Evolutionary stages of Triassic flora in Siberia (Angarida).

N.K. Mogutcheva

Mogutcheva NK 19%. Evolutionary stages of Triassic flora in Siberia (Angarida). Palaeobotantst45: 329-333.

The Triassic flora of Siberia has been studied from three series of Triassic system in continuous sections. Therefore, its successive alterations and stages in the evolution throughout Triassic from the PIT boundary may be traced. Due to alternation of floristic complexes and marine deposits, the age of floristic complex may be precisely determined. The most ancient complex is studied from Induan depoSits. In a single section Permian cordaitean flora is replaced. In Siberia, the Early Triassic flora is heterogeneous. Two major floras, occupying different ecological niches, are distin­ guished: the lycopod flora (dominated by Tomlostrobus and Pleuromeia) being confined to marine plain, and the conifer fern (KorounclJanskaya) flora is distributed Within intracontinental areas where intense volcanism had occurred at that time. The Middle Triassic flora is scanty in Siberia. The Early Ladinian flora differs from both the Early Triassic and Late Triassic ones, while the Late Ladinian /lora is closely related to the Late Triassic /lora.

Key-wor

NK MogutclJeva , Siberian ResearclJ Institute of Geology, GeoplJyslcs & Mineral Resources, Novoslbirlsk 630 104, Russia.

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THE Triassic flora of Siberia is of great interest for replace cordaitean flora in the continuous Permian­ reconstruction of initiation and development of the Triassic sections. Mesozoic flora in the Siberian paleofloristic region as The Early Triassic flora greatly differs from both well as for global correlation of Triassic sections. Permian and Late Triassic floras. It exhibits a com­ bination of paleophytic elements with mesophytic Hence, there is a possibility to trace subsequent chan­ forms being flOUrishing in Late Triassic and Jurassic ges and stages in floral evolution from the PIT bound­ (Table 1). The Early Triassic flora composition in ary to the Jurassic. The presence of marine deposits Siberia is heterogeneous. Two major plant forma­ with ammonites, bivalves in the Triassic sections of tions, the Lycopod flora and the conifer-fern flora, Siberia allows accurate age determinations of floristic were distinguished. They occupied different ecologi­ complexes. The most ancient of these are from the cal nfehes. The Lycopod flora occurred on the eastern Induan deposits of Lower Triassic. They successively margins of the Siberian Platform where in Early Tri- 330 THE PALAEOBOTANIST

