Early to middle Pleistocene paleoceanographic history of southern Japan based on radiolarian data from IODP Exp. 314/315 Sites C0001 and C0002

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doi: 10.1016/j.marmicro.2015.05.001
Author(s): Matsuzaki, Kenji M.; Suzuki, Noritoshi; Nishi, Hiroshi; Hayashi, Hiroki; Gyawali, Babu R.; Takashima, Reishi; Ikehara, Minoru
Author Affiliation(s): Primary:
Geological Survey of Japan, Marine Geology Research Group, Tsukuba, Japan
Tohoku University, Japan
Shimane University, Japan
Kochi University, Japan
Volume Title: Marine Micropaleontology
Source: Marine Micropaleontology, Vol.118, p.17-33. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0377-8398 CODEN: MAMIDH
Note: In English. Includes appendix. 101 refs.; illus., incl. strat. cols., 3 tables, sketch map
Summary: During the mid-Pleistocene Transition (MPT), spanning from 0.8 to 1.2 Ma, the prevailing 41 kyr glacial cycles were replaced by longer cycles with a period of ca. 100 kyr. This event was also accompanied by important climate changes, such as the expansion of the Northern Hemisphere Ice Sheet. The impact of the MPT on the Kuroshio Current off southern Japan remains unknown, however, in the absence of a long core covering the period of the MPT. In this area, preservation of calcareous microfossils is poor, but polycystine radiolarians are abundant and well preserved. Therefore, they are an excellent alternative proxy for reconstructing past climate change. Indeed, because numerous studies have examined the geographic distribution of modern radiolarian species, the relationships between several radiolarian assemblage groups (e.g., equatorial to sub-arctic assemblage groups) and climatic conditions are well understood. We examined the impact of the MPT on the Kuroshio Current off the Kii Peninsula, southern Japan, by investigating radiolarian assemblages in deep-sea cores collected during Integrated Ocean Drilling Program Expedition 314/315. We studied the radiolarian assemblages in 293 samples from cores obtained at Site C0001 Holes E and F and Site C0002 Hole D. The age models for these cores, which are based on biostratigraphy and chemostratigraphy, showed that sediments from the period between Marine Isotope Stage (MIS) 15 and MIS 8, which includes the Mid-Brunhes Event, are missing from these cores. However, continuous data are available between MIS 63 (1.82 Ma) and MIS 15 (0.5 Ma). Therefore, using the ecological properties of 11 key radiolarian species, we reconstructed regional paleoceanographic changes between 1.82 and 0.5 Ma. Radiolarian fauna revealed that the relative abundance of Kuroshio and the Central Pacific water taxa (e.g., Didymocyrtis tetrathalamus and the Polysolenia spinosa/lappacea group, respectively) increased drastically during the MPT, possibly indicating a northward shift of the Kuroshio at that time. The relative abundance of Rhizosphaera mediana, an Oyashio/Kuroshio mixed-water species, also increased during this interval. Thus, a southward shift of the Oyashio Current may have occurred synchronously with a northward shift of the Kuroshio during the MPT. Abstract Copyright (2015) Elsevier, B.V.
Year of Publication: 2015
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Assemblages; Cenozoic; Climate change; Expedition 314; Expedition 315; Faunal list; IODP Site C0001; IODP Site C0002; Integrated Ocean Drilling Program; Invertebrata; Kumano Basin; Kuroshio; Lithostratigraphy; Marine environment; Microfossils; Morphology; NanTroSEIZE; North Pacific; Northwest Pacific; Pacific Ocean; Paleo-oceanography; Paleoclimatology; Paleoenvironment; Pleistocene; Protista; Quantitative analysis; Quaternary; Radiolaria; West Pacific
Coordinates: N331400 N331800 E1364300 E1363800
Record ID: 2015091460
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands