Observations on the Post-Triassic Gondwana Sequence of India

OBSERVATIONS ON THE POST-TRIASSIC GONDWANA SEQUENCE OF INDIA

S. C. SHAH, GOPAL SINGH & M. N. GURURAJA Geological Survey of India

ABSTRACT istic lithology, vertebrate remains and The post-Triassic Gondwana sequence of India rarity of plant fossils. The overlying Juras• is one of the well developed in the Gondwanaland. sic-Cretaceous sequence of rocks have a Its flora has been helpfuLin establishing the strati• rich and distinct floral assemblage commonly graphy of thick continentaL deposits of this period. designated as the Ptilophyllnm flora and The sedimentary sequences containing this flora their stratigraphy is mainly based on floral are developed in widely scattered Gondwana basins evidences. of the Peninsula namely, the RajmahaL hills, Bihar; Satpura and South Rewa Gondwana basins, Madhya Recent studies have indicated that the Pradesh; Pranhita-Godavari basin of Andhra sequence proposed earlier for these J urassic• Pradesh and Maharshtra; East Coast and Gujarat. Cretaceous deposits in India is rather con• In the light of the recent studies the stratigraphic position of the floral assemblages has been reviewed fusing and as such the dating done on floral in the paper. evidences has been a matter of great dispute. The flora is known to continue without any Palaeo botanists like Oldham & Morris, Feist• break throughout the Jurassic and the Lower mantel, Sahni, Jacob, Bose and others Cretaceous. The lower age limit of the floral sequence commences in Lower Jurassic and as such assigned a Jurassic age to these deposits, the views expressed by Spath (1933) and Arkell whereas Spath, Arkell and many others on (1956) suggesting the absence of entire Jurassic the basis of faunal evidences suggested a continental deposits of India is no more tenable. The flora associated with Lower Cretaceous Lower Cretaceous age to them. marine fauna on the East Coast indicates the range Here, the post-Triassic sequences are of the Jurassic floral elements into the Lower being dealt as developed in different basins Cretaceous rather than suggesting any palaeonto• and the problem of age of this sequence is logical contradiction between the faunal and floral being discussed in the light of geological evidences as thought earlier. history and recent palaeontological evidences.

INTRODUCTION Pranhita-Godavari Basin

The post-Triassic Gondwana sequenc2 111 of Indiapost-TriassicembodyingGondwanaa rich sequenceflora is this basin is as follow..>: THEone of the best of its kind developed in the Southern Continent. In Australia, King Kutty this sequence is represented by a great (1881) (1969) development of continental deposits of Jurassic-Cretaceous age, while in Africa Post Chikiala Gangapur formation! Triassic Kota ? Chikiala and South America, this was a period of Gondwanas Kota formation enormous volcanic activity, resulting in Dharmaram forma• limited deposition of continental deposits. tion In India, the post-Triassic Gondwana Up. Triassic Maleri Maleri formation sequence is developed in widely scattered basins: in Rajmahal hills, Bihar; South King (1881) made collection of fossils Rewa - Satpura basins, Madhya Pradesh; including plants from Kotas only and Pranhita - Godavari basin, Andhra Pradesh Chikialas were devoid of fossils. The plant and Maharashtra; Jaisalmer, Rajasthan; fossils were studied by Feistmantel (1877): Cutch, Kathiawar and Himmatnagar, Guja• rat; and along the East Coast in Orissa, Localities Fossils Andhra Pradesh and Tamil Nadu. In these basins, the Triassics, wherever they are Annaram Elatoclad~~s (Palissya) , seen, are distinguished by their character- Chirolepis 221 221 THE PALAEOBOTANist