Table l---<:Omparison of Korvunchana flora with Late Permian, Triassic and Jurassic floras Paracalamites, Equisetites), ferns (Cladophlebis, 1. Tatarina flora of Russian Plalfonn; 2. L'lte Permian flora of Siberia; Sphenopteris, Kchonomakidium), cycadophytes 3. Maltsevo floras of Kuznetsk Basin; 4. Lycopod flora of Siberia; (Taeniopteris), ginkgophytes (RhipidopSis) and seeds S. Buntsandstein flora; 6. Keuper flora; 7. Late Triassic flora; and (Carpolithus, Samaropsis). Floras of such a composi­ 8. Jurassic flora. tion are found in the Induan and Lower Olenekian deposits. In the Upper Olenekian the floral composi­ KorvlIJlchana nora P, I T, I T, I T,., I T,.) I T, tion changes. It shows an absence of Tomiostrobus, Mi"iiituriopl.ylJu", TomiouroOus and the presence of Pleuromeia similar to P. N~dqretroplly"ius Camopltylijrrs sternbergii (Munster) Corda, which is characteristic Tu""",o\,;a Phy/Ul,h«a of the Olenekian-Anisian Buntsandstein flora. NtOQ""Id4ri4 NtostacAytJ Remains of equisetaceous plants (Paracalamites, LaholQ.1I1fularia Neocalamites, Equisetites), ferns (Cladophlebis) and NeocalamUtl SdtiU11llUra pteridosperms (Peltaspermum) are rare. No similar Prynttdaia Equ;setiUs plant associations are found in the Middle Triassic. ParacoJamlus OSl7l""dol,)$;1 Thus, the Lycopod flora is limited in Early Triassic. Todites DtH.aeops;s This flora substituted the cordaitean one, but in­ BM'top,er;s herited less of the latter in composition. The genera MerruJides A(T(;I('arpu.s Neokoretrophyllites, Paracalamites, Sphenopteris, Ehoracia Lobi/alia Rhipidopsisare common for both, however, common C/ado!,hkbi' Pecop,eri, species are absent in both floras. The evolution of the Sphntopleris Katan·op,er,is lycopod flora reveals two stages: CDbiozone contain­ Kdto1fomaltidium Pryltadaeopteris ing Tomiostrobus, Pleuromeiasp. nov., Lepidopteris, Rllaphidop'eris and (ij) biozone containing Pleuromeia sternbergii Mad)'luia S,ytophylJum and no Tomiostrobus. The first biozone is of the Ed)'lldella Ttrs;eUa· Tasari"a Induan-Early Olenekian age, the second is of Late upidoptvl;s Pe/tiJsp"",um Olenekian. A similar stage pattern in the Pleuromeia Yallarsiy;a T ae"ioptuis flora evolution is found in China (Wang & Wang, Tomia 1982). uutltardtia CUllopuris The rich and diverse conifer-fern flora, known as C/ossophy//um Ci1li,O the Korvunchana flora, was abundant in Early Trias­ Splte"oba;va Rhipidops;s sic of Siberia. It includes almost all primary groups of !xonrobus Yuccites Mesozoic plants. Its individual elements are present Vo/tzia in the Lycopod flora. The Korvunchana flora com­ Danuya Wi//s;ostrobus prises more elements, common to the cordaitean Pityoc/adus Lutul;,,;a flora but strongly differs from it in both dominants £/atoc/adus QuadroclAdSI.J.'1 and composition, and total absence of common assic existed a marine plain recurrently flooded by species. It already contains many Mesozoic elements a part of which is widely distributed in the younger the sea. The inland areas of the rest part of Siberia, floras. Most of them reveal their first and the earliest where active volcanic activity occurred, flourished emergence in the geological history, for example, the conifer-fern flora. Though these floras sharply Lobatannularia, Neoannularia, Neocalamites, flourished, differ in dominant elements; they have Neostachya, Acrocarpus, Eboracia, Mertensides, common elements too. Diplazites, Danaeopsis, Madygenia, Scytophyllum, The principal components of the Lycopod flora Williamsoniella, Leuthardtia, Glossophyllum, are represented by lycopsids Tomiostrobus (sub­ Pityocladus and others. Some of these genera of the genus<:>fgenus AnnalepisafterDobruskina 1995) and Korvunchana flora are found in the Late Triassic Pleuromeia sp. nov., occasional pteridosperms floras of West and East Europe, Middle Asia, China, Lepidopteris and Peltaspermum, individual fragmen­ Vietnam. Furthermore, the Korvunchana and tary remains of sphenophyta (Neokoretrophyllites, lycopod floras include elements in common with MOGUTCHEVA-EVOLUTIONARY STAGES OF TRIASSIC FLORA IN SIBERIA 331

Triassic phyloslraligraphy of Middle Siberia

Taymyr. Verehoyanye Tunguska and Kuznetsk b.sins

.~" "'" :-Ieoealamites, Annulariopsis, Sehizoneura. .~ M 0 Cladophlebis. Seylophyllum, Madygeno­ I-- [c: pleds. Sphenozamiles. Czekanowskia, Yu­ c: cciles, Podozamiles 'E'" u'" . c: Schlzoneura.Neocalamites. Taeniopteris. ~ Glossophyl1um.Phoenicopsis. Yuccites. Pity-o- , " 'c hilum lDu...Iilu t1f T,.I~"le :;; Cladophlebis, Villaephyllum, Anomozami- o ~"UOlC~ (lor.. ~ ~ tes. Macrotaeniopteris • ly<:OpOdr&flor .. I • MId'"T..~ flora. c: ~ :~.~~~~.~t co I.. I...... ~...... l ..... 1. .... 1...... ••• .;;; ? '2 Neoannularia, Boreopleris, Menensides. ~ G Cladophlebis, Kalasiopteris, Dan.eopsis, c'" .g -= Lepidopleris, Scylophyllum, Yuceiles, Lu- ,- ... Pleuromeia sternbergii '" 8 luginia, Quadrocladus?, Pityocladus ..>:'" 0'" c ~ ~ r:::; ~ -i Neo~~nnul'"t"iu..Ac:roc ...rpLLll . .K.u.l~iopteris. U MadYJi:cnia. Edyndclla. Tersiella. Volt,...I_. ~ ~ ~1-TomiostrobuS'I :::lC Carney •. Vv'illsiost.robus . . c: 8. Pleuromeia sp. nov .. > r TomiostT"obus. Ncokoretrophyllitcs. Schi- ~ 8 Lepidopteris B ~ zoneura. c;ladophlcbis .. K chon~rnakidiurn. -g >- Vladimiriella karpinsky-charoph . ._ ....l :i ~ ;c:;~~~~%,se't~~~I~di~~:~i'e?;:r~~e~~~~:t/~~

