Late Cretaceous Pollen and Spore Floras of Northern Japan : Composition and Interpretation

Title Late Cretaceous pollen and spore floras of northern Japan : Composition and interpretation

Author(s) Miki, Akio

Citation Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy, 17(3), 399-436

Issue Date 1977-02

Doc URL http://hdl.handle.net/2115/36072

Type bulletin (article)

File Information 17(3)_399-436.pdf

Instructions for use

Hokkaido University Collection of Scholarly and Academic Papers : HUSCAP Jour. Fac. Sci., Hokkaido Unlv., Ser. IV, vil. 17, no. 3, Feb., 1977, pp399-436.

399 LATE CRETACEOUS POLLEN AND SPORE FLORAS OF NORTHERN JAPAN: COMPOSITION AND INTERPRETATION by Akio Miki"

(with 12 Text-figures and 5 Tables)

(Contribution fyom the Department of Geology and Mineralogy, Faculty of Science, Hokkaido Uniyersity, No. 1479)

Abstract

For the establishment of floristic sequences, pollen and spore fioras from the Late Cretaceous sediments ranging from Cenomanian to Maestrichtian of northern Japan are studied. Four areas where the Late Cretaceous sediments are typically weli developed are selected: the Ishilcari coal field (the Campanian-Maestrichtian Hakobuchi Group), Saku area (the Cenomanian-Campanian Middle and Upper Yezo Groups), the Kuji goal field (the early Senonian Kuji Group) and the 3oban coal field (the early Senonian Futaba Group). Nine pollen and spore fioras two of which had been studied by previous investigators, are discussed. Based on fioristic composition and components, the four floras of Cenomanian- Turonian, Early Senonian, Campanian and Maestrichtian ages are distinguishable. The oldest fiora is characterized by diverse pteridophytes, particularly Schizaeaceous spores, and by less diversified angiosperms containing few porate pollen. The second has still the relic of Mesophytic appearance: pteridophytes are more or less superior to angiosperms in taxonomic diversity, containing commonly Schizaeaceou's and Gleicheniaceous spores. Of gymnosperm pollen Cycadopites, Monosulcites, Araucariacites, Rugubivesiculites and Class- opollis are common. Angiosperm are composed predominantly of tricolpate pollen, but are represented by few porate pollen. The third is characterized by the predomint angiosperms and also by diverse species of Aquilapollenites. Pteridophytes are sparsely represented in Schizaeaceous spores. The youngest flora is composed of a predominant porate pollen, which occupies a majority of angiosperm pollen. This flora is characterized also by diverse pollen of uncertain taxonomic position such as Aquilapollenites, "iodehouseia and Ocellipollis. These fioristic sequences in northern Japan shows thqt pteridophytes and gymnosperms forming the major constituents during Cenomanian-Turonian times were gradually replaced by angiosperms towards Maestrichtian time. Late Cretaceeus floristic changes of northern Japan are very similar to those of Eastern Siberia, especialiy of the Zeya-Bureya basin.

Introduction Cretaceous palyRology has been considerably advanced during these two decades, and has greatly contributed to paleobotany. A great deal of

* Present address: Fuyo Petroleurn Deveiopment Co., 1-6-1, Otemachi, Chiyoda-ku, Tokyo. 400 A. Miki palynological studies on the Cretaceous sediments of the world are revealing the precise evolutionary history of the shift from the Mesophytic to the Cenophytic plant Kingdom. Palynological investigations have revealed important information regarding the origin and early development of angiosperms (Couper, 1964; Muller, 1970; Doyle, 1969). Furthermore, recent studies also have revealed that sorne phytogeographical proviRces are distinguishable especially in Eurasia during Cretaceous time (Zaklinskaya, 1962.; Samoilovitch, l967). Based on the establishment of the floristic sequences, Cretaceous palynology has contributed to the exploration of petroleum fields. In Japan, paleobotanical studies on the Cretaceous have not been well developed in the fields of macrofossils and microfossils. Late Cretaceous terrestrial sediments bearing plant fossils are poorly distributed in Japan. Based on leaves, cones and woods, several important contributions have been presented: the Upper Yezo and Hakobuchi fioras in Hokkaido (Stopes and FuJ'ii, i909; Endo, i925; eishi, 1940), Oafai fiora in eastern Honsht} (Oyaina, 1956-61) and Asuwa and Omichidani floras in central }{onshu (Matsuo, 1962, l970). However, Late Cretaceous floristic sequeRces have not yet been fully established. The Late Cretaceous of Japan are composed mostly of mariRe sediments. Therefore, palynological investigations are expected to establish successive floristic clianges in both marine and terrestrial sediments. Sato (i961) published the first contribution to Cretaceous palynology in Japan. He reported on a pollen and spore flora from the Hakobuchi Group in northern Hokkaido with b!ief discussions and descriptions of some new species. Then Takahashi (l964) made an important contribution to the study of the latest Cretaceous microfiora: he revealed a pollen and spore fiora from the }{akobuchi Group in its type area, descfibing about ofie hundred species of pollen and spores. This polleR and spore fiora which represents Campanian to Maestrichtian microfiora in Japan is characterized by diverse Aquilapollenites. Furthermore, Takahashi (l967, 1970) described sofne spores aRd pollen from the uppermost Cretaceous sediments of Hokkaido. Since 1967, tlie author has investigated Cretaceous palynology in northern Japan, because the Upper Cretaceous sediments, both ofmarine and terrestrial origin, are typically well developed there. In 1972 the author described two early Senonian pollen and spore fioras from the Kujj and Futaba Groups of northern Honshu (Miki, 1972a, b). Subsequently he reported a CenomaRian to Turonian pollen and spore flora from the upper part of the Middle Yezo Group of northern Hokkaido (Miki, 1973). He has further investigated the early Senonian marine sediments, the Upper Yezo Group, ai3d also reexamined the Hakobuchi Group. Through these investigations from 1967 to 1974, the author LATE CRETACEOUS POLLEN AND SpoRE FLoRAs 401 could reveal Late Cretaceous pollen and spore fioras of northem Japan, which i-ange from Cenomanian to Maestrichtian time. Some important information is added to the evolutionary history of the Late Cretaceous plant kingdom, especially that of early angiosperm development. In this paper the author describes Late Cretaceous pollen and spore fioras, and briefly discusses fioristic changes. Taxonomical descriptions and discussions will be treated in the succeeding paper. Acknowledgement: The author is greatly indebted to professor Toshimasa Tanai and Dr. Selji Sato, Department of Geology and Mineralogy, Hokkaido University, for their constant guidance and useful advice in the course of the study. Professor Tanai has also devoted inuch time to reading the manuscript and providing inuch helpful criticism. Thanks are also given to Dr. Hajime Hayashi and Mr. Yoichi Yamada of Fuyo Petroleum Development Corporation for their encouragement to complete this manuscript. Acknowledgement should also be accorded to Mrs. Toshiko Watanabe for her help in preparing the typescript.

The Upper Cretaceous Sediments in Northern Japan The Upper Cretaceous sediments are well developed in Hokkaido, and are poorly developed in northern Honshu ([l]ext-fig. 1). In Hokkaido, the Upper Cretaceous is distributed along a long, narrow zoi}e in the ceRtral area of Hokkaido from Cape Soya in the north to Urakawa in the south. These sediments were formed during the geosynclinal stage of the Hidaka orogenic belt. The Uppermost Cretaceous is also distributed in eastern Hokkaido. In northern Honshu, the Upper Cretaceot}s sediments are distributed mainly in some small basins facing the Pacific, on the eastern foot of the Kitakami and Abukuma Mountains. These sediments are called the Kuji Group in the northem Kitakami Mountains, and the Futaba Group in the southern Abukuma Mountains. Small outcropped areas of the Latest Cretaceous sediments are have been discovered at Iwaizumi and Kado in tlie Kitakami Mountains, and at Oarai in eastern Kwanto, Honshu. The general stratigraphy and correlation of the Upper Cretaceous sediments in northem Japan are shown in Table 1 . ffbkkaido The upper part of the Middle Yezo, the Upper Yezo and the Hakobuchi Groups represent later stages of sediments formed in the central geosynclinal basin. The Middle Yezo Group which conformably cOvers tlie Lower Yezo Group of the late Early Cretaceous is predoininated by black shale in the lower part, and is variable in lithology in its upper part. The t}ppermost part of the Middle Yezo Group, the Saku formation in the northern part of the basin, is 402 A. Miki

1420

v o 4so Saku tw

ts HOKKAiOO Ashibetsu V u 6Zl r'i 4 NEMURO Hobetsu -

Kuji 4oo MIYAKO

a fb

l Futaba pai i oARAi l Z]2 Tok.yo CHOSHi 3so . O 200km nt Text-figure 1 Distribution of the Cretaceous sediments in northern Japan. 1. 0utcropped area of the Cretaceous sediments. 2. Studied area. composed of alternatiRg sandstone and siltstone. The Group is 2000 to 3500 meters thick and is dated from the late Albian to Turonian age by ammonites and Inoceramus. The Upper Yezo Group lying conformably on the Middle Yezo Group is 400 to 1500 meters thick, and is of offishore origin. It is composed of monotonous siltstone except for sandy sediments in the middle. The sandy part in the northern area of the basin is called the Otnagari formation. The Group is rich in ammonites and Inoceramus ranging mainly from the Coniacian to early LATE CRETACEOUS POLLEN AND SPORE FLORAS 403

Table 1 Correlation table of the Late Cretaceous sediments in northern Japan (partly arranged after Matsumoto, 1942-43).

Kanto NameofJreglon Hokkaido Tohoku Age (Dornestic) Naka- Ashibetsu- Futaba Saku Nemuro Kuji Minato Agetin YubaTi-Hebetsu oraraZrira

Hus zsts=Roftsza<} Hu4 gM -n Htt3 =9oe-BMOtu" Naka z$

Hu, gx zF<-qg9gYasukawaFm. Lower Hakobuchi '.F TFg,-j]I"gri=iA- tt-"--mTt-- Subgroup t."-anrmr .tu-Tt Fm. M

oA Osoushinai z$g:g9ok£asgp RM Fm. g9o:gMKunitan 92o3:g.n Fm. z<)

Tamayama z$U$zoU o" Fm. Ornagarl 8"£ sM Fm. Tamagawa Kasamatsu rcrr---JTm-u- (TsukimiF.)--tm.uLu- Fm. Fm. Nishichira- Askizawa shinaiFm, Fm. zsZo･tu･2

Saku RM z･ Fm. $Mg$%9's: Mikasa Fm. g2ooBbegpu-: R2oogptgp.: %iE8 gM Sagugawa Fm.

nF Sakotandake M Fm. ua Iaszi .8ge:9kU Shirataki Main Part RM Fm. Moehoro Fm.

* Hui : Lower Sandyshale Fm. Hu2 : Fukaushi Conglomerate Fm, Hu3 : Fukauxhi Sandstone Fm. Hu4 : Upper Sandyshale Fm. Hus : Sanushube Sandstone Fm.

CampaniaR age. The Hakobuchi Group conformably covers the upper Yezo Group, and is less than 800 meters thick. It is predominated by coarse-grained sediments inciuding conglomefate deposited in the shallow marine environment. In the 404 A. Miki central part of the basin the coal bearing terrestrial sediments are developed in the middle part of the fi[akobuchi Group. Based on ainmonites and fnoceramus, the lower part of the Group is assigned to the campanian age and the upper part to the Maestrichtian age. The sediments corresponding to the Maestrich- tian is unknowii in the Saku area in the northern area of the basin. AJbrthern jdenshu The Kuji and Futaba Grot}ps are composed of sediments formed by Senonian transgression, and are of neritic to terrestrial origin. The Kluji' Group: The Group unconformably covers'pre-Aptian rocks, and is 500 to 600 meters thick. It is dominated by littoral sediments such as sandstone aRd conglomerate in the lower part, by neritic fine-gained sandstone in the rniddle and by terrestrial siltstone and tuff in the upper. The Group is assigned to the early Senonian age, based on ammonites and Inoeeramus. The Futaba Group: overlying the Paleozoic system aAd pre-Late Cretaceous granite, the Futaba Group is of shallow marine origiR. It is represented by fine-grained sandstoAe in the lower part. The rniddle is predorninated by cross-laminated fine- to medium-grained sandstone with little siltstone. The upper is predominated by coarse-grained quartzose sandstone. The Group, approximately･ 300 meters thick, is dated from Coniacian to early Santonian by inoceramus.