Localities Fossils CHART 1 - DISTRIBUTION OF POST TRIASSIC GONDWANA FLORA FROM Naogaon T acnioj>teris (A ngiojJt;ri- PRANHITA-GODAVARI BASIN dimn) , Ptilophyllttm awtifolimn NAME OF SPECIES KOTA FM. GANGAPUR Chirakunt Cycadites sp., (=? Elatocladrts (Palissya) CHIKIALA jabalpttrensis FM.) Between the Pagiophyllwn percgrilZ{t'}'It, Equisetites sp. X X villages Maor A raftcarit:;s ettichcnsis Gleichenites gleichenoides X G. rewahens is and Balhanpur X G. sp. X Coniopteris hymeno- x Later on, Rao & Shah (1959a), listed phylloides additional plant fossils from Kota-Maleri Coniopteris sp. X formation and Bose (1966) observed that Cladophlebis indica X X there is an admixture of flora in the assem• Sphenopteris sp. X Hausmannia sp. X X blage given. To remove this confusion Ptilophyllum acutifolium X (Rao & Dutt, 1955-56 and Rao & Shah, Otozamites sp. X X 1957-60, the unpublished reports in the Dictyozamites sp. X Taeniopteris spathulata X Geological Survey of India) the collection is ? Nilssonia sp. X being studied and the results of the preli• ? Cycadites sp. X minary study are summarized here. Elatocladus plana X The plant fossils as mentioned from E. conferta X E. rjabalpurensis X X Kota-Male! i formation belong to Kota E. ? tenerrima X , stage' of King. The list of fossils is given Elatocladus sp. X X in Chart 1. Brachyphyllum sp. X It is observed that there are clearly three Pagiophyllum peregrinum X X Pagiophyllum sp. X and not two zones, as inferred earlier by Torreyites d. constrictus x X Rao and Shah (1959a), namely: A raucarites cutchensis x X Zone C - Fossils from Gangapur Sandstone Araucarites sp. X and Chikiala Sandstone Pagiophyllum peregrinum X Pagiophyllum sp. X Zone B - Fossils from Kota formation (as Podozamites sp. X defined by Kutty, 1969) Zone A - Fossils from Acheli and Ganaram Zone A is characterized by few species of Glossopteris, Thinnfeldia hughesi, Dicroidimn Zone B has plant fossils which are repre• lwghesi, Dicroiditlm odontopteroides, Noegge• sented by about a dozen genera. They are rathiopsis cj. httghesi etc. This assemblage mostly found in limestone. The fossil is from the lower part of the Kota formation forms are fragmentary and the assemblage which is underlain by Maleri formation of consists of: Equisetiies sp. Sphenopteris sp., Carnic-Noric age. Similar floral assemblage Hausmannia sp., Coniopteris hymenophyl• has also been known from the Parsora for• loides, Coniopteris sp., Otozamites sp., Pagio• mation which is overlying the Tiki forma• phyllum cf. peregrium, Pagiophyllum sp., tion (Shah et al 1970; Dutt, P. K. pers. Araucarites cftichensis, Elatocladus sp. comm). This assemblage can easily be The beds containing this flora overlie the assigned as a part of Dicroidium flora which lower Kotas yielding the Rhaetic flora. is prevalent in the Triassic period. Since Associated with this flora arefishes, sauro• the beds yielding the flora similar to that pod dinosaur and ccocodilian remains which from Parsora formation is overlying the are considered as Lower Jurassic (? early formation of Carnic-Noric age, it can be middle Jurassic). Hence this flora is of assigned to Rhaetic age. upper Liassic age or in other words the The lower Kotas have elsewhere been genera represented in this flora were thriv• differentiated as Dharmaram formation ing during this period. (Kutty 1969) and this has not yielded any Zone C has the assemblages of plant plant fossils. But it has been assigned fossils which belongs to the Gangapur for• Rhaetic on the basis of vertebrate mation, Chikiala sandstone and some loca• fossils. lities of Kota ' stage' of King. Gangapur SHAH el at.-OBSERVATIONS ON THE POST-TRIASS1C GONDWANA SEQUENCE 22~

POST- TRIASSIC GONDWANAS IN INDIA

Scole km 320 160 0 l\20km I ,

28 Rajasthan Upper Narmada Volley ROJrnllhol ReqlOn 20 I

Satpuro/1Sansa- Pars oro

\ ,<11),---L",' ------;) -- _ .. ..' , -~ / '<'b; ,.•. ~ ..• ",,, --r Lower Narmada Valle)' Cutch

Wardha '" Cutlack Godavan Volley Baroda

EfloreO"gOI'~ ~\\ West Coast ~EQstCoost

~:~,:,::7Rornnod

formation was considered by King (1881) developed in the western part of the basin as the basal member of the Kota 'stage' and is provisionally considered as equivalent (of King) but Kutty (1969) separated them to Chikiala Sandstone which is developed from the Kota 'stage' and considercd in eastern part of the basin. Kutty had not them a~ overlying the Kota formation with recorded any fossils but observed that the an unconformity. Gangapur formation is flora of Anaram belonged only to Kota 224 tHE pALAE0I30TAN1st