Text-figure I-Triassic phytoSlfatigraphy of Middle Siberia. those of the Buntsandstein flora of Vosges Gagariostrobus) and absence of conifers are the (Schizoneura, Voltzia, Darneya, Wi//siostrobus, peculiar features of the Tutonchana flora. Elatoc/adus, Yuccites, Pleuromeia and Tomiostrobus, The major developrnent ofthe Korvunchana flora the latter being subgenus of the genus Annalepis), took place in the Dvurogy horizon, Conifers Voltzia, The Korvunchana flora evolved distinctly con­ Elatoc/adus, Quadroc/adus, Darneya and Willsios­ nected to the geological stages of the region trobus appeared in this stage for the first time, Yuc­ (Mogutcheva, 1982), i,e., Tutonchana, Dvurogy, and cites were rare as in the Tutonchana flora. Putorana. The Tutonchana flora including more than Arthrophytes reduced in number and diversity; 60 forms shows a wide distribution of arthrophytes Neokoretrophyllites, Phyllotheca, Paracalamites, and pteridophytes associations. Ferns (about 30 Neoannularis, Lobatannularia were differentiated. species) belong to the genera Astherotheca, Osmun­ Ferns partially changed in species and generic com­ dopsis, Todites, Schvedopteris, Lobijolia, Cladoph­ position. Acrocarpus, Mertensides and Boreopteris lebis, Pecopten's and Sphenopteris, Kchonoma­ appeared for the first time, The last two genera are of kidium, Korvunchania and Katasiopteris appeared significant importance for the younger Putorana flora, In the Dvurogy flora Madygenia was widely to be the basic dominant taxa. Arthrophytes were less distributed and Tersiella became more abundant in important, but their composition was rather varied, species, Also, the genus Edyndella appeared, Neokoretrophyllites, Gamophyllites, Tschernovia, Cycadophytes (Taeniopteris, Parajacutiella, Yavo­ Paracalamites, Neocalamites, Equisetites, Schizo­ rskyia) and ginkgophytes (Rhipidopsis) were still of neura and Prynadaia are commonly found, The little importance, Besides, there were occasional Tutonchana arthrophytes and ferns demonstrate lycopsids (Tomiostrobus, Taxhtajanodoxa) there, direct relation to the cordaitean, Madygen, The Putorana flora differs from the Dvurogy flora Buntsandstein and the younger floras, Pteridosperms in different dominant plant groups and in their such as Madygenia, Rhaphidopteris, Leuthardtia, species composition, Ferns became more abundant Tersie//a, Peltaspermum were of limited distribution. and diversified (more than 35 species), Conifers were Relatively diverse cycadophytes (Taeniopteris, widely spread. Pityoc/adus and Lutuginia also ap­ Ctenopteris, Yavorskyia, Tomia, Glossozamites) and peared, Yuccites occurred more frequently, The ginkgophytes (Rhipidopsis) were of minor impor­ specific composition of some conifer genera tance. The presence of lycopsids (Tomiostrobus and changed. Voltziawas absent. 332 THE PALAEOBOTANIST

