Biostratigraphy of the Miocene/Pliocene boundary sections in the Jouetsu-Chuetsu district, Niigata Prefecture, northeastern Japan.

聡, 花方; 功, 本山; 力, 平松; 和恵, 渡邉; 隆司, 辻

doi:10.5575/geosoc.107.565

Cited by 6 publications

(3 citation statements)

References 6 publications

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“…Alternation of sandstone and mudstone Foraminifera (Hanagata et al, 2001a), Radiolaria (Hanagata et al, 2001a) L. pylomaticus-C. sakaii zone before 2.7 Ma (Hanagata et al 2001a) Middle bathyal (according to the M. echigoensis assemblage)…”

Section: Shiiyamentioning

confidence: 99%

“…echigoensis zone (Hanagata et al 2001a) 7. Hokuriku Omma Fine sand-very fine sand Foraminifera (Hasegawa, 1979;Takayama et al, 1988;Kitamura et al, 2001;Takata, 2000), nannofossil (Takayama et al, 1988), Ostracoda (Ozawa and Kamiya, 2001; CN13-CN14 (Takayama et al, 1988;Takata, 2000) Outer-inner sublittoral (Takata, 2000) Junicho Silty sandstone-sandy siltstone Foraminifera (Hasegawa, 1979;Takayama et al, 1988), nannofossil (Hasegawa, 1979;Takayama et al, 1988) CN13 including datum 12 to 11 of Sato et al (2009) (Takayama et al, 1988) Sublittoral (Takayama et al, 1988) Yabuta Fine sandstone-siltstone Foraminifera (Hasegawa, 1979;Takayama et al, 1988;Miwa et al, 2004b), diatom (Watanabe, 2002), nannofossil (Takayama et al, 1988), Ostracoda (Cronin et al, 1994) NPD7B-NPD9 (Watanabe, 2002) Sublittoral to upper bathyal (Takayama et al, 1988;Cronin et al, 1994) PF6-PF 7 (Miwa et al, 2004b) Table 2 Typical on-land sections along the Japanese coast and records of microfossils from these areas (Continued)…”

Section: Shiiyamentioning

confidence: 99%

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Transitional changes in microfossil assemblages in the Japan Sea from the Late Pliocene to Early Pleistocene related to global climatic and local tectonic events

Itaki

2016

Prog. in Earth and Planet. Sci.

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Many micropaleontological studies based on data from on-land sections, oil wells, and deep-sea drilling cores have provided important information about environmental changes in the Japan Sea that are related to the global climate and the local tectonics of the Japanese Islands. Here, major changes in the microfossil assemblages during the Late Pliocene to Early Pleistocene are reviewed. Late Pliocene (3.5-2.7 Ma) surface-water assemblages were characterized mainly by cold-temperate planktonic flora and fauna (nannofossils, diatoms, radiolarians, and planktonic foraminifera), suggesting that nutrient-rich North Pacific surface waters entered the Japan Sea via northern straits. The common occurrence of Pacific-type deep-water radiolarians during this period also suggests that deep water from the North Pacific entered the Japan Sea via the northern straits, indicating a sill depth >500 m. A weak warm-water influence is recognized along the Japanese coast, suggesting a small inflow of warm water via a southern strait. Nannofossil and sublittoral ostracod assemblages record an abrupt cooling event at 2.75 Ma that correlates with the onset of the Northern Hemisphere glaciation. Subsequently, cold intermediate-and deep-water assemblages of ostracods and radiolarians increased in abundance, suggesting active ventilation and the formation of the Japan Sea Proper Water, associated with a strengthened winter monsoon. Pacific-type deep-water radiolarians also disappeared around 2.75 Ma, which is attributed to the intermittent occurrence of deep anoxic environments and limited migration from the North Pacific, resulting from the near-closure or shallowing of the northern strait by a eustatic fall in sea level and tectonic uplift of northeastern Japan. A notable reduction in primary productivity from 2.3 to 1.3 Ma also suggests that the nutrient supply from the North Pacific was restricted by the near-closure of the northern strait. An increase in the abundance of subtropical surface fauna suggests that the inflow of the Tsushima Warm Current into the Japan Sea via a southern strait began at 1.7 Ma. The opening of the southern strait may have occurred after the subsidence of southwestern Japan.