formation and flora from other localities as Laterite (Level above given by King belonged to Gangapur for• sea-level mation. i1tfeet) Further, Chikiala Sandstone was con· sidered to be unfossiliferous till Rao & Shah VI Trap 625 (1959b) recorded some fossils. The fossils Sandstone 600 from some localities given by Rao and Dutt V Trap 530 (1955-56, unpublished report) seemed to Ferruginous, friable belong to Gangapur formation. The assem• sandstone 500 blage, if taken as one unit, is characterized VI Trap 425 by the predominance of conifers. This is Chert beds 420 younger than Lower Jurassic and its exact III Trap 320 age or the upper limit on the basis of consi• Oolitic iron-ore 310 derations other than plants can not be II Trap 250 inferred. This floral assemblage clearly Plastic, white, resembles the flora from Nipania of Ra]• iron-stained 210 mahal' region and also to the flora frGm I Trap 210 Raghavapuram Mudstone, Vemavaram Shales cnd Sriperumbudur beds from cast The number of flows exceeds 15 in number coast and EI1U] fOlmation of west coast. and the total thickness of flows is around 1500 feet or so. The individual flow may vary in thickness from 50 to 300 feet. The Rajmahal Region older flows are represented in the eastern half of the Rajmahal hills while in the The general sequence of the pest-Triassic western half higher flows are recorded along Gondwana strata in this area is as follows: the fringe of the plateau where th0 height Alluvium rises from 750'·1000'. Th~ intertrappeans vary in thickness from 5 to 25 feet but the rRajmahal Traps average thickness is about 5 feet. The Gondwanas Series) earlier three intertrappeans are profusely Post-Triassic l(WithDubrajpurintertrappeanbeds Ra]mahal fossiliferous. They have yielded the richest Damudas flora of the world. The name R;j,jmahal The generalized sections of the Rajmahal plant beds was restricted to first three inter• volcanics and the associated intertrappeans, trappeans. However, the flora from ipania constructed from different sections (as given comes from the 4th and 5th intertrappeans by Ramaswamy 1952-53) is as follows: beds. The flora (Chart II) from these areas cJ.n VII TrapTrapTrapFineTrapLateritegrained Trap 10501200(Level950142011001000140017001250700800above be grouped in two zones: VIIIXIIIXIIXIIXX &BluishWhite-pink,RedFerruginousClay clay,sandstoneclaysandstonebedfriable~andstonewith Ferruginousinsea-levelsandstoneporcellanitesfossilXIVfeet) woodsandstone 725 Zone - A: Flora from upper part of Dub• rajpurs and the intertrappean beds (1-3 from below) associated with Lava flows. This is cha• racterized by broad leaved cycads. Zone - E: Flora from Nipania, i.e. from the 4th intertrappean associated with 4th and 5th lava flows. Earlier also, this flora was con- ·sidered as younger by Vishnu• Mittre (1957). This flora is cha• racterized by its richness in pteridophytes and conifers. Associated with Zone A, are fish scales and a new genus of fish and some unionids. Except for the plant remains which are of course profusely known, there is no other criterion of fixing the age of these beds. ""- M.N.D. lanceolatahalleisantalensisXxX NAMEBEDSBEDSP.Al'aucaritcsA.T.ElatocladusN.E.I.C.OFmantelimahalensismahalel1sisraoilatisulcatumaraucaroidesmorrisianacrassinerviscnsisovatamcclendiibindrabunensistenerimasahniibindrabundcnsisSPECIES cutchensissp.PLANT BEDS PARTSUPPER OF ha1'1'isianaindicaSHAHXPagiophyllumSitholeyaPterophyllumB.NipaniogruhaTaeniopterisD.T.N.peregrinumexpansumflorinimusaefoliaspathulataexpansumprincepsbaghjorensis(2)etNIPANIA(2)raj·Xal.-OBSERVATIONSrajmahalensislataMicrotaeniopterisPterophyll1t1nBeaniopsisBrachyphyllumMehtaiaIndophyllumC.E.var.CycaditesElatocladusM.I.A.MasculostrobusN.ConiferocaulonNilssoniasp.RA]MAHALd.granthiaRA]MAHALnipanicaamarjolenseconfertanipaniensiscurvifoliaXnipaniensisindicumXxXxXrajmahalensisrajmahalensissp.rajmahalensisplanasa}l1Iii-distansON..feist-raj-----.(1)lataTHEX~X POST-TRIASSICB.N.DUBRA]PUR)Nilssonia(INCLUDINGfissamamillarespiroxylon(Continued)morrisianaGONDWANA 225SEQUENCE P.BuclilandiaTV. incisum indicaToditesS.T.C.R.B.W.IV.TV.mahalensissalmiikhail'abanensissahniisrivastaviicll1lnahhalensisnirmalisahniisa}l11iisewardianasantalensisindicus PLANT BEDS PART OF P. PcntoxylonDityopstelopterisThinnfeldiaSagenoptel'isNipniophyllumP.D.Micyophylloptel'isPtilophyllumtetra:"yloidesNipanioxylonOtozamitesSalmioxylonnipanicafasciosteloidesamarjolensebcngalensissahniisp.bhambhaniiLycopodiumLycoxylonCladophlebisMConioptcl'isTinpahariaSplle1lOpterisR.ThinnfeldiaPachypterisacutifoliu11lS.GlcicheniaSphenopterisrajmahalensisD.CladophcibisWilliamsoniag1fptaiphylloidesrajmahalensearattiopsiraoihislopiJacobirajmahalensissp. indiclImgleichenoidessp.shymeno-sinuosaindicagmcilislobatasp.macrocarparaj-sp.(INCLUDING SolenostelopterisS.DanaeopsisDUBRA]PUR)WilliamsoniaRhizomopterisandrewsiiUPPER Dictyozmitesrajmahalensismicropschaksu faleatus RAJMAHAL HILLS, BIHAR (1) Eqltisetitcs rajmahalensis NAME OF SPECIES CHART 2-DISTRIBUTION OF POST-TRIASSIC GONDWANA FLORA FROM 226 THE PALAEOBOTANIST