Description of Pollen and Spore Floras The Late Cretaceous sediments in northern Japan raRge firom the Cenomanian to Maestrichtian ages, as described above. For the establishment of Late Cretaceous floristic sequences and phytogeography, the author has dealt with the following four areas where the sediments are typically well developed: the Ishikari coal field (the Campanian-Maestrichtian Hakobuchi Group), Saku area (the Cenomanian-Turonian Middle Yezo Group and the Coniacian- Campanian Upper Yezo Group), the Kuji coal field (the early Senonian Kuji Group) and the Joban coal field (the eariy Senonian Futaba Group). Cenomanian-71uronian Pollen and 5?)ore Flora Pollen and spore flora, called the Saku microfiora, from the upper part of the Middle Yezo Group (Cenomanian-Turonian) in the Saku area was preliminarily reported by the author (Miki, 1973). The Saku area is situated in the central part of Nakagawa town in northern Hokkaido (450N in latitude, 1420E iia longitude). In this area the Cretaceous sediments comprising the Lower Yezo, the Middle Yezo, the Upper Yezo and the }Iakobuchi Groups are widely developed. All samples were collected from sediments younger than the upper part of the Middle Yezo Group: only the two upper formations of the Middle Yezo Group, the Sakugawa and Saku, yield polien and spores, as shown LATE CRETACEOUS POLLEN AND SPORE FLORAS 405 in Text-fig. 2. The Saku pollen aiid spore flora is represented by l60 sporomorph species (Table 2): they are composed mainly of pteridophytes and subordinately of gymnosperms and angiosperms. Ninety-three species (S8 per cent of the total

1･i tt ･iN>. 'xt I 1 /1 .(r, . il ': i X.l sgl !1-11 t x, 1 i fit'Fg`lski'`t,li,ltli, ,f }clo(."N',[lhNN.... INcl :- t 1 IK'. .]il,gS.l･, ,..tt ･-g,r',y ttlt l 7t ; Lt tc'xrfi),

g.,o. /i, ilix"Iix.,tX,l'lk..Sl:/'fli iii/liti,. .N lt - l'-'-1 IX x Sk3 fik2ju1t lt iit l･,1 't ldJ'f t N .' '' V' k' s' :x Bl,I ･R..o. l: Nc Sx 5k tsxltl lil X: 1 Xl. : 1 x" N X"x di N.x X S-1. l:x -A "N )N,ilrj./isxl¥x rd i,, : ･i:. 1 hzk> ] s i,,, N l L t mt x, Ya o l ,] Nko" 1om "x N, p L, t IL e N,N ,' NX 'i, X /1, .,// .. xx 'X >.x t ' 1 Xl sL. li NOUXsl x xx; Legend X="' IN `'Ssx" IL>..xN(i xxX ag2 X :.ll, Tr: Tertia=y N Xuou ss NxX Yat ¥asukawa Ftn. X K X Ou; Osoush±nai Fin. NxxOM Sxx IIxX xX.x× Xx Om: Omagari Fto. Nc: I"shiehirashinai Ftn. Sks: Upper part o£ Saku Ita. Sk2: }(iddle pa=t oS Saku im. oti X XA : x xx Skl: Lower part ef Saku Ftn. ' ,'x ...... fL e Ky owA Sagugawa Fin. '':[ y Sg2: Upper part of k"o. :':, LS-""t,.X Sgl: Lower part of Sagugava fu. :e x Boimdarv of formations -Y"tslic7i7".i"Gsl"' )] x -'-'- (confomity). bst･･. Oeulldary of fo=mat±ons "/lx ii (uneonfomity). --- Eault s,.xl v

o 1 2km ao?"v> OU Xx, 'Xxs

p Text-figure 2 Outline of geology Saku in areathe (afterHashimoto et al., 1967) and locations of samples. Sgi: Lower part of the Sagugawa fm. Sg2: Upper part of the Sagugawa fm. Ski: Lower part of the Saku fm. Sk2: Middle part of the Saku fm.Sk3:Upper part of the Saku fm. Nc: Nishichirashinai fm. Om: Omagari-fm. Ou: Osoushinai fm. Ya: Yasukawa fm. Tr: Tertiary. 406 A. Miki

Table 2 Occurrence and distribution of sporomorphs in the Middle Yezo Group (revised after Miki, l973). Numbers in brackets are very simgar specimens and those with question mark are doubtful specimens. Cross mark shows presence of the species.

Formation )[IDDllE YEZO GROUP

SAilUaAWA FDRPIATION SA}C[I FDmxurION su no Ho Mo Saojp2 Samples st ou 9 : oou as rl ou 8HKorC) g){8be ts o cogtto$ cooft!o$ f!o$ tsg2!o$ tsgt!8m or8gwo oro of>Lo9 woof!8F g>! f>t F eDeea' 8wo F8e w w tg??etaon

M1 M-2 M-5 M-4 M-5 M-6 M-･7 M--8 M-9 M-10 M-ll M-l2 Stereisporitessp. 1? + 1? Lycopodiacid:Lteshamulatis 1 Lycopod:Lumspo=j.tessubreticulaeBporites + + L.cf.papillaesporites + + Ogrmmdaciditescomaunensis [B + O.wellmanii + + + + + Iodisporitesmajev (+) + + (+) + l AppendiciBpo=itestricomitatuBV.ntnor + (+) 1 (+) + A.cf.caucasica (+) + + 2 l A.cS.sUvestris (+) + A.undosus + 1 1 + + l (i) A.spp.Cicatricosisporitesaustraliensis + + 1 l + C.cf.aorcgengis l C.minuteaestriatus + 1 1 + + + + + 2 2 + + + + C.perforatus + + + + (+) C.tersus + + + C.subrotnmdusC.hughegi + C.breavilaesuratus (+) (+) + C.cf.exilioides + + + + e.cf.pgeudot=ipartitus' + + + C.trieostatus + + + + 5 1 1 KlukisporitesvariegatusC.spp. (+) 2 K.aff.pseudoreticulatus l (i) Iorgodiumsporitessubsimplex + + + Trilobosporitescrassus + + T.marylandensis + + T.trieretieu!osus + + + + + Pilosisporitessp.M.sp. + Schizaeoisporites?spp. 1 + Cleicheniiditescirciniditeg + G.delicatus 5 + 1 1 1 1 + G.Iaetus 7 1 + l 1 2 5 G.senonicug 2 1 G.sp.O=namentiferaechinata + Ilymenophyllungporitesdeltoida + + + E.furcoeusCyathidLtegaustralis + + l + + 1 C.minor 1 2 1 1 5 1 5 2 1 2 C.punctatus + + + Kuylispo=ites1unaris + rerilitesgimplex + + + + l T.taiiaii + I l + + 1 1 1 + 1 + + )CatoniBporiteBef.iwatensisT.gp. 1 DictyophyllidLtestazawaensis 1 + Laevigatosporiteghaamdti l 4 1 + l 5 + 2 + 2 2 2 5 2 AcanthotriletesvarispinosusL.ovatus l + + +1 A.sp.Aequitriraditesspinulosus Apiculatigporissatoii + l + l + 1 + 1 5 + A. sp. + BalrneiBpe=itessp. + Biretisporites?sp. + + Cingulatisperitesdistavervucosus l l + + I + + Concavisporitessp. [51 I + C.sp. ] Convermcosisporitessp. + }eltoiaosporacascadensis 2 + 5 (5) 5 + (i) 2 1 + + + ).halli I 2 + l + D.microfo=nna (+) (i) D.nodaense 5 + (i) + D.psilotoma + l LATE CRETACEOUS POLLEN AND SPORE FLORAS 407

M-I M-2 M-5 M-4 M--5 M-6 l(-7 lh8 l(-9 vaIO M-ll }e-12 I}ensoisporiteB velatus + + + + + Foveosporites cteleetus + F. cf. caxialis + + + + + + F. sp.A + + + F. sp･B + 2 + ge.Grariulatisporites gp.P variabilis (i) + 1 + + + + + J±mbo±spovites simiscalaris + ! + 2 + ! Laevigatosporites hokkaidoensis + 1 + + + beptolepidLtes venmcatus I Lophotriletes spp. 2 + + 1 1foneleiotriletes pamus 1 1 M. samuraihamaensis 1 + + l 2 2 + + + M. subcircularis + + + + + l (5) 2 + + + M.Perotriliteg sp. sp.a + + ?urictatisporites cf. enibetsuensis l + P. cf. pairvigi anulatus l l 5 4 4 1 + Rugulatispor±tes sp. + Stenozonetriletes radLatus + + + + S. ef. exupevans + + PolycinEptatisporiteB reduncus + + + + 1 + Ver=ucosisporites sp. + + Uvaesporites macgarttatus + Indetemined Spores 1 1 l l ] 5 2 2 5 1 2 Cycadopites spp. 51 16 50 17 4 26 l5 5 5 2 6 Monosulcites epakpos 24 22 2 45 8 4S 10 II 6 5 J 10 l4 51 ll I6 6 15 4 5 l I6 H.Vitveisporites spp. pallidus 5 1 1 + 2 1 2 I l + + Ai aucariacStes austra;is + 4 2 7 4 5 + 7 7 1 1 5 4 + 1 l A. Iii[Ebatus 6 Alisperites spp. l 1 4 l 5 4 5 AbieBpollenites sp. 5 1 + I 5 5 5 4 l 2 Abietineaepollenites + Pityesporites + Piceaepollenites 14 2 5 IB 5 24 45 21 23 l5 17 Podocarpidites gp. indet. l 1 + 1 PhyllocladLdites transiens l? 1 l 1 + l l 6 1 Rugubivesiculites sp. ±ndet. Inapertmpollenites spp. (Maxodiaceae- 64 40 77 71 95 91 Cupressaceae Cormplex) 61 29 59 19 I07 54 Inaperturopollenites micrcrugu[Latus + 25 29 ]o Inapertmpol!eniteB ? baculatus + 10 6 6 Inaperturopollenites spp. 5 2 2 1 1 2 2 1 1 ClassopolliB + CirculSna 9 51 J7 55 l5 12 I5 19 20 18 11 18 )lagnosporites ? ovalis m 9 + 6 + + 7 2 Equisetosporites spp. l 2 2 1 1 4 ! 7 2 2 Retitricolpites delicatus 2 l + 2 + 5 5 + 2 +? + 4 7 5 4 5 R.R. ct. Iepidus geogensiB , 1? 2 1 R. Bp.e 1 PsilatricolpiteBR. sp. debUis 1 2 1 2 + + 1 + P. meinohamensis rctundus 5 1 P. cf, Meinohamensis rodunctug 1 I 5 2 ] I 5 P. c£.ef. paarvulus subasper I F)raxineipolleniteB hobetsuensis 2 F. minutiretifomis l + + 1? 4 7 F. micvereticulatus 2 F. ef. elarrireticulatus + + 4 2 1 5 7 1 4 4 e 2 + F. sp. ･A 5 l + 1 rricolpitesF. sp. nininrus indet. 1 I + 2 5 m. psilaennus 1 5 5 1 T. cf. micrereticulabus + m. mpporneug + + + + T. angulolumSnosus + + + m. sp. -A + + + m. sp. inaet. I 1 Tricolporopollenites spp. 1 Vripopopollenites mnor 2 2 ] 5 + T. spp. + + Proteaeidites striatus + + + + P. sp. + Claxratipollenites sp. I Monoeolpopollenites pMugii 2 + l 1 1 l 2 + M. ct. kyushuensis + PeromonoliteB reticulatus 1 6 1 Utriculites visus 5 5 2 1 2 1 1 Incteterm±ned Angiospe]mae l 1 Indetemined Sporomo=phs l l 5 l l Total Specimens 200 200 200 200 2oe 200 200 200 200 200 200 200 408 A. Mil

species) are pteridophytes, 33 species (21 per cent) are gymnosperms, and 33 species (21 per cent) are angiosperms. As already published (Miki, l973), the Saku Microflora is characterized by diverse species of pteridophytes; they are composed mainly of Schizaeaceous spores, Cyathidites n'zinor, Gleieheniidites, 7'}'ilites. Laevigatosporites and Deltoidospora. In particular, Schizaeaceous spores are represented by more than 35 species, including such genera as Appendicisporites, Cicatrieosisporites, Klukisporites and 7->'ilobosporites. Furtherinore, Early Cretaceous spores such as 7'>Ailobosporites spp., .Pilosis- porites sp. and Granulatisporites dailyi are found, though rarely. Among gymnosperms, Cycadaceae-Ginkgoaceous pollen such as Cycado- pites spp., aiid Monosulcites epakros, Taxodiaceae-Cupressaceous inaperturate pollen aRd Classopollis are abundant. Mesopliytic coniferous pollen are corRrnonly found: there are six genera, Araucariaeites, Alisporites, Rugubivesi- culites, Classopollis, Phyllocladidites and Podoeailpidites. Though not common, the following Cenophytic coniferous pollen are also found: Pityosporites, Abietineaepollenites and others. Most angiosperms, represented by tricolpate pollen, are not very diversified. Porate pollen is found only from the Saku forrdation. Early Senonian Pollen and ,S?)ore Elora The pollen and spore flora from the Kuji Group, called Kuji microfiora, and that from the Futaba Grotip, called Futaba microflora, were already desciibed by the author (Miki, 1972a, b). These microfloras are very similar to each other in their floristic compositions aRd components. The pollen and spore flora from the Upper Yezo Group in northern Hokkaido, called Kyowa microflora, to be described later, is also correlated to the above two. All of these three microfioras are from the early Senonian sediments. Kuii Microf7ora The Kuji Group is distributed in the vicinity of Kuji City (400N in latitude, 1420E in longitude) at northeastern end of the Kitakami Mountains. The group is composed of three formations: the Tamagawa, the Kunitan and the Sawayama in ascending order. Seventeen samples were collected from the Keji Group as shown in Text-fig. 3, 4. 0ccurrence and distribution of pollen and spores are shown in Text-fig. 5. The Kuji mjcroflora is summarized as follows: l) It is composed mainly of pteridophytes, with subordinate gymnosperms and angiosperms. These three major taxa comprise S6 per cent, 20 per cent and 26 per cent of the total species respectively. 2) Pteridophytes include predominant Schizaeaceous spores, i.e. five species of Appendicisporites and four species of Cicatricosisporites, and Gleicheniaceous spores. A few Early to Middle Cretaceous elements such as Appendicisporites cf. tricornitatus, A. LATE CRETACEOUS POLLEN AND SPORE FLORAS 409

