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Palaeoceanography of the Japan Sea Across the Mid‐Pleistocene Transition: Insights From IODP Exp. 346, Site U1427

Published version
Peer-reviewed

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Abstract

jats:titleAbstract</jats:title>jats:pLarge‐scale atmospheric circulation patterns, such as the East Asian monsoon, have been proposed as possible feedbacks of the mid‐Pleistocene transition (MPT). Marine sediments of the Japan Sea (JS) record variations in the East Asian monsoon over long timescales and may be crucial for understanding of the MPT. To interpret these sediments correctly an understanding of the JS palaeoceanography is necessary. So far, the JS palaeoceanography has been extrapolated across the MPT from studies of the most recent glacial‐interglacial cycles. These suggest a good connection and unrestricted water‐mass exchange with the open ocean during interglacial sea‐level highstands, while during glacial sea‐level lowstands the JS is nearly isolated. Glacial isolation often results in poor carbonate preservation and unusually low oxygen isotope (δjats:sup18</jats:sup>O) ratios from low‐saline/low‐δjats:sup18</jats:sup>O waters accumulating in the basin. Using the sediments of Integrated Ocean Drilling Program (IODP) Site U1427, a shallow‐water site in the southern JS, we present a continuous foraminiferal δjats:sup18</jats:sup>O record encompassing the MPT. This record shows the JS‐typical low glacial δjats:sup18</jats:sup>O values in the late phase of the MPT, across Marine Isotope Stages (MIS) 24‐17, while earlier MPT glacials, across MIS 39‐25, are characterized by high δjats:sup18</jats:sup>O values. We propose that high glacial δjats:sup18</jats:sup>O values are the result of an improved connection between the shallow, southern JS and adjacent ocean during early MPT glacials. The impact of this palaeoceanographic mode, if continued to deep‐water sites, would make the interpretation of dark/light sediment layers as glacial/interglacial deposits uncertain.</jats:p>

Description

Keywords

3709 Physical Geography and Environmental Geoscience, 31 Biological Sciences, 3103 Ecology, 37 Earth Sciences, 3702 Climate Change Science, 3705 Geology, 14 Life Below Water

Journal Title

Paleoceanography and Paleoclimatology

Conference Name

Journal ISSN

2572-4517
2572-4525

Volume Title

37

Publisher

American Geophysical Union (AGU)
Sponsorship
NERC ‐ IAPETUS DTP (NE/L002590/1)
ECORD (European consoritum for ocean research drilling) Research Grant (n/a)
NERC NIGL (IP‐16668‐111, IP‐1486‐1114)
British Geological Survey CASE partnership (BUFI S270)
Japan Society for the Promotion of Science (JPMXS05E2900001)
Kanazawa University (SAKIGAKE project 2020)