Crookshank (1936) divided the Jabalpur CHART 2 - DISTRIBUTION OF POST• into Chaugan and Jabalpur based on floral TRIASSIC GONDWANA FLORA FROM RAJMAHAL HILLS, BIHAR - Continued evidences only. Jacob (1951) and Agrawal (1963) opined that the two subdivisions NAME OF SPECIES RA]MAHAL NIPANIA should be merged into one. Shah (1966) PLANT BEDS BEDS had indicated that there are three definite (INCLUDING UPPER PART OF subdivisions of Jabalpurs and the fourth is DUBRA]PUR) definitely developed in South Rewa though may doubtfully be present in the western (1) (2) part. Recent stratigraphical and palaeo• M. podocarpoides x botanical studied by Gopal Singh (1967) M asculostrobus sp. X have established three subdivisions as shown Nipaniostrobus sahnii X above. The distJibution of the flora in N. pagiophylloides X N. aciculipholia X these three zones as worked out by him is Ginkgoites rajmahalensis X given in the Chart III. / X O(nkgoitesBa¥ra sp. sp. X Dadoxylon jurassicum X CHART 3 - DISTRIBUTION OF POST• D. rajmahalense X TRIASSIC GONDWANA FLORA FROM M esembrioxylon indicum X SATPURA AND SOUTH REWA BASINS, Cycadospermum indicum X MADHYA PRADESH Cycadolepis indica X Rajmahalia paradoxa X (1 = Chaugan Formation, 2= J abalpur Formation, 3 =Bansa Formation) NAMEX(3)(2)X OF..SPECIESX (1) XXX X X~ G. gleichenoidesIt CycadopterisPtilophyllumHanu.smanni,lH.C.SphenopterisConiopterisOnychiopsisRhizomopterisWeichhasacutifoli'umkathiawarensisindicaauriculatamajuscrookshankibuchiiseliabeenSphenopterisS.CladophlebisCla.lophelebislongipennislobifoliaphylloidesreticulatahymeno-d.psilotoidespulcherrimapointedsp.dichotomarajmahalensisPachypterisSphenopterisOnychiopsis?AdiantitesrajmahalenaisThinnfeldiacf.salicifoliahughesid.outindicusbyindicusindic~tsparadoxusd.sp.oneargutaof us GleichenitesSagenopterisPhlebopterisCladophlebisrewahensissp.sp.cf. (Shah)Equisetitesthat the sp.upper biozone of Dubrajpur(Continued) formed as Dubrajpur equivalent to some portion of first four volcanic flows and the associated intertrappeans. The demarca• tion between Dubrajpurs and Barakars (lower beds Dubrajpurs are also shown to be Barakars; Ramaswamy & Shrivastava, 1952, Sah & Maheshwari, 1969) is not well defined, the lithological characters of the two units being very similar. South Rewa - Satpura Gondwana Basin The post-Triassic Gondwana formations are developed along the northern fringes of Satpura and occur as four isolated patches which are developed near Seoni-Malwa, Hoshangabad district; Narsinghpur, Nar• singhpur district; Jabalprir, Jabalpur dis• trict and Chandia, Shahdol district, all in Madhya Pradesh. These patches stretch for about 600 km. no th-southward. The stratigraphic succession of this basin is as follows as worked by the authors: Satpura South Rewa Bansa formation Post• Jabalpur Triassic formation Gondwanas Chaugan formation Rhaetic Parsora forma• tion Up. Triassic Denwa for• Tiki formation mation SHAH et al. - OBSERVATIONS OF THE POST-TRIASSIC GONDWANA SEQUENCE 227

Camic-Noric age' while in South Rewa those CHART 3 - DISTRIBUTION OF PO;ST• TRIASSIC GONDWANA FLORA FROM are underlain by the Parsora form1.tion of SATPURA AND SOUTH REWA BASINS, Rhaetic age. MADHYA PRADESH-Contimled

NAME OF SPECIES (1) (2) (3) Western India P. distans x x The pest-Triassic Gondwanas show a P. cutchense X X P. jabalpwrensis X wide development as isolated patches in P. instilacallum X Rajasthan and Gujarat and Lower Narmada P. gladiatus X valley. Dictyozamites indica X D. falcatus X Nilssonia fissa X Jaisa1mer Area N. princeps X X Cycadites rajmahalensis X Cycadites ? graminius X The post-Triassic Gondwana sequence is Carpolithes sp. X represented by Lathi and Parihar sandstone Nilssonia sp. X in Jaisalmcr area of Rajasthan. Taeniopteris crassinervis X At the base of thick marine sedimentaries Taeniopteris vittata X Taeniopteris sp. X of Jurassic age, a continental facies repre• Bucklandia indica X sented hy Lathi formation is developed Williamsonia indica X which is considered as Lower to Middle W. microps X Jurassic. They are 60 m. thick and comp• Williamsonia sp. X Ginllgoites lobata X X rise white or red and variegated sandstone G. feistmanteli X containing a few bands of limestone. Baiera d. brauniana X Though they have not yielded any mega• Desmiophyllum indicum X X X Elatocladus tenerrimus X fossil yet the miofloral evidences suggest E. plana X X a closer affinity with Gondwana beyond E. conferta X X X doubt. The mioflora as known after the E. jabalpurensis X X X werk of Srivastava (1966) and Lukose (1971) Elatocladus sp. X Brachyphyllum X X X suggest a Lower Jurassic age. They are mamillare overlain by Jaisalmer strata of Middle B. rhombicum X X X Jurassic age. B. feistmanteli X Higher in the sequence is Parihar sand• B. expansllm X stone of continental nature which is 800 m B. expansum var. indica X Pagiophyllum X X thick. These are unfossiliferous. Because divaricatum of their stratigraphic position, they are P. peregrinum X X X considered of Lower Cretaceous age as they P. cf. peregrimtm X X Coniferocaulon X are underlain by the upper Jurassic and rajmahalensis overlain Aptian, marine horizon, i.e. Abur Araucarites cutchensis X X X beds. A. chandiansis X A. striatus X A. macropetYHs X X Ahmednagar Area A. oldhami X A. latifoliu s X Strobilites sewardi X A fresh-water sequence of strata nearly Conites d. Strobilites X 60 m thick is developed near Ahmednagar. anceps This is called as Himatnagar or Ahmednagar hoeniocopsis X Czekanowskia sp. X sandstone. This has yielded a Gondwana Pityophyllllm sp. X flora assemblage comparable to Than plant beds of Kathiawar. The assemblage is shown in the distribution chart IV and are thus considered of Lower Cretaceous age. Except for evidences furnished by the H. rSandstone with shale and plants, there are no other forms to suggest lmatnagar -< lithomerge Boulder the exact age of these zones. In Satpura sandstone L Conglomerate region, the Chaugan formation is underlain conformably by Bagra-Denwa formation of Erinpura Granite 228 THE PALAEOBOTANIST

CHART 4 - DISTRIBUTION OF POST-TRIASSIC GONDWANA FLORA IN WESTERN INDIA SANDSTONE NAME OF THE TAXA BHUj THAN HIMATNAGAR(4)(3) NIMARLOWER BEDS BEDS STONESAND- (2)

(1)

Equiseti/es rajmahalense x 1soetites indicus X 1. serratifolius X Phlebopteris sp. x Matonidium X X X Gleichenites sp. X Onychiopsis psilotoides X X Weichselia reticula/a X Cladophlebis indicus' X C. d. longipennis x C. kathiawarensis X X Pacopteris tenera X Pachypteris indicus X Sphenopteris specifica X Sphenopteris spp. X x x Otozamites imbricatus X O. bengalensis X Nilssonia tramballensis X Taeniop/eris vitlata X T. densinervis X X Ptilophyllum cutchense X x X P. acutifolium X X Williamsonia blanfordi X Brachyphyllum expansum X Pagiophyllum divarisa/um X A raucari/es cutchensis X A. macropterlts X Ela/ocladus tenerrimalls X Trambaus trilobata X A ctinopteris sp. X Lorumformophyllum serratum X

Kathiawar Area Kutch Area

In Kathiawar nearly 600 m thick strata Upper Gondwana sequence is developed of fresh-water dr-posits nam,~ly Dhrangadhra in Kutch which is cel.lIedas Bhuj Formation. sandstone is developed. The sequenc·>deve• The stratigraphic position .of which as loped is as follows: follows: Wadhwan sandstone Bhuj beds Post Aptian (? Albian) Dh dl rUpper - stoneFerruginousand conglo-sand- Ukra beds Aptian .•ranga 11'a~ m~rates Barren sandstone Lower - Pale sandstone wIth Trigonia beds Valanginian s'l.ndstolle carbonaceous shale Umia beds Barren sandstone l . Ammonite beds Upper Tithonian and coal seam Barren sandstone base? Katrol Portlandian The upper part of the Lower Dhrangadhra sandstone (Than beds) has yielded floral Plant bearing horizons which are now assemblage consisting Ptilophyll2t'fn cutchense, called Bhuj beds are supposed to be post Cladophlebis indictts, C. kathiawarensis, Aptian and have yielded a rich assemblage M atonidimn indicmll, Onychiopsis psilotoides as shown in the distribution charts. In and Weichselia reticttlata which suggest a field, Bhuj formation are apparently seen lower Cretaceous age. overlying the Katrol but are supposed to be SHAH et al.- OBSERVATIONS ON THE POST-TRIASSIC GODWANA SEQUENCE 229

post Aptian on structur,11 basis by Rajnath Golapilli sandstone - An entirely conti• (1932). nental deposit of about 130 m. thick, orange to brown sandstones, grits and conglom~rates EAST COAST is developed around the village Golapilli. The pala~obotanical knowledge of these A number of isolated patches of post• S1.ndstones are due to Feistmantel (1877), Triassic Gondwana sediments are developed Sarma (1957, 1958) and B:tksi (1964). The along the East Coast of India from north plant fossils of these beds are given in the to south. They are represented chiefly by Chart (No. V). Based on flClra they are sandstone in the region of Mahanadi delta considered equivalent to Rl.jm1.hals. near Cuttack, Orissa; Golapilli sandstone, Raghavapmam shal3s - Representing the Raghavapuram shales and Tirupati sand• middle division of the sequence of rocks in stones in the Ellore region; Budavada the area they consist of 50 m. thick white sandstones, Vamavaran shales, and Pavalur and pink, bluish shales or mudstones. sandstone in the Ongole region; between They contain both fresh water plants and Ongole and Guntur, Andhra Pradesh, Sri• marine invertebrates such as ammonites, perumbudur and Satyavedn krmatiom in bivalves and foraminifers. the vicinity of Madras; the Utatur plant The flClra (Chart V) has been desct"ibed beds in Trichinopoly district and the m')st by Feistm1.ntel (1879), S3.rnn & Rlm~sam southerly patch of Sivaganga beds in R:l.Iu• (1962) and B1.ksi (1967). nad district of Tamil Nadu. The foraminifers described are by S).stri These fossiliferous scdim ~ntary pJ.tches & others (1963), Bhalh (1965, 1969) Blbhi represent an admixture of continental and (1968). They suggest a low~r Cretac~ous marine conditions of dep:Jsition, refl'ctcd (? NeocJmian age) to these shales. also in their fossil c:mtcnt. They have Timpati sandstones - The uppermJst proved to be a critical a'"ea of study from division of the sequence of rocks in the area, the point of their stratigraphy ann palaeonto• they occur at Tirupati hill, 37 km. north• logy. east of Ellore. They c0nsist of red to brown sandstones and conglomerates. The m1.rine Cuttack Area invertebrates contained in them have indi• cated a lower Cretaceous (Aptian) age. The post-Triassic sediments of purely Coniferous woods are also recorded from fresh-water origin arc found at Athgarh near these beds. Cuttack. The successions of rocks in this area is as follows: Alluvium The general sequence of rocks in this area Gondwana Athgarh sandstone is as follows: Post-Triassic { Post-Triassic ? Metamorphics Gondwanas The plant fossils from these sandstones ~rPavalurVemwaramsandstoneshale LBl.ldavada sandstone (Chart V) have been described by Feist• mantel (1879), Adyalkar & Rao (1968), Gneisses Jain (1968) and Pandya & Patra (1968). Bftdavada sandstolj,e - This is developed Based on the floral similarity they are con• around the village Budavad1. and c0nsists sideled of the same age as R

