavy min eral of the beaches, au ger samples have been coll ected in fracti ons have been further separated to remove the months of April-May/l 990 al ong th e coast from magnetite usin g horse-s hoe magnet. Ove r and above, low-, mid-, and hi gh- tides and berm regions from 32 the rest of th e sampl es have been passed through stati ons (Fi g. I). Each station is kept away from each Cook Isodynami c separator in ve rti cal pos iti on in O. I other approximately of 10 km di stance. However, amp current to remove th e rest of the magneti cs. In wh erever marshy ground , parti cul arly near ri vel' inclined positi on of th e isodynamic separator hav in g mouths, and a bad land topography blockin g the entry the forward slope of 15° and side ti It 10", at 0.22 into the beach, cau sin g un approachability, such amper current , th e rest of the opaqu es in cludi ng regions have been kept away from sampl es without ilmenites have been removed. After th e removal of maintaining the 10 km interval. In places where th e opaques the non opaque fracti ons were mou nted '5 strong lithological differences by virtue of it s grain on a mi cros lide usin g canada balsa m . By tak in g the size, black sa nd enri chment or mi xin g up of oth er average of heavy mineral assemblage of the samples detrital materi als are observed, in such sectors th e anal ysed from low-, mid-, hi gh-tides and berm auger sa mpl in g was done in less th an, 10 km in terval. regions, the results have been processed III The auger sa mpl es of I m depth have been taken fo r STATPAC package deve loped by Meisc h'v. A analys is to form sub-sa mpl es of 4 numbers havin g the cumulati ve analys is of heavy min eral assemblage by depth interva ls of 0-25 cm, 26-50 cm, 51-75 cm and Q-mode fac tor anal ys is was attempted to un derstand 76- 100 crn . As the sub- samples have not sho wn an y th e influence of diffe rent rock types in the respective va ri ati on in the assembl age among them, an average bl ocks. Each eigen va lu e in the tab le represents a of th osc fo ur sampl es have been taken for th e purpose fac tor (Tabl e 2). Among 10 fac tors, 3 fac tors account of di scussion. After th e removal of organi c matter, to 95 % of va ri ances, hence the sa me are considered carbonates and fe rru genous coatin g on mineral grain , for th e purpose of interp retation. ANGUSAMY & RAJAM AN ICKAM : BEACH MORPHOLOGY 285

Results and Discussion beach of coralline rock, crystalline rock, hard Class(fication of beaches calcareous sand stone and calcrete (Fig. I). Coralline The beaches in the study region are composed of rocks are exposed in the coastal segment of Tuticorin­ primarily of rocky/sandy material. Taking into Alantalai region. account the dominance of a particular type of At few places, the calcareous sandstone shows a lithological presence, the beaches are grouped into clear stratification having a dip < I 0° towards the sea.

ll Table I-General stratigraphy of the st ud y area (After Lo veson ) Age Formation Lithostratigraph y Locati ons Heavy min erals

Holocene Ervadi , , Allu vium, silt Ervadi, Devi­ sillimanite , to Rece nt Pullangudi , Yaigai , cl ay, lateritic pattinam garnet , kyanite and black cotton, qu art z, amphiboles soil s, shell lime stone and coralline sandstone

------Uncon fonni t y ------

Pleistocene Teri dune sand complex Red teri sa nd Tirunelve li Pyroxene, garnet, with lateritic kyani te, ch lorite

------Unc o n formi t y ------

Pliocene Pl!lIangudi , Yaigai, Hi ghl y fri able, Southwest Guntar. poorly so rted, of Kamudi , weathered, fine­ K.R. Puram garnet, kyanite coarse grai ned to Yemb ar amphibol e, pyroxene calcareous sandstone.

------Uncon form it y ------

Middle Silty calcareous subsurface Eocene to sand stone, gritt y (ONGC bore­ pper siltstone. we ll s at Palaeocene Mandapam ).

------Un con formi t y ------

Cretaceous (Upper Gondwana) Si vaga ngai, to Upper Micaceous sa nd Tirupattur, Jurassic ston e, graphite, Ko vilur and basa l bou lder bed Kuttelar and conglomeriti c areas. sand stone.

