The Palaeobotanist, 28-29: 301-307, 1981.

POLLE CLASSOPOLIS: INDICATOR OF JURASSIC A D CRETACEOUS CLIl\fATES

V. A. VAKHRAMEEV Geological Institute of the Academy of Sciences, 109017, Moscow, Pyzhewskyper., 7, USSR

ABSTRACT

Pollen C/assopollis belonging to extinct coniferalean family Cherolepidiaceae are widely spread in the Jurassic and Cretaceous. The material from the USSR provides the most detailed data on the quantitative distribution of the pollen. A low content (1-10%) of Classopollis suggests temperate climatic conditions, whereas a percentage (20-50%) reveals warm subtropical one. The highest content attaining 60-75 % even 90 % (in Oxfordian of the USSR southern regions) testifies to an arid climate. Thus the distribution of the pollen plotted against that of lithological indicators of the climate allows to reveal climatic belts for different epoch of the Jurassic and Cretaceous and to establish climatic fluctuation during this time. Key-words - Palynology, Classopollis, Cheirolepidiaceae, Jurassic, Cretaceous. USSR.

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(short incurved leaves) and Elatocladus (longer POLLENat the beginningClassopol/isof thebecamePalaeogene.extinct incurved leaves). Isolated shoots of Pagio• The data accumulated during the phyllum and Elatocladus in general habit are last decade confirmed the previous opinion similar to those of extant Araucariaceae. of the author (Vakhrameev, 1970) on The study of epidermis and cones found dependence between content of Classopollis together with some of the above shoots, in miospore assemblages and of palaeo• Krassilov (1975, 1978), showed that they climates. belong to the latter family. Nevertheless, Shoots with male cones yielding the it would be erroneous to insist on belonging Classopollis pollen have different appearance, of all isolated shoots attributed to form• and hence were described under various genera Brachyphyl/um, Pagiophyllum and genera: Cheirolepidium, Frenelopsis, Pseudo• Elatocladus to Cheirolepidiaceae or Arau• frenelopsis, Tomaxiella and partly, Masculo• cariaceae only. Noteworthy is that the strobus. These shoots are most densely pollen of both the families, as well as male covered by tightly adpressed scale-like or cones, are well distinguished from one incurved spine-like leaves. When isolated, another. they are assigned to the form-genera Brachy• Frenelopsis and Pseudofrenelopsis have phyllum (scale-like leaves), Pagiophyllum articulate shoots. In their nodes there are 301 302 THE PALAEOBOTANIST

