Palaeoceanography of the Japan Sea Across the MidāPleistocene Transition: Insights From IODP Exp. 346, Site U1427
Published version
Peer-reviewed
Repository URI
Repository DOI
Change log
Authors
Abstract
jats:titleAbstract</jats:title>jats:pLargeāscale atmospheric circulation patterns, such as the East Asian monsoon, have been proposed as possible feedbacks of the midāPleistocene 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 glacialāinterglacial cycles. These suggest a good connection and unrestricted waterāmass exchange with the open ocean during interglacial seaālevel highstands, while during glacial seaālevel lowstands the JS is nearly isolated. Glacial isolation often results in poor carbonate preservation and unusually low oxygen isotope (Ī“jats:sup18</jats:sup>O) ratios from lowāsaline/lowāĪ“jats:sup18</jats:sup>O waters accumulating in the basin. Using the sediments of Integrated Ocean Drilling Program (IODP) Site U1427, a shallowāwater site in the southern JS, we present a continuous foraminiferal Ī“jats:sup18</jats:sup>O record encompassing the MPT. This record shows the JSātypical low glacial Ī“jats:sup18</jats:sup>O values in the late phase of the MPT, across Marine Isotope Stages (MIS) 24ā17, while earlier MPT glacials, across MIS 39ā25, are characterized by high Ī“jats:sup18</jats:sup>O values. We propose that high glacial Ī“jats: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 deepāwater sites, would make the interpretation of dark/light sediment layers as glacial/interglacial deposits uncertain.</jats:p>
Description
Keywords
Journal Title
Conference Name
Journal ISSN
2572-4525
Volume Title
Publisher
Publisher DOI
Sponsorship
ECORD (European consoritum for ocean research drilling) Research Grant (n/a)
NERC NIGL (IPā16668ā111, IPā1486ā1114)
British Geological Survey CASE partnership (BUFI S270)
Japan Society for the Promotion of Science (JPMXS05E2900001)
Kanazawa University (SAKIGAKE project 2020)