------Un co n formi I y ------

Most part of Charnockile and the hinter Rounded zircon, nepheline syenite, land area of monazite. rutil e. Archean ga rnet i ferrous Ramnad, Pink garn et, Colour biotite gneiss. Chidambaranar -l ess ga rn et.magnetit e. Nellai Katta­ bio tit e, hornblende. bomman and si II i manit e, kya n i te. Kanya kumari tourmaline & pyroxene. 286 INDI AN J. MAR SCI. , VOL. 29, DECEMBER 2000

Table 2-Eigen va lu e and th eir percentage The beaches, in general, show an inclination of 1_7°. However, on the basis of inclination, the entire Factor Eigen value Percentage shoreline can be classified into three broad group s­ 38.56 96.40 viz. inclination with (i) <30 (Mandapam-Sethukkarai), 2 0.28 97.09 (ii) 3°_5°, (Valinokkam-Tiruchendur) and (iii ) >5° 3 0.16 97.49 (Manappad-Kuttankuli) (Fig. 2). The configuration of 4 0.13 97.8 1 coastline trends in four diffe rent directions such as 5 0.10 98 .07 E-W, NE-SW, N-S and NT'1E-SSW directions. Each 0.84 98.28 6 direction is characteri sed by typical sedimentological 7 0.78 98.47 parameters. 8 0.73 98.66 Consolid atin g th e various factors invo lved in th e 9 0.7 1 98 .83 configuration of coastline, beach morphology, etc., 10 0.59 98.98 the study region is grouped into fi ve major blocks namely , (i) Mandapam bl ock-B I (Mandapam- Moreover, nt many places beaches display 3 sets of Valinokkam) (ii ) Valinokkam block -B2 joints whi ch enable the waves to remove them in the (Valinokkam-Vaippar), (iii ) Tuticorin block-B3 form of rectangular blocks . The marin e calcareous (Vaippar -Tiruchendur), (iv) Manappad block-B4 sand stones ri ch in quartz and feld spar with embedded (Tiruchendur- Navaladi), and (v) Kan yakulllari bl oc k­ shell s of molluscs are exposed in man y places like B5 (Naval adi-Kanyakumari) (Table 3). Mandapam, Timchendur and Manappad in the hi gh tide and berm zo nes. At Timchendur, th e exposures Distribution of heavy minerals of sand stone stand s several metres above mean tide The principal heavy mi ne rals, of beach placers In level, suggestin g the relative Holocene sea level aiong the order of abundance are zircon ( 1.74-33.78%), this region probab ly after cementati on of the sand II. co lourl ess garnet ( 10.61-37%), pink garnet (10.40- Ex posures of crystalline rocks of khondalite­ 41.17%), chl orite (0.47-39.96%), and bi otite (0.19%- charnoc kite abut the beach segment of Kanyakumari­ 14.62%). The heavy min eral assemblage shows a Periyathalai. The monsoonal wave climate may characteristic variation from block to bl oc k. sometimes strip off the sandy beaches, exposin g the Similarl y, th e shape, roundness, colours, etc ., of cliff to face th e wave attack and eros ion. As a result, heavy minerals like zircon, garn et, chlorite help to erosive features like kettle hol es, sea caves and wave characteri se th e respective bl ock. Such differences in cut platforms are well developed in thi s part of the the nature of heavy mineral s in the five bl ocks are shore. described below: Tn Mand apam bl ock, th e heavy min eral assembl age Depending upon th e nature of beach sediments and is predominantly represented by co lourless ga rnet their compos iti on, sanely beaches can be grouped into (27.24 %), chlorite (17.91 %), and pink ga rnet calcareous beaches, si I iceous beaches, algal/seaweed ( 14.26%) (Fig. 3). Chlorite, bi otite, ga rnet and hyper­ ri ch beaches, heavy min eral- ri ch beaches and muddy sthene show strong etcling. A criss-cross fracture beaches (Fig. 2). Medium-grai ned sands with pattern in zircons and well rounded garnets indicate intercalations of she ll fragments occur in the sand y their long transportation. At and beaches. Quartz, fe ld spar and other siliceous mineral s Sethukkarai stations ch lorites sh ow a two fo ld predominate in the beaches from Mandapam to increase over Mandapam station . Valinokka m. Lithifie el calcareous sand hill s for a The heavy mineral assemblage in Val in ok kam length of 30 km occur within a few hundred metres block is similar to th at of Mandapam block wi th from the coastal stretc h of Manappad. The entire relatively hi gher zircon content especiall y in Vcmbal' foreshore and backs hore regions with ri ch (37 %) zone (Fig. 3). The absence of flaky mincral ~ concentrati ons of black sands, with an ad mixture of like chl orite, biotite and mu scovite is vcry much quartz and feldspars ca rpet the beaches in Kall ar and evident in this block. Vaippar, Kud uthalai to Ka,nyakumari regions. Patches In Tuticorin bl ock, the Vaippar, Sippikulam and of dark grey to black muddy deposits dominantly Kallar stations are marked by the abun dance of cover the shores off Tamirabarani river. garnet, zircon (rounded I I % to 2891"), rut ile, ANGUSAMY & RAJAM AN ICKAM : BEACH MORPHOLOGY 287

