Biostratigraphical and Paleontological Studies on the Endothyroid Foraminifera from the Atetsu Limestone Plateau, Okayama Prefecture, Japan

Biostratigraphical study of the Lower Carboniferous through the endothyroid Foraminifera, has very recently been advanced by some paleontologists of North America and Russia. But their biozones are proposed only by E. J. ZELLER (1957) who has studied endothyroids from the Mississippian rocks of the Cordilleran region, North America. In the Atetsu limestone plateau the Carboniferous deposits are named Mitsudô group by the writer, and further subdisivisible into two formations, i. e. the lower, Nagoe formation of Mississippian and the upper, Kodani formation of Pennsylvanian in age. By careful thin section study of samples from the lower Nagoe formation of the Morikuni-Kodani measured section and two other adjacent ones in this area, the present writer recognizes the following five foraminiferal fossil zones in ascending order ; 1) Plectogyra communis zone, 2) Plectogyra primaeva zone, 3) Endothyra spiroides zone, 4) Endothyra symmetrica zone and 5) Atetsuella meandera zone. The endothyroid faunal succession of the inter-mediate three zones is very similar to that of the Osagian to the Upper Meramecian faunal zones proposed by E. J. ZELLER stated above, and moreover both species of Plectogyra communis and P. primaeva from the lowest two zones were described by D. M. RAUSER-CHERNOUSSOVA (1936) from the Lower Tournaisian in the central Kazakhstan, Russia. However, the lower part of the Endothyra spiroides zone yields such coral forms as Hexaphyllia sp. and Siphonodendron sp. generally thought to belong to the Upper Viséan (Chesterian) Onimaru type fauna which has never been reported from the Carboniferous limestone of Chûgoku. Al-though it has been believed generally that Profusulinella follows Millerella in phylogenic position of Fusu-linidae, the present writer discovered Profusulinella from the uppermost limestone of the Nagoe formation underlying perhaps disconformablly the lowest part of the Pennsylvanian Kodani formation in which Millerella appears first. The fact that a distinct abrupt change in faunas is recognizable between the upper-most Atetsuella meandera zone of the Nagoe formation and the overlying Pennsylvanian Kodani formation may stratigraphically indicate there a noticeable disconformity between the Mississippian and the Pennsylvanian deposits. A new genus Atetsuella, which is an intermediate type of Fusulinidae and Endothy-ridae, two new species of Atetsuella, three new species of a new genus Paraplectogyra belonging to the Endo-thyridae, and a new species of Granuliferella are described

Endothyroid Foraminifera, Endothyranopsis from Japan

Four species of Endothyranopsis are described and illustrated from the Pseudoendothyra spiroides zone of the Akiyoshi Limestone group, Akiyoshi plateau, Southwest Japan, and No. 17 horizon of the Onimaru formation, Kitakami massif, Northeast Japan. They are Endothyranopsi hirosei sp. nov., E. compressa (RAUSER-CHERNOUSSOVA and REITLINCER), E? sp. A, and E? sp. B. The foraminiferal assemblage in association with Endothyranopsis strongly suggests that the Pseudoendothyra spiroides zone of the Akiyoshi Limestone group is equivalent in age to the Onimaru formation (upper Viséan).今村外治教授退官記念特集

Carboniferous Palaeotextulariid Foraminifers from the Akiyoshi Limestone Group, Southwest Japan

Nine species of Palaeotextulariidae are described and illustrated from the lower part of the Akiyoshi Limestone group; Palaeotextularia consobrina, P. vulgaris, P. sp. A, Cribrostomum sp., Deckerellina sp., Deckerella sp., Climacammina antiqua, C. volgensis, C. sp. A. The zones below the Millerella sp. A zone are characterized with the dominance of Palaeotextularia, while the Millerella sp. A zone and the overlying ones with higher percentage of Climacammina. The progressive change of chamber arrangement, aperture pattern and test size as well as the stratigraphic distribution bear close resemblance to what have been observed in the British Visean and Namurian

Microbiostratigraphical Studies on the Foraminiferal Faunas of the Lower Carboniferous Formations of the Chûgoku Region, Southwest Japan

