Satoshi Hanagata

This study discusses paleoceanographic changes in the Japan Sea across the Miocene/Pliocene boundary based on foraminiferal distributions and geochemical evidence obtained in the Akita Prefecture of northern Japan. Q-mode cluster analysis differ- entiates six foraminiferal associations from a total of 55 assemblages. Their paleoceanographic implica...

This is the first comprehensive, fully illustrated systematic report of both plank- tonic and benthic foraminifera from the Pliocene Shimajiri Group in Miyakojima Island, southern Ryukyu Island Arc. A total of 47 planktonic species in 18 genera and 267 ben- thic taxa in 151 genera have been identified in 31 matrix samples covering almost all horizo...

Planktonic foraminiferal assemblages from rock samples collected by Tatsuro Matsumoto and colleagues in 1991— 1993 from the Cenomanian and Turonian transition of the Penke-wakka-tannenai-zawa River section in the Hobetsu district of Mukawa Town, Hokkaido were re-examined based on the same materials (washed residues) initially reported in 1994. All...

Radiolarian abundance in rock-samples (R/g), sand content (SC; wt.-%), organic carbon analyses by CHN-Corder and Rock-Eval pyrolysis, and visual kerogen (VK) analysis were conducted on rock samples from the Cenomanian/Turonian (C/T) transition of the Hikagenosawa and Saku formations of the Yezo Group from different locations in the Oyubari area, Ho...

Forty-three species belonging to thirty-seven genera of benthic foraminifera were differentiated from the Eocene Shitakara Formation in the eastern part of the Kushiro Coalfield, eastern Hokkaido. The foraminiferal assemblages show upward transgression from the inner to outer sublittoral condition. They contain abundant agglutinated and calcareous...

Planktonic foraminiferal zones PL4 and PL5 were correlated to the siltstone facies of the Shimajiri Group distributed in Miyagi-jima and adjacent islands, east of Okinawa-jima. The base of the Chinen Formation has yielded Pleistocene CN13b calcareous nannofossils and N22 planktonic foraminiferal zones. The Yonabaru and Shinzato formations in southe...

Proposal of a new name for a junior homonym.

Four rock samples taken from the Yezo Group, Kaneopetsu River section, Oyubari area, Hokkaido by Tatsuro Matsumoto and Yoshitaro Kawashita in 1991 yielded 18 species of planktonic foraminifera belonging to nine genera. The occurrence of Rotalipora greenhornensis (Morrow) in a sample in the lowermost horizon indicates a Cenomanian age for the studie...

Miocene-Pliocene foraminifera recovered from three subsurface sections in the Yufutsu Oil and Gas Field, southern Hokkaido, are studied in detail to infer paleoceanographic and paleobathymetric impli- cations and to clarify the history of the basin. Foraminiferal faunas indicate a progressive increase in bathymetry from a brackish shallow marine to...

Foraminiferal faunas from the Upper Oligocene Minaminaganuma Formation recovered from boreholes of the Yufutsu Oil and Gas Field and MITI Umaoi located in southern Hokkaido are characterized exclusively by the large elphidiids Elphidium mabutii and Cribroelphidium ombetsuense. They indicate cold water temperatures and an inner to middle sublittoral...

Benthic foraminifer Miliammina echigoensis diagnostic of the M. echigoensis Zone appeared in the earliest Pliocene in the Japan Sea. It was accompanied by agglutinated foraminifers including Martinottiella communis, Cribrostomoides subglobosus, Guppyella miocenica and Cyclammina japonica which had survived from the Miocene. This agglutinated forami...

Planktonic foraminiferal (> 75 µm) biostratigraphy in the eastern islands off the Katsuren Peninsula, Okinawa-jima was described based on 45 samples collected from the surface sections. This region provides excellent distributed exposures of the Shimajiri Group and the overlying Chinen Formation in the study area, which provides materials suitable...

Foraminiferal assemblages from the Miocene Teradomari Formation, which forms a major source rock in the Niigata oil and gas field region, back arc of northeastern Japan, are characterised by the occurrence of abundant agglutinated foraminifera. The scarcity of taxonomic studies on foraminifera from the Teradomari Formation has prevented discussion...

Stratigraphic ranges of foraminiferal assemblages of the Miocene-Pliocene boundary sections in the Niigata oil-fields region of northeastern Japan are described, and their paleoceanographic implications are discussed on the basis of modern foraminiferal ecology and additional geochemical data from the Rock-Eval analysis. Q-mode cluster analysis gr...

Geohistorical implications of several middle Eocene-lower Oligocene formations distributed in the western Hokkaido are restudied mainly from published data of foraminiferal assemblages. These formations are correlative to the Poronai and Momijiyama formations. Foraminiferal assemblages from the Utsunai and Magaribuchi formations in northernmost par...

The middle to upper Eocene Poronai and overlying Oligocene Momijiyama formations in Hokkaido are the major Paleogene strata studied by many workers in Japan. Recent progress in biostratigraphy and foraminiferal paleoecology requires a thorough revision of the regional geohistory interpretations. Depositional environments of the Poronai and Momijiya...

Radiolarian and foraminiferal biostratigraphy was investigated in the Fukaura district of western Aomori Prefecture, northern Japan, where the Miocene-Pliocene chronostratigraphy is well established. Based on the newly obtained data and reinterpretations of the previous studies, we determined that the Odoji Formation ranges in age from the Middle t...

In subsurface sections of the Yufutsu-Umaoi district, Hokkaido, northern Japan, three Eocene benthic foraminiferal assemblage zones were defined in the Ishikari Group and the overlying Poronai Formation. They are in ascending order: Evolutinella subamakusaensis - Haplophragmoides crassiformis Assemblage Zone, Globocassidulina globosa - Cribroelphid...

Pliocene foraminifera and calcareous nannofossils from a borehole section “Kainosawa Onsen” in the eastern part of Akita City, Akita Prefecture, Japan Sea borderland of northern Japan were examined. The information on biostratigraphy and inferred paleoenvironment from the study section will furnish basis for further study on the Pliocene formations...

Planktonic and benthic microfossils, including radiolarians, diatoms, calcareous nannofossils and foraminifers from the onshore sections of the Jouetsu-Chuetsu district, Niigata Prefecture, northeastern Japan, were studied to construct a time-stratigraphic framework for the Upper Miocene and Pliocene strata, which are characterized by interbedded h...

Stratigraphic horizons marked by the last occurrence of Spirosigmoilinella compressa and first occurrence of Miliammina echigoensis (benthic foraminifera) have been used as important biohorizons in the Neogene of the Sea of Japan region. We have elucidated ages of these horizons on the basis of radiolarian biostratigraphy in seven onshore sections...

Haplophragmoides yoshidai Hanagata nom. nov. is proposed as a replacement for Haplophragmoides kushiroensis Yoshida, 1963.