TAMIL NADU

o 10 20Km SO ----.. 45' 100 0 1 M uddy Beach ~ Corolline Beach 1+++1A lgae/Seaweed Enriched 1000I Colcarews Beach 1== =1 Heavy Minerals Enriched 1;: . ... ':1 Siliceous £3 I;::: I Morine Calcareous Sand S tone 15' CIJ Gently Sloping CD Steeply Sloping [TI Moderately Sloping 77. .,a d 7830' 790'£

Fig. 2-Classi lication of beaches by composition and gradient

Table 3-Classilicati on of th e stud y area on the basis of beach morphology and heavy min erals

Mandapam Valinokkam Tuticorin Manappad Kanyakumari

Type of hard Calcrete rocks Calcrete rocks Coralline rocks Marine calcareous Crystalline rocks materi al (M andapam- Tuticorin- sa nd stone Kanyak um ari- Sethukkarai Alantalai Manappad Periyath alai Tiruchendur Compositi on Calcareous Siliceous heavy Calcareous muddy Siliceous Heavy min eral rich mineral Rich Gradient Gently sloping Moderatley slopin g Moderatley sloping Steeply slopin g Gen tl y sloping 1-3" 1-3"(Mandapm- 3-5" (Valinokkam 3-5"(Tuti corin- 5-7" Alantalai Ovari Vattakkott ai Sethukkari ) to Vaippar) Kaya l Pattinam} Manappad Kanyak umari Tex tural Fine sand Medium-line sand Medium s::lI1 d Fine sand mod er- Medium to line sand parameters moderately so rt ed moderately well moderately well ately sorted moderately well fine skewed so rted symmetri - sorted coarse- coarse skewed so rted coarse mesoku rti c call y skew.ed line skewed meso- Ieptok urtic skewed, mesokurti c lep toku rti c very leptok urti c Contiguration E-W NE-SW NS NNE-SSW E-SW Wave ref- Inept zo ne Divergence- Convergence- Inept- Convergence raction co nvergence divergence di vergc nce Landform s Eight seri es of Marinc terraces Massive beach Coalescencc One se ries of beach ridges cuspate foreland ridges partiall y of beach ri dges beach rid ge longilUd inal stabilised dunes Mass ive Teri dunes mud Il ats sp it s dune complex Heavy mi nerals 5- 10.59% 5.05-64.40% 7.7 1-63.78% 2.8 1-23 .51 % 8.46-86.92% Mineral Chlorite, Biotite p. lallco- Euhedral zircon Broken zi rcon Rou nd ed zircon assemblage sillimanit e ph ane hyperst hene topaz andalu sil e monazi te rutile 288 INDIAN J. MAR SCI, VOL. 29, DECEMBER 2000

