PETROLOGY A D PALYNOSTRATIGRAPHY OF SOME \V ARDHA VALLEY COALS, , ANAND-PRAKASH Birbal Sahni Institute of Palaeobotany, Lucknow-226007 & R. C. KHARE* * Banaras Hindu University, Varanasi

ABSTRACT INTRODUCTION

The present paper deals with the petrographic India the Lower Gondwana coal and palynological studies of Wardha Valley coals deposits are well known. Their of Maharashtra, India. The coals are generally dull, hard, granular and indistinctly banded. occurrences in various parts of the Durain forms the dominant constituent in the coal country have been extensive;y investigated, seams. It occurs as thick bands of hard, compact in view of the prob~ems related with their and granular mass, having dull lustre. Clarain is the next dominant constituent of these coals origin, constitution, icent ifica1ion and naturc which is more common in the south-eastern part etc. However, Hry little is known in the of the coalfield. Fusain is present in the form of literature regarding Warc1ha Valley Coal• thin patches and lenses. Vitrain occurs as thin field. This parer incorrorates some aspects bands except at places wherc it has attained con• of thc physical constituents of the coals siderable thickness of local importance. Micro• scopic study of durain components indicates par1icularly retro'ogical and palyno'ogical inertinite, vitrinite and exinite as main macerals. aspects with a view to understand the Microspores and megaspores are found mainly in nature of coal cons1ituents and their rela1ion exinite constituents. Microscopic analysis of coals with other Lower Gondwana derosits. also indicates that durite, fusite and vitrite are The earliest rcfcrencc of the Warc1ha tho important microlithotypes. The inorganic mineral matter is mostly composed of clay minerals; Valley coal is givcn in "Glcanings of silica and pyrite. Sciencc" (1831) in which the occurrence Sporological study of '¥ardha Valley coals of coal has been mentioned on the banks reveals the presence of trilete, monolete, mono• saccate and disaccate forms. Brevilrileles, Horridi• of near Kumbhari (19°57': Irileles, Lopholrileles, Microbaculispora, Micro• 79°6'). Blanford (1867) found a 1·82 m foveolalispora, Parasacciles and Sclzeuringipollenites thick coal seam towarcls the side are well represented genera in these coals suggesting on the bank of Wardha River. Oldham the Lower Barakar affiliation. (1869) has given a summarised account of The petro-palynological study of 'Vardha Valley coals indicates that the coals are derived from Wardha VaJley coals. In 1870, a colliery Permian coal swamps of Lower Barakar entities was set up at (19°56': 79°7'). (based on spores and pollen analysis) which meta• Hughes (1877) has given the systematic morphosed into a dull coal type (durain type• account of the Wardha VaHey Coalfield. characteristic of Barakar Stage) showing variable coalification towards the south eastern part of the Thc has been coalfield due to probable changes in physio• resurvcyed during last few years. Geo'o• chemical conditions. The petrological composition [,ical Survey of Inc'ia and Directorate of shows a high proportion of "inerts" and sedi• Geo~ogy and Mining, Maharashtra are now mentary matter in the coals which may cause engaged in systematic geological mapping problems in coal preparation for utilization. However, the coal quality may be improved by and prospecting of coal in the area. Hem• selective sampling, screening and cleaning processes. mady examined the Majri area and its The petrographic analysis of coals from different surroundings and proposed the exploratory collieries reveals better type of coal in the southern drilling through the Kamthi beds near the part of the coalfield and hence, it is suggested that contact with the TaJchirs between Sumthan this area is more promising for working, and for future exploration. and Avnc1h (20°04': 79°13') to find out the

*Now in Geological Survey of India. 124 PRAKASH & KHARE- PETRO-PALYNOLOGY OF WARDHA VALLEY COALS 125

