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Integrated Pliocene-Pleistocene magnetostratigraphy and tephrostratigraphy of deep-sea sediments at IODP Site U1424 (Yamato Basin, Japan Sea)

Integrated Pliocene-Pleistocene magnetostratigraphy and tephrostratigraphy of deep-sea sediments at IODP Site U1424 (Yamato Basin, Japan Sea)
Integrated Pliocene-Pleistocene magnetostratigraphy and tephrostratigraphy of deep-sea sediments at IODP Site U1424 (Yamato Basin, Japan Sea)
Sediments from the semi-enclosed Japan Sea are sensitive to paleoclimatic perturbations and they offer great opportunities for many regional and global paleoceanographic and paleoclimatic studies. These studies often require a robust chronology. However, due to rare preservation of calcareous microfossils and drastic changes in surface water salinity during glacial lowstands, the construction of a traditional oxygen isotope stratigraphy for Japan Sea sediments is often difficult. Here, we use sediments recovered at Integrated Ocean Drilling Program (IODP) Expedition 346 Site U1424 to build an integrated Pliocene-Pleistocene reference magnetostratigraphy and tephrostratigraphy for sedimentary sequences from the region. Rock magnetic experiments indicate that magnetic remanence of Site U1424 sediments are carried primarily by (titano)magnetite with small contributions from high coercivity minerals (e.g. hematite) and possibly iron sulphides (pyrrhotite and/or greigite). Dark-colored 3 sediments appear to contain less (titano)magnetite probably due to reductive diagenesis under euxinic conditions. Natural remanent magnetization (NRM) of u-channel samples covering a continuous ~167.6 m sediment sequence at Site U1424 were repeatedly measured at 1-cm intervals before and after stepwise demagnetization. Despite lower NRM intensity in dark colored sediments, NRM directional data from both dark- and light-colored sediments are considered suitable for the construction of magnetostratigraphy. Site U1424 sediments clearly recorded the majority of the polarity Chrons and subchrons within the last ~4.89 Myr, with the Cobb Mountain subchron, the end of Kaena subchron, and the onset of Nunivak subchron less well preserved. Sixteen tephra layers from the site were sampled for chemical composition analyses and the results were correlated to reference tephrostratigraphy of the region. Ages of the identified tephras are consistent with and can be well integrated with the magnetostratigraphy. The resulting age model suggests that sedimentation rates at Site U1424 range between ~1.7 and 7.6 cm/kyr with an average of ~3.3 cm/kyr. The acquired magnetostratigraphy and tephrostratigraphy at Site U1424 provide a reference chronology that can be correlated with and transferred to other sediment sequences in the region to study paleoceanographic and paleoclimatic changes of the region as well as their links to other regional and global changes.
IODP Expedition 346, Japan Sea, Magnetostratigraphy, Paleomagnetism, Site U1424, Tephrostratigraphy
2197-4284
Xuan, Chuang
3f3cad12-b17b-46ae-957a-b362def5b837
Jin, Yuxi
a7d27955-300a-491d-85ab-32e3363ba59e
Sugisaki, Saiko
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Satoguchi, Yasufumi
ea6a8a03-395b-43f0-a33f-29bf7452434d
Nagahashi, Yoshitaka
65fecd61-8166-4e1a-b1d6-f7a3bfc5c6c4
Xuan, Chuang
3f3cad12-b17b-46ae-957a-b362def5b837
Jin, Yuxi
a7d27955-300a-491d-85ab-32e3363ba59e
Sugisaki, Saiko
5c1df0fd-d2a7-4679-aef5-85927dbfc919
Satoguchi, Yasufumi
ea6a8a03-395b-43f0-a33f-29bf7452434d
Nagahashi, Yoshitaka
65fecd61-8166-4e1a-b1d6-f7a3bfc5c6c4

Xuan, Chuang, Jin, Yuxi, Sugisaki, Saiko, Satoguchi, Yasufumi and Nagahashi, Yoshitaka (2020) Integrated Pliocene-Pleistocene magnetostratigraphy and tephrostratigraphy of deep-sea sediments at IODP Site U1424 (Yamato Basin, Japan Sea). Progress in Earth and Planetary Science, 7 (1), [60]. (doi:10.1186/s40645-020-00373-9).

Record type: Article

Abstract

Sediments from the semi-enclosed Japan Sea are sensitive to paleoclimatic perturbations and they offer great opportunities for many regional and global paleoceanographic and paleoclimatic studies. These studies often require a robust chronology. However, due to rare preservation of calcareous microfossils and drastic changes in surface water salinity during glacial lowstands, the construction of a traditional oxygen isotope stratigraphy for Japan Sea sediments is often difficult. Here, we use sediments recovered at Integrated Ocean Drilling Program (IODP) Expedition 346 Site U1424 to build an integrated Pliocene-Pleistocene reference magnetostratigraphy and tephrostratigraphy for sedimentary sequences from the region. Rock magnetic experiments indicate that magnetic remanence of Site U1424 sediments are carried primarily by (titano)magnetite with small contributions from high coercivity minerals (e.g. hematite) and possibly iron sulphides (pyrrhotite and/or greigite). Dark-colored 3 sediments appear to contain less (titano)magnetite probably due to reductive diagenesis under euxinic conditions. Natural remanent magnetization (NRM) of u-channel samples covering a continuous ~167.6 m sediment sequence at Site U1424 were repeatedly measured at 1-cm intervals before and after stepwise demagnetization. Despite lower NRM intensity in dark colored sediments, NRM directional data from both dark- and light-colored sediments are considered suitable for the construction of magnetostratigraphy. Site U1424 sediments clearly recorded the majority of the polarity Chrons and subchrons within the last ~4.89 Myr, with the Cobb Mountain subchron, the end of Kaena subchron, and the onset of Nunivak subchron less well preserved. Sixteen tephra layers from the site were sampled for chemical composition analyses and the results were correlated to reference tephrostratigraphy of the region. Ages of the identified tephras are consistent with and can be well integrated with the magnetostratigraphy. The resulting age model suggests that sedimentation rates at Site U1424 range between ~1.7 and 7.6 cm/kyr with an average of ~3.3 cm/kyr. The acquired magnetostratigraphy and tephrostratigraphy at Site U1424 provide a reference chronology that can be correlated with and transferred to other sediment sequences in the region to study paleoceanographic and paleoclimatic changes of the region as well as their links to other regional and global changes.

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Xuan et al _ 2020 _ PEPS _ Accepted (Archive on Pure) - Accepted Manuscript
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Xuan_et_al-2020-Progress_in_Earth_and_Planetary_Science - Version of Record
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More information

e-pub ahead of print date: 7 October 2020
Keywords: IODP Expedition 346, Japan Sea, Magnetostratigraphy, Paleomagnetism, Site U1424, Tephrostratigraphy

Identifiers

Local EPrints ID: 445023
URI: http://eprints.soton.ac.uk/id/eprint/445023
ISSN: 2197-4284
PURE UUID: 917b72fe-4c23-4e5e-85b4-7d3b04cd48c6
ORCID for Chuang Xuan: ORCID iD orcid.org/0000-0003-4043-3073

Catalogue record

Date deposited: 18 Nov 2020 13:17
Last modified: 26 Nov 2021 03:01

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Contributors

Author: Chuang Xuan ORCID iD
Author: Yuxi Jin
Author: Saiko Sugisaki
Author: Yasufumi Satoguchi
Author: Yoshitaka Nagahashi

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