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Section: Shiiyamentioning

confidence: 99%

Section: Shiiyamentioning

confidence: 99%

Transitional changes in microfossil assemblages in the Japan Sea from the Late Pliocene to Early Pleistocene related to global climatic and local tectonic events

Itaki

2016

Prog. in Earth and Planet. Sci.

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“…The geomagnetic polarity time scale is from Cande and Kent (1995). Reported age references: *Machida and Arai (1992); **Kato (1989); ***Kato and Sato (1983); ****Kato and Akahane (1986); *****Nishimura and Hoyanagi (1992); and ******Hanagata et al. (2001).…”

Section: Discussionmentioning

confidence: 99%

Evolution of the Komiji Syncline in the North Fossa Magna, central Japan: Paleomagnetic and K–Ar age insights

Niitsuma

Saito

2003

Island Arc

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We carried out paleomagnetic measurements and K–Ar dating on Neogene andesitic lavas and sills of the Shigarami Formation in North Fossa Magna, central Japan. The Shigarami Formation is distributed in the axial part of the Komiji Syncline in the folding zone of the southwestern North Fossa Magna. Results of the present study indicate that the Komiji Syncline was formed shortly after 4.42 ± 0.12 Ma during the Pliocene. The sedimentary rocks of the Shigarami Formation consist of shallow marine and fluvial deposits. Intrusions of andesitic sills are found in the shallow marine deposits and two andesitic lava flows are present in the fluvial deposits. Oriented samples were taken from the sills at four sites and from the lavas at three sites. The samples produced stable remanent magnetization through stepwise alternating field and thermal demagnetizations. Results of a positive fold test indicate that the stable remanent magnetizations concentrate around a mean reversed polarity of declination = 169.0°, inclination = −58.5° and 95% confidence limit = 9.0° after corrections have been made according to the direction of the bedding of the sedimentary rocks. Four fresh samples were selected for K–Ar dating from the samples used for paleomagnetic measurements. The groundmass of three samples taken from the sills yield ages of 4.42 ± 0.12, 4.49 ± 0.22 and 4.69 ± 0.13 Ma, whereas the one taken from the lower lava has an age of 5.91 ± 0.26 Ma. We believe that the Komiji Syncline was formed after the emplacement of lavas and sills in the area, because the descending Miocene strata were folded concordantly with the Shigarami Formation. The Pliocene and Pleistocene strata rest unconformably on the folded strata. The deformation might have progressed during the Pliocene, then slowed down in the Early Pleistocene. Our results suggest that the northwestward motion of the Philippine Sea Plate and the collision of the Tanzawa Block affected not only the South Fossa Magna, but also the North Fossa Magna.

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Miocene-Pliocene Foraminifera from the Niigata oil-fields region, northeastern Japan

Hanagata¹

2003

Micropaleontology

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Biostratigraphy of the Miocene/Pliocene boundary sections in the Jouetsu-Chuetsu district, Niigata Prefecture, northeastern Japan.

Cited by 6 publications

References 6 publications

Transitional changes in microfossil assemblages in the Japan Sea from the Late Pliocene to Early Pleistocene related to global climatic and local tectonic events

Transitional changes in microfossil assemblages in the Japan Sea from the Late Pliocene to Early Pleistocene related to global climatic and local tectonic events

Evolution of the Komiji Syncline in the North Fossa Magna, central Japan: Paleomagnetic and K–Ar age insights

Miocene-Pliocene Foraminifera from the Niigata oil-fields region, northeastern Japan

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