Impact of early Oligocene deep water circulation to the benthic Foraminifera in the eastern Equatorial Pacific

Author(s): Takata, Hiroyuki; Lee, Jong-min; Sakai, Saburo; Nomura, Ritsuo; Tsujimoto, Akira; Nishi, Hiroshi; Lim, Hyoun Soo; Khim, Boo-Keun
Author Affiliation(s): Primary:
Shimane University, Research Center for Coastal Lagoon Environments, Matsue, Japan
Pusan National University, South Korea
Japan Agency for Marine-Earth Science and Technology, Japan
Tohoku University, Japan
Volume Title: Micropaleontology
Source: Micropaleontology, 61(3), p.177-184. Publisher: American Museum of Natural History, New York, NY, United States. ISSN: 0026-2803 CODEN: MCPLAI
Note: In English. Includes appendix. 29 refs.; illus., incl. sketch map
Summary: We investigated benthic foraminifera in the eastern equatorial Pacific Ocean at the Integrated Ocean Drilling Program Site U1334 (∼3580 to 3650 m paleo-depth) during a time interval of ∼33.2-31.9 Ma, which is characterized by paleoceanographic changes after the "overshoot" associated with the Antarctic glaciation across the Eocene-Oligocene transition. Correlation between MDS axis I (faunal composition of benthic foraminifera) and the fragmentation rate of planktonic foraminifera was positive. MDS axis 1 was also positively correlated with the δ13C values of benthic foraminifera at Site 1218. The positive correlation between the benthic foraminiferal δ13C values at Site 1218 and the fragmentation rate at Site U1334 did not correspond to the general relationship between the benthic foraminiferal δ13C values and carbonate corrosivity. Transient common occurrence and subsequent gradual decrease of Astrononion echnolsi, a characteristic species of MDS axis 1 that appeared to expand temporarily from the Southern Ocean to the abyssal Pacific, occurred abundantly during ∼33.2-31.9 Ma. The similarities among MDS axis 1, the fragmentation rate and the benthic foraminiferal δ13C values were likely explained by the heterogeneity in carbonate corrosivity changes, associated with different extent of export production in the Southern Ocean compared to other oceans after the Oi-1 Antarctic glaciation. Such heterogeneity might result from the transient expansion of the Southern Ocean deep water into the abyssal Pacific during the earliest Oligocene.
Year of Publication: 2015
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Assemblages; Benthic taxa; C-13/C-12; Carbon; Cenozoic; East Pacific; Equatorial Pacific; Expedition 320; Expeditions 320/321; Foraminifera; IODP Site U1334; Integrated Ocean Drilling Program; Invertebrata; Isotope ratios; Isotopes; Leg 199; Lower Oligocene; Marine environment; Microfossils; North Pacific; Northeast Pacific; ODP Site 1218; Ocean Drilling Program; Ocean circulation; Oligocene; Pacific Ocean; Paleo-oceanography; Paleoenvironment; Paleogene; Protista; Stable isotopes; Tertiary
Coordinates: N080000 N080000 W1315824 W1315824
N085300 N085300 W1352200 W1352200
Record ID: 2016024858
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.