TY - JOUR
T1 - Paleoceanographic history of the Northwest Pacific Ocean over the past 740kyr, discerned from radiolarian fauna
AU - Matsuzaki, Kenji M.
AU - Nishi, Hiroshi
AU - Suzuki, Noritoshi
AU - Cortese, Giuseppe
AU - Eynaud, Frederique
AU - Takashima, Reishi
AU - Kawate, Yumiko
AU - Sakai, Toyosaburo
N1 - Funding Information:
The authors express sincere gratitude to Prof. Thierry Corrège and two anonymous reviewers for helpful reviews of the manuscript. The samples were provided by the Japan Agency for Marine–Earth Science and Technology (JAMSTEC). This research was supported by Japan Society for the Promotion of Science , Tohoku University International Advanced Research and Education Organization , and Global Center of Excellence Program for the Global Education and Research Center for Earth and Planetary Dynamics at Tohoku University (leader: E. Ohtani). The study was financed by the Ministry of Education, Culture, Sports, Science, and Technology of Japan . The authors gratefully thank Prof. N.G. Pisias and Dr. T. Itaki for providing their surface sediment data.
PY - 2014/2/15
Y1 - 2014/2/15
N2 - The Northwest Pacific Ocean is characterized by a strong mixing of water masses, due to the interplay of three distinct currents, i.e., the Kuroshio, the Tsugaru, and the Oyashio. The C9001C drill core site, located east of the Shimokita Peninsula and directly influenced by the Tsugaru warm current and the Oyashio subarctic current was used here to reconstruct the paleoceanographical history of this region, especially focusing on the Mid-Brunhes Event (MBE) and its consequences. This core provides a continuous record from marine isotope stage (MIS) 18 (740. ka) to the present. Polycystine radiolarian assemblages were analyzed to highlight paleoceanographic and sea surface temperature changes at this site. Based on the radiolarian fauna, seven time periods are defined, which coincide with changes in the dynamics of the Tsugaru and Oyashio currents, respectively. The oldest time interval covered by our analysis (i.e., VII: 740-621. ka) was marked by generally sluggish ocean circulation. The Tsugaru Current influence increased during the following Interval VI (621-478. ka) which encompasses interglacials MIS 15 and 13, while the Oyashio Current strengthened during the Interval V (478-337), i.e. from glacials MIS 12 to 10. These latter intervals (VI to V) constitute a long climatic transitional period where Tsugaru Current and Oyashio Current influences are strengthened. In the time period from Interval IV to Interval I (0-337. ka), the warming intensity of interglacials (MIS 9, MIS 5) appears to be close to the modern one. However, several unusually warm glacials, associated with a relatively strong Tsugaru Current flow, were identified during this interval (e.g., MIS 8 and MIS 6). Radiolarian productivity data suggest that during Intervals VII to V, deep water masses are rich in nutrient content. However, a high vertical mixing event is recorded after Interval IV, when high nutrient concentrations appear to shift to the surface layer.
AB - The Northwest Pacific Ocean is characterized by a strong mixing of water masses, due to the interplay of three distinct currents, i.e., the Kuroshio, the Tsugaru, and the Oyashio. The C9001C drill core site, located east of the Shimokita Peninsula and directly influenced by the Tsugaru warm current and the Oyashio subarctic current was used here to reconstruct the paleoceanographical history of this region, especially focusing on the Mid-Brunhes Event (MBE) and its consequences. This core provides a continuous record from marine isotope stage (MIS) 18 (740. ka) to the present. Polycystine radiolarian assemblages were analyzed to highlight paleoceanographic and sea surface temperature changes at this site. Based on the radiolarian fauna, seven time periods are defined, which coincide with changes in the dynamics of the Tsugaru and Oyashio currents, respectively. The oldest time interval covered by our analysis (i.e., VII: 740-621. ka) was marked by generally sluggish ocean circulation. The Tsugaru Current influence increased during the following Interval VI (621-478. ka) which encompasses interglacials MIS 15 and 13, while the Oyashio Current strengthened during the Interval V (478-337), i.e. from glacials MIS 12 to 10. These latter intervals (VI to V) constitute a long climatic transitional period where Tsugaru Current and Oyashio Current influences are strengthened. In the time period from Interval IV to Interval I (0-337. ka), the warming intensity of interglacials (MIS 9, MIS 5) appears to be close to the modern one. However, several unusually warm glacials, associated with a relatively strong Tsugaru Current flow, were identified during this interval (e.g., MIS 8 and MIS 6). Radiolarian productivity data suggest that during Intervals VII to V, deep water masses are rich in nutrient content. However, a high vertical mixing event is recorded after Interval IV, when high nutrient concentrations appear to shift to the surface layer.
KW - Mid-Brunhes Event
KW - Oyashio Current
KW - Radiolaria
KW - SST
KW - Tsugaru Current
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U2 - 10.1016/j.palaeo.2013.12.036
DO - 10.1016/j.palaeo.2013.12.036
M3 - Article
AN - SCOPUS:84892999125
VL - 396
SP - 26
EP - 40
JO - Palaeogeography, Palaeoclimatology, Palaeoecology
JF - Palaeogeography, Palaeoclimatology, Palaeoecology
SN - 0031-0182
ER -