Vemavaram shales - These are too conti• beds are too fragmentary. An indetermi• nental and marine in nature. The rocks nate species of Dictyozamites sp. is known. consist of hard and soft white and grey As these beds overlie the Sriperumbudur shales containing both mega and micro beds (probably homotaxial to Raghavapu• plant fossils and marine invertebrates such ram shales in Ellore area) they are consi• as ammonites. Fossil fishes are also known. dered equivalent to Tirupati Sandstone of The flora (Chart V) is known after the work Ellore area. of Feistmantel (1879), Suryanarayana (1954), Ramanujam (1957), Kar & Sah (1969), Jain (1968) and Bose & Jain (1967). Trichinopoly Area On mega floral evidences they were known to be Kota (Middle Jurassic) in age. The The post-Triassic Gondwana succession microflora (Kar and Sah 1969) indicates in this area is as follows: an upper Jurassic age. However on the Cretacrous Utatur group faunal evidences afforded by ammonites Post-Triassic Utatur Plant beds and fish remains, thev are considered to be Gondwanas ? Conglomerates (at of lower Cretaceous (upper Neocomian) age. places) PavalM sandstone - They are developed Mctamorphics around Pavalur. Lithologically they are Utat~tr plant beds - These are purely essentially made up of sandstcnes. No continental deposits and are found near fossils in situ are known from this horizon. Utatur in Trlchinopoly district consisting of Since they rest on the Vemavaram shales white to reddish sandstone at tim.rs conglo• they are considered equivalent to Tirupati meratic which alternate with brcls of shales sandstones. or pass into grey and white clays. The plant fossils (Chart V) are fragmentary and are known through the work of Feist• Madras Area mantel (1879) and Chowdhury (1958). Blanford (1962) had remarked, despite The sequence of rocks in this area IS as absence of marine fossils "they appeared follows: both on stratigraphical and lithological Post-Triassic grounds to be not vcry widely separated in Gondwanas {SatyaveduSriperumbudurbeds beds time from Cretaceous rocks immediately overlying them". Chowdhury (1958) pend• Metamorphics ing detail work, suggests these "plant beds There are a number of small patches of are homotaxial with the Jabalpur-Tirupati upper Gondwana rocks around Madras of group". which only those of Sriperumbudur and Satyavedu are well known. Ramnad Area SriperumbudM teds - They are developed about 15 km. west-southwest of Madras The post-Triassic Gondwana sediments and are primarily argillaceous consisting of of this area show the following sequence: shales. The beds have yielded both fresh Recent Alluvium & water plants and marine invertebrates inclu• Laterite ding ammonites and arenaceous foraminifers. The flora (Chart V) of these shales are known post-TriassicGondwanas {Sivaganga beds through the work of Feistmantel (1879) - Unconform.ity & Suryanarayana (1953, 1955). Based on flora they were considered Kota Archa<:an rocks in age i.e. Middle Jurassic. However ammo• Sivaganga beds - These are purely conti• nites and arenaceous foraminifers suggest nental deposits and are developed around a Lower Cretaceous (Murthy & Sastry 1962) Sivaganga, made up of conglomerates, age to these shales. sandstones, grits and shales. Satyavedu beds - Developed in the area Gopal, Jacob & Jacob (1957) described of Satyavedu hills northwest of Madras, these beds in detail. The plant fossils these beds are mainly arenaceous, consisting (Chart V) and undetermined lamellibranchs of purple or pink ferruginous sandstones in them suggest a Kota (middle Jurassic) and conglomerates. Plant fossils from these age to these beds. '1

Pages 233-234 TABLE 1 POST-TRIASSIC GONDWANA SUCCESSION IN INDIA ,~ ~ BIOSTRATIGRAPHIC UNITS I -L--IT-H-O-S-T-R'-A-T-IG-R-A-P-H-I-C- . ------. U",,,

I I ' .·l I I Uppr Narmada Val!ey West Coast' East Coast I'! I ------Standard Scale Assemblage Zone I Rajmahal Region vVardha Godavari Satpura I Bansa Lower Narmada Rajasthan Cutch Region Baroda Kathiawar Cuttack ! Ellore Ongole i Madras Trichinopoly Ramnad Valley Parsora Valley I t 1--·---, - .------Lower Cretaceous 'I vVeichselia-Ony- Unfossiliferolls Inter- Bansa beds ? Lower Nimar Parihar 1 Bhuj formation I Songir Sandstone/ Tirupati Sandstone Pavalur Sand- Satyavedu beds I chiopsis Zone trappeans associated beds/Katkot Sandstone (Including Narha I I-limatnagar Sst./ Raghavapuram stones/Vema.- Sriperumbudur with flows (Nos,5-11) I Sandstone beds) \Vadhwan Sst,/ Shales varam Shales beds I I of Hajrnahal Vol- 'Up,-i'l'Iid. Dhrangadhra Budavada Sst. I canics Sandstone (including I , oS Than beds) I .~-

c; I I ;~ Upper Jurassic : -'pagiOPhYllum- Nipania intertrappean I ' Gangapur for-I Jabalpur ------I . Lowermost Dhrang- . -'-- .---- -? Sivganga j; = Brachyphyllum beds between flows mation/Chikiala beds dina Sst. beds ,T, = Zone (Nos. 4-5) of Raj- formation I ~ t Volcanics I

.£ -- -- ~ Lower Jurassic 0:; Dictyozamitcs- Raj mahal plant beds Kota formation Chaugan Lathi Al!hgarh ? Golapili Sst. ? Utatur . " !,terophyl!um as Intertrappcans beds formation beds Plant beds ~if"}:

I"'~ ~ I Zone between flows (Nos, I 1 to 4) of Rajmahal -t~ Volcanics/Dubrajpur I "~t'o beds (upper part) t I I I 1------1~ ------1-·- I: -. ------1------I ~ .::: II

RhaeUc I ~~. Ip~:~~," I I I !