extent of its overlapping the Barakars and the presence of possible coal seams. Recent to Pleistocene Alluvium, Older gravels As regards petrological and palynological and laterite studies of Wardha Valley coals, the fo~rner has been analysed by Pareek from Maj>i area, whereas, the later has been sLudied Lower Gondwar.a Kamthi Group by Agashe and Chitnis (1969, 1972) from Barakar Group Hindustan Lalpeth Colliery (Chanda area). Talchir Group The above studies are rather preliminary ------Unconformity ------and restricted to a particular area. Pura~la Formation Vindhyan Limestones at'd Shales. GEOLOGY OF THE AREA VINDHYANS The Wardha Valley Coalfield covers an area of about 1440 sq km between Latitudes The Vindhyans lie unconformably upon 19° 28' and 20°27', Longitudes 78°50' and the metamorphics and occupy a large area 79° 45' for a length of about 115 km from in Yeotmal and districts. The NW to SE almost in a straight line. There limestones, dolomitic limestones, sandstones are large tracts of wide spread alluvium and purple shales are the constituent rock deposits of sand and gravels. Only at few types. The limestones and shales are mostly places isolated out-crops of rocks are found. found towards the western part of the The Archaean rocks are found in the eastern Wardha Valley, while the sandstones are part whereas, the Puranas and the found mainly towards the east. The areas Vindhyans are towards the west. The in which the Vindhyans are well exposed rocks found near Chandrapur are folded are Kelapur and Wani of Yeotmal district form!ng an anticline with its axis much and , Brahampuri and Sironcha of nearer towards the south-western limits . of the area. Due to the folding, the Gondwana outcrops are divided into two TALCHIRS arms, each extending north-westwards along one side of both the boundary faults towards In the central part of the Wardha Valley the south west. The shale3 and the lime• the Talchir beds with disconnected and stones of the Pakhal Series are found border• thin outcrops of Barakars in its neighbour• in~ the Gondwana tract with a few scattered hood are present. The Ta1chirs are repre• patches of Sullavai Sandstones. sented by boulder beds, greenish sandstones The Wardha Valley Coalfield has been and greenish shales. The boulder beds divic'ed into 8 different areas in Chandrapur are composed of the boulders of different (Chanda) and Yeotmal districts. (for size and shape, some having glacial markings. geo~ojcal map see Hughes, 1877). BARAKARS 1. Warora The coal is found in the Barakar group, 2. Majri which is the most important lithological 3. Ghugus-Telwasa unit of the area. The rocks are sandstones 4. Rajur and Wun and shales with interbedded coal seams. 5. Ban:iar Sandstones are white, buff to reddish in 6. Chandrapur Town colour, coarse-grained containing quartz, 7. Ballarpur feldspar and mica as major mineral COIl• 8. Sasti- stituents. Thinly bedded carbonaceous shales are found interbedded with the coal seams. GEOLOGICAL SETTING KAMTHIS The following stratigraphical succession The Kamthis are very well developed is found in the area under discussion. in the area. These are mostly exposed ill 126 THE PALAEOBOTANIST

the eastern part of the coalfield. Kamthis part extends from Nilijai to Ghugus and rest unconformably over the Barakars and further south to Penganga River. A coal overlap them extensively. Although, seam of 18·59 m thickness with partings Kamthis do not contain coal seams but their was recorded at Junera opposite Telwasa. occurrence is helpful in deciphering the In a borehole at Nilijai, 2 seams of 9·98 and presence of coal in the strata below them. 11·37 m thickness have been found. A The lithological units are mainly sandstones, 10 m thick seam is being worked at shales, clays and conglomerates. Robertson Incline and Pit no. 2 of Ghug-us Colliery. The trend of the seam is NNW• ALLUVIUM AND SOILS SSE, dipping 8° towards west. The seam has been C'iyided as top, middle and bot tom Under these, is included all the area on the basis of shale partings. covered by the soils and subrecent gravels which are seen exposed on the banks of CHANDA TOWN AREA Wardha River. The soil near Chandrapur is red in colour but in the other parts of the Chanda (19° 56': 79° 18') is situated on area they are grey and blackish. Kamthi rocks on the eastern edge of a large The Wardha Valley Coalfield includes tract of Ta1chirs. Barakar out-crops occur 8 different areas in Chandrapur and Yeotmal south west of Chanc~a about Hingnala (190 districts. They are (1) Warora (2) Majri 54': 790 17') and in the Erai River south (3) Ghugus-Telwasa (4) Rajur-Wun (5) of Chanda at Charwat (190 53': 79° 18'). Bandar (6) Chanda town (7) Bal1arpur and The thick seam is now being worked in t.wo (8) Sasti-Tajura. Out of these 8 areas, working collieries of this area namely Hin• only 5 areas namely, Majri, Ghugus, Chanda dustan Lalpeth and Rayatwari. The third, town, Ballarpur and Sasti are the working Mahakali Colliery is now abanconed due horizons. As the present study is confined to flooding in the mine. to only working areas the nature of the The strike of the coal seam is NW-SE seams and description of each coal horizon and dips about 100 to 14° towards NE. is given in brief: The individual thickness of the seam in these collieries varies from 8 to 16 m. MAJRI AREA BALLARPUR AREA In Majri (20° 8': 79° 2'), the northernmost coal horizon of Wardha Valley Coalfield, Ballarpur Colliery is situated near the Barakars underlie a thick cover of Kamthis Ballarshah town (190 51': 790 21') in the and Lametas. The working coal seam of Chandrapur District. This area is the con• this area is 9·2 m thick. The bottom portion tinuation of the Chanda Town COJ.lfielcl (3·5 m) of the seam possesses good quality towards south. Hughes (1877} rerorted of coal while upper part of the seam is shaly only two thin seams, 3 m and 6 m thick at in nature. The coal seam dips at 12°_15° a depth of 60 m in a borehole. In 1900, a towards south-west. The seam is not found systematic st udy was carried out at Ballar• outcropping at the surface. Hughes (1877) pur which produced good result s. reported a coal seam of 15·24 m thickness The seam in Ballarpur Colliery is 16 m between Majri and Wardha River at the thick and has been divided on the basis of depth of 22·86 metres. Fox (1934) report ed shale partings into three sections, top (4·26 two coal seams of 4·57 m and 17·37 m thick• m), middle (1·2 m) and bottom (3·2 m) thick. ness in separate boreholes towards west The top and bottom sections are being of Majri near Kona1gaon. The thick seam worked at present. The seam dirs about represents the two lower seams of the 4° towards ESE. Warora area which are united in the Majri area. SASTI-RAJURA AREA