one (PseudoFenelopsis) to three (Frenelopsis) Paleoclimatic reconstructions for the Late short triangular leaves adpressed to the Jurassic compared with the distribution of axis. The male cones born on shoots of lithological indicators of climate and plant this structure yielded Classopollis pollen only remains (Strakhov, 1960; Vakhrameev, (Watson, 1977; Alvin et al., 1978; Dolu• 1964; Sinitsyn, 1966) show that the northern denko, 1978). Thus, these genera belong to part of Eurasia was a belt of temperate• the Cheirolep·diaceae family. warm and humid climate. The Classopollis Especially abundant material on the content does not exceed here 6-10 %. In the Classopollis content in the Jurassic and Lena River Basin and in the north-east of Cretaceous was obtained by Soviet Palyno• the USSR, where the Upper Jurassic is logists who provided the percentage of the represented by coal-bearing deposits, the pollen in miospore assemblages. This en• Classopollis pollen either occurs a<; solitary abled me to draw the curves showing changes grains, or is missing at all. of the Classopollis content throughout Juras• Southwards, in West Europe, the central sic and Cretaceous plotted against latitudinal p:ut of the Russian platform and in the belts crossing the vast territory of the south of West Siberia, the climate was European part of the USSR, West and warmer and its humidity was seemingly Middle Siberia, Kazakhstan, Middle Asia decreasing. The content of Classop0 lfis and the Caucasus. These curves are based pollen in the Upper Jurassic varies here on published data of Alekseeva, Alimov, from 10 to 30-40 %. In Moldavia, Crimea, Barkhatnaya, Blyakhova, Bondarenko, Dani• Caucasus, South Kazakhstan and Middle lenko, Dobrutskaya, Fokina, Ivanova, Asia (a belt of semiarid and arid) hot climate il'ina, Khachieva, Klimko, Kotova, Kosen• is situated; this being evidenced by wide kova, Kuvaeva-Smirnova, Markova, Nes• distribution of gypsum, and locally presence terova, Orlova, Petrosyants, Pogodaeva, of rock salt. The content of Classopollis Perfilieva, Polumiskova, Ponomarenko, pollen is over 50% here. Such a regularity Rovnina, Sakulina, Shramkova, Shugaev• supports the opinion of many workers skaya, Tarasova, Terekhova, Voittsel, Yaro• claiming that the Cheirolepidiaceae producing shenko and some others. Reference to Classopollis pollen were thermophilic. their publications are given in Vakhrameev The second peculiarity in distribution (1970, 1978) and Vakhrameev and Dolu• of Classopol/is pollen is its enormous quan• denko (1976). tities in rocks sediments deposited in the Palynologists from other countries do not belt of semiarid and arid climate. As it has give, as a rule, the percentage of these or been already mentioned, the content of this other pollen genera and species; they only pollen within this belt exceeds 50 % every• mention their frequent or rare occurrence. where, and that in Oxfordian deposits reaches This fact does not enable a construction of 90 %. Such a percentage of Classopollis curves of the quantitative content according pollen suggests that Cheirolepidiaceae sur• to their data. vived well in dry climate, whereas the role Before analysing the above mentioned of other plant groups in vegetation, especially curves and elucidation of their relation to ferns, abruptly decreased with aridity of climatic changes, the spatial distribution of climate up to their complete disappearance. Classopollis over the greater part of Eurasia The Classopollis pollen is related to for the Late Jurassic epoch should be at• mostly shallow-water, near-sea-shore and tempted (Text-fig. 1). This time is particularly deltaic sediments. It is distributed in lacus• favourable for establishing dependencies trine deposits of intermontane depressions between the Classopollis percentage and as well (Karatau ridge in South Kazakhstan, disposition of climatic belts. It is Upper etc.). Text-figure I clearly shows that the Jurassic deposits that yield maximum content of this pollen appreciably decreases amounts of the pollen, and the quanti• from the West Siberian lowland occupied tative distribution of the latter, and hence, by a shallow water sea in the Late Jurassic distribution of conifers producing them in the eastern direction, where Upper (Cheirolepidiaceae) seems very convin• Jurassic and Lower Cretaceous coal-bearing cing. Text figure 1 shows that the Classo• deposits are developed filling some depres• pollis pollen content increases gradually sions (Vilyui, Zyranka, etc.). In the conti• southwards. nental Upper Jurassic of the Transbaikalian VAKHRAMEEV - POLLEN CLASSOPOLIS 303

TEXT-FIG. J - Contents of Classopollis pollen in palynological samples. Symbols: 1- solitary grains 2-from 1 to 2%, 3-frol11 6 to 10%, 4-from 30 to 40%, 5-from 50 to 70%, 6-75 to 90%, 7• land. Land and sea boundaries are given for Oxfordian age (Atlas of Jithologo-paleogeographical maps of the USSR, v. IIf, 1968, and other sources). area, and Bureya depression the Classopollis higher dratned of the forested land. The pollen content does not exceed 1-2 %. The Cheirolepidiaceae played a considerable role same pattern of the Classopollis pollen in the composition of the latter. It is natural content in synchronous near-sea-shore and that the Classopollis pollen content in near• coal-bearing deposits was established by sea-shore sediments increases considerably. Yaroshenko (1965) for the Pliensbachian of This peculiarity of ecology of Cheirolepi• the North Caucasus. The Cheirolepidiaceae diaceae somewhat disturbs the regularity of producing Classopollis pollen seem to have their distribution in climatic zones. avoided swampy overflooded habitats, pre• An opinion that Cheirolepidiaceae were an ferring to grow on drained slopes or pene• analogue to the recent mangrove plants plated uplands. growing in a very narrow shore intertidal This fact is likely to explain an increase of band (Kondratiev, 1970; Hughes & Moody• Classopollis pollen in transgressive portions Stuart, 1967), causes a serious objection. of successions (Upper Jurassic of the Russian This analogy is opposed by considerable platform & West Siberian lowland). The content of Classopollis pollen (50-70 %) in sea, while transgressing over near-sea-shore Upper Jurassic continental deposits in north lowlands covered by moisture-loving vege• and north-east Kazakhstan accumulated at a tation with prevailing ferns, approaches large distance (about 500 km) from the shore 304 THE PALAEOBOTANIST

