Mid-Miocene to Pleistocene radiolarian fossil record from IODP Expedition 346; faunal response to the global climatic changes and local/regional tectonics

Author(s): Itaki, T.; Motoyama, I.; Kamikuri, S.; Tada, Ryuji; Murray, Rick W.; Alvarez Zarikian, C. A.
Author Affiliation(s): Primary:
Geological Survey of Japan, Tsukuba, Japan
Yamagata University, Japan
Ibaraki University, Japan
University of Tokyo, Japan
Boston University, United States
Texas A&M University, United States
Volume Title: AGU 2014 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2014; American Geophysical Union 2014 fall meeting, San Francisco, CA, Dec. 15-19, 2014. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: It is well known that radiolarian fossils can be used as a geological tool for the age assignment and paleoceanographic reconstruction. In this study, we analyzed radiolarian fossils for seven drilled sites of IODP Exp. 346 from the Japan, Yamato and Ulleung (JYU) basins in a marginal sea of the mid-latitude NW Pacific. Significant variations of the well-preserved fossil assemblage imply that the unique oceanic circulation changes in the basins through Mid-Miocene to Pleistocene might be controlled by global climatic changes and topographic changes with local/regional tectonics. Warm water radiolarians Dictyocoryne spp. and Tetrapyle spp. characterized in the Tsushima Current water occurred commonly since 1.7 Ma suggesting a beginning of the warm water inflow from the southern strait of the basins. It might be coincident with an opening of the Okinawa Trough in the East China Sea. On the other hand, during the Pliocene period, sporadic occurrence of the warm water species was recognized in southern part of the examined area. This implies that a minor influence of the warm water was present in the southern coastal area of the Yamato Basin. Typical deep dwelling species such as Cornutella profunda and Peripyramis circumtexta is absent in the present JYU basins, however they occurred frequently during Pliocene and Miocene. This suggests the deep-water exchange between the JYU basins and the North Pacific via the deeper strait, which might be present in the northern part of the sea. These deep-water radiolarians disappeared from the JYU basins at the early Pleistocene (∼2.7 Ma to 1.7 Ma), which is almost coincident with the Northern Hemisphere Glaciation.
Year of Publication: 2014
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Cenozoic; Expedition 346; Integrated Ocean Drilling Program; Miocene; Neogene; North Pacific; Northwest Pacific; Pacific Ocean; Pleistocene; Quaternary; Tertiary; West Pacific
Coordinates: N313700 N434600 E1390500 E1285930
Record ID: 2015114657
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