GHUGus-TELWASA AREA This coal horizon is situated on the south western bank of the Wardha River and This area consists of two parts: (a) opposite to Ballarpur Colliery. The thick Northern part is Telwasa and (b) Southern seam of Ballarpur extends south of the PRAKASH & KHARE-PETRO-PALYNOLOGY OF WARDHA VALLEY COALS 127

Wardha River into this area. The thickness and water was maintained throughout the of the seam in this area is about 10·64 m whole process in order to get a smooth and and is being worked in three sections as in scratch free surface of the coal. Ballarpur Colliery. This field includes three The coal b!ocks were studied in reflected areas Rajura, Antargaon and Lathi. A light under high magnifications. The pro• 7·0 m thick seam was proved in a borehole portion of the various macerals were near Dapta (190 48': 790 20') north of evaluated through the point counter method. Rajura. Hughes (1877) has recorded a For separation of the microfossils the 1·82 m thick coal seam on the bank of coal from homogeneous representative Wardha River south of Lathighat near samples was taken for maceration. The Antargaon (190 33': 790 29'). maceration procedure adopted during the investigation was same as described by Bharadwaj (1962) and Bharadwaj and MATERIAL AND METHOD Salujha (1964). About 15-20 gm of the crushed material was taken from each The material for investigation was sample, washed 2-3 times with water and collected from the following working collie• covered with commercial nitric acid. After ries of Wardha Valley Coalfield namely complete acid action the material was washed Majri, Ghugus, Rayatwari, Lalpeth, Ballar• with water several times. The material pur and Sasti representing complete thick• was then treated with 10% KOH solution ness of the coal seam worked in them. A and again washed 3 or 4 times to remove the debris and to make the macerate alkali systematic channel sampling was carried out in orcler to represent the entire thickness free. The residue was made water free by of the coal seams investigated. The tech• centrifuging the material. Slides were made nique of examining the coal in polished in glycerine jelly. From each sample 200 surface through incident light has been miospores were counted. applied in the present investigation of micro• constituents of Wardha Valley coals. PETROLOGICAL CHARACTERISTICS Different lithotype blocks were suitably cut into 8 X 4 cm size, embedded and polished for general observation of the Megascopic observation of Wardha Valley structure of the coal. In addition to this coals shows that durain is the most dominant about 5-10 gm of the material from overall component in almost all the areas of the coal samples crushed up to ± 18 B. S. size coalfield. Clarain and fusain are the next was utili sed in the preparation of coal pellets lithotypes occurring in order of dominance. and the quantitative estimation of different Vitrain occurs mainly in the form of thin macerals. streaks and patches. Thick and persistent As embedding material, molten carnuba vitrain bands are rare. At places these wax and sometimes Araldite C. Y. 230 has coals are semibright in nature due to the been used. The method of embedding the presence of thin vitrain layers mostly in material was same as described by Navale the south-eastern part of the area namely, (1963) and Navale and Srivastava (1967). Ballarpur and Lalpeth collieries. Fusain Grinding was done over an electrically is widely distributed and occurs in the form operated brass disc using successively finer of lenses and patches, mainly in the northern grades of carborundum powder (80, 200 areas of the basin. In Majri and Ghugus and 300). This grinding was continued collieries, fusain occurs in thick bands up till a fresh and even surface of the coal was to 10 cm in thickness and locally known as exposed. The final grinding was done over Bhusa Coal. Apart from the organic com• a glass plate using the finest grade of ponents, inorganic mineral matter is also carborundum powder (600) till a uniform present in these coals, mainly in the form scratch free surface emerged out. Polish• of shales. ing was done over an electrically operated Microscopically, the coals are charaete• brass disc covered with a thick soft felt rised by the fine state of maceral division cloth using a colloidal solution of Aluminium and by the presence of significant proportion oxide grades I and II as polishing medium. of mineral matter finely dispersed and in• Continuous fine jet of the polishing medium timately associated with the organic 128 THE PALAEOBOTANlST

constituents of the seam (Histog-ram-I). between vitrain and durain. The durains The proportion of mineral matter generally are dull and hard in appearanc~. Vitrain increases with that of organic inerts changing bands are uncommon. Fusain is present coal type from clarain to duroclarain and in the form of thin patches and lenses. Shale finally to durain. bands are frequent. The general petrological analysis of Microscopically, the coal type A is charac• Wardha Valley coals has rcvealed a charac• terised by the clarain rich microconstituents teristic pattern of changes in the various of vitrinite and exinite maceral grours organic microconstituents of the coal. The (Histogram III). Vitrinite is the cominant most interesting feature of these changes constituent of this coal type and occurs up is the variation in the microlithotype and to 45%. It is mostly of non-structured maceral compositions of the coals occurring (collinite) variety. Structured vitrinite is in the northern and the southern sectors of rarely seen. Inerjinite is the subdom'nant the coalfield. The coals in the northern constituent and occurs up to 28%. Fusinite areas (Majri) are mainly rich in the iner• is the important maceral of inertinite group tinite contents whereas, the coals of the and occurs up to 16%. In this coal type southern areas (Ballarpur) are rich in fusinite is less in comparison to the other vitrinite (Histogram-I). Between these two coal types. Semifusinite and micrinite (Ghugus and Rayatwari) a transitional do not show any remarkab'e inciC:ence, stage is present in which both vitrinite and whereas fusinised resins are common and inertinite occur almost in equal propor• mostly confined in the bottom section of tions. Hence, a gradual change in the coal the seam. These fusinised bodies occur type is evident in the area. up to 4%. They are present in various The percentage compositions of micro• forms. Large vesicular bodies with numer• lithotypes and macerals have been plotted ous vacuoles often accompanied with in Histogram-I and Histogram-II respec• dettrital infillings are common. tively. Both these his:ograms are con• The microlithotypes recof,nised une"er tte temporary to each other and show that the microscope are vitrite, clarit e, durit e and variations in the macerals and microlitho• fusite. This type of coal is characterised types are almost identical. In Majri area by c1arain rich microconstituents. Vitrite the durite and fusite are closely followed and clarite forming the dominant micro• by the vitrite and clarite. Similarly, iner• lithotypes occur up to 39% by volume. tinite is the dominant maceral group in the (Histogram-IV). Durite is the subdominant Majri area followed by the vitrinite and microlithotype and occurs up to 33%. Durite exinite macerals. Contrary to this, vitrite is rich in exines and composed of micro• with clarite has become the dominant mi• spores, megaspores, cutic:es and other crolithotype in the Ballarpur and Sasti organic material often associated with areas followed by durite and fusite. mineral matter. Fusite and trimacerite Macerals also form the same pattern, vitrinite (trimaceral group) are more or less present being dominant component followed by in the s,ame proportion. Fusite shows inertinite and exinite. The rest of the various stages of fusinisation of bark and areas occurring between these show the wood cells of the plant material. intermediate position in the percentages The coals of the working horizons of of vitrite, clarite, durite, and vitrinite and Sasti, Ballarpur and Lalpeth collieries are inertinite with somc minor variations. included in this coal type. On the basis of microscopic studies of these coals three main coal types (A, B & COAL TYPE 'B' C) have been suggested (Histogram-III & IV). The coals included in type-B are indis• tinctly banded, dull, hard and granular in COAL TYPE 'A' general appearance. This type is charac• terised by the inertinite and vitrinite group This type is characterised by the of macerals. Inertinite is the dominant dominance of clarain and durain lithotypes. microconstituent and occurs up to 38% The coal is intrinsically striated by dull by volume. Vitrinite which is the dominant constituents and has an appearance in constituent in coal type-A has become Page 12()

DISTRIBUTION OF ORGANIC AND INORGANIC MICROCONSTITUENTS OF WARDHA VALLEY COALS

INDEX ..~ VITRINITE !l!1 ~ EXINITE

t%~;;~~~ 0.;;'0···.: INERTINITE

k·'!:/)5:!MINERAL MATTEI\

://.~:;\).:. ::'~'" ::::rm~ if::{~~·?' ,r?:t;::;Hi~ ~[/(~~::~:); :':'.:\.:~:~ :::.~:!::;::; II:::.:;':'(;): :·>:~·:.f./I:~.:~ ?\It?t BOTTOM MIDDLE TOP BOTTOM MIDDLE TOP LALPETH BOTTOM TOP BOTTOM top BOTTOM TOP BOTTOM MIDDLE 'fOP COLL PIT- I PIT-2 (SASTI COLLIERY) (BALLARPUR COLLIERY) (RAYATWARICOLL} (GHUGUS COLLIERY) (MAJRI COLLIERV)