" +-++"+ V 671o2sOl + 66102818 ll･li:-11).s. .. . ,-i',SXpt ftfta4i6o+, + 111rntitl' -l :x. giilllillV + lg, tl,: ]'E2: i: tt,ki 6'i,. g-gi /.,. ,÷ # + 67i02.,05tX l..･,'X'Si>6iol2SQs ÷ + .L+.' .' ,- + +I:･ 1d -l: 1.ge-' :--urur-t-a K L. +÷ + 7Set,,･ .. I,i ' "+ + Mifiiltiiiiiiiiiii[i 111ilifiil --sX,67I02512liu + Il L"-kl,"l Gli xN Xx

'- r ijjj' N" ollLl Kuji "ifisleZiiill Kuji Bay iiipi t"f UIilLii/tauiili""iiVlivaiV"iiVilii11 1 ..-..rr." 1 + l1- + - :. ･:..;, '.'ll'..ixel ii ' 660827e9 'i': ++ s'.. .･･;:.ff: :i iiII ++++- i!i"vait:1' t/gl/i;l: +-+ -;1::::::- l -;c･:･:･:･.･,- L----+- i Tx'.'. + ++ v.N:; l [[[:]Il ttx.lf. Noda Gr. iIli)tllt.:[:･[L.Iill?:l"lli-l;i- T6eQ,41ur ee Sawayarna Fm. + .X [lll 1I] >.h Noda Kunitan Fm. -t' + t'--" I･1･Irr... i'1:･ ttt tt tt t- + -l- N..x-N. '÷I-Ils Tamagawa Fm. ++ ::. -. ･-'-!"-- 671o2901 Otanabe-Akkagawa Fm, +#" ww ･.'x 660B1509 - ' li',.c[1:llsll Granite O12345km

Text-figure 3 Geological map of the Kuji area (after Sawara, l967) with locations of samples. ethmos, Cicatricosisporites australiensis, (lyathidites australis, and 7)ilites spp. are found. There are some spores generally found in rather younger sediments, Late Senonian or Earliest Tertiary: they are Lycopodiacidites hamulatis, Reticulosporis sp., Reticuloidosporites repandus, Rzsciatisporites divergens, Punctatisporites enbetsuensis and Schizosporis scabratus. 3) Pinaceous winged and Taxodiaceous inaperturate pollen dominate the gymnosperms. Ctycadopites and Monosulcites are also commonly included. Mesophytic coniferous pollen such as Araucariacites, Phyllocladidites, Podocarpidites, Rugubivesieulites and Classopollis share important roles among conifers. 4) Angiosperm pollen is composed mostly of the tricolpate type; the porate type is represented e by only a few specimens of 7>`iporopollenites. S) Aquilapollenites evanidus occurs frequently within the Aquilapollenites group. Ocellipollis obliquus is encountered only in the Sawayama formation, but rarely. 410 A. Mil

"--rr.T-

66102818" ------'67102605 zoi:<2crota A---=-T LEGEND

Unconforraity vvvV t. t. .t t. .t .. tt t. tt .tt "-H-"--L" <2 vvvv Tuff ttt.tttt..tvvvvvm------Vvvv Vv-v-v-v-v 't' t. t. tt .t tt tJ .' .t Hmtt t ---rmm ---H-----:----:--:-H-t-- --wwnt-vvvvvvttttttt.tt.' < Sltt stone :-:==-=Hm-m- > " t-tttttttt.. +' .' rt':.'::.',. <9 H---vvvvv = tlttlt.t.t --Hm-mN-H--ve vvvvv tttttttttt. .t .t t. tt tt tt. t. tt H""---"m- .t tt tt tt tt < o ttt.ttttt Sand stone VVVVVV vvvvv---m------co ttttttttttttttttttttt "mt--mt-H"m-m- cr ttttttttttt ==.rr=tt..tt.t...t'=='.L.'='=n--n Congtomerate .67102512 o vvvvvv esSwmbO'v'.'vv"vvvvvv r::･':･･'･･tttttttt 66081502 Basement rocks tt " ++ tttttttt'Tww--Z"n m---nv- ttttttt r680416o2 ttt.t...tt. z

K s Ebrmation uj Gr ou p reamagawa FormatSon Lower gpper Sawayama eo!snation SaQ)p2es co or e wo or - en H ov el st ov ov as co m noouo-tw o o oFHstomn-anokO'onHcoowoo onHcooveonecoMtso o H owecoH>N tso o oum ut utH tsHstoto - as woNtfocowoHstodium co ou cuoHts ovoHF ouoHts rvoHtu rvoHts cuorlwo coov ve wo wo wo wo wo v wo wo wo wo ℃ e wo wo wo e m tr---- Stereisporiteslquosporitesant'''M' -"--- wa ----- gl------S.apolaris -im LycopodLaciditesampluBS.grcssus ------`"nd ------L.ha:rulatis Tl"f- ym-- OsmundaciditeswellmanSi ------O.adpinus i Todisporitesmajor ------Gleieheniiditessenonicus rondi mu ------tu ------± ------ww --v--T alaetus.a.eircinictttes ------G.marginatus p l ------G.cf.delicatus i --- ornamentite=acf.eehinata ------"- Appendicisporitescf.tricornitatus --l---i"" ----- "-- f"- -- -s---- -}- Aethmos.A.problematicus ---i-i l -b--- A.subtricornStatus l1'""" A.cS.potomaeensis ---- Cicatricos±sporttesaugtraliensis C.mediestriatus r"" C.cf.dorogensis + 1 ------1 Ischyo.sporitessp. 11 "---- C.sp.Retieulosporissp.A ------t--- Trllitessimplex .l- + -i- T.tanaii 1 --tg

T.sp.tt " l----' l CyathiditesaustralSs ------...-i. ------J"-H ----- { )(atonisperitegiwatensisC.ninor ------r---- t M.tenuiexinus' Laevigatosporiteshaardtx ------"------" ･--+- -...ua-...-..---.------i -"------!- L.ovatusPolypodlldrtessp,Attt ------l ---i-- I P.sp.BRetiouloidosporttesrepandus ------i-- + Baimeisporitestunutus ."-- I + BiretigporStessp. 1 ----

Ceratosporites?sp. 1 -p-- Cingtilatisporitesdistavermcosus ------1 l}eltoidosporacascadensis ----- pt d ------D.psilotoma ---- l D.nodaense ----- I-- .-..--.ma. --T------D.cf.vhytigma l MctyophyllidStestazawaensis ----i- Faseiatisporitesdivergens I ------eldi- ww

' l FoveosporitessawayamaenBis + ----- , Fbveospovitesesawadaensis ---" 1 de Granulatisporitesvariabilis ------Jimboisporiteskujiensis ------l- 1 J.simisca[taris ------" + hm + Monoleiotriletessamuraihamensis ---- ."J ------+ l ------i--- - -l-- t K.parvus ------t- M.sp.Punctatisporites e"ibetBuensis P. ef. sp.A embetsuensSs ?.Rugulatisporites sp.B sa[Lebresug Toroisporis sp. Dietcrverrusporttes simplex VvaesporiteB margaritatus Sohizosporig scabratus + Spore type A Spore type B Cycadopites cf. follicularls M.Monosule±tes simplex epakrcs Vitreispovites pa[Llidus .-.-- + Araucariacites australis - ÷+ + + PityosporitesA. Iimbatus piercei + Abietineaepollenites sp. + Piceaepollenites saccellus -= 412 A. Miki

?, F t" en wo en or pa tr pt pt zz om m?,I o o :fl oH M N m o Mzz l.- tso o pt oif-. oan o o o M ocF o - ov " w ¢ps mpa ca N gge gpt N Mtr Ntr auH diH N Htt Htt 8 o o g o o F[! o o o I tr-N H ano coo o H o H o o H - D ts 8 ¢ F ts o o ts wo [ LO kO to v LO o v w ov w v D LO o w Cedripites sp. l + Podocar[pidites ezoensis + I + Phyllocladidites traiisiens + l i + Taxodiaceae-Cupressaceae Complex ----rm Larleoidites sp. l a l･ Classopoll±s ezoensis i Rugubivesiculites cS. fluens ------±-- EquisetospoTites spp. -.---"--.- +l ....-- "'-`" i ...-.- Monocolpopollenites kyushuensis vr------T------l------l------th-]-i-+---H + -----i M. cf. universallis -t= l + ".H -'-'t'-"'-- i M.r{onosuleites pflugii perspinesus .+-..- l Retitricolpites vulgaris + -[ R. cf. prosimilis .-- -..H ------sw----I 1 R. Iepidus i II""' PsilatrleolpitesR. ?sp. meinohamensls meinehamensis l ---- .- i P. meSnhamensis rotundus ----" + + 1 --- ++ P.Cupliferoidaepollenites sp.A libTarensis fallax -.--:-]'---'-1:] F2]a)dnoipollenitesC. intrapunctatus hobetsuensis l I -･"H i F. microbaculatus l l F:L:-...... ""-.. ..H , ..... F. sassai +------l+------t-----]- F. minutiretSfomis - "･--- F. cf. retieulatus l I -]Y-- lt Tricolpitesge. baeulatussp.A I v """ T, nlpponieus I ."-- I l T. afS. psilascabratus 1l+ Tricolporopollenites sp. indet, '"""' i I MTiporopollenites shimensis I l.-...... Monipites hekkaidoensis + Agui.lapollenites evanidus - --H---- F---i -- OcellSpollis obliquus [ ericolpites?sp. /, l igllg: tyg:S I I '{ Sporomozlph type7 li -ffm-----1 --Tm- ...m

'-""- C).5 - 5.0% + P=esent (less than s.5 V'{,) 5･5 - 9･5 % N IO%-- Text-figure S Occurrence and distribution of sporomorphs in the Kuji Group (partly revised after Miki, 1972a).

nt taba microflora Futaba area is situated on the eastern foothills of the Abtikuma Motmtains in Fukushima Prefecture (approximately 370N in latitude and 1410E in longitude). The Futaba Group is composed of three formations: the Ashizawa, the Kasamatsu and the Tamayama formations in ascending order. Thirteen samples were collected as showii in Text-fig. 6. Futaba microflora was preliminarily discussed by the author (Miki, 1972b), and its floristic composition is sumiinarized as follows: l) Microflora is composed mainly of pteridophytes wkh subordianate gymnosperms and angiosperms (Table 3). Of 120 sporomorphs identified, 57 species (48 per cent of the total) are pteridophytes, 26 species (22 per cent) are gymnosperms and 37 species (30 per cent) are angiosperms. 2) Pteridophytes 4 13 LATE CRETACEOUS POLLEN AND SPORE， FLORAS 醤か巻灘量君十十十十毛十＋，＋、紅’ 十十÷十十一鉱…・※烈響｝護十十十＋十、．く’，層層’『・層■．．層．，■．・『・．・卜・7・．・’・：．P・．、十｛．．墾獄．一．「冨3窟君罫十1 十十斗十十 120 ← 6710210］L ← 67102205 十十÷十－ナ←．蚤．斗一＋、＋．＋家船k、 p 4 100 ’ ・翁コ十1十十十十÷十十十十、

」』盆憶、 … 80 捻十降。 68011006 偏一 6 68011007 、㌦ ÷ r ← 6θ041005 覧3、、一 60 ス御0伽3釦沖切⊂ 「3 サヒ・：・：・：・：＝『． 55㌦’．．9’卜’．層『｝㌔ハ．1 己圃．層層「r．．．．㌍．’ ・… ㌔三68。n。、。、。士68。、ユ。。9 ＿68011011’i・・．、∴．・・，． ←・ 67102202 悼：妻………難簿… 40 6801100g L・ U8Q工1006 ＋＋．気亟・ib・勇一恐… Ki七azawa’・，ぐ，．．．．’・．．

7・ @・．・．♂・，＋ 0・ikik・sen警÷ラ．》・て∴・1＝・’ P 「 ● 20 ロイ斗十「、一響寧坤彪晦輪！7 ■ 7 ， ■ 7 ■ ． ”『 Dン．ド ← 68041］LO］・＋＋＋＋甚ナ eτき、、・・，、．＋＋＋＋67．緬 ” ・t・靴：十十，＜ 680】ユ010 1’∠ 藩’ 0 680］．1011 繋 8 67102う0工七，i：蔑∴∵∴一．十十

’～：÷：・：÷：・．∵． ← 67102う04 ＋6夷噸…iiiii 1・∴ ・． g：∵∴∵∴∵ ＋一再喋9……≒ 。．、・，㌦・．・7・．’9’7」．’ ∵殴：・： ← 67102502 ・：・＼：・：：：：：：：：：l M 」一て． 67102501一メL …ii≡≡ 築・ 6・ず醒、、

・ ● ・、國i；書i態…i∵ 十十爺㌧、士。． ○ ．・ δ、弄ミAsh主z餌琶………・ 6 卿十十十十． 6 ．㌧ロバにぞ 2’？十＋十÷ 陰． ■ Cて‘＝必 t．，’一町しレ ”’．馬舟 Eみ〆∴ r7て㌦’・ア．・：・：・：・：・＝・．、三喜重Siltstone 十：：・二・：‘で：：：：：：二：：三詳∴iii： ’〈∴ 饗雛≡Fine Sand。t。ne ＋、、。。㎝。七。調ノ∵・

． rP 圏．P 7 ●、．

r・r．汀’Lπき．…「ボ∫F二轟「、

ソぴり．▽v》ド▽vv Tu聾げげ ∀ V 》［「Une・PQsed 。1，；i‡’ 67102101

ロロサマのリヤドドへのヒコ：：：：：：：1：Tamayama Fm・．．：醗、！ll、．

≡ii≡・i…P ． ●．’∫・：・：・：・： ’・：・： ≒i…iiii Kasamatsu Fm． ’～：・：・：・：幽幽・：・匡垂ヨ・・・…w…．・退・ill…◎…：

Text－f量gure 6 Geolog重cal map of the Futaba area（after Iwao and Matsui，1961）with locations of samples and columnel section a重Kitazawa with horizons of samples． 414 A. Miki

Table 3 Percentage distribution of sporomorphs in the Futaba Group (revised after Miki, l972b). Question mark sliows doubtful specimens. Cross mark shows presence of the species.