MANDAPAM

10 30 VALINOKKAM 5 o

PUDUMADAM

KILMUNDAL

SETHUKKARAI TERKU MUKKAIYUR 30

20 KILAKKARAI

10

40 ERVADI 30 20 5 o o

Fi g. 3-Di stribution of hcavy minerals in difrerent stati ons or Mandapam and Valinokbm blocks ANGUSAMY & RAJAMANICKAM: BEACH MORPHOLOGY 289

tourmaline and topaz (Fig. 4). The zircon content The movement of littoral currents in the study region I7 18 varies from 2% (Vellar) to 7% (Kallar) of the total prevails in the northerly direction . • The influence 40-55% heavy mineral assmblage. But at Tuticorin of littoral sedimentation can be evidenced from the and Kayalpattinam stations, the rounded zircons are shallowness of the shelf region and strong progra­ reduced by 5% with a subsequent ups hoot in chlorites dation at Periyappattinam by way of hook like spit (20.22%-36.06%). Prismatic, elliptical and elongated development, without the contribution of any riverine forms of pink tourmaline are found in this block. sediments 19. Colourless garnet with a characteristic dodeca­ In Valinokkam, glaucophane and chlorite are hedral cleavage, pink garnet and flaky minerals are admixed with garnet and tourmaline. This is ascribed preponderant with more topaz at Tiruchendur, to the prevalence of high energy environment or wave Alantalai and Manappad stations in the Manappad convergence in southeast wave direction and wave block (Fig. 4). Rounded zircons are dominant over divergence in northwest and north north west other minerals at Periyathalai and Ovari regions. Only directions (Table 4). Such condition leads to the at Ovari monazite makes an appearance by about 8%. sorting of heavies by strong winnowing action of the From Kuduthalai to the end of this block, a complete waves and the dumping of unsorted sediments in reduction of flaky minerals is inferred from their divergent condition. At Vembar, an increase in zircon distribution. distribution (35 %) is earmarked to the substantial The heavy mineral assemblage in Kanyakumari input of sediments from the river and to strong block is represented by rounded zircons, (Fig. 4) convergence of wave orthogonals in southeast and overgrown and outgrown zircons to the tune of 40 to northwest. As a result, selective segregation of 20 50%. Euhedral zircons with minute apatite, zircon, heavies takes place. Slingerland has also suggested opaque and gaseous inclusions or hour glass structure that the progressive sorting of heavy minerals plays in zircon are common. The presence of minute an important role in the concentration of denser inclusions provide a spotty appearance to some minerals. zircons. A few varieties of zircon show well In Tuticorin block, the abundance of garnet and developed crystal faces. However, the presence of zircon at Kallar and Vaippar stations is attributable to outgrowths and overgrowths demonstrate the longer the strong convergence of wave orthogonals in most stay and post depositional diagenesis of the sediments part of the year. An appreciable concentration of in the depositional basin. A total reduction in flaky flaky minerals (12.5%) at Sippikulam is assigned to minerals together with the characteristic presence of the strong divergent conditions in northwest and monazite is characteristic of all the stations. south south west wave directions. The absence of In general, Mandapam block registers the topaz, glaucophane and rutile in Tuticorin beach is dominance of chlorite,biotite and glaucophane than significant, because Tamirabarani river bed sediments zircon, tourmaline and rutile. A higher concentration consist of these minerals in appreciable quantity. This of the flaky minerals can be attributable to the block has been situated adjacent to these rivers, the prevalence of low energy conditions caused due to lack of topaz, glaucophane and rutile helps to infer strong divergence in all the three predominant wave that the Tamirabarani river sediments may not be directions (Table 4). Chlorites show a negative reaching these beaches in a significant proportion 11 . correlation with zircon (r=-0.39), garnet (r=-0.25), Similar studies on the sediments of the Vaippar river 21 monazite (r=-0.44), and tourmaline (r=-0.55) and of , as well as the northern beach of 22 23 positive correlation with biotite (r=0.67), muscovite Tamil Nadu . have shown the negligible contri­ (r=0.44) and tremolite (r=0.35). Its antipathetic bution of heavy minerals by these rivers to the relationship with sorting of sediments (-0.56) respective beaches. Strongly etched chlorites, garnets indicates that strong winnowing action of waves acts and glaucophane in Tuticorin region suggests either a as the controlling factor for chlorite's distribution. longer transportation of sediments or longer stay of Highly rounded zircons and garnets indicate the role sediments in the depositional basin. of recycled sediments rather than the contribution In Manappad block, the predominance of zircons from nearby rivers. This region is serving as the place and garnets are earmarked to the accumulation of for the deposition of sediments brought by waves and sediments in a trough like basin formed due to th e littoral currents, advancing from downsouth d irection. tectonically controlled blocks24 . Iv '-0 0

