sedimentological and palynological studies of sub …

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Int. J. of Geol. & Earth Sci., 2016 L Mahesh Bilwa et al., 2016

SEDIMENTOLOGICAL AND PALYNOLOGICALSTUDIES OF SUB-SURFACE SAMPLES OFKOYAGUDEM AREA, KYG-451, GODAVARIVALLEYCOAL FIELD, LOWER GONDWANA,

ANDHRA PRADESH, SOUTH INDIA

INTRODUCTIONGondwana sedimentary basin is a unique sys-tem largely with fresh water sediments withfairamount of floral remains. Gondwana stratig-raphy in India has attracted many earth scien-

tists to understand more about its distribution andevolution aspects of flora. Gondwana researchsupports to understanding more about coal de-posits and floral distribution in India. From pastseveral decadessedimentological and palynologi-

ISSN 2395-647X www.ijges.comVol. 2, No. 3, September 2016

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Int. J. of Geol. & Earth Sci., 2016

Research Paper

Sedimentological and Palynologicaldata from the subsurface samples from the bore-hole #KYG-451, located in the southwestern margin of Godavari sub-basin and Northern part ofKothagudem sub-basin of Koyagudem area, Lower Gondwana, Andhra Pradesh. Present studyhas been chosen to depict the relationship between sedimentological and palynological databased on the mineral assemblage with palynoassemblage. Present study is for ten core samplesfrom bore-hole which are sandstone, shale and shally coal. The objective of the study is toidentify the minerals and its grain size, shape analysis, sedimentation character and nature ofsource rock, palynoassemblage study and age assessment. Thin section study reveals shapeof the grains which discloses the source rock relationship for the sediments during depositionand also some heavy minerals like zircon, garnet, hematite, chlorite are also identified and thesource rock potential identified. Cementing materials areidentified which flows through intergranular space between adjacent minerals of sediments which reveals the depositionenvironments of the sediments. Palynological data applied to understand distribution pattern offloral remains. Palynological study reveals fifteen well preserved palynoformsarerecovered.Basedon the dominance and sub-dominance of palynoforms Scheurangipollenites palynoassemblageidentified and possible to assign the age for the sediments under consideration.

Keywords: Sedimentology, Palynology, Koyagudem, Bore-hole sample, Lower Gondwana.

Prameela M1, L Mahesh Bilwa1*, C J Nagamadhu2 and P Madesh1

*Corresponding Author: L Mahesh Bilwa [email protected]

1 DOS in Earth Science, University of Mysore, Mysuru, Karnataka, India.2 Yuvaraja’s College, University of Mysore, Karnataka, India.

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cal research were carried out on variousGondwana coal basins of India (Jacob 1952, KJacob, et al., 1958, P G Adyalkar 1964, Sengupta1970, Singh IndraBir 1975, Lakshminarayan1995, R C Tewari and M Chandra Das 1996,Suresh C Srivastava and NeerjaJha 1989, SureshC Srivastava and NeerjaJha1996, Pauline SabinaK S et al., 2007, Nagamadhu C J et al., 2012,NehaAggarwal, NeerjaJha, 2013). Gondwanasediments are characterized by cyclic nature ofdeposition. Lithostratigraphicallythe Gondwanasediments were classified into Lower and UpperGondwana as bipartite division. Present sedimen-tological and palynological data are from LowerGondwana Formation, south western margin ofGodavari sub-basin Godavari valley coal field ofPermian period. Present study an attempt hasbeen bring out the possible relationship betweensedimentological data with palynological data.Sedimentological and palynological study givesan ample of scope to understand the mineralassemblage, grain size and shape, nature ofsource rock, palynoassemblage andfloral distri-bution.