'!~

~i.1

-.~

.l-~

l.1~~'JII .tl:}J~ SHAH et al.- OBSERVATIONS ON THE POST-TRIASSIC GONDWANA SEQUENCE 235 DISCUSSION is poor. This may perhaps be attributed to want of sufficient palaeobotanical work In the preceding pages the stratigraphic done in the area. The only older beds in position of the plant bearing ho'-izons of the post-Triassic sequence where the floral po~t-Triassic sequences has been analysed. assemblage is rich are the Rajm,hal plant In this analysis the associated faunal evi• beds. This can, it seems, be reasonably dences in some of the formations suggest equated with Kota form1.tion. If this be the following three different ages to them. true, the Rajmahal plant beds are L')wer Post-Aptian urassic or Lower l1ri1"sic- Middle Jurassic in age. Since the flora from the Chaugan (? Albian) rBhujEast CoastFormationGondwanas Upper formation, Golapilli sandstone, and Athgarh Neocomian sandstone show affil1ities with Rajm3.hal ~lAthgarh(excluding UtaturGolapilli,& plant beds, they may be of similar age or to Sivaganga beds) some part of Lower Jurassic - Middle Ju• Lower to Kota fornntion and rassic range. These beds m'l.Ybe considered Middle L,thi formation roughly of the same age. The Kota and Lat 11 i fOJnHtions can be Higher up in the sequence are the fl')ral considered of lower J wassic age base<1 on assemblage from the East Coast Gondwanas the faunal evidences. The form(;r rocks (excluding Golapilli sandstone and Athgarh have yicl<1edthe lower Jurassic fishes while sandstone) Gangapur form'l.tion, and the latter are overlain by amm')nite bearing Nipania beds. Wherever, the East Coast J aisalmer limestone of Callovian-Oxfordian Gondwanas are associated with marine age. Thus these two form,tions being fossils they are of undoubted upper Neo• Lower Jurassic in age with possibility of comian age. The Gangapur fonu'1tion which ranging into early part of Mid<1loJurassic overlies the Kota formation, unconform• can hardly be doubted. But these two ably, possess a flora comparable to the fl')ra formations are palaeo botanically very poor of the East Coast Gondwanas. Thus the and no rich assemblage of m 'ga fossils is Gangapur fornHtion m'l.Yrange from middle known. The Kotas from which, m)st of Jurassic to L')wer CretJ.ceous (upper Neo• the flora was described by Fc:istmantc1 comian). Same age can be adduced for (1877) now has beon proved to com" from Nipania beds. But in the latter case, the strata younger than Kotas and as such older beds in R'l.jmJ.hal hills are of Lower• they cannot be considered of the same age. Middle Jurassic age. Hence the Nipania Therefore, Kotas as defined earlier specially beds should be of upper Jurassic rather than the term Kota floral stage looses its signi• Upper Neocomian in age so also the Jabalpur ficance. The Lathis have not yielded any form:],tion. If this is accepted, it follows mega plants. However, microfossils have that there was no floral difference between proved its upper Gondwana affinity beyond the upper Jurassic and upper Neocomian. doubt. It is thus evident that the flora of It may be mentioned here that receptly Lower Jurassic age is not very well known McDougall and McElhinny, (in McElhinny, and whatever little is known could not be 1970) have suggested that the Rajm'l.hal of much help to correlate the other known Traps of India are of Albian age on K-Ar terrestrial deposits. determinations. In other words, the two The fore-runners of younger flora are biozones associated with the Rajmahal represented in the fossil ass-:;mblages of Traps become younger to the flora from Parsora formation. The climatic condi• Upper Neocomian East Coast Gondwanas tions which were unfavourable during the containing ammonites also. major part of the Triassic improved at its But the flora from the Upper Neocomian close, i.e. Rhaetic and thus a rich floral age is correlatable to the fl')ra from upper assemblage during the Lower Jurassic could biozone of Rajmahal hills. In view of this be expected reasonably. Further there is contradiction, K-Ar age determination is no indication of any major climatic changes not in conformity with plant evolution. or any break in sedimentary continuity be• Still higher in the sequence are the floral tween Rhaetic and slightly younger rocks. assemblages from the Himatnagar and The only undoubted Lower Jurassic pJ::tnt Dhrangac1hra sandstones, Bansa and Bhuj beds containing mega plants are known in forma.tions. Of these, except the last, Kota formation where the plant assemblage others· have yielded typical Lower Creta- 236 THE PALAEOBOTANIST ceous plant fossils, which indicate, that 1. There were definite Jurassic conti• Lower Cretaceous is represented in these nental deposits in India. beds. The Bhuj formation however, is of 2. The Rajmahal hills offer a good scope post-Aptian age based on the considerations for the zonation of the Jurassic-Lower of marine fossils and structural evidences. Cretace-cus flo]a and Rajmahal plant beds The typical lower Cretaceous fossils in the are of Lower Jurassic-Middle Jurassic age Dhrangadhra sandstone comes from 'Than as observed earlier by Feistmantel (1877) beds' which occur in the upper portion of and Sahni (1937). the Lower Dhrangadhra sandstone and the 3. The evolution of floral elements during base of this formation is not known. Be• Jurassic - Lower Cretaceous times was very cause of Weichselia reticulata, they are slow. generally considered to be of Wealden age 4. There is no clear boundary between (=Lower Neocomian). The age of the the Upper Jurassic and Lower Cretaceous Lower part of Nimar sandstone containing flora as most of the plant genera continued very few Gondwana plants cannot be decid• from Jurassic to post-Aptian (? Albian) ed. It may be anywhere in the Lower times, it is only their preponderance that Cretaceous. varied.