line and especially in north-west China that Araucariaceae did not grow in somewhat had never been overflooded by Mesozoic appreciable amounts. Further studies of seas. both the epidermis of isolated shoots, and Distribution of Classopollis pollen (Text• pollen of fossil Araucariaceae are necessary fig. 1) agrees well with the distribution of for a more accurate delimitation of areas of rainfall in the Jurassic and Cretaceous these two families in the Mesozoic. periods with Eurasia as reconstructed by While passing from Pliensbachian to Sinitsyn (1966). His maps show a belt of Toarcian a considerable increase of the arid and semiarid climate stretching from Classopollis content is observed (Text-fig. 2). the Arabian peninsula to western China and The Toarcian peak is marked in all three further pinching out eastwards. The belt curves; for the southern regions (Caucasus) embraces the southern part of the USSR. the peak is better pronounced, whereas in The northern and eastern parts of the USSR North Asia (Vilyui & Khatanga depres• were within humid climate and it is here sions) the Classopollis content does not w~e!e the Classopollis pollen content proved exceed 10-15 %. mlnlmum. The dependence between the Classopollis Summing up the data one can say that the content in the Toarcian and warming of Cheirolepidiaceae producing Classopollis climate is supported by other data as well. were thermophilic plants as evidenced by a This time was characterized by penetration of rapid decrease of the pollen from south to some thermophilic ferns and bennettites to north. During the conditions of humid the north. For instance, along with Classo• climate such groups of gymnosperms as pollis, spores of Matonisporites, Marattio• Ginkgoales, Czekanowskiales, Podozami• sporites, Contiguisporites, usually confined tales and older Pinaceae were successfully to more southern regions, were found in competing with the Cheirolepidiaceae. The Toarcian of the Vilyui depression and on latter avoided swamped lowlands within the Anabar River. In the Kolyma River which coal-bearing beds were formed. They Basin imprints of Thaumatopteris and Ptilo• gave preference to drained slopes, and likely phyllum, in South Alaska - Otozamites and flattened peneplated uplands. Therefore, Dictyophyllum, and in the Kuznetz and in East Siberia and in the Far East, where Kansk-Achinsk basins - Phlebopteris poly• humid climate was predominant and the podioides and Marattiopsis muensteri, were coal formation took place (Sinitsyn, 1966), found. the Cheirolepidiaceae were not in appreci• The warming in the Toarcian time caused able amounts in vegetation throughout considerable advance of subtropics north• the Jurassic and Cretaceous. Sediments ward reaching the southern regions of with abundant Classopollis pollen gravitate Siberia and South Alaska. The breadth of most frequently toward in intercontinental the tropical and subtropical belt consider• basins (depressions) as well. ably increased. At the same time, the The Cheirolepidiaceae resisted the change Toarcian warming did not cause appreciable of humid climate for semiarid or even arid expansion of arid climate, traces of which one, becoming in this case monodominant. have been found neither in the Soviet Union This process resulted in an abrupt decrease nor in South Europe. This is evidenced by of ferns that could not survive in dry con• a complete absence of evap~rites in Toarcian ditions and the afuresaid hygrophilic gymnos• deposits of these regions, and a much lesser perms. Along with Cheirolepidiaceae content of Classopollis pollen (less than 30• forms, as the author believes in low sparse 40 %), as compared to the Upper Jurassic. forest, many Bennettitales also grew. In Aalenian and Bajocian the Classopollis Under conditions of warm and hot cli mate, pollen content abruptly decreased every• but humid, the Araucariaceae could grow where to 1-2 %, and eventually to complete together with Cheirolepidiaceae. The dis• disappearance. This is well-correlated to tribution of extant representatives of the the cooling and moistening of climate, former family growing in the southern reaching maximum value in Bajocian. The Hemisphere, is confined to areas of humid northern boundary moved southward. Mio• climate. In regions of semiarid and arid spore assemblages, especially Bajocian ones, climate abounding in Cheirolepidiaceae due begin to abound in spores. Process of coal to elimination of hygrophilic plants, the accumulation was widely distributed. VAKHRAMEEV - POLLEN CLASSOPOL1S 305 .( o.

