Magnetostratigraphy of the Late Cenozoic of the Boso Peninsula, Central Japan

Marine Pliocene and Pleistocene beds of the Boso Peninsula are more than 3 km thick and contain abundant fauna and flora. Almost continuous deposition occurred at a high sedimentation rate from the early part of the last reversed geomagnetic polarity epoch to the middle part of the last normal polarity epoch. Several microbiostratigraphic marker horizons enable correlation with deep-sea sediments fully independent of magnetostratigraphic zonation. Globorotalia truncatulinoides first occurs below the normal polarity event BO-B-2, which is correlated with the Olduvai Event in deep-sea sediments, whereas the disappearance of discoasters and the first occurrence of Gephyrocapsa caribbeanica are recognized at the top of BO-B-2, and the first occurrence of Gephyrocapsa oceanica is recognized at the top of BO-B-1. Based on the correlation of the Boso section with Mediterranean stage stratotype sections, the transition from the Pliocene to Pleistocene is estimated to be in the lower part of the Kazusa Group.

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Fission-Track Ages of Tuff Layers Related to the Pliocene-Pleistocene Boundary on the Boso Peninsula, Japan

Quaternary Research ◽

10.1016/0033-5894(90)90086-z ◽

1990 ◽

Vol 33 (1) ◽

pp. 86-93 ◽

Cited By ~ 8

Author(s):

Masao Kasuya

Keyword(s):

Fission Track ◽

Middle Part ◽

Late Cenozoic ◽

Boso Peninsula ◽

Normal Polarity ◽

Fission Track Ages ◽

Age Constraints

AbstractFission-track ages of zircon crystals from four tuff layers in the late Cenozoic sediment sequence of the Boso Peninsula,.Japan, are 1.6 ± 0.2 myr (the Kurotaki Formation), 5.5 ± 0.6 and 5.2 ± 0.5 myr (the uppermost part of the Amatsu Formation), and 11.5 ± 0.8 myr (the middle part of the Amatsu Formation). These ages provide numerical age constraints on magneto-biostratigraphy. The normal polarity interval in the lower part of the Kiwada Formation corresponds to the Olduvai polarity subzone. The boundary between the Pliocene and Pleistocene lies slightly above the Olduvai polarity subzone.

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Laser 40Ar39Ar ages of tephra from Indian Ocean deep-sea sediments: Tie points for the astronomical and geomagnetic polarity time scales

Earth and Planetary Science Letters ◽

10.1016/0012-821x(95)00087-s ◽

1995 ◽

Vol 133 (3-4) ◽

pp. 327-338 ◽

Cited By ~ 54

Author(s):

Chris M. Hall ◽

John W. Farrell

Keyword(s):

Indian Ocean ◽

Time Scales ◽

Deep Sea ◽

Deep Sea Sediments ◽

Geomagnetic Polarity

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Geochemical and Mineral Properties of Quaternary Deep-Sea Sediments in the Central-Tropical Pacific and Its Response to the Mid-Pleistocene Transition

Journal of Marine Science and Engineering ◽

10.3390/jmse9111254 ◽

2021 ◽

Vol 9 (11) ◽

pp. 1254

Author(s):

Haifeng Wang ◽

Liang Yi ◽

Xiguang Deng ◽

Gaowen He

Keyword(s):

Clay Mineral ◽

Deep Sea ◽

Global Climate ◽

Tropical Pacific ◽

Middle Pleistocene ◽

Central Pacific ◽

Weathering Processes ◽

Deep Sea Sediments ◽

Middle Pleistocene Transition ◽

Geomagnetic Polarity

Global climate and oceanic water masses have undergone profound changes during the middle Pleistocene transition; however, due to a lack of foraminiferal fossils, the nonfossiliferous pelagic deposits were less detected in previous reports. In this work, a gravity core from the Kamehameha Basin in the Central Pacific was studied in terms of magnetostratigraphy, clay mineral and geochemical elements. The main results are: (1) nine magnetozones are recognized in the core, which can be correlated to the geomagnetic polarity timescale from chrons C2n to C1n; (2) smectite is the dominant clay mineral, and the others are illite, chlorite and kaolinite; and (3) the sediments are mainly composed of Al2O3, Fe2O3, MnO, Na2O and TiO2. Based on these results, a geochronological framework for the study area was established, and the depositional rates are estimated as 3–7 m/Myr in the Quaternary, showing an increase during the middle Pleistocene transition. By comparing the findings to various paleoenvironmental processes, it is inferred that the increased sedimentation in the Kamehameha Basin may have resulted from the induced weathering processes and the strengthened aeolian inputs from inner Asia. Moreover, regional circulation related to bottom water evolution has experienced a rapid reorganization across the middle Pleistocene transition. All these findings illustrate the potential of deep-sea sediments in the central tropical Pacific in revealing some key features in paleoclimatology and paleoceanography, which are worthy of further investigation in the future.