Histogram-I Page 130 DISTRIBUTION OF MICROLITHOTYPES IN WARDHA VALLEY COALS

INDEX _ VITRITE

~~~ICLARITE ~ DUROCLARIH

_ CLARODURIT~ ~ VITRINERTITE

_ DURITE

[Q·:-o.:·9::!FUSIT E :0:::9:'.0: ~il li~i ~ll If~~If~i~1IIf~! r):.:;:·)~jCARMP..GJl,.ltE lill illi ":".:-:.' lDJIii...... :.::.;::: 1.:::-::"::,:,::; lil ~OTTOM TOP' BOTTOM MIDDLE TOP I,..ALPETH eOTTOM TOP BOTTOM TOP BOTTOM BOTTOM MIDD~e TOP CaLL. PIT -I PIT-2 (SASTI COLLIERY) (BALLAAPUR COLLIERY) (RAYATWARICOLL) (GHUGUS COLLIERY) (MAJRI COLLIERY)

Histogram-II t>RAKASH & KHARE - PETRO-PALYNOLOGY OF WARDHA VALLEY COALS 131

COAL TYPES BASED ON MACERAL as thin streaks to thick bands showing ANALYSIS cellular structure of the woody source material. It occurs up to 18'% by volume. Fusite is intrinsically associated with the micrinite and the cell walls are more disinte• grated than in coal type-A. The cell lumens are mostly filled with clay minerals. The trimaceral group does not show any re• markable change but it is more in proportion than in type-A. The carbargilite is well INDEX distributed and associated with organic

•• VITRINITE matter (Histogram-IV). The coals of Rayatwari and Ghugus come under this type forming the transition bet• Ii~~-IlEXINITE ween type-A and type-C coals.

COAL TYPE 'C' !~~\~i~1FU51NITE

MINERAL MATTER The coal type-C is different from the types -A and B described earlier. This coal is very hard, dull and shaly in appearance. In general outlook it resembles coal type-B but on closer examination, it is found more indistinctly banded. This is characterised by the abundance of durain. Fusain is also widely distributed and present in the form of thin patches and lenses. The sedi• A B c mentary mineral matter which is chiefly responsible for high ash content is widely distributed. Indistinct vitrain bands are Hist03ram-III present. Microscopically, this type of coal is characterised by the abundance of inertinite subdominant and occurs up to 37% by group of macerals. Vitrinite and exinite volume. Inertinite and vitrinite have more are the other dominant groups present in or less the same proportion. The exinite the coal. Their distribution is less than is also well represented and occurs up to in types-A and B. Inertinite which is the 19%. It shows a gradual decrease in the dominant microconstituent occurs up to proportion of exinite from coal type-A. 57% by volume. In maceral composition Among the inertinite group of macerals, the fusinite which is less dominant in the fusinite occurs in considerable amount and types-A and B has become most dominant fusinised resins do not show any remarkable constituent in the present coal and repre• change. The fusinite cells are mostly filled sents up to 64% of the total volume. with clay or carbonate minerals. The sedi• Fusinite is mostly associated with mineral mentary mineral matter is widely distri• matter and differs from type-A in which buted and occurs up to 6% by volume mineral matter is less in proportion. The (Histogram- III). cell lumens are mostly filled with clay and Among the microlithotypes, c1urite is the carbonate minerals. Semifusinite which is dominant microconstituent and occurs up present in low proportion in other two coal to 35% by volume. This microlithotype types has also become conspicuous. It does not show much variation in proportion occurs up to 3% by volume. Fusinised than type-A excepting a slight increase in resins and other macerals of inertinite group distribution. Vitrite and c1arite which are do not show any remarkable change and are the dominant microlithotypes in type-A present in low proportion. Vitrinite which have become subc10minant constituents and is dominant in type-A has become less in occur up to 31% by volume. Fusite occurs distribution (26%). It shows gradual de- 132 THE PALAEOBOTANIST

COAL TYPES BASED ON MICROLITHOTYPE ANALYSIS

INDEX ---- VITRITE.DURITECLARITEVITRINERTITEDUROCLCLARODURITEARITE -_m!ill!!!!-

III fgg.~$~FUSITE h·\Y\YI CARBARGILLITE A B c

Histogram-IV crease in proportion from type-A to C. It Local concentration of clay mineral complex also reveals that the proportion of dull is quite common in this microlithotype. constituents are increasing from type-A The mineral matter is more than in types to type-C. Exinite constituents are also -A and B. Vitrite and clarite together form less than coal tyre-A occurring only up to the second dominant microlithotype con• 10% by volume (Histogram-III). stituent and occur up to 20%. This group The microlithotypes recognised under the has become subdominant, and differs from microscope are chiefly durite, vitrite, c1arite, type-A where it forms a dominant group. fusite, trimaceral and carbarg-ilite. Durite Fusite also shows the variations from type-A is the dominant microlithotype and occurs to C. In this coal type it has become more up to 37% by volume. Durite which is prominent and occurs up to 21 % which the subdominant constituent in coal type-A shows a gradual increase in distribution. has become the most dominant constituent This coal type is characterised by mixed in this type. The durite is mostly rich in fusite which is mostly associated with inertinite constituents. In this respect it micrinite and inorganic constituents. The differs from type-A. Sedimentary mineral cell lumens are filled w-ith clay minerals. matter is generally evident and occurs homo• The trimacerals which are less in proportion geneously throughout the durite contents. in types-A and B have become prominent PRAKASH & KHARE - PETRO-PALYNOLOGY OF WARDHA VALLEY COALS 133