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TEXT-FIG. 2 - Curves of Classopo/lis pollen contents in Jurassic and Cretaceous deposits. Symbols: 1 -curve for USSR southern regions (Moldavia, Crimea, Caucasus, South Kazakhstan, Middle Asia). T he right part of curve embracing Upper Cretaceous is drawn according to samples from Middle Asia, 2• cu rve for central part of Russian platform (Moscow Basin, Vyatka-Kama depression, etc.), 3 - curve for West and Middle Siberia (Vilyui depression), 4 - curve for the northern margin of Asia (Ust- Yenisei and Khatanga depressions).

In Bathonian, southern regions of the Tn Callovian deposits the Classopollis USSR show a gradual increase of the content begins to increase. Even in the Classopollis content (up to 20-30%). In northern region (Ust-Yenisei depression, etc.) Middle Asia, particularly in Ferghana, one it increases in the Upper Callovian and can observe impoverishment of the floristic Oxfordian from solitary grains in a sample to composition in plant megafossils, at the 10% In the centra I parts of the Russian expense of falling out of more hygrophilic platform and West Siberia the Classopollis forms. Representatives of some genera have content becomes very significant (>50 %), appreciably reduced leaf laminae. In more but especially high in southern regions northern regions, for instance, in the central (80-90 %). In some samples taken from part of the Russian platform and in West Oxfordian deposits the spore-pollen spectra Siberia the increase of the Classopolliscontent consist practically of only Classopollis pollen is negligible. No increase of Classopollis (Text-fig. 2). pollen was recorded along the northern In the Oxfordian there was one of the margins of Eurasia. Changes recorded in largest transgressions in the Northern Hemi• southern regions are related to the first sphere coinciding in time with the warming of hardly noticeable phase of the climate climate. This can be evidenced by a signi• warming pronounced rather clearly in the ficant northward advance of coral construc• south of the Soviet Union only (Crimea, tions recorded for Europe. Aridization of Caucasus, Middle Asia). In Middle Asia climate, as compared to the Callovian, this warming was accompanied by the became still stronger, as shown by the ap• aridization of climate, evidenced by the re• pearance of gypsum and, locally, rock salt. duction of leaf laminae and cease of coal The wash down of clastic material from land accumulation. framing in the north the Tethys and Para.- 306 THE PALAEOBOTANJST

