Received date Sep. 30, 2023

KCC - J-DESC
Repository Core Re-Discovery

Proposal No.

No. 002

New / RevisedRevise(Above For Official Use Only)

Program (ReCoRD)
Proposal Form
Basic Information
Title: The Japan Sea paleoceanography and paleoclimatology during
the Miocene
Keywords: paleoclimate, Miocene, non-destructive measurement, the Japan(5 or less) Sea, tephra
Lead Proponent: Arisa Seki
Affiliation: Shinshu University
Address: 3-1-1, Asahi, Matsumoto, Nagano
Phone: 0263-37-2486
E-mail: a_seki@shinshu-u.ac.jp
Permission is granted to post the proposal contents on www.j-desc.org.
☒ Granted.
☐ Not Granted.

Scientific Objectives (250 words or less)To understand the oceanic environment changes in the warmer-than-today world areimportant for addressing future global warming. In this project, we reconstruct short time scaleoceanographic changes of the Japan Sea during the warm Miocene period. To understandoceanographic condition properly, comparison of sediments deposited at different water depth
at the same time is necessary. Since sediments taken by IODP Exp. 346 provide many scientificresults, the Miocene oceanographic reconstruction is limited because comparison of different
water depth is available only during sort period. During ODP Leg 127, many Miocene sediments
were drilled from the deeper part of the Japan Sea. However, high-resolution (less than orbitalscale) oceanographic reconstruction has not been conducted enough.
Therefore, in this project, our objective is to reconstruct millennial-scale, three dimensional
oceanographic changes during the Miocene. We will especially focus on;a) centennial to millennial scale oceanographic changes recorded in laminated sediments.
b) rapid warming event and subsequent oceanographic condition.
The detailed objective is;

1 / 71) Revise age models of Leg 127 cores by tephra dating, revising biostratigraphy, andcorrelation of cores to Exp. 346 cores utilizing chemical composition (XRF core scanner), CT,and logging data.
2) Reconstruct the high-resolution oceanographic condition changes for each Site utilizing
XRF core scanner result and core observation, and compare the reconstructed conditions
with other Sites deposited in different water depth at the same time, including on-landsections.
3) Sampling of the sediments for further analysis to more precisely understandoceanographic changes and background climate changes.

Proposed Target Cores
Leg/Exp.

Site-HoleCores

Leg127Site 794 Hole B

1R-27RLeg 127

Site 795 Hole B

1R-33RLeg 127

Site 797 Hole B

24X-53X

Leg 127

Site 797 Hole C

1R-8R

Exp. 346

Site U1425 Hole B

23H-54H

Exp. 346

Site U1425 Hole D

20H-67H

Exp. 346

Site U1430 Hole A

9H-29H

Exo. 346
Site U1430 Hole B
Add lines as needed[Note: Only cores in KCC are available.]

9H-27H

Proposed analysis prior to sampling
X-ray core scanner (ITRAX): Sites U1425, 794, 795, 797 (well-preserved interval only)
X-ray CT: Sites U1425, 794, 795, 797
split core image (WH and AH): Sites 794, 795, 797
microscopic imaging of smear slide: Sites 794, 795, 797[Note: Please describe above any analysis needed prior to sampling. Standard set is X-ray
CT, split core image (WH and/or AH), microscopic imaging of smear slide and/or
thin section.]

Summary of previous studies of the target cores

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For Leg 127 Sites, correlation of Miocene sediments obtained from Sites 794 and 797
were proposed using FMS data (Tada, 1994). The paleontological analysis (Benthic andplanktonic foraminifers, Diatoms, Nonnofossils, Radiolarians) were conducted andreveal biostratigraphy of the sediments (Brunner, 1992; Nomura, 1992; Rahman, 1992,etc.). Depositional water depths are also reconstructed from benthic foraminifer
analysis (Nomura, 1992). From the paleontological analysis, the sedimentlogicalanalysis (degree of lamina preservation etc.), geochemical analysis, and biogenic silica
analysis, paleoceanographic condition (Myr time scale) was reconstructed for eachsedimentological Units (Tada, 1994).
Using Miocene sediments recovered from Sites U1425 and U1430, paleoceanographic
condition (100kyr time scale) were recovered from Radiolaria fossils, carbon andnitrogen isotope, major and trace element analysis (Matsuzaki et al., 2018; 2020; Zhaiet al., 2021). The sediments sources were reconstructed from XRD data and chemicalcomposition of the sediments (Shen et al., 2017; Anderson et al., 2019; Lee et al., 2022).
Using carbon isotope of black carbon in the sediments of Site U1430, the historicalchanges of vegetation types of source areas were reconstructed (Shen et al., 2018). The
age models for Sites U1425 and U1430 were constructed by cyclostratigraphy(Kuwokawa et al., 2019).

Proponent List
Name

Affiliation

Position

Arisa Seki

Shinshu University

JSPS
research
fellow RPD

Ryuji Tada *Tomohisa Irino

Country

ExpertiseJapan

Geochemistry(XRF
corescanner analysis)

Chiba Institute of Principal
TechnologyResearch
ScientistJapan

sedimentology

Hokkaido University Associate
ProfessorJapan

physical property

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KenjiMatsuzaki

M. The University of AssistantTokyoprofessor

Japanmicrobiology(Radiolarians)

Jumpei Yoshioka The University of Doctor
Japan
Cyclostratigraphy,TokyocourseU-Pb dating ofstudent
tephra layer[Note: For proponents who do not have J-DESC memberships, please put an asterisk (*)
AFTER his/her name.]

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