GEOLOGY OF THE STUDYAREAGodavari valley coal field is the one of the largestcoal producing area in southern IndianGondwana basins.The coal field is extendsNNW-SSE direction and located inbetweenlatitude N 16º 38’ and 19º 35’ andlongitude E 79º 12’ and 81º 39’ which covers anarea about 17,000 sq.km.According to Raja Rao,1982, the valley is structurally divided into foursub-basins Godavari, Chintalpudi, Kothagudemand Krishna-Godavari tract. The presentSedimentological and Palynologicalinvestigation

for the core samples from subsurface bore holeNo.KYG-451, Koyagudem area,Kothagudemsub-basin of Andhra Pradesh. Koyagudem arealocated in the southwestern margin of Godavarisub-basin andNorthern part of Kothagudem sub-basinand situated under Lingala-Koyagudemcoal-belt. This coal-belt is situated between thetwo active mining centers of Ramagundem areain the North West and Kothagudem in the SouthWestern part. This Lingala-Koyagudem coal beltextended by 50km long unbroken stretch ofBarakar Formation occurring between Lingalain the NW to Koyagudem in the SE on westernmargin of Godavari graben. The coal beltbounded by N 17º 35’ to 18º latitude and Eastlongitude 80º 03’ to 80º 30’ on GSI topo sheetnumber 65 C/5, C/6 and C/10 and it covers an area

Figure 1: Geological Map ofGodavari Valley Coal Field

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about 192 km2 in Khammam district of AndhraPradesh.The rocks of Archean gneiss, Proterozoic Pakhalsuper group and PhenerozoicGondwana sequence are exposed in theKoyagudem area. The Koyagudem area in LowerGondwana sequence represents by parts ofsynformal structure and the area is traversed byrepeated faults. Lower Gondwana sediments inthe Koyagudem area belonging to Talchir, Barakarand Kamthi (sensu Raja Rao 1982). Formationshave been established by surface andsubsurface data. The bore hole KYG 451 locatedin the Lingala-Koyagudem coal belt Koyagudem

area bounded by N 17º 37’ 465" and E 80º31’ 631"and falls in the survey of Indiatopo sheet No.65 C/10 and C/11, 1:50000 scale respectively (SCCL2011). TheGeological map of the study areashown in Figure 1 and lithostratigraphy of the areashown in Table 1.

MATERIALS AND METHODSTen bore hole samples are selected forsedimentological and palynologicalstudyfromKoyagudem area, bore holeNo. KYG-451. Thesamples are collected according to referred depthand lithological wise. Total depth of the bore hole

Table 1: General Lithostraigraphy of Lingala - Koyagudem Coal belt

Age Group Formation General Lithology

Recent Reddish and reddish yellow sandy soil

Permian

UpperGondwana

UpperKamthi

Alternating sequence of pebbly sand stone, pebble bed, medium to coarse grained yellowishferruginous sand stone, fine to medium grained white quartizitic sandstone, pink and purplelaminated sand stone with intervening pebble beds and micaceous reddish brown hematitebands beds.

MiddleKamthi

Alternating sequence of red, green, white and grey clays, shales and siltstones, inter beddedwith fine to coarse grained argillaceous and ferruginous sandstone

Conformable contact

LowerKamthi

Coarse, Pebbly, feldspathic, highly Kaolinated sandstone with alternating thick clay and sandyclay beds.

BarrenMeasures

Alternating sequence of grey immature feldspathic sandstone. Mg to Cg. Ferruginoussandstone hard and compact reddish brown to brown iron stone bands with green and greyclays and shales.

Conformable contact

BarakarCoarse to very coarse, pebbly poorly sorted grey white sandstone, alternating with siltstones,grey and white clays, shale and coal seams.

LowerGondwana

Conformable contact

TalchirFine grained Greenish sandstone, siltstone, greenish and brown clays and dark green needleshalesinterbedded with dark grey, parallel bedded compact fine grained andstone(Rhythmites).

Conformable contact

Pakhal Quartzites, Phyllites, slates, Dolomitic limestone with quartz vein.