In the present paper, the Carboniferous of the Chûgoku region, Southwest Japan, especially in the Atetsu, Taishaku and Akiyoshi limestone areas, are microbiostratigraphically studied regarding to the foraminiferal zones of them. These limestones are lithologically and biostratigraphically subdivided into two parts of the lower and the upper. The lower consists mainly of well bedded limestone with schalstein and chert, and contains a lot of such "smaller Foraminifera" as endothyrids, palaeotextularids, archaediscids, tuberitinids, tetrataxids, etc. which take 60-90% of all foraminiferal specimens recognized in thin sections. The upper part consists of the unstratified limestone overlying disconformably the lower, and is characterized with the primitive fusulina-ceans as Millerella spp., Eostafella ikensis, Ozawainella sp., Pseudoendothyra spp., and Pseudostaffella antiqua. Thus the lower facies of smaller Foraminifera and the upper one of primitive fusulinids are dis-criminated, and it is plain enough that the former indicates the faunal characters of the Viséan and the latter that of the Bashkirian to Moscovian in age. On the basis of the faunal characters and the most rich species of Foraminifera, the strata of the lower facies are subdivided into three zones and also those of the upper can be separable into four zones in descending order as follows: 7. Fusulinella imamurai-F. biconica (Fusulinella-Fusulina) zone 6. Profusulinella toriyamai - P. beppensis zone 5. Pseudostafella antiqua zone 4. Eostafella sp. A - Millerella sp. A zone Disconformity 3. Mediocris sp. A - M. mediocris zone 2. Endostafella delicata zone 1. Endothyra sp. A zone The correlation among these zones of the Atetsu, Taishaku and Akiyoshi districts and their geologic ages are tentatively shown on the Table 2. The zonal species of the lowest zone, Endothyra sp. A is similar to E. cara SCHLYKOVA from the Oka substage of the eastern Jugoslavia. The foraminiferal fauna of the Endostafella delicata zone is composed of such endothyroids as Endothyra omphalota samarica RAUSER-CHERNOUSSOVA, E. similis RAUSER-CHERNOUSSOVA, E. pauciseptata RAUSER-CHERNOUSSOVA, E. masanae (OKIMURA), Endostafella delicata ROSOVSKAYA, Mediocris breviscula (GANELINA), Palaeotextularia vulgaris (REITLINGER), P. consobrina LIPINA and some others, and it is referable to the Middle Viséan in age. The characteristic faunal elements of the Foraminifera listed below are common to both of the lower subzone of the Mediocris mediocris zone of Akiyoshi and the Onimaru formation, the latter of which is the type of the upper Lower Carboniferous of Japan; Endothyranopsis hirosei OKIMURA, E. compressa RAUSER and REITLINGER, E. spp., Mediocris mediocris (VISSARIONOVA), Endostafella parva (MÖLLER), Palaeotextularia spp., and primitive Climacammina. They are the important species of the foraminifetal fauna from the lower Serpukhova substage (Upper Viséan) of USSR. On the other hand, the foraminifcral assemblage from the lower part of the Nagaiwa formation listed below closely resembles that from the Eostafella sp. A - Millerella sp. A - zone and the Pseudostafella antiqua zone of the Chûgoku region; Eostafella ikensis VISSARIONOVA, Globivalvulina spp., Millerella sp., Planoendothyra spp., Ozawainella cf. aurora SCHLYKOVA, Climacammina antiqua (BRADY) and a few others. Consequently the upper part of the Mediocris mediocris zone may be referable to the hiatus between the Onimaruan and the Nagaiwan in age, and also to the uppermost Lower Carboniferous, Namurian Protova horizon of USSR. The writer would like to propose the new stage name of Ohkuboan for the upper part of the Mediocris mediocris zone in the Chûgoku region

A New Species of Lithostrotion (Siphonodendron)(Rugosa) from the Hina Limestone, Okayama Prefecture, Southwest Japan

A new rugose coral species, Lithostrotion (Siphonodendron) hinensis is described in this paper. It was collected from the Carboniferous Hina limestone in Okayama Prefecture, Southwest Japan. Judging from the paleontological data, the age indicates probably Late Viaean, Early Carboniferous

Abodehella, A New Genus of Tetrataxid Foraminifera from the Late Permian

A new genus, Abadehella comprising three new species (tarazi, coniformis, and biconvexa) is proposed and described. So far as the morphologic features are concerned, the genus is considered to be a specialized genus in the family Tetrataxidae. This characteristic genus is found from the basal part of the Abadeh Formation in central Iran, the lowest member of the Zewan Formation in Kashmir, the Palaeofusulina limestone in Malaysia, Lepidolina multiseptata limestones in Cambodia and northeast Japan, the Takauchi and Reichelina-Colaniella limestones of the Maizuru belt, and the Lepidolina kumaensis zone of Shikoku in Japan. The stratigraphic occurrence is limited to the Late Permian and the genus is considered to be useful for international correlation