POrTRation wrABA GRO[ff)

Ashizawa Ftaa･ Kasamatsu Ftn. Tamayama Fta. ooori HoHN NoN'Lou MrioH oHo" NoHH ou nooH ts asoecou SatPples ecobCXov stoN'tou orooH oouou ooH

st ocowo oHFe oHtsv oNtswo Hocowo Hoenwn stocowo Hocos oHFm ocowo H Moco℃ oNFD oHtru tt 1e StereisporStes?sp.inaet. O.5 i + LO 1 Lycopodia¢iditeshamulatis 16.5 Lycopoaiaciaitessp.A,B l 1 IO.' Camanczonosporitesrud±s l Lycopodiumsporitessubreticulaesporites i2-5 o.5? 2.0 I.O I Osnnmdacidites?sp. l Wodisporitesndnor LO ' l1.5 l.O l Appendicisporitescf.tricomitatusV.cf.ntnov + O.5 i O.5 + 5･5 L5 l.O l Cicatvicos±sporitegaustraliensis l + + O.5 O.5 1 C.cS,australiensis l2.5 + 1.0 + ' C.huguesi l L5 O.5 + l CicatvieosiBporitessp.tndet.C.ninutaestriatus O.5 1.0 1.5 + o･s l.O 1 Retieulosporissp.B l O.5 1.0 l 1.0 O.5 l ].o Gleioheniid±tes!aetus O.5 ± 2.0 l Q.cf.delicatusAff.Gleicheniiditesgp. 2.0 O.5 l ? Cyathiditesaustvalis l+ + + E 1.0l O.5 O.5 1.0 l 2,O IL5 1.0 O.5 urrilitessimplexC.ninor 5.0 I.O l2.5 M.tarlaii O.5 LO + l + l.O + O.5 }Catonisporitesiwatensis l O.5 O.5 2,5 + 5･51i6.oi Matonisporites?sp. O.5 O.5 Laevigatosporitesovatus LO 1.0 2.5 17･o I.5 2.0 L5 s,e 5･S 18.0 2.0 l.O l2.o O.5 5.0 5.0 8.5 2.0 LO i L.haardtiAequitriraditesspinulesus + + + ApieulatispoTIssp. 1 O.5 l Balmeisporitesholodictyus 1+ + l t O.5 1.e l Baculatispor±tes?sp.B.ninutus Ceratosporitessp. l I.5 5.0 1.0 1 O.5 Cingulatisporitesdistavemmcosus LO ' l Crybercfiporitessp. i L5 1.0 )eltoidesporanodaense 5･5 l g O.5 l D.cf.nodaense E 9･5 l.5 D.cascadensis 5.0 l ).halli O.5 l L5 d 1.0 D.aff.halllDeltoidosporasp. 1.5 i l.O I Densoisporites?sp. + l i + DistaverrusporitesBimplex + i Poveosporitesintrabaculatiformj.s +i 2.0 Poveosporitessp. + + l JimbeispoTStessimiscala=is l + + LO O.5 + l 6.o Lygodieisporitessp. i O.5 e Monoleiotriletessamuraihamensis O.5 1.5 5,O L5 L5 ' l 5･5 M.cf.sanTuraihamensis 1.0 ' M.purvus e I.O 15･5 M.ef,.UmuS + 1.0 + l I M.subci=cularismacroletieulatisporitessp.indet. O.5 Perotrilitesspp. O.5 1 O.5 ' Punctatispori±･esaarie-nnis O.5 l l O.5 O.5 Punctatisporitessp. I+ l Vorcisporissp. ' 1.0 1 t i.5 O.5 Uvaesporitesmargaritatus 1 Verxucosigpoyitessp.indet. O.5 [O.5d2.5 SporetypeB E2.0 l.O Spo=egen.etsp.indet. O.5 O.5 ].o L5 4.o 2.0 L5 O.5 1.0 i l 1.0 CycadopitescS.follicularis O.5 i O.5 1' o.s O.5 7.0 O.5 C.gtganteus l l.O O.5 l,O 1116.5l Cycadopitegsp.C.parvus 2.5 1i 1.0 Monosulcitesepakros 2.0 9･5 15.0 7･5 2.5 5t5 5.0 M.Iongus 1.0 1 2 5 4 5 6 7 8 9 10 11 l2 15 LATE CRETACEOUS POLLEN AND SPORE FLORAS 415

Spovemorphs 1 2 5 4 5 6 7 B 9 10 11 12 15 Monosuleites spp. LO O.5 10.0 O.5 O.5 l.O O.5 2.5 2.0 : 1.0 O,5 l O.5 V±treisporites pallidus . I(O.5) Araucayiacites austraUs LO LO1 + 1.5 4･5 F 7.0 1.0 5.0 5･5 4.0 1･5 l O･5 ].o A. Iimbainis 1 i M)iespollenitea sp. o.5 1 AbietSneaepollenites Bp. 2.5 1.5 1 Piceaepollenites saccellus 2,O 2.0 1,o I 2.5 I.5 O.5 4･5 g 5.0 Pityespovites al±£omis 4.0 I 6.0 5.0 4.o 2･5 1 11.5 11.5 7･S ]･5 21.0 l l P.Pityosporites piercei spp. + O.5 I 2.0 2.5 1.0 Pityosporites + Abietineaepolleniteg 2.5 4.0 I 1･5 6.5 1.5 l 27.0 Bivesiculate Pinaceae gen. et sp. inaet. 17･5 2.5 4･5 5.0 4.o 6.o 20.5 2.5 l.O 20.51 1.0 LO l rosugaepollenites sp. o.s + l Iarricoidites sp. l 5-5 1 PodoearpidLtes ezoensis O.5 l + 1 PodocarrpidLtes sp. l O.5 O.5 LO + 2.0 Phyllocladidites transiens l L5 + +1 Itugzibivegiculites fluens 6.0 l O･5 l.5 IO.5 5t5 6.0 O.5 4.0 l5･5 5.0 1.0 1.0 1.o 12s.s Inaperturopollenites laevigatus 46,o 29.0 16,5 l14･5 7･5 s.o 2.0 14･5 6.o 8.0 4.0 l.o 1 1･5 O.5 2.0 l.s l ClassopollisI. pseudodubius ezoensis 5.0 6.o 7.5 26.5 L5 2.0 21 .o 18.0 Sl.O 6.s l Equisetosporites spp. 1.0 2.0 O,s I 1,O l.5 2 .o 5･5 O.5 5}5 LOlL5 i l Retitricolpites delicatus O.5 1 2,5 LO 1.0 1.0 1.0 O.5 1 R. Iepidus l,O 2.0 l O.5 O.5 1.5 1.0 l.O 1 O.5 ll.O R.Retitvicolpites milgavis Bpp. + O.5 I O.5 O.5 22.5 1 o.5 l.O Psilatricolpites debilis o.s 1 1.0 O.5 O.5 2.0 1 LO 5.0 1 O.5 O.5 1 O.5 P. meinohamensiscf. ditiB rotundus LOg 1.0 1 P. mLnutissimus O.5 l O.5 l P. cf. parvulus l l 1.0 O.5 1 1 O.5 P.Psilatricolp±tes s±mplicissimus sp. A 1 Cupliferoidaepollenites intrapunctatus 2.0 1 O.5 4.0 C. Iibrarensis fa!1ax 1.0 1 1 Fraxino±pollenites s]. E L5 O.5 l 2.0 1.0 I.5 4･o I 1 o . i' + I F. hobetguensis 2 o O.5 l 1.5 . l ff. cf. ninutus l 1.0 O.5 L5 . o + IO.5 O.5 F. tunutiretifoirmis O.5 l F. tautabramaensis rudis 1 l 2.5 Ftraxinoipollenites sp. indet. O.5 1.5 1 2.0 + O.5 O.5 o.s l O.5 Clavatrieolpites cf. prclatus 1.5 l 1 Tricolpites ninimus l 9.0 L5 l.5 + 11.0 2.0 D. psilaBcabratus O.5 l O.5 1.0 1 O.5 M. hironoensis 1 2.0 f l o l.5 l.O 7,O M. nipponiaug - 1 Z5 l l 1.0 l.5 Tricolpites ? sp. 2.0 . o 5･5 i 7･5 + o.5 l o O.5 O.5 l erricolporopollenites sp. indet. . O.5 l O.5 + LO O.5 l.O Mnipollenites eninens I Triporopollenites shimensiB O.5 1.0 l 1.0 Triporopollenites ep. indet. O.5 l l +t Car]rapellenites chikuhoensis 2.0 l Cf. Mliacidites dividuus l 5.0 i l Spinizonoeolpites eehinatus O,5 O.5 O.5 t Monocolpopollenites kpsshuensis l,5 5.0 i 4･5 8.5 1.0 1.0 I54.0 6.0 O.5 2.5 1 O.5 lL5 5.0 M.Monocolpopollenites pflugii sp. indet. LO r 1･5 O.5 O.5 l.O 1.0 5.0 L5 l Peromonolites cf. reticulatus 0.5 t O.5 i O.5 2.0 1.0 l.O Ericaceo±pollenites sp. i I l.O l 1.0 Angtosperm gen. et sp. inaet, O.5 I O.5 Sporcmomph type 7 5.0 1.0 l L5 5.0 t Indetermined sporomorphs 5･S l O･5 f Total specimens 200 200 200 2oe 200 200 200 2oo 200 200 200 200 99

are characterized by diverse Schizaeaceous spores, including three Appen- dicisporites species and five orcatricosisporites species. It is also noteworthy that they contain several species generally identified in the Early to Middle Cretaceous, i.e. Cieatricosiporites hughesi, Cyathidites australis, Aequitrinadites spinulosus aRd Densoisporites velatus. 3) Gymnosperms are characterized by the predominance of Cycadaceae-Ginkgoaceous pollen, Pinaceous bivesiculate pollen, Taxodiaceae-Cupressaceous pollen and Classopollis. Gymnosperms are composed of eight geRera of Mesophytic pollen and six genera of Cenophytic. 4) Angiosperms are characterized by being sparsely represented in porate type species by only a few grains of CZzryapollenites, Alnipollenites and 7}'iporopollenites. K)vowa microL17ora Kyowa microflora was obtained from the Upper Yezo Group in the Saku afea, which is composed of the following three formations, the Nishi-' chirashinai, the Omagari and the Osoushinai. Seventeen samples were collected as shown in Text-fig. 2. Kyowa microflora is named after the sampling location, Kyowa village. Microflora is dominant in both pteridophytes and angiosperms with nearly equal frequency,'but is less. dominant in gymnosperms. Of the 146 sporomorphs identified (Table 4), S6 species (38 per cent) are pteridophytes, 36 species (2S per cent) are gymnosperms, and S4 species (37 per cent) are aRglosperms. The characteristic features of Kyowa microfiora are summarized as follows: 1) Pteridophytes are represented mainly by Gleicheiiiaceous spores of the Gleicheniidites group and Deltoidospora nodaense, and Cyatheaceous spores of dyathidites minor. Schizaeaceous spores are sparsely represented. 2) Gymno- sperms commonly contain Ginkgoaceous pollen of the Monosulcites group, Taxodiaceae-Cupressaceous pollen such as Iitaperturopollenites laevigatus, , and Pinaceous bisaccate pollen. Gymnosperms are composed of eight Mesophytic genera and seven Cenophytic ones. 3) Angiosperms are markedly charact'erized by very diversified tricolpate and less diversified porate pollen. The appearance of some new types of tricolpate pollen with strioreticulate aRd foveolate exine for the first time is noteworthy. 4) Several species ofAquilapollenites are pfesent. The early SenoAian pollen and spore flora is geRerally eharacterized by remaining Mesophytic appearaRces. Pteridophytes are more or less superior to gymnosperms and angiosperms in number of species. Late Mesophytic pteridophytes, the Schizaeaceae and the Gleicheniaceae may characterize the early Senonian flora. Both Cycadaceae-Ginkgoaceous and Mesophytic coniferous pollen, including Araucariacites, Classopollis, Phyllocladidites and Rugubi- vesiculites, share important roles in gyrnnosperms. The tricolpate type is predomiRant in aRgiosperm pollen, while the porate type is less developed. OR the other hand, latest Cretaceous to earliest Tertiary elements such as Aquilapollenites are even less diversified, with only several species. dampanian Pollen and Spore Flora Pollen and spore flora from the Lower Hakobuchi subgroup was called the Lower Hakobuchi pollen fiora by Takahashi (1964). The author reexamined it, LATE CRETACEOUS POLLEN AND SPORE FLORAS 417

Table 4 Occurrence and distribution of sporomorphs in the Upper Yezo Group. Numbers in brackets are closely similar specimens and those with question mark are doubtful specimens. Cross mark shows presence of the species.