Conformable contact

Pre-cambrianArchean

Granite gneisses, Biotite gneisses, amphibolites, quarts, Chlorite Schists.BASEMENT

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is about 682m. From 002m to 308m and from403m to 682m are non-coring sediments so thatsamples are unable to collected from thesementioned depth. From 95m thickness tensamples are collected and subjected to standardmaceration technic for palynological study andthin section are made to sedimentologicalstudies.For preparation of thin section study freshbore hole representative samples are selectedand section taken vertically by along the coresamplesand mounted onglass slide with aralditefixed with canadabalsam and hand grounded andobserved under the microscope and continuedtill all the mineral grain boarder clearly visible,when section attains to 0.03mm thickness. Thethin section slides are ready for observation. Thissedimentological thin section slides observedunder the Leitz with digital camera attachedoptical microscope by selecting appropriatemicroscale.Thin sections are prepared in sectioncutting lab at Department of Earth Science,University of Mysore. The same samples areselected for palynological maceration procedurefor the recovery of palynofossils. For palynologicalmaceration analysis 50 grams of selectedsamples are washed with distilled water, burnedwith alchohol and crushed into pea nut size withironpestel and mortar. The crushed samples aretreated with 10% of HCl to remove the carbonatematerial, conc.HNO3 to removehumic materialsand finally treated with 40% of HF to remove silicacontents, every acid treatment stage the samplesare thoroughly washed with distilled water toremove the acid content if any. The collectedorganic material sieved by sieve cloth andcentrifuged by taper ended test tube. Thecollected organic material mixed with a polyvinylalchoholas a preservative and smeared on glass

cover slip and mounted on palynological slide byusing canada balsam and cooked andfixed,cleaned and labeled and palynologicalslides are ready to observe under palynologicalmicroscope and photographed digital cameraattached Carl Zeiss microscope atVijanaBhavana, IOE, University of Mysore.Scanning Electron Microscopic study carriedoutfor the same rock samples was used to separatepalynofossils and identified ultrafine morphicfeatures of spores and pollens under ScanningElectron microscope and photographed atVijanaBhavana, UPE, University of Mysore,Mysuru.

SEDIMENTOLOGICAL STUDYThe investigation so far carried out for on aspectsof sedimentology data from subsurface samplesfrom Koyagudem area, KYG-451, Godavari valleycoal field, Andhra Pradesh. Presentpapercontributes much about on sedimentologicalstudies for ten core subsurface samples atdifferent depth and for different lithology. Theprepared thin section slides are analyzed underpetrological microscope and identified differentminerals, its character, and shape of the grains.After the detailed analysis of thin sections quartzgrains are in abundance and are in sub angularto angular grain shape.The angularity of thequartz grains infers the immaturity of thesediments and also reveals the source rock isvery near to the sediment depositional site. Thepresence of heavy minerals like zircon, garnet,hematite and chlorite are also identified from thethin section studies. The heavy mineral analysisdepicts the source rock of the sediments for thedeposition. The core sample and itscorresponding optical thin section description for

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Table 2: Microscopic Description of Sedimentary Thin Section andCorrelation with Palynological Data

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each samples are tabulated in Table 2. In thistable an illustrative account on samples, depthdata, sedimentary minerals data, textures,mineral assemblage and palynoforms areprovided. The palynological assemblage data arecompared to bring out a comprehensive accounton the sub-surface palynological aspects. Thethin section are observed under the opticalmicroscope by 10X objective micro photographswithout cross Nichols and with cross Nichols.All optical properties studied in detail for identifyingminerals. Colour of the minerals and outlines ofmineral optical characters like shape, undulate

extension and pleochrohic schemes are studiesin detail. Size of grains are measured by microocular scale.The nature of cementing materialsas observed as in the sections, where as toidentify to decipher the deposition conditions.Sedimentological activity is to findout whether thesediments are deposited in reducing or oxidizingenvironment. Iron oxide solutions are observedas cementing material during the thin sectionstudy which flows through the inter spacebetween the minerals which reveals thesediments are deposited due to chemicalweathering and also deposited in oxidizingenvironment. To support thin section photos areshown in Figure 2.

