Magnetic properties of deep-sea sediments from the North Pacific; a proxy of glacial deep-water ventilation

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doi: 10.1029/2018GC007735
Author(s): Shin, Ji Young; Yu, Yongjae; Seo, Inah; Hyeong, Kiseong; Lim, Dhongil; Kim, Wonnyon
Author Affiliation(s): Primary:
Chungnam National University, Department of Geology and Earth Environmental Sciences, Daejeon, South Korea
Korea Institute of Ocean Science and Technology, South Korea
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, 19(11), p.4433-4443. Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. 50 refs.; illus., incl. 1 table, sketch map
Summary: The magnetic properties of deep-sea sediments in the North Pacific vary in sync with glacial-interglacial climatic changes and have thus been considered as a paleoclimate indicator. However, the causes of these variations in magnetic properties, including the concentration, grain size, and mineralogy of magnetic minerals, remain poorly understood. Here we investigate the magnetic properties of deep-sea sediments recovered from the Shatsky Rise in the North Pacific to investigate the cause of the variability associated with glacial-interglacial cycles. Compared to the potential sediment provenances, the interglacial-stage and more than half of the glacial-stage sediments reveal magnetic mineralogical properties (S ratio and L ratio) of the Gobi and Taklimakan deserts, probably indicating dust from the both sources. During glacials, an abrupt decrease in the concentration of magnetic minerals is associated with increases in the average grain size and in the proportion of hematite relative to magnetite. The changes during glacials are mostly a result of dissolutions of magnetite by exposure to ambient ocean environments after deposition. Both magnetic and geochemical proxies validate that poor ventilation of the glacial deep waters in the North Pacific possibly induced iron-reducing conditions. With comprehensive compilation with the S-ratio data in the North Pacific sediments, our result indicates that the poorly ventilated deep waters reached up to water depths of ∼2,500 m during glacials. Abstract Copyright (2018), American Geophysical Union. All Rights Reserved.
Year of Publication: 2018
Research Program: ODP Ocean Drilling Program
Key Words: 17 Geophysics, General; 24 Surficial Geology, Quaternary Geology; Asia; Cenozoic; China; Clastic sediments; Correlation; Deep-sea environment; Deep-water environment; Detroit Seamount; Dust; Emperor Seamounts; Far East; Glacial environment; Gobi Desert; Hematite; Interglacial environment; Leg 145; Leg 198; Magnetic properties; Magnetite; Marine environment; Marine sediments; North Pacific; Northwest Pacific; ODP Site 1209; ODP Site 882; Ocean Drilling Program; Oxides; Pacific Ocean; Paleoclimatology; Quaternary; Sediments; Shatsky Rise; Taklimakan Desert; Ventilation; West Pacific; Xinjiang China
Coordinates: N250000 N500000 E1800000 E1400000
Record ID: 2019048129
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom, Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union