Fbrmationkc- UPIERYEZOGROUP xNpgl･iii,,lik ITISHICHIRASIIIAIiN. er{p.GARIm{. OSOUSIIIIIAIMC. "omou"omwonotocutsaco" FooroubocouteeaecFoanwo o-ooNtsoooodNcuNoeee"aspabeocoovHenewbeocow t"AFsu"odiut rtoasNtseureemomcuFocowo enooroutsocoocuotroutsoobewhHcooutsecowo co asHassutvom"stoenNNoots × elmouFodi"

ation V-･1 U-2V-5 v-4 V-5 u-6 U-7 u-s U-9 V-10 V-UU-l2 U-15 V-14U-IS u-16 U-17 StereieporiteHantiquospariteB

S.aporalie lIi/tdit+l1iIIi++,+L lyeepeaSumsporStessubreti¢ulaesporites BaeulatisperitefieemaumensisL,retieulumsporites OsmundaeiditesvellmHnii],vallidius Todisporiteemajor +ioI+//tt+,[11lI+1+c' Append±cisper±tesef.trieomitatuET.mlnor A.6ubtri¢omitatuE A.sp.tndet,CicatricosisporitesaustTaliensiE C.perforatusC.hugilesi 1lll]++e+''li!2 aleicheniiditefisenomeusC.gp.lnaet, 2:l6121:･:]ill+;2',1,t1+,i11++,i G.civeiniditesG.Iaetus

G.ef.delicatus +i.[B2.ilil.li1221-{]],1+6l12+/i+i++i+2+Ili/+2f'62S6]4,171i8?11sr)622r Ornamentiferaechinata I)eltoidogporanodaense Cyathiditeeaustralis "irSIStessimplerC-mlnor "l,ef.simpkexml.tanai± l{ateniBporiteuiwateneiB l{.magnueLaevigatesporiteshaandti L.ovatueReticuloidosporitesrepandus Leptolepiditesc£.tenuis l521 Apieulatispor±teesatoi Balmeisporitesminutus 11.lli+I1/FE+ CingulatSspori±esdistaveriucesus +/i+?+lll+2,1''/g11i/+tt{+t D,halliDeltoidesporacascadensie D.sp.I)ensoieperitesvelatue Dictyophyll±ditestazawaenBis )istavermlsperitesuimp!exD.sp. /iEt,+l,+-'iF1 Ibveesporitestntrabaculatifomis GranulattaporitesvaliablligF.sp. JimbeispoTiteseimSsealarts VfonoleiotrileteEparvus M.EubeireularisI(,satmnraihamensis 1+1: llevesiBporitesHp. PerotrSlitesBp.indet. +I+?s+++t1+ imatatisporitesembetsuensie (+)t,1+a,+i'++l+,1++i/:t/+tt++1+,,.+++1+ P.er,parvigTanulosus ffriporeletessp. itugulatispe=itesealebresus StYXEP. PolyoingulatisporitesredEmcus Sporegen,etsp.indet. g.ef.gtganteusCyeadop±tescf.fragilis i,1+;+:1, C.cf.scabratue Monasuleitesepal[ro6C.spp. M.fusSformiH 4024l555547I21]T21i19]T72219142l+1?ti' M.praeaeutusM.Iongus 25]261±l162i41444++++ M.sinplex :;i::},iZ}'}i.:;.4i+1++1:+l+++111'lll2],11+1al]'1+4+]2:4÷25ll]111]2,6Sl4456l41i2l+,2dS1Illl2+Sel2t524,1926T51[1,{1)d/2]4]T.1s6issgi22665T214+dl!129281eO447789ISTTI91,ID2eO?49S9}11625,i+ll M.spp.Vitreisperiteepallidus Araucariacitesaustralis A.Iimbatus A.?sp.Ab±espollenitessp. A.sp.BAbietineaepelleniteusp.A PSeeaepollenitessaeeellueA.sp.inaet.A,sp.C PityosporStespieraeiP.sp.inaet. P.sp.CP.alifornis BiveBtculatePinaaeaegen.etsp.indet,P.sp.indet. LarieeidStessp.indet. I.pseudedubiusInaperturopolleniteslaevigatus 418 A. Miki

U-1 U-2 . u-s u-4 v-5 u-6 v-･T u-e u-9 U-10 U-ll if-12 V-1} U-14 U-15 U-16 U-17 d Sequoiapellenites parvipapillosus b+ ' + 1 Podecarp±aites eEeensis + + + +[ ' + + 1 P. ep. indet. lt b + PhyllecladiMtes transiens l 12 2 11 2 1 l 2 1 2 2 4 6 + 14 PhyllocladiditeB parwns 2 + 1 2 l 22 '2 1 + + 2 1 i +l ' ibegubivefiiculitee ef. fluens + + + +l d l 4 2 4 1 ] + Inaperturepollenites sp. indet, 1 1 ] +5 t +p+ t 1 2 ClaHsopollis ezoensSs IS i ] l2 2 15 , l4 15 7 15 2] 20 6 1 12 l 6d2 d 2 CL SP- 1 Eguisetesperites an1±icostatuH l+ I 4 2 +: 1 1 2 1 2 E. sp.) I+ `+ E. sp.C + i I: + 2 + E. sp.n 1 + + 4 1 1 11 l 1 1 MonosuleiteBE. Bp. pergp±noEus±ndiet. l･l + Palmaepollenitee sp. 1 + 1 1 Liliac±dites ef. peroreticulatus + E l+ L. sp.A l + 1 4' L, sp.B ± l L, ?sp. , 1 Monocolpopollenites kyuBhuensls l 4 5 2 5[ l + 1 1 l2 l 1 1 M. pflugii li2 1 + M. shuparoenBiH 1? 2 2 li l il + l N.Retimonocolpitee sp. inaet.? up. indet, 1? 1 l I? Alnipollenites eminenfi 1 i Monipites eonstatus l + l I + l l 2 M. hoklcaideensis 4 1 2 + + l ] ] ÷ l M. 8P- ++ l, l? Retitrieolpites del±aatus 2 + 1 1 ]l6 6 2 1 1 2 R. ce. georgengis +1 , R. lepidus 2 1 2 ] + 1!4 5 1 2 s 2 5 s l ' 2F5 R. vulgaTis + ,2 2 + 2 1 R. upp, 1 o) [ 1+5e l l ClavatrlcelpltpR prolatuB + d+ + l+ 1 PsilatrieolpStefi diebilis l 4iT ] i 1 1 P. meirs:hdmensiE meinehamensis ] l? g P. meinohamensSs rotunduB 1 2 4 i 1 1 2 l P, ninutiEsSmuu 1 c P, ef. parvulus s 1 ] li 1 l2 P. subasper l d + P. EubpunctulatuG 2 1 ! I 2 P. sp, A + 5 2 l ll 5 l 1 2 1 Cupliteroidaepellenites librarens±s falla)[ l c. intrapunetatus l l Fboutnoipolleniteu hobetsuensis + 1 1 F+ + le 1 4 2 F, nicrobaculatuE 1 1 5 1 ) l 51 2 4 + 1 2 F. nicroclavabes l li p. microreticulatuH 2 + L 1 (i) i F. minutiretifomis 2' l II] I + + + F. nicrofoveoteticulatus +l + F. reticulatus (1} 1 ` i+ + 1 F. sassai 2 d2 l 2 16 1 1 il F, tEu}cimiensSs ts ( + P. sp. A 5 8 T 1 ls 1 5 5 6 F. sp. indet. 1 2 5 2 li]4 l II 2 1 1 5 1 2 Trieolpites minillitle l g 1 2 T. pBilaextnus 2 + I: E T. psilascabratus 1 l +14 + 1 4 1 m. nippenicus l + i + l + , l 1 as- striereticulatuH 21+ i + + r. et. nicrcreticulatue + t { 2 1 1 m. sp. A + i12 2g+ as. sp, inaet. l 2 Erieaceeipellenites ? sp. , 1? J Aquilapollenites hakobnehiensSs d + ` i 1 A. r±gidue + 1 l 1` + 1 2 A. ef. rigidus +l A, evmiaus 2 + + + +, 1? + li+ + + + + + 4 + A. sp. B + I+ I A. sp. indet, l 1 , l 1 Periperate type pellen 1 i Moneporate ? pollen L 1? Angiesperm gen. et sp. indet. , , 2:1 1 Utlieulites v±sus t il Angtosperm ? pellen 1 ] t! Sporomorph type 7 1 2 +2 2'1 i 1 Total 2oe 2oe 200 200 200 200 2oe 2eo 200 2eo 2oe 200 200 200 2oe 2oe 200

based on samples from three localities in central Hokkaido. An assemblage frorn the Yasukawa formation, contemporaneous with the Lower Hakobuchi subgroup in Enbetsu, was reported by Sato (1961). The author also investigated an assemblage from the same formation in Saku. These assemblages are very similar to that of Lower Hakob"chi pollen flora in composition and components. The pollen and spore assemblages from the Ylrzsukawa formation in the Saku area The Yasukawa formation locally distributed in the Saku area is similar m LATE CRETACEOUS POLLEN AND SPORE FLORAS 419 lithoiogy to the Hakobuchi Group. This formation is inferred to be of Campanian age, based on ammonites and Inoceramus. ORIy two samples were collected from the Yasukawa foimation. Occurrence and distribution of sporomorphs from them are shown in Tabie 5. The sporomorph assemblage is predominated by angiosperm pollen, aRd is inferior in pteridophytes and gymnosperms. Pteridophytes contain Laevigatosporites haardti, L. ovatus and Gleicheniidites senonicus. Monosulcites group, 1lf. epakros and others, and Phyllocladidites transiens are the main elements among the gymnosperms. Among angiosperms the tricolpate type is superior to the porate type. The assemblage is markedly characterized by the diverse and abundant polleR of the Aquilapollenites group with 12 species and 42 per cent of the total angiosperm pollen grains. The assemblage investigated by Sato (1961) was from carbonaceous rocks collected a few kilometers west of the locality mentioned above. It contains very abundant monolete Polypodiaceous spores aRd Ilasciatisporites divergens, commoRly Punctatisporites enbetsuensis, and rarely dyathidites minor and Appendicisporites subtricornitatus. It also coAtains abundant pol!en of the Taxodiaceae and euercus sp., and commonly contains Betulaepollenites. Phyllocladidites transiens, Podocarpidites ezoensis, Alnipollenites, Aquila- pollenites hakobuehiensis and A. eretaceus are found, though rarely. Lower H17kobuchi mieroflora The Upper Cretaceous sediments ranging from the Lower Yezo Group to the Hakobuchi Group are developed in the Ishikari coal field and its southern extenslon. . Three well-developed sections of the Hakobuchi Group were selected for the investigation: Ashibetsu, Yubari and Hobetsu areas. The Group is divided into two subgroups, the lower Hakobuchi and the Upper Hakobuchi. Twenty samples wefe collected from the Lower Hakobuchi subgroup: five of them were from Ashibetsu, Rine frorn Yubari and the rest frorn Hobetsu. Their localities and stratigraphic positions are shown in Text-fig. 7, 8. Of 169 sporomorphs identified (Tabale 5), 56 species (33 per cent) are pteridophytes, 36 species (21 per cent) gymnosperms, and 77 species (46 per cent) angiosperms. The Lower Hakobuchi rnicrofiora are summarized as follows: 1) This microfiora is characterized by predominance of angiosperm pollen. They occupy about half of the total sporomorphs in terms of number of species and specimens. 2) Except for Gleiclzeniidites senonicus aRd Cyathidites minor which appear with low frequency, Schizaeaceous spores are quite scarce. On the other hand, Osmundaceous spores are comparatively dominant. Some pteridophyte spores such as jFlasciatisporites divergence, Monoleiotriletes 420 A. Miki

di b) a) I LI c) ASHIBETSU ka dt .fi yueARI VK a 2 e `a 1 ii:' ;1 LL s si Pg lt ,tlt tMdiIZan R. 7207ogo7-gl : ¥u Sx Ntttt 2goZ!Ai=. K'x i,k `,ykNx )±N 'N.,.Yu NsNt i, eLtz) Hk-･96 ,,,,tlltliiilllill,IXk,'iiM¥,:,gi 70070515-V6 of }lk-･90 t Reb 7Xt tLs e uxlh. Pg }llt-B6 rmTsukimiBawa [a 8 }Ik'"58 Hk-54 Yu Ni. g lllc-･45 Hkx.ss x "o N k/ ueIi61