PALYNOLOGYPalynological analysis data for the studiedsamples gives the ample of scope to assess theage of the sedimentary sequence. In the presentstudy for analysis of ten samples at different depthand lithology. Based on the qualitative andquantitative analysis of the ten samples themonosacates, non-straiteddisaccates, striateddisaccates are recovered and trilets are very rare.Based on the dominance and sub dominance oftaxa one palynoassemblagemarked at a depthof 388m. The palynoassemblage zone revealsthe dominanceof non-striatedpalynoformScheurangipollenites (45%) along with sub-dominance of striated Faunipollenites (16%) andassociated taxas like Striatopodocarpites (6.2%),Striatites (1.5%), Sulcatisporites (3.1%),Rhizomaspora (9.3%), Ibisporites (4.6%),Primuspollenites (1.5%), Lahirites (1.5%),Ginckocycadophytus(1.5%), Vesicaspora(4.6%), Virkkipollenites (1.5%), Parasaccites(1.5%), Laevigatosporites (1.5%). The other

Figure 2: Some Selected Thin SectionMicrophotographs ShowingTextures and Mineralogy

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samples are poor recovery of palynoforms.Some of the samples even afterrepeatedlychecked which are unproductive may be due tomineral grain size control. It may be concludethat the samples like shally coal, shale are verymuch productive but sandstones unproductivesample from the present studies. The unevendistribution may be due to because of size of thegrains in the sandstone which allows topercolation of water along with palynoforms. Thisis one of the valid reasons for uneven distributionof palynoforms in the study area. The distributionpattern of the spores and pollens at a depth 388m

are shown in Figure 3. Some of the identifiedpalynoforms are shown in Plate1(Lightmicroscope photography) and Plate 2 forScanning Electron Microphotograps. ScanningElectron Microphotographs are of high resolutionshowing all features of sacs, nature of centralbody with detailed ornamentation helps to identifythe species.

RESULTS AND DISCUSSIONAfter detailed investigation of subsurface samplesfrom the bore hole KYG-451 which gives a pictureof mineral assemblage, source rock fordeposition of sediments, depositional

Figure 3: Frequency Distribution Pattern of Spores and Pollensfrom B. H. KYG-451 at 388 m Depth

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environment, and assessment of age.Sediments are analyzed sedimentologically andpalynologically from bottom to top following order

of superposition of the bore hole at various depths.According to Singh (1975), the presence ofangular quartz grains and high feldspar content,

Plate 1: Microphotographs of Selected Spores and Pollens from the B. H. KYG-451. All PhotoGraphs are Taken Under X1000 Magnification with Oil Immersion Until

and Unless Mentioned, Bar Scale Indicates 50µm Size

Scheuringipollenitesmaximus (Hart)Tiwari, 1973b

Scheuringipollenitestentulus, Tiwari1973 Tiwari,1973

Faunipollenitesperexiguus Bharadwajand Saluja 1965

Faunipollenitesvarius,Bharadwaj,Bharadwaj, 1962 emend.Tiwari et, al., 1989

Ibisporitesdiplosaccus,Tiwari, 1968

Striatopodocarpiteslabrus,Tiwari, 1964

Striatopodocarpiteslabrus,Tiwari, 1964

Striatitesmultistriatus, (Balme& Henn.) comb.nov. 1955

Striatitesrhombicus, Bharadwajand Salujha, 1964

Lahiritesincertus BharadwajandSalujha, 1964 Rhizomasporamonosulcata Tiwari,

1968Rhizomasporaindica Tiwari

1965

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pointing to textural and mineralogical immaturityof sediments. Microscopic study reveals thatpresence of sub-angular to angular fragmentsof quartz grains shows the immaturity of thesediments and it suggests that limited chemicalweathering prior to transport and source is verynear to the sediments deposition site in the studyarea. The angular fragments with unduloseextension of the quartz which are dominant insandstone which shows the source rocks areplutonic granites and gneiss. Presence of heavyminerals reveals that the different source rocks