Stratigraphy of the Permian Karita Formation in the Environs of Hiroshima, Japan: With Paleontological Descriptions of Foraminifers

The stratigraphy of the Permian Karita formation exposed near Hiroshima City is described and its correlation with the Maizuru group in the Maizuru belt is discussed, with special reference to the stratigraphic relationship among the Lepidolina toriyamai, the Colaniella cf. minima and the Leptodus richthofeni horizon. Paleontological descriptions of some important foraminiferal species are presented as an appendix

The Upper Paleozoic Formations in and around Taishaku-dai, Chugoku Massif, Southwest Japan; with Special Reference to the Sedimentary Facies of Limestones

It has well been known that in the Inner Zone of Southwest Japan there are several isolated large masses of the Carboniferous-Permian limestone, surrounded by contem-poraneous thick series of sandstone, shale and chert. An example is in and around Taishaku-dai, a part of the Kibi plateau, Central Chugoku. Two distinctive facies, the central and the marginal, can be recognized in the limestones and the overlying clastic rocks of Taishaku-dai. The stratigraphy is as follows in ascending order. Central facies Dangyokei formation (Endothyra zone), 150 m. thick: Characterized by the predominance of basic volcanic and pyroclastic rocks, with some intercalation of limestone. Eimyoji formation (Millerella, Profusulinella, Fusulinella and Fusulina zones), 150m. thick: Composed exclusively of massive limestone. Uyamano formation (Pseudoschwagerina, Parafusulina, Neoschwagerina and Yabeina zones), 400～500 m. thick: Massive limestone. An unconformity is at the base, and a hiatus, of smaller scale is also inserted between the Parafusulina and Neoschwagerina zones. Oshigatani formation (Yabeina zone), 100～300 m. thick: Massive black shale, containing lenses of limestone. An ill-sorted, heterogeneous conglomerate occurs locally. Marginal facies Lower Idaniyama formation (Endothyra zone), 200m. thick: Chert with intercalation of limestone and basic volcanic rocks. Upper Idaniyama formation (Millerella, Profusulinella and Fusulinella zones), 200～250 m. thick: Chert and limestone repeated in various thickness, often showing a graded bedding as in the Lower Idaniyama. Zenbutsujidani formation (Pseudoschwagerina and Parafusulina zones) and Arita formation (Neoschwagerina and Yabeina zones), 400～500 m. thick: Massive limestone with a small amount of chert. An unconformity is at the base of each formation. Maedani formation (Yabeina zone), 1000 m.± thick: Sandstone and shale in graded alternation, succeeded by thick sandstone with a conglomerate at the top. Small lenses of limestone are included in places, and layers of basic volcanics and acid tuffite are also intercalated. Notabiyama formation: Chert and the succeeding siliceous shale, with intercalation of acid tuffite. The microscopic examination of limestones from more than 600 localities shows that the two facics have their respective suites of rock-types concerning the sedimentary petrographic features. The limestones of the central facies are mostly sparry; oo-sparrudite and -sparite are dominant in Carboniferous and biosparrudite (especially fusuline biosparruditc) in Permian. An autochthonous biolithite is also characteristic of this facies, though the occurrence is rather limited. Most of the Carboniferous limestones of the marginal facies are, on the contrary, micritic; bio-micrudite and -micrite rich in fragments of crinoid, bryozoa etc. are common. In the Permian marginal facies develops a calclithite, which consists of pebbles of contemporaneous limestones as well as those of older ones, cemented by biomicritic matrix. Judging from the distribution of macro- and micro-facies mentioned above, it may be concluded that the central facies represents sediments on reef proper (probably like a table reef) and the marginal facies those on fore-reef slope to near-reef basin. They are combined to form an organic reef complex on the submarine volcanic mound. The facies-development and the sedimentary history arc diagrammatically shown on Plate V

Cement generations and diagenetic history of the upper Ordovician Cliefden Caves Limestone Group of New South Wales, Australia