:!l (~~ -I>- I ZIRCON 0 GARNET (C.LESS) GARNET PINK ~...., HYPERSTHENt: :::r c HORNBLENDE t/J 0 CHLORITE ~ ~ "tl <: ::l - BIOTITE P '"0 P 0 -< >-l ...., MUSCOVITE P r ... =tl r e r ~ "tl 0 TOPAZ "tl >-l e OJ ... P P < GLAUCOPHANE P (j ::::: r '< P ::::: RUTILE -l 0 :l -l :;:l ~ r ::l 0 n 2- 2 :.l >- » :r. ~ fool <' ..... fUW~ ~ ~...... Z ::l c. ZIRCON 3:: GARNET (C.LESS) » ~ GARNET PINK Al g HYPERSTHENE Vl "'C (') v , HORl\BLENDE ~ 0 t"l ~ CHLORITE 0 <: ~ ~ 0 e ::::: L BIOTITE 0 p p < g ~ c: ~ 2 0 on MUSCOVITE ~ .... P :2 -l P -l r 0 SILLE\1ANITE r -l "'C N ;:c P 'C -l ANDALUSITE P ~ "'C - c r p p r TOPAZ - p >- 0 n r 0 tTl 0 RUTILE .... p (') ::::!. GLAUCOPHANE .... - tTl ::l MONAZITE 3:: 3:: N CO OJ tTl ::l " Al '-' ""Cl ZIRCON N ""Cl 0 0.) GARNET (C.LESS) 0 c. GARNET Pfi'iK :;::: 0 '-' HYPERSTHt:NE P ~ lIOR1'IBLEi'iDE :2 <: e -< P -l e-l ~ CHLORITE ;... -l -l ~ BIOTITE >- OJ Fr >- ~ 77" MVSCOVITE ":< :2 8 '"0 c TOPAZ c: ~ :l ~ ::::: >- ..,0.)_ . RUTlLt: p r § STAUROLITE ::::: r ..... ~ -< ..... 0 VlONAZITE r. ~ ! '""or. ANGUSAMY & RAJAMANICKAM: BEACH MORPHOLOGY 29 1

Table 4-Energy conditions prevailing in th e study region in different wave directi ons Wave Direction Area S45 °E NW NN W Wave Period 6S SS IDS SS IDS SS I. Mandapam I D D C 2. Pudumadam C C C I 3. Sethukkarai D 4. Kil akkarai D D 5. Ervad i D D D D 6. Valinokkam D C C D D C 7. Kilmundal D D D S. Terkumukkaiyur I I D 9. K R Puram I I I 10. Vembar C I C C I I II. Vaippar I C C D D D 12. Sippikulam C I D I C 13. Kall ar I C C C C 14. Tuticorin D C C I I D 15 . Kayalpattinam C D D D D 16. Tiruchendur C C D D D 17. Al anlalai D D D D D IS. Manappad C C C D D 19. Periyathalai C C 20. Ku dlllhalai 2 1. Ovari I 22. Kodivil ai I I ?~_J. KlIttankllli C C 24. Vij ayapathi I 25 . KlItt appalli C 26. Variyur 27. Vattakkottai 2S. Kanyak llmari