are contributed. Heavy minerals like garnetbearing rocks of Precambrian granitic mighthave deposited as input. Presence of heavymineral zircon reveals that the mineral derivedmainly from acid igneous and metamorphicrocks like granites or gneisses as source forthese minerals. The presence of chloritemineral indicatesthat they are derived from lowto medium grade metamorphic rocks.According to Singh 1975, the abundance ofpresence of microcline along with feldspar alsodemands presence of significant amount ofgarnetic gneisses in the provenance. Iron oxidesolution indicates the oxidizing environment.Triple junction marks are noticed in some ofthe thin sections which reveals metamorphicprocess taken place during the sedimentdeposition. According to Tiwari and ChandraDas (1996), the occurrence of cyclic sequenceof sandstone reveals braided depositionalenvironment condition. In the present study alsosimilar cycl ic sequence of sandstoneoccurrence suggests that the sediments underbraided environmental depositional conditionobserved in thesub-surface bore hole KYG-451,Koyagudem area. Palynological ly thepalynoassemblage zone marked at 388m depthfrom the bore hole. The palynoassemblagereveals dominance of non-striated disaccatesScheurangipollenites along with str iateddisaccate Faunipolleniteswith other associatedtaxa shows the affinity towards Early PermianLower Barakar age (Neerja 2006, SureshSrivastava and NeerjaJha 1989, Mahesh Bilwaet al., 2012). This result is at the depth of borehole between 308m to 403m (95m is totaldepth). Sedimentological and palynologicaldata can be well fitted with one another.

Plate 2: Scanning Electorn Microphotograps

Scheuringipollenitesmaximus,Hart,Tiwari, 1973b

Scheuringipollenitesmaximus,Hart,Tiwari, 1973b

Scheuringipollenitestentulus Striatitesmultistriatus,(Balme&Henn.)comb.nov. 1955

Lunatisporites sp.,Bharadwaj, 1962 RhizomasporamonosulcataTiwari, 1968

RhizomasporaindicaTiwari (1965) Faunipollenitesvarius,Bharadwaj, 1962emend.Tiwariet, al., 1989

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CONCLUSIONPresent study conclude with aspects ofsedimentology and palynology of the sub-surfacebore hole samples. Sedimentologicalstudyreveals mineralogy, grain size,texture analysis which depicts the source rockand depositional environment of the sediments.The mineralogical study suggests that thepresence of heavy minerals like garnet, zircon,which indicates the sediments are from differentsource rock as material. Palynological studyreveals identification ofpalynoassemblagesat388m depth based on the dominance and sub-dominance of palynotaxa. Based on thequalitative and quantitative analysis of spores andpollens assigned palynoassembalage zonewhich reveals dominance of non-striatedScheurangipollenites and sub dominance ofstriated Faunipollenites along with other taxaswhich assigns Early Permian, LowerBarakareffinity.

ACKNOWLEDGMENTAuthorsare thankful tothe Dr. K V Rama Rao,Supt.Geologist, Mr. D Sathya Prasad and Mr GuruMurthy Superintendent Geologist, SingareniCollieries Co.Ltd., (SCCL), who had given thepermission andsupported in the field to carryoutfield work and collect the samples from the borehole.We thankful Mr Surendra Kumar, Geologistand Mr Md. Absaltheir co-operation and helpduringthe field work. Mr.Karuppuwamy Basin Manager,Southern Regional Laboratory, ONGC, Chennai,thanked for providing lab technician to preparepalynological slides in our department. Ourimmense thankful to the IOE, VijanaBhavan,University of Mysore for permitting to takepalynological light micro photograph and also

UPE, VijanaBhavan, University of Mysore forallowed to do analysis of Scanning ElectronMicroscopic studies. Junior author Ms PrameelaM, thankful to the University of Mysore for grantingthe UGC-BSR Research fellowship (New Delhi)for Meritorious students (RFSMS) to carryout theresearch work. Chairperson of the departmentand all Staff members of Department of Studiesin EarthScience, University of Mysore, forencouraging directly and indirectly to carryout theresearch work.

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