ACKNOWLEDGEMENT CONCL USIONS Grateful thanks are due to Slui M. V. A. From the foregoing observations and the Sastry, Director, Central Palaeontolcgy discussion on the post-Triassic Gondwana Laboratories, Geological Survey of India, flora, the following conclusions become for keen interest and valuable suggestions evident: in this work.

REFERENCES

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KING, W. (1887). The Geology of the Pranhita SAH, S. C. D. & MAHESWARI,H. K. (1969). Plant Valley. Mem. geol. Surv. India. 18(1): 750-311. mega fossils from the Bansloi Valley, Rajmahal KUTTY (1963). Some contributions to the strati• hills, Bihar with remarks on the position of graphy of the Upper Gondwana formations of Dllbrajpur group. J. Sen. Mem. Vol.: 369• the Pranhita-Godavari Valley, Central India. 375. Jour. geol. Soc. Ind. 10(1): 33-42. SAHNI, B. (1938). Recent advances in Indian LUKOSE (1977). Palynological evidences on the age Palaeobotany, Presidential Address, Botany of Lathi Formations, western Rajasthan. Sem. Section, Silver Jubilee Session, Calcutta. Pres. Palaeopalynol. & Ind. Strat. Calcutta (Abs.). Add. 133-176. McELHINNY, M. M. (1970). Formation of the SARMA, B. B. G. (1957). Geology of Nuzvid area Indian ocean. Nature. 227: 977-979. with special reference to the sedimentary MURTHY, N. G. K. & SASTRI, V. V. (1962). Fora• formations. Q. Jl. Min. metall. Soc. India. minifera from the Sriperumbudur Beds near 29(3): 141-154. Madras. Rec. geol. Surv. India. 89(2): 445-456. - (1958). Equisetales compressions from East PANDYA, K. L. & PATRA, B. P. (1968). A note on Coast Gondwanas. Indian Sci. Gongr. (Abst.). the occurrence of some Ptilophyllum species at 3: 221. J agannath Prasad. Puri District, Orissa. SARMA,B. B. G., RA]U, C. H. V. & MURALI, A. V. Prakruti-Jour. Utkal Univ. 5(2): 31-33. (1962). Geology of Golapilli area with special RA]NATH (1932). A contribution to the strati• reference to the sedimentary formations. Proc. graphy of Cutch. F. Jr. geol. Min. metal Soc. Indian Sci. Gongr. Pt. III, p. 202-203. Ind." 4. SHAH, S. C., GOPAL SINGH & SASTRY, M. V. A. RAMANU]AM,C. G. K. (1957). Microfossils from a (1970). Biostratigraphic classification of Indian carbonaceous shales near Vemavaram (Jurassic) Gondwanas. Int. Symp. Strat. Min. Resources. in the East Coast Gondwanas of India. J. Gondwana System, Aligarh: 306-326. Indian bot. Soc. 36(3): 348-372. SPATH, L. F. (1933). Revision of the Jurassic RAMASWAMY, S. K. (1953). Progress Report. cephalopod fauna of Kutch (Cutch). Mem. Geol. Surv. India for 1952-53 (unpublished). geol. Surv. India. Pal. Ind. 9(2): 639-945. RAMASWAMY,S. K. & SHRIVASTAVA,R. N .. (1958). SRIVASTAVA,S. K. (1966). Jurassic mioflora from In KRISHNAN, M. S., General Repoyt of the Geol. Rajasthan, India. Micropalaeontology. 12(1): Surv. India for the year 1954 (unpublished). 87-103. RAMANU]AM,C. G. K. (1957). Microfossils from a SASTRI, V. V., CHANDRA,A. & PANT, S. C. (1963). carbonaceous shale near Vemavaram (JurassIc) Foraminifera from Raghavapuram shales near in the East Coast Gondwanas of India. Jour. Tirupati, Andhra Pradesh. Rec. geol. Surv. Ind. Bot. Soc., Vol. 36, No.3, pp. 348-372. India. 92(2): 311-314. RAO, C. N. & DUTT, D. K. (1956). Progress SURYANARAYANA,K. (1953). Mesembrioxylon tiru• Report. Geol. Surv. India for 1955-56 (un• mangalense a new species from he Sriperum• published). dur group near Madras. J. Indian bot. Soc .. RAO, C. N. & SHAH, S. C. (1957). (1960; Progress 32(4): 159-164. Report. Geol. Surv. India for 1957-58, 1958-59, - (1954). Fossil Plants from the Jurassic rocks 1959-60 (unpublished). of the Madras Coast, India. Palaeobotanist. RAO, C. N. & SHAH, S. C. (1959a). Plant fossils 3: 87-90. from the Kota-Maleri beds, Adilabad district, - (1955). Dodoxylon rajmahlense Sahni from Andhra Pradesh, Abst. Proc. Indian Sci. Coastal Gondwanas of India. Ibid. 4: 89-90. Gongr. pt. III: 278. VISHNU MITTRE (1958). Studies on the Fossil RAO, C. N. & SHAH, S. C. (1959b). A note on the Flora of Nipania, Rajmahal Series India• fossil Flora of the Chikiala Beds, Pranhita• Pteridophyta and general observations on Godavari Valley (abs.). Ibid. III: 279. Nipania fossil flora. Ibid. 7(1): 47-66.