In ferns, Cladophlebis dominated; Sphenopten's, strombergensis (Sew.) Town. Taeniopteris d. ensis Katasiopteriswere rather diversified; Boreopterisand Oldh., Glossophyllum sp. and Podozamites distans Mertensides were common; Eboracia, Eleganopteris (Presl) Braun in other sections (Dobruskina, 1982). were present. Arthrophytes were not abundant, but Representatives of both the Early Triassic and Late represented by Trizygia, Lobatannularia, Neoan­ Triassic floras are present in this assemblage. In nularia, Neostachya, Phyllotheca and Paraca­ northern Siberia plant remains were found in the lamites. Madygenia was absent in pteridosperms, Ladinian which is also supported by the marine whereas Scytophyllum appeared for the first time. fauna. The Anisian deposits are marine and contain Cycadophytes were not widely distributed too and no plant remains. represented by the genus Yavorskyia. There were Two different assemblages were found from the occasional occurrences of Williamsoniella. It is the Upper and Lower Ladinian. The first one is derived earliest finding of this genus. from the Lower Ladinian in association with marine The Korvunchana flora appears to be coeval and fauna on the Anabar Bay Coast (Mogutcheva, 1981). parallely evolved with the Lycopod flora. The finding Not numerous plants of this assemblage are en­ of the Tutonchana type flora in the Lower Induan of countered there, such as Cladophlebis aff. chantaj­ Verkhoyanye and Tomiostrobus in the lowermost kensis Mogutch., Cladophlebis sp., Sphenopteris sp., Tutonchana horizon (including the Maltsevskaya Vittaephyllum anabarense Mogutch., Anomo­ Formation from Kuzbass) suggests the Tutonchana zamitesparvzjolius Mogutch. and Macrotaeniopteris horizon to be Induan. The Dvurogy horizon is con­ sp. The assemblage is characteristic by the presence ventionally correlated to the Upper Induan­ of pteridosperm Vittaephyllum which is one of the Olenekian, whereas the Putorana horizon - to the typical representatives of the Scytophyllum flora of Upper Olenekian and Anisian. Eurasia, and the presence of cycadophytes Anomo­ The Lycopod and Korvunchana conifer-fern zamites and Macrotaeniopteris uncommon to the floras have also genera in common with those of the Siberian Triassic flora. Just these very peculiarities known European and Chinese floras, that makes make the assemblage look unlike the known floristic possible the comparison ofthe Siberian Triassic floras assemblage of the Siberian Triassic ones but similar with them. The most important of these are to the Middle-Late Triassic flora of Novaya Zemlya Pleuromeia, Tomiostrobus, Schizoneura, Equisetites, (Vassilevskya, 1984). As a whole, the northern Lepidopteris, Peltaspermum, Glossophyllum, Voltzia, Siberian Triassic is sometimes marked by the increase Darneya, Willsiostrobus, and others. There are also of cycadophytes in the floras. Thus, in Eastern Taimyr genera of the Madygen flora of Middle Asia and in the vicinity of the Tulai-Kiryak Uplift the following similar to the Late Triassic floras of Eurasia. remains were found: Equisetales gen. et sp. ind., The Middle Triassic flora of Siberia is very scanty Cladophlebis sp., Scytophylluni! sp., Nilssonia sp., because plant remains in the alluvial Middle Triassic Macrotaeniopterisd. novozemelicaVassil., Taeniop­ are rare and in small amounts. In Verkhoyanye of the teris d. kryshtofovichii Vassil. Taeniopteris ex gr. Unguokhtakh R. Basin, the lower Middle Triassic (the stenophyllaKrysht., Taeniopterissp., Phoenicopsisex Tolbonskaya Formation) is found to contain gr. angustijolia Heer and Czekanowskid? sp. As Paracalamites sp., Neocalamites sp., Equisetites d. cycadophytes are dominant in the collection, this sixteliae Mogutch., Cladophlebis sp., Sphenobaierci assemblage shows a highest similarity to that from sp., Yuccitesex. gr. spathulatusPryn. and Carpolithus Novaya Zemlya and is likely to be close to it in age, sp. In the upper Middle Triassic partially penetrated i.e., the uppermost MiddleTriassic-early Late Triassic. into the Karnian there are Neocalamites carrerei The second assemblage is known from the Upper (Zell.) Halle, SchizoneuragrandijoliaKrysh. et Pryn. Ladinian in the Triassic section on the eastern coast Equisetites sp., Podozamites sp. There is an interest­ of Taimyr (Mogutcheva, 1982). Schizoneura gran­ ing finding of lycopsids, i.e., Cylomeia aff. undulata dijolia Krysh. et Pryn. and Neocalamites carrerei (Burges) White, which indicates a direct relation to (Zeiller) Halle are common there and Glossophyllum, the Lycopod flora. There are Neocalamites uralensis Podozamites, Yuccites, PhoenicopsiS, Pityophyllum Tur.-Ket., Paracalamites aff. taradanica Vlad., Dic­ are in abundance, whereas Cladophlebis, Adiantop­ tyophylluni! sp., Cladophlebis sp., Lepidopteris aff. teris, Madygenia, Scytophyllum, Peltaspermum, MOGUTCHEVA-EVOLUTIONARY STAGES OF TRIASSIC FLORA IN SIl3ERIA 333