O-t4Skm e s lokm O Skm Text-figure 7 Locations of samples from the Hakobuchi Group at a) Ashibetsu, b) Yubari and c) Hobetsu. Yu: the Upper Yezo Group, Hk: the Hakobuchi Group. Pg: the Paleogene Tertiary. Ng: the Neogene Tertiary.

samuraihamensis and Punctatisporites enbetsuensis are found through all the samples. It is noteworthy that there are Lycopodiacidites amples and L. hamulatis though rare: these two are commonly found from the Maestrichtian to the Eocene of North America and Europe. inundatisporites tbmiuchiensis is restricted to the Lower Hakobuchi subgroup. 3) Among gymnosperms, Cycadaceous pollen such as C)2cadopites, is encountered occasionally, while Ginkgoaceous pollen such as various species of Monosulcites freq"ently occur. Five genera of Late Mesophytic coniferous pollen, Phyllocladidites, Podocar- pidites, Araucariacites, Rugubivesiculites and Classopollis, are found, though their occurrences are quite few except for the first. On the other hand, six genera of Cenophytic coniferous pollen are present; Pityosporites aRd inaperturopollenites are particularly abundant. 4) Angiosperm pollen is characterized by diverse tricolpate type with high frequency. juglandaceous and Btulaceae-Myricaceous porate pollen show medial to low frequency. Tricolpate pollen is far more domiRant than porate. 5) Diverse species of Aquilapollenites, Orbiculapollis, Ocellipollis and Cranwellia, especially l3 species ofAquilapollenites, are characteristic. The above-noted distinctive features of Lower Hakobuchi microflora are commonly observed in all the Campanian pollen and spore fioras of northern Japan. Maestrichtian Pollen and S?)ore Flora Pollen and spore flora from the Upper Hakobuchi subgroup, called Upper Hakobuchi microflora, was reported by Takahashi (1964). A pollen and spore 42l LATE CRETACEOUS POLLEN AND SPORE FLORAS

? HAKOBVCHI SUBGROUP 8 o R ets & to

dILssI""1]"rl"TilHlue/v.

/f･/ .iil･]･1,;l';:;･:{'iliiIIil/11, //t./II,li"{'rJ"Ilr/.tt/tft./.1t"l/4/t., IIIII:)El >7>">s,/:/:/llt: ;`lol"ll/11.ili･'lli'; IIIIIIIIi,i!IIilili '' ttttttt I:l"4a:,' il1s -.,r .:l ,l ttt "F"m' tttt }}'}' .v /ttt ee･lz･k･,i/iliiill.i,i,i-l /1.::///..//.ttttttttt/t i/ IHI tt ,;:･ft/tt/tt 'lli'- t/t lllli /t/,J.T ,!,IPii .tt ttttttttt/. Er.･/･; tt T

-UPPER HAKOBUCHI SUBGROVP LOWER

co o w?" en it Tm. T" pt repa co rc conF co,H o o o 8 ts ts oots"- p o o oo kg tso tv tso ootsts I 1 1 l'si,

:'iz･ /tt/ :,:..ttt' ;:J;...: llll,l,.,.,l･ tt. /il1･.,. l.iilltili ;:.:.;./..::;, : :tt.// :t:.' t./ l･i-lil,1･//i,.: '-i'IIf o=O ::-;::'e/tt't/'t l,giliii±illl･liii･l,lij'･;Iii'i'･f'/tL?E`eFidlll'li,t:llt/i･F:llli'l l IIIiililiiiilXllillllillllil }/:,･cF.it ::.tlllllThl'i t'-lIilI ::Eb:t-:tt:tt/t::.. i:illll/Iplll {::''Ooo tt i:Il tt l,,,7t t-t I':,!lu:l{i:1. e.Jo ,.u::,:L'･:,.,,":i.e'fi+:: M e ul ]L"/t[[ JIIItlLI?,,c. ;: ' tt :':lllE/1./i oe tt /' g}gl .1.ttt i't'/'t" -pm- [gl[ ::tt;:t/tttt. g#sc lf-]kLiiiXE il･/ ;tttt "./ ･i･ll･f!:,:･iF･-tt ii ill[{[l tl/･////,'.p ttttt i' -:･ ,)isli'l- t::::.L,h' ::::. ill/ltl bc" tttt tttt en t t:tttt.. i"t't'/1/tt"'/ti' :":1'ii,:[.:,:: eo,bec '' nep 1 /..,t tttt ' f:/tttttltt ll= et eo w t't-'7±' E

R g LOWER HAKOBUCHI SUBGROUP z

ltH : gg si gg st e CrS4 e 8 8 8 o mt ,l, T 9 ut )} )} x ): ,: ,: x = = = = = T x r = & d p

A< v E 9 o

8 tuc g/l,11･-'ki" tu wts s ff S s e nt : 2 en = WM8 W. e iv m o v ca Q = us eus nd

Text-figure 8 Columner sections of the Hakobuchi Group at (A) Hako buchi valley in Yubari area and (B) Tsukimi-sawa in Ashibetsu area, and horizons of samples. 422 A. Miki

Table 5 Occurrence and distribution of sporomorphs in the Yasukawa formation and the Hakobuchi Group. Numbers in brackets are closely similar specimens and those with question mark are doubtful specimens. Cross mark shows presence of the species.

ff Pormtion Yatinkuy ppErHakebuchi Svbgroup kt?a Porzautior Lover Hakobuchi Subsreup kaushiSst. EY-nt u.s.tttt" Saku AshibetGu IubarS Uo'tsetmJ Yubari ttob Tub. Sats)le T LO}Loie' LOLO n .tt" ou tt/-h iu' : Hge ttiEt t-com st s- o)as m .IRn Q o tt " ff1th cu " - /rl Feple ctt"oo g8pt ggl?lpl'i e/o9lffstaltai Wta vut Tdi Tes T 9e x ri/Hoo ptIptttt ooemmest lg:F-tt n£tvua ajeldildt?en tsti- mt"mm/ b./"- en RIRF"- RiRb.r. a/oetr't'ts 88Qe- fi･fiiR/2.i MHeslastl N 6 ewc"ew T1-1V-2 oooelt-"- tLt..t lt-tttt H-ln-2 A-1 A-2A-SA-4A-S Y-5 Y-4 I-S r-6 Y-7r-6 V-9 Eb-1 Hb-2 ffb-5Hb-4 Kb-SEb-6 V-10r-lllV-l? Hb-T Y-15

StereiEporitesanttquo6poritee f + 1 1,1 1 ys 5 ]s 1 14 E l4l5 S,aporalie + + i + S.IimbafuH 2++ + 21 5 + Sl ll i 1 + + + 40 1 4 104 s S.pseudouteree±des +IS2 i S,cf.regnum ' ++ 1 Lycopediu=-sporiteeNubreticytlaeGporites . LyeopodiaciditeEEmplvs + s " i + + ] + + 9 lpiculutieporlsinoueiL.hEmlatis 1 T 1 l 9 1 i laculatieporitegconuumgn-Sg l i + + 9 ' 1 B,vallidtte + + l + + ? 1 emmdaciditeeyellmanii + '2 + 4 1 TodieporiteemEjor 2++ 1 4+ 1 (+) + T,mnorlppendiciEpoTiteeaf.tricorTiitatus + + 1.evMrieorriitatue + +l+ 2 1 . + + 1 + Lep.indet,CicatriceEisporiteshakebuehiensiR + 4 + + e.sp.indeLHetieulaaperisEp,A 1 + 1+ GleichenitditenEenenieu" j 2 l + IT 1 ] 1 1+ + 2+ 242 12 G,eirciniditeHa.Iaetvs + +1+ 6 6 g.marginatue + + 21 + G e.ct.deliaattie 1 Clavifera?sp. 2 belteidD6poranodaenfie ? + C]rathiasteaauetra!is 1 + 1 + + + + 1 + s p + C,niner 5 TrSliteHetmplex 611+ + ++ T.ef,etmplei 1 + +1 T.tanaii + . blateni6ForitesmagnUa 1 ? + + LaevigatespariteshaaniLi 2e 26 15 lr) il 10 14 s le s S2? 40 219T2 S5 4 pm 1 2 2] 9 4 17 IT5 65# ]O915 s } Reticulo!doEporUesr"pandus l44 5 ? 5 1 L,ovatus 1la6+ 4i lei4 1 14 l LepbolepiaiteEcf.tenueis 1? + + ++ + 4+ Scar;tomperiteB?Ep. l+ 1 CSptatiEPOriteEsp. ] Ceneavisperitessp,inaet. 1

) ] )elteideeporacaecadenEie + 7? + 17 2 6?(6} ' {]) (+) ).halli 1 1 1 + 1 1 D.Ep･)eneeisper±tesvelatus 15 + )ictyophylliasteetazavaeneis + 1 4 + FasetatisperiteediyergenE 1 1 2 + 1 1 5 5 }1 1 IS ),sp. 2 ?byeoeperiteeeavayamaeneie + ?1 1? GlanulatisperiteHyaliabilis + 1 rriundiatieperiteeteal"ehieneis 2 ++ 2 1 + + SinbeSepariteskuMeneiE + + 1 j.eimiscalariE + ] 1 + taevigatSfipariteeholtkaidoe"fiim ÷1÷{i} 2 }loneleiotriletesparvue 1 1 l H.eEmuraihamennin + + 2 2 . , 9 2 H.subcircule=te + 1j++ + i AmatatieperSteeembetsuenBig e 1ll ] 15 1} 19 1 l 17 1? 24J 1? nadia]isperitesradiafue P.sp, + + Triporeletessp, l+ 2 9 lugulatiEpo=itegsalebrvffus 1 1 + StyI9P, + 1+ 2 VenmeoEisperiteesp.Sndet, 1? SehitoGpariBscabrabefi + + + + + 5 2 Sporegen,etsp,Sndet- 5+ 11 1 l 1 ] 1 Cyeadepite"ef.SolliealariB 1 l 1 a.cf,rragiliB 2 11 2 6 l C.cS.eeabrafus + ÷+ )1 C.cf,gisanteue + 2 ?2l 2 2 2 +t 1? nonosulcttefiepakpaEC,-pp` J96 2 2 5 1 l2 14 10 10iO }innosuleiteEfuEitoniE l l 5642 12 l ] l 25t) 111 l? 6 11 6 S16 l7 T5 4 5 H,simplex 2 2 2 2 1 1 15 + + 2S 745 M.IongufiM.Ep.- 111 1 51 M,praescut"fi 1 2 2 5 2 5 16 1 ] 2 1? li,GPP'Vitreisporiteepallidus + 411 2 + ATauca=iacttelleuetralts ]1 1 5?l + 2] l l2 ++ 1 l k.7sp.Abiespolleniteafip, 2 1 + + hbietineaepolleniteGep.A 5 1 2 1 4 4 2 1 1 + + 1 (]) IIt 1.Ep.BA.Ep.indet,A.ep,e 1 ] l 2 1 ?iceaepolleniteesaecellue l + + 2 1 F ? 2 2 l. 1 + + lil 1 P.sp･ l PitJoEporiteepteTceiP.Ep,indeL, + + + t) 6 1 (?) + l 9 l22 P,alSfermis 6 i 2 lo91251 + + 2 l 1 P,ep,M 2 l '' 2 9 P,sp,c s l 4 11 4 P,Ep.indet.CedripitesEp,indet, l . ]ive"SaulatePinEceaeEen.etep.indet, l2 l 2? 2 1 2 1 1 I ]ul ? bisperimpollentteaIEevigatue 105 s l4]F)TO raIY 4 i2 4P ss l240 47 41 ]5 14l9 egl 5 9 1 ' 6i14' SequoiapolleniteeputipapilloaniEI,peeudedubiue 2 + 1 PodocarptditefiexoeneSs + +2 ' ++ + + + I 9i P,gp.iildet, + I j -lyllecladiditentrannienB 1 +2 t+ l 1+ + + + " + 44 ?' 22 ' l+ +12+ ' P.parmtis ' ftgtJbivesiculiteact.fluens ..I + LATE CRETACEOUS POLLEN AND SPORE FLORAS 423