Diagenetic features of the upper Ordovician (Caradocian) Cliefden Caves Limestone Group (N. S. W., Australia) were studied by the cathodoluminescence (CL) method, and their relation with depositional environments was discussed. The Cliefden Caves Limestone Group was deposited on a shallow marine carbonate platform developed on a volcanic island. The limestone succession reveals intertidal-subtidal lithofacies and consists of the Fossil Hill, Belubula, and Vandon Limestones, in ascending order. The Fossil Hill Limestone mostly consists of bedded limestone rich in brachiopods and sedentary organisms. The Belubula Limestone is a typical Middle-Upper Ordovician peritidal succession with syn-depositional dolomite and silicified fossil grains. The Vandon Limestone consists of fossiliferous stratified limestone occasionally containing red brown argillaceous limestone beds. The Cliefden Caves Limestone Group was subjected to various diagenetic processes. The investigation of CL is the best or only method to differentiate the diagenetic products. There are at least three cementation stages and a dissolution stage. The cements of the first stage are mainly dull fine-grained (10-30 µm) calcite crystals fringing inter- and intra-granular porosity, which typically indicate a marine phreatic environment. In some specimens of the Belubula Limestone, cement of the first generation exhibits meniscus fabrics suggesting precipitation in a marine vadose environment. The dissolution formed both molds of aragonitic skeletal grains and fabric-unrelated void spaces which can exceed several cm in diameter. Lack of the first generation cement within the dissolution voids indicates that the dissolution postdated the marine cementation. After the dissolution stage, the second cementation precipitated granular calcite crystals composed of non-luminescence, dull, and bright zones in the peripheral order. The relative thickness of non-luminescence and bright zones probably related with a redox condition during their diagenesis. The last generation of cements formed in a deep burial environment, is normally dull and filled almost all remained porosity. This diagenetic history fits to the change of depositional environment which may have been controlled by both of local and global environmental settings

Foraminiferal Zones Underlying the Profusulinella beppensis Zone of the Akiyoshi Limestone Group

The Carboniferous formations widely distribute on the southern slope of Minamiyama and Daiyama of Akiyoshi Plateau, Southwest Japan, where the type localities of the Millerella sp. a Zone of Toriyama, and the Endothyra Zone of Murata were recognized. They show a general trend of NEE strike and following 5 sedimentary facies can be recognized probably in ascending order. 1) Sandstone and chert facies Fault? 2) Schalstein facies with chert and limestone lenses 3) Oolitic limestone facies with intercalated thin chert 4) Algal limestone facies with small limestone pebbles in its lower part 5) Massive limestone facies (chiefly fine calcarenite) The strata of the lower three facies indicate the south dip while the dip and strike of the upper two ones are uncertain. Throughout the faunal arrangements of 120 localities on 6 routes in this area, it was rocognized that the characteristic variation of foraminiferal faunas exceedingly matches that of rock facies. And following five fossil zones can be distinguished by each peculiarity of their foraminiferal faunas, probably in ascneding order. a) Endothyra sp. A zone b) Pseudoendothyra spiroides zone c) Millerella sp. A zone d) Pseudostaffella sp. A zone e) Profusulinella beppensis zone The above-stated faunal zones can be established by the comparable thin section study of the foraminiferal faunas mainly composed of Endothyroids, Palaeotextula rids, Tuberitinids, Archaediscids and primitive Fusulinids. It is interesting to have confirmed the Endothyra sp. A zone, Pseudoendo- thyra spiroides zone both without Millerella, and the Pseudostaffella sp. A zone with similar foraminiferal fauna to that of the Millerella zone without any form of Profusulinella. But the Pseudostaffella sp. A zone may be included in the Millerella zone or Profusulinella zone by a detail study in future. The above-stated five fossil zones in this area can 'safely be correlated to the five foraminiferal zones of the Mitsudo group of the Atetsu limestone plateau, Okayama Prefecture, as follows; 　　　Akiyoshi　area 　　　 Atetsu area a. Endothyra sp. A zone -------------------- Plectogyra communis zone b. Pseudoendothyra spiroides zone ----- Endothyra spiroides zone c. Millerella sp. A zone---------------------- Endothyra symmetrica zone d. Pseudostaffella sp. A zone-------------- Atetsuella meandera zone e. Profusulinella beppensis zone---------- Profusulinella zone Foraminiferal fauna of the Pseudostaffella sp. A zone is comparable to that of the Atetsuella mean-dera zone except Profusulinella and Atetsuella. The above-mentioned five fossil zones of this area probably range from the upper Lower to the lower Middle Carboniferous in age. Palaeontological study of endothyroid Foraminifera has been complicated in confusion according to the two different original definition of genus "Endothyra", but recently it has made great strides and Endothyridae has been divided into 5 subfamilies, 19 genera. As a result of the study progressed, zone fossil names of the Atetsu limestone are unavoidably retouched as follows; Plecto-gyra communis = Endothyra sp. A, Plectogyra primaeval = Endothyra sp., and Endothyra = Pseudoendothyra.木野崎吉郎教授退官記念特集