and occur up to 15% by volume. Carbar• have been observed mainly in c!arain and gilite is also more than the coal types-A and in durain lithotypes of the coal. Imrortant B (Histogram-IV). amongst these are triletes and disaccates. Quantitative evaluation of the above mio• COMPARISON WITH OTHER COALS spores reveals that the following genera form the characteristic association in the present assemblage. The general Detrolosical charaderis1 ics Brevitriletes of the Wardha Valley coals described above H orriditriletes clearly suggest their resemblance to the Parasaeeites Barakar Coal type (Pareek, 1967; Navale, 1971, 72; Ghosh, 1962). Durain is the S eheuringipollenites dominant lithotype in the Barakar Coal Ginkgoeyeadophytus type. It is charaderised by vitrinite, iner• Pilasporites tinite and exinite group of coal macerals. The following genera consistently occur These maceral groups combine in variable in all the samples closely following the proportions forming duroclarite, clarodurite quantitatively more prominent miosrores and durofusite microlithotypes. The (Histogram-V) . Barakar flora formed the source material Cyclogranisporites for the formation of the Barakar Coal type. Lophotriletes Comparing with the Barakar coals of the .~ierobaeulispora maior Gondwana basins the Barakar coals hfierofoveolatispora H ennellysporites of Damodar Basin (Raniganj, lharia, Giridih, Striatites Bokaro and Karanpura Coalfields) may be Lahirites differentiated by their charaeteris~ ic broad lamination of vitrinite and exinite mace• F aunipollenites Illinites rals. Fairly big tissues and persistent sheets of vitrinites showing well preserved Vesieaspora structures are common. Inertinite group Tiwariasporis of macerals are minor in composition. The In adejtion to above, the following genera are also present but in rare amounts. Barakar coals of (Ta1cher Coal• Leiotriletes field, Ib-River Coalfield), Satrura and Callumispora Godavari basins resemble the present coals I ndotriradites in the nature and composition of coal con• stituents. All these coals are characterised Caheniasaeeites by durite and fusite microlithotypes. Iner• Potonieisporites tinite constituents are conspicuous in the Plieatipollenites composition showing fusinised, semifusinised Stroiersporites and resinoid tissues. Vitrinite constituents Cuneatisporites exhibit intensive fragmentation and cecay Primuspollenites with the result no structural details are Creseentipollenites found. Although re€,10nal variation in pet• Ibisporites The miofloral studies of Wardha Valley rological composition prevails from one coals from various collieries rev-eal that the area to another due to physio-chemical conditions to which the coals have been present miosrore assemblage consists of one characteristic association excepting some subjected, yet the nature of coal forming variations which are considered as the local plants and the petrological characteristics appear to be similar in all these basins, changes of less importance. In general, (Wardha, Godavari, Mahanadi and Sat• the Wardha Valley coals are characterised pura). by the dominance of following miospores. Brevitriletes 36% Scheuringipollenites 25% PALYNOLOGICAL CHA.RACTERISTICS Horriditriletes 12% Pilasporites 14% The palynological study of the coal samples Thus, it is evident that the coal seam from Wardha Valley Coalfield has revealed worked at various places, namely Sasti, rich microflora. Different types and forms Ballarpur, Lalpeth, Rayatwari, Ghugus and 134 135

PERCENTAGE FREQUENCY HISTOGRAM OF MIOSPORE GENEBA IN VARIOUS COLLIERIES OF WARDHA VALLEY COALFIELD

LEIOTRILETES I ~ I CALLUMISPORA

H£NNELLYSPORiTES 1 'II I CYCLOGRANISPOR1TES I I I I ~ LOPHOTRILETES I' BREVITRILETES ... HORRIDITRILETES ,.. .' MICROBACULISPORA ... MICROFOVEOLATISPORA I r-r-rr- INDOTRIRADITES 1

PARASACCITES ~ I I I I I CAHENIASACCITES .~I , POTONIEISPORITES .I PLiCATIPOLLENITES .r I CUNEATISPORITES } PRb\1USPOLLENIT ES I ~ STRIATiTES I ) I I LAHIRITES , r I ~ ~ CRESCENTIPOLLENITES , STROTERSPORITES

STP-\ATOPODOCARPITES I"II; FAUNIPOLLENITES I 1111 I ILLINITES I ~ VESICASPORA SCHEURINGIPOLLENITES ~ lBISPORITES ~ ... ~... T IWARIASPORIS - - GINKGOCYCADOPHYTUS PIlASPORITES ~ I. ~ ~ I. .. II. ~ BOTTOM MIDDLE •TOP BOTTOM MIDDLE TOP BOTTOM MIDDLE TOP BOTTOM MIDDLE TOP .101.

'J 136 THE PALAEOBOTANIST