I-In ept co ndition; D-Div erge l ~ ce; C-Convergence

The heavy mineral assemblage (zircon, monazite, different to the catchment rocks. In Valinokkam rutile, hypersthene and garnet) in the Kanyakumari block, the heavy mineral assemblage indicates the block reflects the patterns of shoreline erosion and contribution from granitic gne iss and graniti c rocks accretion of denser heavies. A reduction in fl aky but th e catchment area is represented by the presence mincrals and amphiboles in these areas demonstrates of more of composite gneiss, c harnockite and selective removal and transportation of the minerals al luvium. The Tuticorin block is suggestive of a by strong winnowing action of waves and northerly predominant influence of recycled sediments while littoral drift. The significant contribution of zircons the catchment in the hinterl and is c hi efly made of and garnet in Oregon areas has been attributed to composite gneiss, granite, alluvium and cora lline 25 shoreline erosion by the continuous wave action . rocks . Manappad sediments display a close affinity to The presence of mineral assemblage like c hlorite, green schi st facies whereas th e catchment behind is mica, glaucophane, etc., in Mandapam block suggests primarily of c harnockite, minor amount of quartzi te the contribution of low grade metamorphic rocks. But and alluviu m. The heavy mineral assemblage of th e catchme nt is manifested with onl y a ll uvium sands. Kanyakumari block is represented by the It is interesting to observe that the minera ls are predominance of minerals li ke rounded and euh edral 292 INDIAN J. MAR SCI., VOL. 29 , DECEMBER 2000 zircon, and garnets of recycled nature. But, in value of 1.00. The communality value here, ranges Kanyakumari bl ock, the entire region is barren of fro m 0.776 to 0.997 for all the sampl es. sedimentary formations and well developed drainage Factor I consists of colourl ess garnet. hypersthene, network. Such contrad ictory nature of assemblage topaz, chlorite, bi otite, muscovite, glaucophane, enables us to point out their deri vation mainly from epidote, actinolite, tremolite and tourmaline. It 26 28 offshore. Rajamanickam & Gujar . have shown reflects the derivation of sediments from granite from the variation of texture and mineralogy of beach gneiss, schi stose rocks and charn ockite . and offshore sediments that the landward mi grati on of Factor II is represented by the dominance of sediments is a major phenomena takin g place along euhedral, rounded, outgrown, overgrown, coloured, the west coast of India. The sediment distribution of elliptical zircon and hornblende. This indicates that Oregon's beaches29 and the beach pl acers of east the contribution of sediments is mainly derived from Australia30 also have shown the onshore migration of recycled sediments of sandstone, limestone and sediments. alluvium. Once the value of heavy mineral di stributions are Factor III is rich in zircon (broken), dark and li ght normalised, the factor analysis with th e necessary pink garnet, chl orite, andalusite, topaz and staurolite. correlation has been initiated. In that, after rotation, This assemblage points out the influ ence of low grade a ll the samples are observed to depict hi gh metamorphic rocks of green schi st fac ies in nature. communality value which means that a good The Triangular diagram, prepared usin g these three description of a ll the samples has been obtain ed onl y factors after normali sin g factor components, has by using three factors in the maxi mum theoretical shown a clu stering of points in the c nter suggesti ng