Sagenopteris, Taeniopteris are occasional. The The Early Norian assemblage shows a closest generic and species composition of the Late Ladinian similarity with the Late Triassic floras of Eastern Ural assemblage is very close to that of the Late Triassic (Kiritchkova, 1969) and Gorny Altai (Mogutcheva & Siberian flora. The Late Ladinian is most likely to be Batyaeva, 1987). These floras have many species in considered as the onset of the Late Triassic stage in common (Cladophlebis crenulata Kiritch., C. the Siberian floral history. The first appearance of jolkinensis Pryn., C. uralica Pryn. Yuccites nanus Czekanowskiales (Phoenicopsis) and conifers and others). They are also similar in the dominance (Podozamites, Pityophyllum) is in favour of such a of Cladophlebis and in having a close composition of consideration. These genera exhibit the widest dis­ Equisetales, abundant Yuccites and insignificant tribution in the Jurassic flora of the Siberian cycadophytes. paleofloristic region. Thus, the Siberian flora has little in common with The Late Triassic flora is typically mesophytic. It the Late Triassic floras from other regions (Pechora is closely related to the Early-Middle Jurassic floras, Basin, Southern Priuralye, Kazakhstan, Kirghizia, but its general composition is similar to the Early-Mid­ Southern Primorye, China, Swalbard) and, as a dle Triassic floras. It was studied from Eastern Taimyr whole, greatly differs from these. There are two major and Verkhoyanye. The age of the Taimyr as­ stages in the history of the Siberian Triassic flora: (j) semblages is strictly dated by the intercalated marine Early Triassic and, probably, Anisian, and (ij) Late layers in the plant containing deposits and that of the Ladinian-Late Triassic. Verkhoyanye is determined through correlation. The Early Ladinian flora appears to hold a some­ In the Carnian deposits of Verkhoyanye, plant what isolated position. It considerably differs from remains are not frequent. They are represented only both the Late Ladinian flora and the Korvunchana by Neocalamites carrerei (Zeiller) Halle, Equisetites, flora, though it has elements in common with them. Cladophlebis, Madygenopteris irregularis Sixt., It is possible that further evidence will suggest a more Phoenicopsis and Podozamites. In the Norian correct pOSition for this flora. Cladophlebis occurs more often and Cycadocar­ Ifthe floral evolution during the second stage was pidium is found in good number. Among conifers, progressive, the Korvunchana and Lycopod flora Elatocladusa nd Treematostrobusoccu r together with Podozamites. Of the Rhaetian, the only one location were to have undergone essential reconstructions. of plant remains is known. Cladophlebis nebbensis REFERENCES (BrongnJ Nath. is dominant there and Yuccites,

Borysthenia, Podozamites and Elatocladus occur in Dobruskim IA 1982. Trbssic nor~sof EurJsiJ. Trans GIN AN SSSR 36S : subdominance. 1-196 (in Itussbn). A more rich assemblage (more than 30 species) Dobruskin~IA 1995. Keuper (Tri~ssic)nor~from Middle Asi~.H('turySd. 5: 1-49. was found in the Lower Norian of Taimyr Kiritchkov~AI 1969. The m~teriJIson the study of the Lower Mesozoic (Mogutcheva, 1982). Conifers (2 species of nor~of the EJstern UrJb. Tr. VNIGR/268: 270-349 (in HlIssiJn). Podozamites and Yuccites) and ferns 05 species of MoglitchevJ NK 1981. New finding of Middle Trbssic norJ in E~s(ern Siberi~.In Stratigraphy and paleontology of Siberia 43-48 Cladophlebis) prevail there. Dictyophyllum and Novosibirsk (in ItllssiJn). Kugartenia irregularis Sixt. are found. Among Equi­ Mogutchev~NK 1982. Correbtion of the Lower Trbssic in Middle Siberb setales Neocalamites carrerei(Zeil.) Ha lie is the most from nor~1d~t~.In. Regional and locul stratIgraphic units/ur the abundant, whereas Annulariopsis is rare. Pterido­ large-scale geolugical mapping ()f Siberia: R9-97. Novosibirsk (in sperms (scytophyllum, Rhaphidopteris), ginkgo­ Itussi~n) Moglltchev~NK 1982. On the study ofTri~ssicnor~on the EJstern TJimyr. phytes (Gingko), cycadophytes (Taeniopteris, sphe­ In Biu-and lithostratigraphy of the Siberian Triassic 63-71. nozamites) and Czekanowskiales (Czekanowskia, Moscow, N~ub-Press(in Itussi~n). Ixostrobus) are not common, but Glossophyllum, Mogutchev~NK & 13~tYJev~SK 1987. New evidence on the Tri~ssicfrom Gorny AltJi In' Boreal Triassic: 96-99. Moscow, N~lIb-Press(in Yuccites and Lepeophyllum in association with these Hussbn), are rather abundant. V:lssilevskJyJ ND 1984, TIle first findings of the plJnt remains in the This Early Norian assemblage is similar to the Late bbnds of Nov~y~ZemlyJ, Yezhegodnik Vsesoyuznogo Paleontol. Ladinian one but differs in the dominance of ferns, Obva. 27: 109-123 (in Russi~n), WJng Z & WJng L 1982, A new species of the lycopsid Pleuromeia from Yuccites and Podozamites and in the absence of the EJrly TriJssic of ShJnxi. ChinJ, ~ndits ecology. Paieuntology2S pteridosperms -Madygenia. :215-225