scholarly journals A slope to outer-shelf cold-seep assemblage in the Plio-Pleistocene Kazusa Group, Pacific side of central Japan

2003 ◽  
Vol 7 (4) ◽  
pp. 279-296 ◽  
Author(s):  
TOMOMI KITAZAKI ◽  
RYUICHI MAJIMA
Keyword(s):  
Outer Shelf ◽  
Cold Seep ◽  
Central Japan ◽  
Pacific Side

scholarly journals Millennial-scale changes in sea-surface temperature and productivity along the Kuroshio–Oyashio boundary during MIS-19 based on the radiolarian record from the Chiba composite section, central Japan

2020 ◽  
Author(s):  
Takuya Itaki ◽  
Sakura Utsuki ◽  
Yuki Haneda ◽  
Kentaro Izumi ◽  
Yoshimi Kubota ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Sea Surface ◽  
Middle Pleistocene ◽  
Central Japan ◽  
High Productivity ◽  
Pacific Side ◽  
Composite Section ◽  
The Kuroshio ◽  
Millennial Scale

Abstract A high-resolution radiolarian record from 800 to 750 ka was examined from the Chiba composite section (CbCS) of the Kokumoto Formation, including the GSSP (Global Boundary Stratotype Section and Point) for the Lower–Middle Pleistocene boundary, on the Boso Peninsula, Pacific side of central Japan. Total radiolarian abundance was closely related to biological productivity in the sea-surface layer and was observed to increase and repeatedly decrease in the millennial-scale period. Summer SST (sea-surface temperature), which was estimated based on the radiolarian assemblage, was 19°C at the end of MIS-20 (790-793 ka) and fluctuated between 21 and 26°C during MIS-19, with the warm periods tending to be synchronous with high productivity. Recent observations have revealed that productivity increases with a northward shift of the Kuroshio along the Kuroshio-Oyashio boundary zone. Therefore, high productivity in the warmer and stratified conditions during MIS-19 can be interpreted as being closely related to millennial-scale oscillations of the Kuroshio Extension. Such millennial-scale climatic changes were also recognized in southern Europe and are likely related to shifts in climate systems such as AO (Arctic Oscillations).

scholarly journals Millennial-scale changes in sea-surface temperature and productivity along the Kuroshio–Oyashio boundary during MIS-19 based on the radiolarian record from the Chiba composite section, central Japan

2020 ◽  
Author(s):  
Takuya Itaki ◽  
Sakura Utsuki ◽  
Yuki Haneda ◽  
Kentaro Izumi ◽  
Yoshimi Kubota ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Sea Surface ◽  
Middle Pleistocene ◽  
Central Japan ◽  
High Productivity ◽  
Pacific Side ◽  
Composite Section ◽  
The Kuroshio ◽  
Millennial Scale

Abstract A high-resolution radiolarian record from 800 to 750 ka was examined from the Chiba composite section (CbCS) of the Kokumoto Formation, including the GSSP (Global Boundary Stratotype Section and Point) for the Lower–Middle Pleistocene boundary, on the Boso Peninsula, Pacific side of central Japan. Total radiolarian abundance was closely related to biological productivity in the surface layer and was observed to increase and repeatedly decrease in the millennial-scale period. Summer SST (sea-surface temperature), which was estimated based on the radiolarian assemblage, was 19°C at the end of MIS-20 (790-793 ka) and fluctuated between 21 and 26°C during MIS-19, with the warm periods tending to be synchronous with high productivity. Recent observations have revealed that productivity increases with a northward shift of the Kuroshio along the Kuroshio-Oyashio boundary zone. Therefore, high productivity in the warmer and stratified conditions during MIS-19 can be interpreted as being closely related to millennial-scale oscillations of the Kuroshio Extension. Such millennial-scale climatic changes were also recognized in southern Europe and are likely related to shifts in climate systems such as AO (Arctic Oscillations) and PDO (Pacific Decadal Oscillations).

Longibrachium arariensis, a new species of Onuphidae (Annelida: Polychaeta) from the shallow water of Izu Peninsula, central Japan, with notes on its feeding behavior

Zootaxa ◽  
2009 ◽  
Vol 2081 (1) ◽  
pp. 46-56 ◽  
Author(s):  
EIJIROH NISHI ◽  
TETSUYA KATO
Keyword(s):  
New Species ◽  
Feeding Behavior ◽  
Shallow Water ◽  
First Record ◽  
Central Japan ◽  
Izu Peninsula ◽  
Shizuoka Prefecture ◽  
Pacific Side ◽  
Western Side ◽  
A New Species

A new species, Longibrachium arariensis, is described from shallow sandy bottoms, at the western side of Izu Peninsula, Shizuoka Prefecture, Pacific side of central Honshu, Japan. Longibrachium arariensis most closely resembles the Australian L. longipes Paxton, 1986 and European L. falcigerum Paxton and Gillet, 2004 in having a combination of large and small hooks in its prolonged parapodia. The new species can be distinguished from these two species by having shorter antennae and recurved hooks with differently arranged spines. This is the first record of the genus from Japan. We are reporting a unique collecting method of this large onuphid worm using hook and line and illustrating with underwater photographs the feeding behavior of the new species.

scholarly journals Millennial-scale oscillations in the Kuroshio–Oyashio boundary during MIS 19 based on the radiolarian record from the Chiba composite section, central Japan

2022 ◽  
Vol 9 (1) ◽  
Author(s):  
Takuya Itaki ◽  
Sakura Utsuki ◽  
Yuki Haneda ◽  
Kentaro Izumi ◽  
Yoshimi Kubota ◽  
...  
Keyword(s):  
Kuroshio Extension ◽  
The Arctic ◽  
Middle Pleistocene ◽  
Central Japan ◽  
Boso Peninsula ◽  
Precipitation Record ◽  
Pacific Side ◽  
Composite Section ◽  
The Kuroshio ◽  
Millennial Scale

AbstractMarine isotope stage (MIS) 19 is considered to be the best orbital analog for the present interglacial. Consequently, clarifying the climatic features of this period can provide us with insights regarding a natural baseline for assessing future climate changes. A high-resolution radiolarian record from 800 to 750 ka (MIS 20 to MIS 18) was examined from the Chiba composite section (CbCS) of the Kokumoto Formation, including the Global Boundary Stratotype Section and Point for the lower–middle Pleistocene boundary on the Boso Peninsula on the Pacific side of central Japan. Millennial-scale oscillations in the Kuroshio warm and Oyashio cold currents were revealed by the Tr index, which is estimated using a simple equation based on radiolarian assemblages. The estimated Tr values ranged between 0.1 and 0.8 for MIS 18 through MIS 19, with minimum and maximum values corresponding to values observed off present day Aomori (41°N) and the Boso Peninsula (35°N), respectively. The observed patterns tended to be synchronous with the total radiolarian abundance associated with their production. Multiple maxima in radiolarian abundance occurred during periods of the Oyashio expanded mode before 785 ka and during periods of Kuroshio extension after 785 ka in MIS 19. Such increases in radiolarian abundance with the Kuroshio extension during MIS 19 are likely related to improvements in nutrient and photic environments with the development of a two-layer structure along the Kuroshio–Oyashio boundary zone. A similar pattern of millennial-scale climatic changes was also recognized in a precipitation record from the Sulmona Basin in central Italy, suggesting a close relationship with the CbCS record as a result of a large-scale climate system similar to the Arctic Oscillation in the northern hemisphere.

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