1I GRANITES .AND GRANITE GNEISS, CHARNOCKITES o MANOAPAM '* VAlINOKKN/; eTUTlCORIN 1:, MANAPPAD 0.8 o KANYAKlJMARI

o o c

o

1IfL...---r----,~__r-__,--t---._-_,_-~-~---r RECYCLED SEDIMENTS) GR£ENSCHIST f AC IES SANDSTONE,. ALLUVIUM

Fig. 5-Q-Modc i'actor triangul ar diagram on th e poly top oi' thrce end mcmbcr". ANGUSAMY & RAJAMAN ICKAM: BEAC H MORPHOLOGY 293 the possible deri vation of sed iment from all th e three References different types of rocks (Fig. 5). However, Kanya­ I Kulm L 0 & Bryne J Y, Sedimentary response to kumari block sediment s are di stributed close to the hydrography in th e Oregon estllray, Mar Ceol. 4 (1966) 85- 11 8. termin al indi catin g recycled sediments. The 2 Rajamaniekam G Y. Heavy min eral , tlllli es of Cretaceous­ Valinokkam and Mandapam bl ock sediments are, Teniary rormations or Pondicherry. South In dia. C eo Soc however, separated out from Kanyakumari suggestin g India, Memoir II. (1968) 234-238. their derivation fro m granite and green sc hi st facies, 3 Zemstov A A, Mineral composition of Quaternary deposits respectively . The Manappad block is iso lated from and problems in paleogeography of the north or Western Siberia, Int Ceo ReI'., 16, ( 1974) 1162-1 167. the rest by being closer to the factor lIT, in ot her 4 Rajamaniekam G Y. Ceological in vestigations of offshore words, low grade metamorphic rocks. heavy lIIin eral placers of Konkan coast, Maharashtra, Indio, The different nature of beach confi gurati on, Ph.D. thesi s, Indian School of Mines. India. 1983. compositi on and gradient influence the different 5 Rajamani ekam G Y. Provenance of the sed iment s in fcr red littoral drift, particular to the wave refracti on pattern . rrom th e transparent heavy min erals on the innershel r or Central Maharas htra, in Proc oj Second SOlllh Asia The presence of promontori es in Valinokkam and Ceological cOll gress ed it ed by Wij ayan3nda P, Cooray P G. Manappad enable convergence In thi s region. Peter Mosley (GEOSAS- II , Colombo) 1993, pp. 25-30. Similarly , the Tamirabarani ri ver mouth also 6 Gujar A R, Heavy lIIin eral placers in th e nearshore areos oj contributes strong convergence directin g th e lack of SO ll th KOllkan Maharashtra:their natllre, distriiJlltion. origin and econolllic em/llation Ph.D. thesis. Tami l Universit y, terrestrial sedimentation in the adjacent beaches. The In dia, 1996. dominant divergence existing in th e Mandapam sp it 7 Lee H J, Jeong K S. Han S J & Bank K S. He:lvy min era ls enables a complete change in the compos iti on of indi cat ive of Holocene transgression in th e southe:lstern heavy mineral assembl age. Moreover, th e coastal Yellow sea. Mar Ceol, 8 ( 1988) 255. 8 Darby 0 A, Trace clement s in ilmenit e:A way to di sc riminate confi guration is also found to have a strong influence provenance or age in coastal sand s. Ceol Soc Allier BII/I, 95 in the distribution of heavy mineral assemblage in the (1984) 1208-1218.9. study region. 9 Chadrasekar N. Placer lIIin eml resen'e el'a/iwtion aiung Ihe In view of the above factors, discussed so far on central Tall1il Nadll coastal region, Ph.D. thesis. Tamil Uni versity, India. 1992. the di stributi on of heavy minerals in th e study region, 10 Mohan P M, Identijicati(J/1 of coaslal placer deposits along it is inferred th at there is no relat ion between the coast betllleen Mar/llranthagalll and Madras, Tech. catchment mineral assemblage and th e rea l Report (Depl. Science & Technology, Govl.Or India, ew di stribution of heavy mineral assemblage in the Delhi ) 1998, pp. 175. coastal sector. It is therefore in ferred th at the mineral II Loveson Y J, Ceologic(" and geolllorphological investigations related 10 se(l level l'ariation and heal'\' assembl ages in the investigated area are derived from lIIineral acclllllulation along the SO llthem Talllil Nadll mixed source of sed iments. Further, the in compatibl e beaches, Ph .D. thcsis, Madurai Kamaraj Un iversity. India, heavy min eral assemblage of the beach sediments 1994. with respect to the nature of catchmen t rocks in five 12 Jacob. K Ilmenite and garn et sands or Chowghat (west coast). Tinnevelly, Ramnad and Tanjore coasts. Ceol SlIr\l different blocks of the study region has also indi cated India, 82 ( 1956) 527-602. the possibility of heavy min erals suppl y from 13 Jacob K, Raman P & Dallloclaran R, Report on th e offshore. investi gation 1'01' heavy mineral sand s in the coastal part s or Tirunelveli district , Tamil Nadu stat e. V npllh. Field RC/lort (S tate Geo Min , Tamil Nadu) 1955. pp. 15. Acknowledgement 14 Milner I. Sedilll entllr\' f/ elrogmpflv (Georgc All en & Unwin Authors are thankful to Department of Ocean Ltd-London), 1962 pp. 643. Development , New Delhi , for the fin ancia l assistance 15 Galehouse J S, Counting grain mounts number percentage and the authorities of Tamil Uni vers ity for extendin g Ys number frequ ency, .I Sed Petrol. 39 ( 1969) 8 12-815. all the facilities to complete this work. We record our 16 Mei sc h A T. Q-mode ractor analysis or co mp ositional dat a. COIl1PII and Ceosci. I ( 1962) 147- 159. gratitude to Dr. V.J . Loveson, for hi s ass istance in 17 Chanclramohan, P Lungshorc sedilllelll trans/lor! lIIodel lI 'ith sample co ll ect ion, Dr. P.M. Mohan and Mr. P. particlliar reJerence to III dian coast Ph.D thesis, In dian Udayaganesan for their assistance in factor ana lysis In stilU te or Technology, Mad ras , Indi a, 1988. and invalu ab le suggestions and Mr. G. Ramachandran 18 Ahmed E, CO(lslal geolll orpllOlogv oj India. (O ri ent Longman, Delhi ) 1972, pp. 260. and Mrs. R. Sivagama Sundari for their cartographi c 19 Loveson V J & Rajamanickalll G Y. Prograd:ltion as and typing assistance. evid enced arou nd a submerged anciell! port, Periyapallinam. 294 INDIAN J. MAR SCi. , VOL. 29 , DECEM BER 2000