Majri represent one and the same seam indentical to the E and F assemblages of sporologically. Pench-Kanhan Coalfield, i.e. in the Lower Barakar Stage of the Lower Gondwana MIOFLORISTICS AND STRATIGRAPHY stratigraphy. The Lower Gondwana succession III Wardha Valley consists of three main for• GENERAL DISCUSSION AND mations. The lowest formation, Talchir, CONCLUSIONS comprises boulder beds, green needle shales and sandstones followed by a thick series The petro-palynological investigation of of fluviatile or lacustrine deposits of sand• some Wardha Valley coals has been under• stones, shales and coal seams (Barakar). taken with a view to determine the structure, Barakar is the main coal bearing group. the coal type based on the composition of The sandstones of this group are mostly organic and inorganic components and the whitish grey in colour, loosely packed and stratigraphical value of the c:ispersed fossil feldspathic in nature. These are overlain spores and pollen grains. by the Kamthi beds. It comprises sand• The Archeans and the Pre-Cambriano, stones, shales and clays. The sandstones (Vindhyans) formed the basement for the are mostly red in colour. Coal seams occur deposition of Gondwana seciments which only in Barakar Stage and occupy a very were deposited in shallow fresh water con• small area in comparison to Talchir and ditions in a s'owly sinking basin. Initially Kamthi beds. the coal was deposited in the form of drifted The coal seams in 6 working collieries vegetal matter, which was later buried of Wardha Valley Coalfield contain miospore under the sediments. This process involved assemblage, where Brevitriletes is most various cycles and thereby formed the coal prominent followed by Scheuringipollenites seams. and Horriditriletes. Therefore, this assem• In Wardha Valley Coalfield the Lower blage forms the index spore assemblage Gondwana sediments are mostly developed for the Wardha Valley coals. The miofloral around Chandrapur forming an anticlinal comparison provides sufficient data for the fold. The whole area appears as a trough estimation of the stratigraphic position of between two parallel faults. The Vindh• these coal beds. The present mioflora is yans occupy a large area in Yeotmal and also separable from the Karharbari mioflora Chandrapur districts. The important litho• described by Kar (1973) from North Karan• logical units are limestones and shales. pura Coalfield in the absence of the Talchirs are present in the central part of Karharbari index assemblage dominated by the coalfield. The coal is found in the the varitriletes group of miospores. The Barakar Stage. Kamthis are very widely Lower Barakar assemblages described by distributed and do not contain any coal Bharadwaj and Srivastava (Assemblage A, seam. The rest of the area is occupied by 1969 from and Bisrampur alluvium and soils. Coalfield, Assemblage A, 1970) bear some The coal samples from 5 working areas similarities with the mioflora of Wardha have been palynologically and petro~ogically Valley coals. These assemblages though studied. The miospore assemblage recovered comparable with the present mioflora due to from these coals has been placed in the Lower the dominance of Brevitriletes and Scheur• Barakar Stage. The mioflora consists of ingipollenites in significant amounts, differ Brevitriletes, H orriditriletes, Parasaccites, in the absence of Microbaculispora and Scheuringipollenites Ginkgocycadophytus and Microfoveolatispora. Bharadwaj, Navale and Pilasporites as the dominant genera while Anand-Prakash (1974) have worked out the Cyclogranisporites, Lophotriletes, M icro• Barakar mioflora of Pench-Kanhan Coalfield baculispora, Striatites, Illinites, Vesicaspora, and have described a distinct miofloral zone lbisporites, etc. are less significant in the in the Lower Barakar Stage. The mioflora assemblage. The Histogram-V prepared of Wardha Valley Coalfield compares very on the basis of palynological analysis pro• closely with the younger assemblages vides the index spore assemblage for Wardha E and F of the Pench-Kanhan Coalfield. Valley coals for identification and correla• Thus, the present mioflora occupies a place tion of seams. It is closely comparable PRAKASH & KHARE - PETRO-pALYNOLOGY OF w'ARDHA VALLEY COALS 137 with the assemblages E and F of the matter in the basin. The sraeual increase youngest succession of Pench-Kanhan Coa'• of vitrinite content towards the southern field (Bharadwaj, Navale and Anand• areas suggests that the basin was c'eq'ET Prakash, 1974). in the south and shallow in the north. The petrological study of Wardha Valley Similarly, the grac:ual increase of inertinite coals has revealed the presence of yitrain, content towards north also SUP] orts the durain, c1arain, fusain, megaspores, micro• above rossibility. This might ha,-e been spores and resin bodies as the main organic the reason for more of fusinisation of the components of the coals. Durain is the peat material caused by the sha"ow water most dominant coal lithotype in almost all conditions in the northern rarts of the basin. the areas of the coalfield. Clarain and Contrary to this, in the south the deerer fusain are the next important lithotypes. water conditions eluring the formation of Inertinite constituents are characteristic of the peat has created fayourab'e conditions the coal type. They occur in various ce• for the jellification of the peat material gradational stages of fusinised tissues and resuli ing into the format ion of vitrain. resin bodies apart from completely disin• Sedimentary matter is wiee'y distributed tegrated organic matter (macrinite and in these coals which show high ash content. micrinite). The vitrinised tissues occur as The thickness of the coal scam is also more very thin layers. Vitrinite constituents towarc's southern part of the coalfield. exhibit intensive fragmentat ion. No struc• There'ore, the ma;or coal reserves in the tural details are found in vitrain bands. Ware'r:a ,-alley are present in the