r-s v-4 T-s r-6 I-i VrS t-9in)-l Hb-2 Efu-] rm-4 1ib- Eb-a V-10 Y-11 V-l2 rib-7 V-lj Inape=furDpeUenitee sp. imdet, 2 ClasfiopalliH ezoensie V. . .,i,l l SguiBetosperites fip. B v ',+i ii l+ E. gp,C 1 L 1 1 E. gp,D 1 + [neteceaepolleniteuE, ep. tr,det. ep. i ii i I bonosulciteeperspinomili + ClavAtipeilenites sp. 1? 1++ 6 + LiUaeidites Gp, A + 2I + l L. Ep, 8 6 2 ii 7i )lonocolpepellentteekyiahuenets 1 p i 1 1+ s 1] 1 + H. pflvgii } 1+ 1] ]42+ l 1]4 e+ 1 M, fihupareensie + Seveelatue i +? H, 4j l 1 2 M. sp. ifidet. i + 21 1 ? Weylarldipollie retiSarmis 1 ]21 9 2? 29 1 1. T4 ++ 1 + PtermcarTapollenttes mp. 25 74 4? 1'i s 1 + ?elvporopellenites Ep. I 1 l -1 (2) ] 1 + 1]1++ Alnipollenitee eainEn6 i 1+- + ]l+ ] l51 letuIEc-pellen±tes normalis 1 i ] 1] j9 {2) 4 I1+ ll +22 1 l B, uir.utulus 1 (+) le 6++} ] 1 S 10! kozalpiteG eengtainLe" 1 l+ l + 4?+1 + K, hokkaidoeneiE {T) T=iparepelleniteme fegtatue 4411 2 ++ 211 I + (T) (]) 1 T. kfiEu"'ae-sis 61 2 l 1 t ]l i4 + + l+ l+ 10 12 41' 2 V. ehimensiE 2S ?1 ]1 l i 2: UImotdieipitee punctatas l Anaeelesidi±teg ? sp. 1 ii' Erieaceeipellen±teG ep, I(1}1+(2) (i} 2+ ]+ Retitricolpiteedelioatus 2+ 1 ] 1 + 1 I 16 i' 1 (l) 1 U, lepidua 1 IS 1 +21 2 R, mJlguris l +2 11 E, velidus + 1 + 1 t 5 {2) 1 I R.PfiilatrtcalpitesdebillG Gp. ]? P. ditiB + P, neinahamns±e neinehEmensis 6 + 1 P, meinohEntensis =Dtufidug ] i ]1 g6 ll e 2 1111 l S547] l l P. pmibp"rletulatuE l j + 1 1 +9 2 112 1 aaplSfemideaepollenites librerensis Sablax (e) 1 1 o} P. sp･A 1 7 l 1 1] 4 1 l4 IS 2 15 21 C.SraxineSpellenitee intrapunctatus npJ A 6 l 61 Cl} 16 1 1 l le s 1 ll 1 6 41 e+ l P. hebetcuensis + 25 s2 l2 ?4 2T 4} 922?2 5e J 7 1 21 7 ?2 4 F, nicrvbaculatue 9 + 1] 1 14 + IO IO 17 IS 1 6 ]1 1 le 4 l21 (2) ?, EasBai 17 4 e 4 ?, minutirettfOrEiS 1 (l> 11 (i) l P. mteroreticulabue + 2 F. =etieulaine } + ] 2 2 P, tEuininienEis 2 + IO + F,ibveotriaolpitesnicrofeveoTeticulatus ep. indeL 25 l22 11I }]11] 1 + StriatopellSfi pEilastriatus 221 2 2 2' 51 !+ ! 1 6) (1 I 1 1 4? TrieelpttesS, up. niniemifi 51 T. pGilaerinvs 2 + T. aSS, psilaeoabratuu i + + + V, n!pponioufi 9 + V.T, etT±aretiaul-tusparvietriatug (2)2 + 1 M. sp,A l T. ep. Sndet, + bongEevipelUs etvirieus 141 262 VricalperopellenStesbr"viaolpus + 5IS 1 4 + 1 11lll TriperopellenitesT, fipp. ep. A 1l1+ +1 +

1 T. Gp,B 1 6 T. Ep,C 2 1 1 Il T. fip. Sndet. }i Aguilapa11enitefihahebechSeneis + IS IS 12l27 6 A, attenttatus l4aT]2} 42 A. et, turbidus 1 24 }2 {5 5 1 A. agper 22 + 1 A. rectus 2 A, rigidus ? 45 A. cr. rigiaus ++ 11 s 66 i A. quadirintts + + + A, evanidufi 6 A, sakuensie 4 A. aff, pasblcufi 4e 4 16 } 5 12 l6 27 l A. borEalia l +++ . {i) k. retia"lutus + l 1117+ t 1]+ 2 A, arEtaceus l +- ?1+ +l(1)+1 A.A, conatusstriatuE nSpponicus GBIIs++ 1++ 52 A. sp.c 426 2 A,A. ep,Esp.D i A. 8p,F 2+ + A, ep,C + A. sp, BP,H tndet, 4 2 9 Cranvellia mnEevene±e 20 17 Kurtzipites ezoen6is se 26 9 44 OrbiculapellSE cf, luciaue , 2S l2 ++12+1?? Oeellipellis rmmitue i ]2 1+ e, obliquus +4 + Jl TricolpitesstTiatvs 5S4 12 Vedehottseia Epinata 262 V, parvtis 8 ?ollen t)Te 1 l21? Spormrph tyve T )? 61 Monoperate ? pollen 2 ] kngiosperm gen. sp. indet, 1 200 200 2oo 2ao 2oo 2oo 200 2eO 2oo 2oo 2oo 2oo 2oo 2oe 2oo2oe2oo2oo 2oo2eo2eo2oo2ee2oo 2oo2ee2eo14 Tetal 424 A. Mil'om the Nemuro Group in eastern "okkaido Takahashi (196S) reported a microflora from the bore-hole samples (Sk-1) of the latest Cretaceo"s sediments, the Nemuro Group, drilled in Nishibetsu, Bekkai-mura, eastern Hokkaido. According to Takaliashi Nishibetsu microffora contains some common species with the Upper Hakobuchi; of them, Betulaepollenites minutulus has been restricted to the Upper Hakobuchi subgroup. There are several latest Cretaceous elements: Cranwellia striata, C. c£ rumseyensis, Proteacidites thalmani, which have been found only from the Maestrichtian and the Tertiary, and three species belonging to the Aquila- pollenites group, A. parvus, A. cf. mirabilis, Mancicorpus sp. Takahashi suggested that the Nishibetsu microflora might be equivalent to the Upper Hakobuchi. The author fu11y agrees with him. The characteristics of Maestrichtian pollen and spore fiora are summarized as follows: i) Angiosperms are main components of the fiora, occupying the majority of the sporomorphs. 2) Among pteridophytes aRd gymnosperms Late Mesophytic elements are scarcely found. 3) The porate type is predominant among angiosperm pollen; it is represented largely by Ulmaceous pollen. 4) Japanese Maestrichtian microfiora is characterized by the diverse pollen of uncertaiR taxonomic position such as Aquilapollenites, Wodehouseia and Ocellipollis. Among the Aquilapollenites group, "71riprofectus" type appears in this microflora first, while "Fibulapollis" type probably disappears before Maestrichtian time.

Late Cretaceous Pollen and Spore Floristic Sequences in Northern Japan In the preceding chapter nine Late Cretaceous microfioras were discussed; they were grouped into four floras, based on their floristic composition and the vicissitudes of stratigraphically restricted sporomorphs (Text--fig. 9). These four represent the Cenomanian-Turonian, Early SeRonian, Campanian and MaestrichtiaR floras respectively. The differences among the four in the composition were summarized in Text-fig. 10. Pteridophytes predominant in Cenomanian-TuroRian flora were gradually replaced by angiosperms toward Campanian-Maestrichtian flora. Such compositional changes may represent the gradual development of early angiosperms during Late Cretaceous time. Such an. evolutionary treRd is clearly shown by the relative frequeRcy of angiosperm 426 A. Miki

d Cenomanian- Lower b Maestrl- ' Campanian [ffuronian Senoni an t ehtian Inapeyturopollenites microruguIatus Inaperturopollenttes ? baculatus Cireulina pa]rva Lygodiumsporites subsimplex ------"-p---"-[- Trilobosporites spp. AILisporites bilateralis Punctatisporites cf. parvigrranulatus Stenozonotriletes rad±atus Magnospor±tes ? ovalis Tr±poropollenites ninor Cicatricosisporites winutaestriatus

Delto±dosporaC. perforatus hallii Cicatricosisporites anstral±ensis

Apiculatispor±s sateii JimbolsporitesC. hughes± sim:Lsealaris Polyeingulatisporites reduncus A]raucariacites limbatus PsilatM±colpites cf. pammlus Monoleiotriletes parvus Densoisporites ' velatus Cyath±d±tes australis Granulatisporites valiabilis rrrilites simplex T. tanaii Reti,trleolpites delicatus Psilatricolpites debilis Deltoidospora nodaense Podoear[pidites ezoensis Phyllocladidites parvus Iibeaxinoipollenites sp. A Monosuleites epakros Viereisporites pallidus MMieolpites nipponieus Piraxinoipollenites mtcroreticulatus Lyeopodiacidites haniulatis ------Deltoidospora cascadensis --"dir' Itugubivesieulttes fluens Cyathdites minor RetitrieoZpites lepidus Cycadopites spp. Araucariacites australls ------Phyllocladidites .transiens -----p---o--- Psilatricolpites meinohamensis rotmdus Mricolpttes psilaexinns lhraxinoipollenttes h6betsuensis Appendicisporites cf. tricornitatus Retieulosporis spp. Fasciatisporites divergens Foveosporites saMrayamaensis Punctatisporites enbetsuensis Retitrieolpites vulgaris Aquila[pollenites evanidus

A.Mricolpites rigidus strioretieulatus Appendicisporites subtrlcoirnitatus Jimboisponttes kujiens'is itugulatisporites salebrosus Reticuloidosporites repandus TriporopolMenites shimensis Momipites constatus M. hokkaidoensis Cvpliferoidaepollenites intra[punctatus C. Iibrarensis fallax LATE CRETACEOUS POLLEN AND SPORE FLORAS 427

' Cenomanian- Lower l Maestri- a Carrlpen?ian {furonian Senonian : ehtian FraJcinoipollenites microbaeulatus

F.A[Lnipollenites sassai eminens Stereisporites pseudostereoides bycopodiacidites amplus ;･ Schizosporis scahratus Ocellipollis obl±quus Fraxino±pollenttes tsukiniensis Aquilapollenites hakobuchiensts Apiculatispoms inouei Baculatisporites validus Inundatispor±tes tomiuchiensis ]oveotnicolpites microfoveolatus Aqilapollenites cf. turbidus A, aff. rombicus Ocellipollis munitus Stereisporites limbatus Radialisporis Tadiatus Weylandipollis retifomis Betulaepollenites normalis Tricolporopollenttes brev±colpus Aquilapollenites reckus A, cf. rigidus A. reticulatus A. cretaceusborealis KurtzipitesA. striatus ezoensis Ort)ieula[pollis cf. O. Iucidus Pterocacya[pollenites sp. Striatopollis psilastriatus Betulaepollenites minutulus Ulmoideipites punctatus bongaevipollis s±biricus Aqutlapollenites conatus nlpponieus Aquiia[pollenites sp. C

TricoipitesA. quadrinus striatellus Wodehouseia spinata Pollen type X Wodehouseia parva Aquilapollenites asper

Text-figufe 9 Time range of selected sporomorphs from the Late Cretaceous of northern Japan.

species agaiRst pteridophytes and gymnosperms: angiosperms increase from 21 per cent in the earliest fiora to 56 per cent in the youRgest. Furthermore, this development is accentuated by the morphological changes of pollen. Earlier angiosperm pollen are represented largely by the tricolpate type but a few are the porate type: these tricolpate pollen are mostly single-layered, non-or-simply sculptured but few are tectate in exine; triporate pollen provide a simple pore structure without a pore chamber. On the other hand, younger angiosperm pollen are mainly represeiited by both types: tricolpate pollen are commonly tectate and sometimes striate or foveolate in exine as shown in Text-fig. 1 l ; the

/ porate pollen have complex and or multi pore. 428 A. Mil

FtORA COMPOSITIONC'le}604020 PlrERIDOPHYTES GYMNOSPERMS ANGIOSPERMS AGE !esgEkX=x 302looet, 604020O"te 642 6 cM :i::::::' 6

gecg"tao89K=9f ((v)@b;-iii,:= llgttttttttgggs9-- tsasee 6 1::::::[ :

7 @b'･l.!･

,i(ilii), <)IZ; -- ?- cM 9sY- I::::]:::I: l-t ee g @@b::,,:Jiil,::- '

g!llll)) a.gBE;D[IIL)ly)mc-gI osOthers mai i---- cM .1.: ･1･1 2 I[::1:I] -t-I waggg 3 v- 8 Etw 4 asesGilllik} @@(li)> kigs .R- , caB- es 6 lffi:..o I:]I:l]:: ------6C es7 )Mny-v- - L5 aswh(gZII}in 7M @@(C:)> @8 Regw11 '

Text-figure le Outline of Late Cretaceous pollen and spore flora in northern Japan. In the second column, numbers in squre bracketes are the total numbers of.species constituting each flora. In the fourth column the ratio of Schizaeaceous spores to tota} numbers of spore species and the numbers ofSchizaeaceous species in some genera are given. In the fifth column, the nufnbers of genera of Meso (M)- and Ceno (C)- phytic elements are given. In the sixth column the ratios of four pollen groups to the total m}mbers of angiosperm species are given. 1. Angiosperms. 2. Gymnesperms. 3. Bryophytes and Pteridophytes. 4. Reticulos- poris. 5. Appendicisporites. 6. cicatricosisporites. 7. Klukisporites and Trilobosporites. 8. Tricolpate type polleR. 9. Tricolporate type pollen. 10. Porate type pollen. I1. Aquilapol- lenites- Wodehouseia-Orbiculapollis-Ocellipollis-Ku itztipites- 7>'icolpites striattellus complex. LATE CRETACffOUS POLLEN AND SPORE FLORAS 429

Cenomanian Turonian EartySenonianlCampaniant Maestrichtian UpperYezo SagugawaFrn, SakuFm, Ku`jFutabaGrs. HakobuchiGroup reticltate

---.-.;..... Nv.:.-..ti;t itate 1' ":..1;.I.t}'' r{.Npsilate l. ttttttt.ttt

tttvr.'=.'r l,i;i"'jiitt.'.,r,."{',-,Scabrate

...'.J..;-.-..-."