tethys seas sharply decreased. This was 1978).. The Albian lowering of temperature most probably associated with aridization of waS likely global. In the southern hemi• climate and drastic shrinkage of the surface sphere it was recorded in Australia (Douglas, drainage. This resulted in deposition of 1~76) and S)uth Atlantic (McLachlan & carbonate rocks in some regions near the Pleterse, 1978). However, the decrease of shore line. temperature in the near-equatorial belt did In Kimmeridgian-Tithonian deposits, as not appear to be appreciable, as the Classo• in the Oxfordian, represented by shallow• pol/is content in Albian deposits remains water or near sea-shore sediments the significant. It can be judged from the absolute content of Classopollis p~llen palynological investigations of core material somewhat decreases. The latter takes place from some deep sea holes drilled by D. V. mostly at the expense of great amounts of "Glomar Challenger" in the Marocc) marine dinoflagellates. The latter are fre• Basin and the Cape Verde Basin (Kotova, quently observed along with spores and 1978). The Classopollis content in Aptian pollen of land plants. Therefore we had to and .Albian doeposits reaches 80 % (in Neo• interrupt the curves for this time. cOlman - 70 %, and in Cenomanian - 60• While passing to the Cretaceous, the 65%). Classopollis content invariably decreases, The Albian age coincides with dispersal of reaching its minimum in the Albian. How• angiosperms, and especially broad-leaved ever, for various regions this part of the forms of this group. Noteworthy is that in curve is not identical. In the north of all northern and central regions the Classo• Eurasia Classopollis disappears as early as pollis pollen in post-Albian deposits dis• in Berriassian-Valanginian. In the central appears. In the Upper Cretaceous of the part of the Russian platform, Mangyshlak USSR southern regions the pollen are still peninsula and West Siberia the Classopollis observed in great amounts in Middle Asia content abruptly decreases not exceeding and South Kazakhstan. In the Crimea and 20-25 % in the Berriassian-Valangnian; its Caucfl:sus typically marine, mostly carbonate amounts in the Hauterivian become negli• deposIts are nearly devoid of miospores. In gible (a few per. cent), .and i,: the Lower Middle Asia the Classopollis content, being Aptian depOSIts It practIcally dls~ppears. minimum in the Albian, begins to increase The cooling of clImate IS eVIdenced by in Cenomanian reaching its maximum in penetration of buchias (aucellas) to the the Tu.ronian-Coniacian and decreasing in south, up to the Mangyshlak and North SantonIan. The last rise of Classopollis Caucasus. These buchias are widely distri• accounts for Campanian-Maestrichtian. buted in Late Jurassic and Early Cretaceous Then the curve descends. In the Upper on the northern margins of Eurasia and Palaeocene the Cheirolepidiaceae disappear North America, and gravitate towards the from the Eath's surface, this being confirmed belt of temperate or temperate-warm climate. by complete disappearance of Classopollis. Increase of fern spores in miosp~re assem• The Turonian-Coniacian corresponds blages, and disappearance of evaporites maximum to a rise of temperature and an testifies to humidization of climate. increasing aridization of climate. This is The situation is different in Middle Asia asserted by appearance of red beds and where the Classopollis content remained high gypsum in Middle Asia. The second maxi• up to the Upper Aptian (Text-fiig. I). This mum rel.ates to well-known warmi ng in the appears to be related to the fact that in this CampanIan age. The available data on the region, where continental red beds with Classopollis content in the Upper Cretaceous dolomi te and gypsum were still accumu1:lting, of Middle Asia and in other regions are in• the climate was dry enough preventing from sufficient. The distribution of this pollen is distribution of ferns. This is also confirmed not clear enough due to two factors: (i) in by a negligible amount of spores in the samples from the Upper Cretaceous shallow• deposits of this age. wate.r mari ne deposits, these bei ng pre• The minimum content of Classopol/is domlllant, there are numerous unicellular accounts for the Albian (Text-fig. 2). This is alg~e forcing out miospores from palyno• well-confirmed by the curves made separately logIC'll spectra, (ii) appearance of Gnetacea• for the Crimea, South-East Caucasus, Uz• pollenites pollen belongi ng to gymnosperms bekistan and Turkmenia (Vakhrameev, i n Upper Cretaceous deposits. Require- VAKHRAMEEV - POLLEN CLASSOPOLIS 307

ments of these plants to the environment were It may be said again that in climatic similar to those of Cheirolepidiaceae. The interpretation of the Classopollis content the competition between both groups influenced lithological composition of beds yielding on their proportion in miospore spectra. samples are to be considered. It is neces• On the whole, the curves of the Classo• sary to remember that samples from coal• pollis content show good agreement with bearing beds deposited even under condi• paleotemperatures measured by Ca/Mg ratio tions of subtropic:l.I or tropical climate (Yasamanov, 1975, 1976), with the data on contain, as a rule, sm:dl amounts of Classo• plant megafossi18 (Vakhrameev, 1978; Vakh• pollis (Jurassic & Lower Cretaceous of India). rameev & Doludenko, 1976), as well as with Therefore according to this feature they distribution of lithological indicators of should not be used for reconstructi on of climate (Ronov & Khain, 1962; Khain, changing paleotemperature. The Classo• Ronov & Balukhovsky, 1975). Warmings in pollis content in shallow-water, near-sea• the Toarcian, Late Jurassic and Campanian shore and continental (but not cJal-bearing) time, and a cooling in the Albian C:l.nwell be deposits is a reliable indicator of climate, traced throughout the northern hemisphere. and can also be used for stratigraphic corre• The Albian pessimum is recorded in the lation purposes, particularly when deposits southern ehmisphere (Australia) as well. are poor in other organic remains.