south The above diagnostic features of the eastern rart of the coalfield. The conc:i• Wardha coals are typical of the Barakar tions of coal formation were probably better coal type (Pareek, 1967; Navale, 1971, 72) towards the south and it may be suggested recognised in Mahanadi (Talcher and Ib-Ri ver that this part of the basin may provic'e more coalfields), Godavari, Satpura and Wardha promising area for rresent and future coal basins. The nature and comrosition of explorations. these coals are broadly comparable with The petro'of,ical comrosition of coal sean-s each other (based on their genesis and for• has particular bearing on coal preraration, mation). It may, therefore, be reasonable identification and correJat ion of coal seams. to presume that the conditions of vegetal Therefore, stanc1ard analysis based on broad depositions and coal formation were by and groups of imrort ant coal constituents of large similar in Mahanadi, Pench-Kanhan, Wardha Valley coals has been made for Wardha and Godavari basins. assessment and comrarison purroses (Histo• Regional variation in pet ro10&ical com• gram-I, II). The analysis reveals high position of coals from basin to basin prevails prorortion of "inert" constituents and sec"i• due to local factors (physio-chemical con• mentary matter in the northern rart of the ditions of the basins). In the present coals coalfield. These entities make the problem the petrological composition has shown a of coal preparation for utilization more characteristic pattern of changes in the difficuit. Nevertheless an optimum rroc]uct various organic microconstituents. A would probably emerge out by selective distinct variation in the microlithotyre sampling and efficient "cleaning process", and maceral comrosition of the coals has been found" between the nort hem and southern parts of the coalfield. The coals ACKNOWLEDGEMENTS of northern side (Majri & Ghugus) are rich in inertinite constituents, whereas, the coals We are thankful to Drs D. C. Bharaowai of southern side (Ballarpur) are rich in and G. K. B. Navale for their kind guidanc~ clarain contents. 'A transitional stage is throughout the work. One of the authors found in the coals of the area present between (RC.K.) - thanks the authorities of the them which shows intermediate petrological Birbal Salmi Institute of Pa'aeobotany for characters. Based on the present study 3 the facilities rroviced to him for carrying coal types have been suggested, i.e. coal out the research work and Dr. R M. Singh type-A, Band C. of Geology Department, Banaras Hindu The petrological behaviour of these coals University for having suggested the rroblem suggests variable coalification of the vegetal and continued encourage"mcnt. 118 THE PALAEOBOTANIST REFERENCES

AGASHE. S. N. & CHITNIS. S. R. (1969). Palyno• GHOSH.T. K. (1962). Microscopic study of Tandur logical investigation of coal seams of Lower coal, Godavari Valley, . fl. Gond wana strata from Maharashtra, India. geol. Min. metall. Soc. India. 34 (4): 169• Palynol. Bull. 6: 6-8. 173. IDEM (1972). Palaeopalynology of a Permian coal HUGHES. T. W. H. (1877). The Wardha Valley seam from the Hindustan Lalpeth Collie I y. Coalfield. M em. geol. Surv. India. 13 (1): 1• Chandrapur dist. Maharashtra. India. Pro• 154. ceedings of the seminar on Palaeopalynology and KAR. R. K. (l973). Palynological delimilation of Indian stratigraphy: 22-29. 1971- the Lower Gond wanas in the North Karanpura BHARADWA]. D. C. (1962). The miospore genera sedimentary basin. India. Palaeobotanist. 20(3): in the coals of Raliganj Stage (Upper Permian). 300-317. India. Palaeobotanist. 9 (1 & 2): 68-106. NAVALE.G. K. B. (1963). Palynological studies of BHARADWA], D. C. & SALU]HA. S. K. (1964). Merlabach coals in conjunction with Potrographic Sporological study of seam VIII-Ra'liganj structure. Ibid. 12 (3): 232-249. Coalfield. Bihar (India). Part I - Description IDEM (1971). Some aspects of the physical consti• of Sporae dispersae. Ibid. 12 (2): 181-215. tution of certain Lower Gondwana coal seams BHARADWA], D. C. & SRIVASTAVA.S. C. (1969). of India. Economic geology. 66: 632-640. Correlation of coal seams in Chirimiri Coalfield, IDEM (1972). Petro-palynology of Lower Gond• M.P. on the basis of Sporae dispersae. Ibid. wana r1.urain coals. Proceedings of the Seminar 17 (l): 36-42. on Palaeopalynology and Indian Stratigraphy: IDEM (1970). Sporological correlation of coal 109-119, 1971- seams in Bisrampur Coalfield, M.P.. India. NAVALE, G. K. B. & SRIVASTAVA,S. C. (1967). Ibid. 18 (l): 87-94. Tho natme of coal and some recent methods of BHARADWA], D. c., NAVALE, G. K. B. & ANAND• coal preparation for microscopic studies. Metals PRAKASH(1974). Palynostiatigraphy and petro• Miner. 6 (6): 3-9. logy of Lower Gondwana coals in Pench• OLDHAM. T. (l869). In Fox (l934). Rec. geol. Kanhan Coalfield, Satpura Gondwana Basin. Surv. India. 2: 94. M.P .• India. Geophytology. 4 (l): 7-24. PAREEK, H. S. (1969). Some observations on the BLANFORD. W. T. (1867). In Fox (l934). Rec. lithology of coal bearing bEds and the p.atufC geol. Surv. India. 1: 23. of coal of the major Gondwana basins of India. Fox, C. S. (1934). The Lower Gondwana coalfiolds Gondwana stratigraphy. I.U.G.S. Symposium. of Lelia. Mem. geot. Surv. India. 59: 1-386. Buenos Aires. 1967: 883-903.