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Ethologic and ecologic interpretation of complex stellate structures in Pleistocene deep-sea sediments (Otadai Formation), Boso Peninsula, central Japan

Palaeogeography Palaeoclimatology Palaeoecology ◽

10.1016/s0031-0182(02)00683-1 ◽

2003 ◽

Vol 192 (1-4) ◽

pp. 143-155 ◽

Cited By ~ 6

Author(s):

Nobuhiro Kotake

Keyword(s):

Deep Sea ◽

Central Japan ◽

Boso Peninsula ◽

Deep Sea Sediments

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PALYNOLOGICAL RECORDS ON DEEP-SEA SEDIMENTS IN THE SOUTH CHINA SEA AND ITS PALEOENVIRONMENT

Marine Geology & Quaternary Geology ◽

10.3724/sp.j.1140.2009.01025 ◽

2009 ◽

Vol 29 (1) ◽

pp. 25-30 ◽

Cited By ~ 1

Author(s):

Yulan ZHANG

Keyword(s):

South China Sea ◽

South China ◽

Deep Sea ◽

The South China Sea ◽

The South ◽

China Sea ◽

Deep Sea Sediments ◽

Palynological Records

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Empire's Legacy

10.1093/oso/9780190875664.001.0001 ◽

2019 ◽

Cited By ~ 1

Author(s):

John W.P. Veugelers

Keyword(s):

Voluntary Associations ◽

Alternative Interpretation ◽

Middle Part ◽

Political Opportunity ◽

Far Right ◽

Historical Approach ◽

Southeast Region ◽

Main Thesis ◽

Postwar Europe

Building on the idea of latent political potential, this book offers an alternative interpretation of the contemporary far right. Its main thesis is that relations between colonizers and colonized implanted a legacy that, under certain conditions, translated into support for the far right in France. To make this argument, the book offers a model for the study of political potentials that combines a situational approach to identity relations, a networks approach to subcultural practice, and a historical approach to political opportunity. The early part of this book traces the origins and development of this potential among the European settlers of French Algeria. The middle part examines its transmission via voluntary associations and its channeling into mainstream parties. The latter part examines the conditions under which this potential redirected into the far right. Starting with colonial Algeria, after independence in 1962 the book moves between politics at three levels: France, the southeast region, and Toulon (which in 1995 became the largest city in postwar Europe to elect a far-right administration). Complementing economic explanations for nativism, this book argues that our understanding of modernity errs when it disregards the potency of anachronistic remnants.

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Mechanism and Influencing Factors of REY Enrichment in Deep-Sea Sediments

Minerals ◽

10.3390/min11020196 ◽

2021 ◽

Vol 11 (2) ◽

pp. 196

Author(s):

Jiangbo Ren ◽

Yan Liu ◽

Fenlian Wang ◽

Gaowen He ◽

Xiguang Deng ◽

...

Keyword(s):

Deep Sea ◽

Research Progress ◽

Bottom Current ◽

Knowledge Map ◽

P2o5 Content ◽

Deep Sea Sediments ◽

Potential Resource ◽

And Migration ◽

Adsorption Desorption ◽

Sediment Interface

Deep-sea sediments with high contents of rare-earth elements and yttrium (REY) are expected to serve as a potential resource for REY, which have recently been proved to be mainly contributed by phosphate component. Studies have shown that the carriers of REY in deep-sea sediments include aluminosilicate, Fe-Mn oxyhydroxides, and phosphate components. The ∑REY of the phosphate component is 1–2 orders of magnitude higher than those of the other two carriers, expressed as ∑REY = 0.001 × [Al2O3] − 0.002 × [MnO] + 0.056 × [P2O5] − 32. The sediment P2O5 content of 1.5% explains 89.1% of the total variance of the sediment ∑REY content. According to global data, P has a stronger positive correlation with ∑REY compared with Mn, Fe, Al, etc.; 45.5% of samples have a P2O5 content of less than 0.25%, and ∑REY of not higher than 400 ppm. The ∑REY of the phosphate component reaches n × 104 ppm, much higher than that of marine phosphorites and lower than that of REY-phosphate minerals, which are called REY-rich phosphates in this study. The results of microscopic observation and separation by grain size indicate that the REY-rich phosphate component is mainly composed of bioapatite. When ∑REY > 2000 ppm, the average CaO/P2O5 ratio of the samples is 1.55, indicating that the phosphate composition is between carbonate fluoroapatite and hydroxyfluorapatite. According to a knowledge map of sediment elements, the phosphate component is mainly composed of P, Ca, Sr, REY, Sc, U, and Th, and its chemical composition is relatively stable. The phosphate component has a negative Ce anomaly and positive Y anomaly, and a REY pattern similar to that of marine phosphorites and seawater. After the early diagenesis process (biogeochemistry, adsorption, desorption, transformation, and migration), the REY enrichment in the phosphate component is completed near the seawater/sediment interface. In the process of REY enrichment, the precipitation and enrichment of P is critical. According to current research progress, the REY enrichment is the result of comprehensive factors, including low sedimentation rate, high ∑REY of the bottom seawater, a non-carbonate depositional environment, oxidation conditions, and certain bottom current conditions.

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