Tamil Nadu , Indi a, Indian J Landscape Sl'stellls & 26 Rajamani ckam G V & Gujar A R, Sediment deposi ti onal Ecological SlIIdies, 12 (1988) 94-91\ . environment in so me bays in cent ra l weSt coast of Indi a, 20 Slingerland R L, Role of hyd rauli c sorting in the origin of Indian J Mar Sci, 13 ( 1984) 53-59. flu vial pl acers L G, J Sed Petrol. 54 ( 1984) 137-150. 27 Rajamanickam G V & Guj ar' A R, Indicati ons given by 21 Udayaganesan P, A stlldy of detrital lIIin erals j imn the median di stribution and C M pall ern s in Kalbadevi, Mirya sediments of Vaippar basin. Tamilnadll. M.Phi!. thesis, and Ratn agiri bays, Ciom ale di Ceologie, 47 (1985) Tamil University, Indi a, 1993. 23 7- 25 1. 22 Muthukrishnan N, A stlldy of detrital lIIin erals from th e 28 Rajamani ckam G V & Gujar A R, Depositional processes sediments ofCadilalll river basin, Tallliinadll . M.Phi!. thes is, inferreel fro m the log probability di stribution, in Researches Tamil Universit y, In dia, 1993. ill sedilllentology, edited by V Jhingran (Hindu stan Publ Co, 23 Mohan P M. Di stri bu ti on of heavy minerals in Parangipett ai Delhi ) 1993, pp. 154- 164. (Porto Novo) beac h Tamil Nad u, .I Ceol Soc of In dia. 46 29 Clemens E K & Kumar P D, Oregon beach- sand (1995) 401-401\ co mpos iti ons produced by th e mixing of sediments under a 24 Loveson, V J, An gusamy, N & Rajamanickam G V, transgr ssin g sea, J Sed Petrol, 58 ( 1988) 51 9-529. Usefulness of ideniifying different geomorphic blocks along 30 Kudrass H R, Transgressive re wo rking uf East Au stra li an th e coast of so uth ern Tamil Naelu, In dian J Ceolll. I ( 1992) shelf sed iment s an d th e origin of beach placer deposit s, in 38-44. Proc (~r th e Second Intem ational Conference on offshore 25 frihy E O. & Komar P D, Lung term shoreline changes and Min eral Resollrces. Olfl'hore Prospectillg and Mining the co ncentra ti on of heavy minerals in th e heach sand s of th e Prohlellls, edited by P G Telcki, M R Dobsan & Moore J R Nil e Delta, Egypt , Mar Ceol, 115 (199 1) 25 3-26 1. (Ri edel Publishing Co, Tokyo) 1984, pp. 273-282.