REFERENCES

ALVIN, K. L., SPICER, R. A. & WATSON,J. (1978). RONOV, A. B. & KHAIN, V. E. (1962). Jurassic A Classopollis - containing male cone associated lithological formations of the world. Sovetskaya with Pseudofrenelopsis. Palaeobotanist, 21: geol., 1: 9-34 (in Russian). 847-856. SINITSYN,V. M. (1966). Past climates of Eurassia, DOLUDENKO,M. P. (1970). The genus Frenelopsis pt. 2. Mesozoic. Leningrad Univ. Press, 221 p. (Coniferales) and its findings in the Cretaceous (in Russian). of the USSR. Paleont. Zh., 3: 107-121 (in STRAKHOV,N. M. (1960). Principles of lithogenesis Russian). theory. 1. Isdat. Akad. Nauk SSSR, 212 p. DOUGLAS,J. G. (1976). Mesozoic climate in Victoria, (in Russian). Australia. Abstracts 25th Geol. Congress, 1: VAKHRAMEEV,V. A. (1964). Jurassic and Early 301-302. Cretaceous floras of Eurasia and the palaeo• HUGHES, N. F. & MOODy-STUART,J. (1967). Paly• floristic provinces of this period. Trudy geol. nological facies and correlation in the English Inst. Akad. Nauk SSSR, 102: 261 (in Russian). Wealden. Rev. Palaeont. Palynol., 1: 259• VAKHRAMEEV.V. A. (1970). Regularities in the 268. distribution and palaeoecology of Mesozoic coni• KHAIN, V. E., RONOV,A. V. & BALUCHOVSKY,A. N. ferous Cheirolepidiaceae. Paleont. Zh .• 1: 19-34 (1975). Cretaceous lithological formations of the (in Russian). world. Sovetskaya geol., 11: 10-39 (in Russian). VAKHRAMEEV.V. A. (1978). Climates of the northern KONDRATfEV,G. K. (1970). Distribution of Classo• hemisphere in the Cretaceous and palaeobota• pollis pollen over Pre-Enisean part of the West nical data. Paleont. Zh .• 4: 3-17 (in Russian). Siberian lowland. Geol. Geophizica, 11: 79-86 VAKHRAMEEV.V. A. & DOLUDENKO,M. P. (1967). (in Russian). Middle-Late Jurassic boundary as very important KOTOVA, 1. Z. (1978). Spores and pollen from changeover in the history of development of Cretaceous deposits of the eastern North Atlantic climates and vegetation of n6rthern hemisphere. Ocean. Deep Sea Drilling Project, Leg 41, sites Sovetskaya geol., 4: 12-25 (in Russian). 367 and 370. Initial reports of the Deep Sea WATSON,J. (1977). Some Lower Cretaceous conifers Drilling Project, 41, Washington: 841-881. of the Cheirolepidiaceae from the U.S.A. and KRASS[LOV,V. A. (1977). Fossil Araucaria from the England. Palaeontology. 20 (4): 715-749. Sahara. Priroda, 5: 65-68 (in Russian). YASAMANOV.N. A. (1975). Temperature conditions KRASS[LOV, V. A. (1978). Araucariacea as in• of Cretaceous and Paleogene seas.in Middle Asia. dicators of climate and paleolatitudes. Rev. Izvest. Akad. Nauk SSSR. ser. geol .• 12: 92-102 Palaeobot. Palynol., 26: 113-124. (in Russian). McLACHLAN, J. & PlETERSE,E. (1978). Preliminary YASAMANOV.N. A. (1976). Temperatures of the palynological results: Site 361, Leg 40, Deep Sea Late Jurassic seas of the European part of the Drilling Project. Initial reports of the Deep Sea USSR. Dold. Akad. Nauk SSSR, 231 (5): Drilling Project, 40, Washington: 857-881. 1206-1209 (in Russian).