'--ht'.:tY'sk'i""'!//"t"t''/t;t't"''t't't""'ititt.-....･ttt/tr iliimicrbbacuiate

t11lll...".-...It't.''t-..-t..'tlllAl-----..-:h..'t"';;flli11':L:.';l...tt;l-1dl1lllliiI1 reticutate >

"Rarg retiauEate

lntraunctate

clavate

''"t-t..t.li

tol*･'' ..1,iEi-lll-.t.･.i./".･striate

tttttLtt-.. ,e.7.,i.,t{･,//,l'.,-t.:};:------'CT.L.Tt;.r'tfi.t..'p'rYC.-foveotate

striate

strioretic[ate EtyglillikSil}pTffoivE6vsEtityoipe

Text-figure ll Morpho!ogical variation of tricolpate pollen and their first appearances in northern Japan.

Porate pollen are, in general, considered to be rather more advanced than tricolpate pollen. The porate type which appeared in the Turonian Saku formation rapidly increased both in taxonomic divefsity and in total number of speciiiRens during Campanian time, aH.d became one of the representative angiesperm pollen during the Maestrichtian. It is a coRspicuous fact that angiosperm pollen of uncertain taxonomic position such as Aquilapollenites, Wodehouseia increased drastically m numbers of specimens and species dvring the Campanian and Maestrichtian, as is also found in Siberia and western North America. The Aquikipollenites group first appeared in the Coniacian age (the Kuji and Kyowa microfioras). The earlier pollen of this group is represented by the `ft4quilapollenites" and fll7ibula- pollis" types. The first appearance of the `fkitegricorpus" and `EMancicoilpus" 430 A. Miki types was during late Campanian (the Lower Hakobuchi microflora). The "Zr'iproieetus" type first appeared during Maestrichtian (Upper Hakobuchi microflofa). Ocellipollis, Orbiculapollis and Kurtzipites appeared in Lower Hakobuchi microfiora, and l4iodehouseia appeared in the MaestrichtiaR time. Pteridophyte spores and gymnosperm pollen gradually decreased in numbers of species and specimens. It is noteworthy that Mesophytic elements such as Schizaeaceous spores gradually diminished toward the Campanian. Schizaeaceae is known as oRe of the representatives of Late Mesophytic peteridophytes. Cenomanian-Turonian rnicrofloras comprise a large number of Schizaeaceous spore species such as Appendieisporites, Cicatricosisporites, Klukisporites and 7>'ilobosporites, but younger microfloras comprise only a small amount of them. Moreover, Schizaeaceous spores are almost completely absent in the Maestrichtian microflora. Among the gymnosperms, Cycadaceous pollen, such as Oeadopites, decreased in number of grains during the Maestrichtian age. Late Mesophytic coniferous pollen st}ch as Araucariacites, Podocarpidites, Phyllocladidites, Rugubivesieulites and Classopollis gradually decreased and was replaced by Cenopliytic. Alisporites and Circulina are encountered occasionally and only in the earliest microfiora. The plant world on land had dramatically changed its composition during Cretaceous time by the rapid development of angiosperms which fi'rst appeared approximately in earliest Cretaceous time and by the decline ofpteridophytes aiid gyrnnosperms Floristic changes through four pollen and spore floras in Rorthern Japan revealed that angiosperms developed step by step with increasing numbers and taxonomic diversity and that they became gradually superior to pteridophytes and gymnosperms. Such fioristic changes confirmed by Cretaceous palyRology in northern Japan are consistent with the evolutionary development of the Cretaceous plant kingdom on land in the Northern Hemisphere.

Comparison of Japanese Pollen and Spore Floras with those in Siberia Comparing Late Cretaceous microfioristic sequences in Japan revealed in the preceding chaptei- with those of the East Asian continent is important for cretaceous phytogeography. Before proceeding.to the comparison, the author would like to refer briefiy to a few problems about regional or latitudianal differences in floristic composition during Cretaceous time. Many paleobotanical contributions during the last twenty years suggest that some phytogeographical provinces or Iatitudinal differences in fioristic composition might have existed during the Mesozoic Era (Markova, 1962; Zaklinskaya, 1962; Vakhrameev, 1964; Pokrovskaya, 1966; Samoilovich, l967; Takahashi, 1970; Vakhrameev, et al., 1970). An inference that the two major LATE CRETACEOUS POLLEN AND SPORE FLORAS 431 phytogeographical provinces, the Siberian and the Indo-Eufopean, existed iR Eurasia during Cretaceous time is well aceeRted by many investigators. A view that the Siberian province may have contained western North America is widely accepted. Samoilovich'(1967), based on Palynological study, proposed that the Siberian province during the Late SenoniaR to Danian ages was divided iRto two regions, the northern Khatanga-Lena and the southern Enisey-Amur. It has been suggested by some authors (Bolkhovitina, 1959; Markova, l962; Pokrovskaya, l966) that the appearance of angiosperms was somewhat different in age in various areas of Siberia. OR the whole, the appearance and radiation of angiosperms in northeastern Siberia took place at a latter stage than in southern Siberia. The author has successfully compared the Kuji, Futaba and Saku microfioras with Siberian microfloras by taking the phytogeography and the regional or latitudinal differences of the angiosperm development during Cretaceous time into account. 7"7ze Pollen and Spore FZoras in the Zeya-Bureya Basin Cretaceous terrestrial sediments are developed in the Zeya-Bureya basin in the Far East Soviet UnioA, which is iRcluded in Enisey-Amur floristic province. Chlonova (1969) and Bratzeva (1969) described Late Cretaceous pollen and spore floras of this region.

6oeE leoeE.. l4oeEix / liLx 700N - x.1 l NN - i s KHATANGA 1-X x - / ,stJt vsJ9 x K " ,/(-S¥RxGl'tV"IR,Ui,l".Ni,l"ki{IIII'-')..,l,'; " xx 600N - x x - / .. .. .fKi' yOAyA H' ,XK. ifi-' - Y' X- x PRii.REEy.sH "s 1 / i g-s-- L>t:lp' / ･,fii - soeN - - 1 A-BJ;u- ' -rm rz- Ey-tt"REyA , ?kl;IY 4ooN lt 1 i - e KUJrt l t'"t tt FUTABA "Y 1 pt

Text-figure l2 Index map of the locations of Late Cretaceous microfloras in northern Asia. According to Bratzeva, who established the floristic sequences, the CenomaniaR-Turonian pollen and spore fiora have the following characteristics similar to Saku microflora: l) Pteridophytes constitute approximately more than half of the total species. Schizaeaceous spores occupy about 40 per cent of the total pteridophyte species. 2) Angiosperms occupy nearly 10 per cent of the total: they are represented Iargely by the tricolpate type, and with a few of the porate type. Early Senonian pollen and spore flora are dominated by gymnosperms and pteridophytes, and ai'e not common m angiosperms. Pinaceous and Taxodiaceot}s pollen are abundant amoAg gymnosperms, and botli tricolpate and Aquilapollenites pollen are abundant among angiosperms. Aquilapollenites is fepresented by the `fAquilapollenites" and "jFibulapollis" types. These floristic characteristics are closely siinilar to those of the Kyowa microfioras. Maestrichtian pollen and spore flora are similar to the Upper Hakobt}chi microfiora and are characterized by diverse and abundant angiosperms which occupy more than half of the total species. Angiosperm pollen are composed mainly of divefsified Proteacidites, the porate type such as Ulmaceous aRd Betulaceae-Myricaceous pollen, and various pollen of taxonomi- cally uncertain position. Aquilapollenites has 19 species. Pteridophytes rarely have Schizaeaceous spores, and gymnosperms include small amounts of Cycado-Ginkgoaceous pollen. But, Late Cretaceous microfioras in Japan slightly differ from those of Zeya-Bureya: Japanese microfloras contain no Cedrus-like pollen and rarely contain Proteaceous polleR. However, Cedrus-like pollen are commonly found throL}gh Late Cretaceotis time in Zeya-Bureya, while Proteaceous pollen are only found in M[aestrichtian microfiora. It can be concluded that Late Cretaceous microfioristic changes in the Zeya--Bureya basin show no essential differences from that of northern Japan: the development of Cenophytic land plants progressed with similar featt}res. 7U7ze Pollen and Spore Floras in the Bilyui Basin From the Cretaceous tefrestrial sedirnents in the Bilyui basin in the Central Yakut Lowland, Late Cretaceous pollen and spore floras have been reported by Bolkhovitina (l959) and Samoilovich (l964). According to Boikhovitina (l9S9), Cenomanian to Turonian polleR and spore flora is composed largely of pteridophytes and gymnosperms, and poor in angiosperms. Angiosperms constitute approximately 10 per cent of the total species, and have few porate types. Schizaeaceous spores constitute 20 per cent of the total spore species. Gymnosperins include Late Mesophytic coniferous pollen such as Araucaria, Protopicea and Podocarpus. The Santonian pollen and spore fiora is generally similar in flofistic composition to those of the previous age, but contains somewhat more LATE CRETACEOUS POLLEN AND SPORE FLORAS 433 angiosperm pol}en. Of angiosperrris, the porate type increased, but Aquilapol- lenites pollen was absent. Though gymnosperms are dominated by Pinaceous polien and Taxodiaceae--Cupressaceous pollen, Araucaria, Psophosphera and Podozamites spp. are present. According to Samoilovich (1964) the pollen and spore fiora from the MaestrichtiaR?-Danian is characterized by abundant angiosperms which are stiperior to the two other taxa, and diverse species of the Aquilapollenites group. The porate type represented largely by Myricaceous pollen is superior to the tricolpate type. Gymnosperms consist mainly of Pinaceous and Tax- odiaceous pollen. Comparing the Late Cretaceous pollen and spore fioras in the Bilyui basin with those of Japan, Cenomanian-Turonian pollen and spore flora in the Bilyui basin resembles the Kuji' and Futaba microfioras in general outline, though it is slightly lower in angiosperm representation. "Maestrichtian?-Danian" pollen and spore flora in Bilyui is more similar to the Danian-Paleocene pollen and spore ftora of the Zeya-Bureya basin and the Paleocene pollen and spore fiora of westerR North America than to the Upper Hakobuchi microflora for the following reasons: 1) it is lower in representation of angiosperms but much higher in gymnosperms than the Maestriclitian; 2) and it is abuRdant in Myricaceous pollen and lacking in Ulmaceous pollen. Floristic changes from Ceiiomanian to Santonian times in the Bilyui basin are generally similar to those of Japan, excepting a somewhat slower development of angiosperms. To speak conclusively, Late Cretaceous floristic changes in northerR Japan are very similar to those of eastern Siberia, especially to those of the Zeya-Bureya basin. Northern Japan appears to have belonged to the Enisey- Amur province includiRg the Zeya-Bureya basin and to have been distinguished from the Khatanga-Lena province.

Conclusion Late Cretaceous pollen and spore floras of northern Japan are divided into four according to floristic composition and components, as summarized in Text-fig. 10: they represent Cenomanian-Turonian, Early Senonian, Campanian and Maestrichtian fioras respectively. The characteristic feature in these floristic sequences is the fact that pteridophytes and gymnosperms forming major constituents auring Ceno- manian-Turonian time were gradually replaced by angiosperms toward Mae- strichtian time. Such an evolutionary change is distinctly shown in th.e relative frequencies of the three major taxa during each age in northern Japan: Angiosperms constitute approximately 20 per cent of the total species in the Cenomanian-Turonian, 25-40 per cent in the early Senonian, 46 per cent in 434 A. Miki the Campanian, and 56 per cent in the Maestrichtian. The development of angiosperms did not occur abruptly during a short interval, but gradually progressed with the diversification of angiosperms themselves. The porate type is few in the Turonian, coinpared with the rather common tricolpate type, and gradually increased with diversity towards the Maestrichtian. The tricolpate type also diversified with complicated exine sculptures, as already show in Text-fig. 11. The formatioR of the Cenophytic plant world was accelerated by the decline of pteridophytes and gymnosperms; gradulal changes of these two earlier major taxa are ciearly shown by decreasing Schizaeaceous spores in pteridophytes and decreasing Mesophytic genera in gymnosperms. Late Cretaceous fioristic changes of iiorthern Japan are vefy similar to those of Hastern Siberia, especially the Zeya-Bureya basin. The development toward the Cenophytic plant kingdom in East Asia progressed gradually during Late Cretaceous time.

R eferen ces

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(Received on July l3, l976)