sedimentological studies of beach sand of tamil nadu and kerala coast, india – implications on...
DESCRIPTION
The present investigation deals with sedimentological studies of beach sand of Tamil Nadu coast and southern coastal part of Kerala. As many as 133 samples were collected from Chennai to Kanayakumari along the East coast and 41 samples collected from Kanyakumari to Alappuzha along the West coast, and those samples were subjected to textural and heavy mineral analyses. Textural characteristics of the sediments and heavy mineral assemblage provide clues to understand depositional environment and provenance. The textural analysis of the East coast samples shows that generally the sand size varies from fine to medium grained, sorting from moderately well sorted to well sorted, Skewness from nearly symmetrical to coarsely Skewed and kurtosis from platykurtic to leptokurtic. It is evident from the skewness that an erosional condition is prevailing in the beach from Chennai to Kalpakkam, Veerampattinam to Panithittu, Pudupettai to MGR Thittu, Pradabakkarai to Vattaikkaraniruppu, Tiruchendur to Kulasekarapatinam segments of the East coast. Subsequently, the moderately well sorted to very well sorted nature of the sediments reveals that these areas have been experiencing moderately high energy condition.TRANSCRIPT
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SenthilNathan,BijilalBSSedimentologicalstudiesofbeachsandofTamilNaduandKeralacoast
SedimentologicalstudiesofbeachsandofTamilNaduandKeralacoast,IndiaImplicationsonprovenanceanddepositionalenvironments
DSenthilNathan&BSBijilal
DepartmentofEarthSciences,SPCAS,PondicherryUniversity,Pondicherry605014,IndiaEmailaddress:[email protected]
Abstract. ThepresentinvestigationdealswithsedimentologicalstudiesofbeachsandofTamilNaducoast and southerncoastal part of Kerala. As manyas 133 samples were collected fromChennai to KanayakumarialongtheEastcoastand41samplescollectedfromKanyakumaritoAlappuzhaalongtheWest coast, and those samples were subjected to textural and heavy mineral analyses. Texturalcharacteristicsofthesedimentsandheavymineralassemblageprovidecluestounderstanddepositionalenvironmentandprovenance.ThetexturalanalysisoftheEastcoastsamplesshowsthatgenerallythesand size varies from fine to mediumgrained, sorting frommoderately well sorted to well sorted, SkewnessfromnearlysymmetricaltocoarselySkewedandkurtosisfromplatykurtictoleptokurtic.Itis evident from the skewness that an erosional condition is prevailing in the beach from Chennai toKalpakkam, Veerampattinam to Panithittu, Pudupettai to MGR Thittu, Pradabakkarai toVattaikkaraniruppu, Tiruchendur to Kulasekarapatinam segments of the East coast. Subsequently, themoderatelywellsortedtoverywellsortednatureofthesedimentsrevealsthattheseareashavebeenexperiencing moderately high energy condition. Whereas it is also inferred that a depositionalenvironment is prevailing in thesegments betweenKalpakkamandBanayul, AalambarikuppamandKunimedu,PalaiyarandKallar,VettaikkarraniruppuandnearTiruchendur,ManapaduandKoodatapanai, Kuthankuzhi andVattakottai. Further, themoderately sorted to moderately well sortednature of thesedimentsrevealsthattheareahasbeenexperiencingmoderatelylowenergycondition.Similarly,theWestcoastbeachsandsaregenerallymediumtofinegrained,moderatelywellsortedtoverywellsorted, finetonearlycoarselyskewedandkurtosisvariesfromveryleptokurtictoleptokurtic.Theskewnessandsorting nature of the samples indicate that an erosional condition is prevailing in the beach fromKarinkulamAdimalaturaarea,Valiyatura,VeliEdamkantamregion,andKappil,whereasadepositionalconditionexistsinthesegmentfromColechaltoKovalam,Shangumugamarea,andVarkalatoAlappuzhasegmentexcludingthelocationKappil.ThetexturalcharacteristicofthesebeachsandsexhibitthatthestudyareaoftheKeralacoastisexperiencing moderatelyhighenergyhighenergyenvironment.Theheavymineralanalysisofthesamplesshowsthattheconcentrationofheavymineralsvariesmuchindifferentlocationsofthestudyarea. TheheavymineralassemblageintheEastCoastfromChennaitoKaraikal(Pumbuhar)segmentincludesPyriboles,EpidoteandgarnetwithminorIlmenite,Rutile,Zircon,Monazite with very low sillimanite, hornblende, hypersthenes, kyanite. Whereas Rameswaram toTiruchendurisdominatedbyIlmenite,Rutile,Zircon,MonaziteandSillimanite,veryminoramountofPyribolesandGarnet.ThruchendurtoKanyakumarisegmentconsistspredominantlyofIlmenite,Rutile,Zircon,MonaziteandSillimanitewithGarnet.However,KoodatapanaitoKundalstretchisenrichedwithGarnet,withminoramountofIlmenite,Rutile,ZirconandMonazite. SimilarlyintheWestCoast fromAlappuzhatoVarkala,themajorheavymineralassemblageincludesIlmenite,Rutile,Zircon,MonaziteandSillimanite, with very minor amount of Pyriboles andGarnet, It is observed that the beach sandofNeendakara,SakthikulangaraandChavaraisenrichedwithilmenite,rutileconstitutingabout80%oftheheavy minerals. Varkala to Manavalakrichi segment possesses Ilmenite, Rutile, Zircon, Monazite andSillimanitewithGarnet.TheseheavymineralassemblagessuggestthatthesourceforbeachsedimentsofnorthernpartofTamilNaducoast,wouldbemediumtohighgrademetamorphicrocks, GranitoidandGneisses,CharnockiteandGranulites,whilesouthernpartofTamilNaduandKeralacoastmighthavereceived sediments from High grade Migmatites (Khondalite Group), Granites, Charnockite andGranulites.
Keywords:Sedimentology,HeavyMinerals,TamilNadu,KeralaCoast,India.
ShajiE&PradeepkumarAP(Eds)2014 MineralResourcesofKerala Trivandrum:DeptofGeologyUnivofKeralaISBN9788192344904 181