气候变化领域集成服务门户(CCPortal): Chronology of serpentinization: Paleomagnetic evidence for 20 Ma serpentinization of the Oeyama ophiolite, Wakasa, Southwest Japan

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DOI	10.1016/j.epsl.2020.116656
	Chronology of serpentinization: Paleomagnetic evidence for 20 Ma serpentinization of the Oeyama ophiolite, Wakasa, Southwest Japan
	Otofuji Y.-I.; Fujihara M.; Uno K.
发表日期	2021
ISSN	0012821X
卷号	554
英文摘要	Serpentinization of mantle peridotite generates magnetite that is able to acquire a remanent magnetization parallel to the ambient geomagnetic field. The paleomagnetic direction of serpentine provides insights as to the timing of serpentinization. This study examines paleomagnetic properties of serpentine in the Paleozoic Oeyama ophiolite in Wakasa (35.39°N, 134.39°E), Southwest Japan. Reversed polarity magnetizations with clockwise deflections from the south were observed in the serpentine in the high temperature component (HTC) magnetization with an unblocking temperature (Tub) of ∼580 °C. The mean reversed polarity direction was D = 226.0°, I=−37.8°, α95=5.9°, and n=30. The remaining samples with an HTC of Tub between 400-450 °C show the present-day geomagnetic field direction. Rock magnetism reveals that the reversed direction is carried by single-domain (SD) grains of magnetite, whereas multi-domain (MD) magnetite grains carry the present-day geomagnetic field direction. Magnetite grains originated from olivine during serpentinization grew to SD size and acquired the chemical remanent magnetizations during a reversed polarity interval. As serpentinization progresses, SD magnetite grains increased to MD magnetite grains and/or were subjected to maghemitization. The mean reversed direction yielded a paleomagnetic pole at 47.4°N, 230.3°E (A95 = 5.7°), which overlaps with the 20 Ma segment of the apparent polar wander path for SW Japan. We conclude that serpentinization occurred in the Oeyama ophiolite at approximately 20 Ma during the clockwise rotation of SW Japan. © 2020 Elsevier B.V.
关键词	ophiolite paleomagnetism rock magnetism serpentine serpentinization
英文关键词	Clocks; High temperature effects; Magnetite; Magnetization; Serpentine; Chemical remanent magnetization; Clockwise rotation; Geomagnetic fields; High temperature components; Paleomagnetic directions; Paleomagnetic evidence; Paleomagnetic poles; Remanent magnetization; Geomagnetism; chronology; geomagnetic field; magnetic reversal; magnetite; ophiolite; paleomagnetism; remanent magnetization; rock property; serpentine; serpentinization; Chubu; Fukui; Honshu; Japan; Wakasa
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203245
作者单位	Institute of GeoHistory, Japan Geochronology Network, NPO, 1599 Susai, Akaiwa, 701-2503, Japan; Hiruzen Institute for Geology and Chronology, Co., Ltd. 2-5 Nakashima, Naka-ku, Okayama, 703-8252, Japan; Department of Earth Sciences, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama, 700-8530, Japan
推荐引用方式 GB/T 7714	Otofuji Y.-I.,Fujihara M.,Uno K.. Chronology of serpentinization: Paleomagnetic evidence for 20 Ma serpentinization of the Oeyama ophiolite, Wakasa, Southwest Japan[J],2021,554.
APA	Otofuji Y.-I.,Fujihara M.,&Uno K..(2021).Chronology of serpentinization: Paleomagnetic evidence for 20 Ma serpentinization of the Oeyama ophiolite, Wakasa, Southwest Japan.Earth and Planetary Science Letters,554.
MLA	Otofuji Y.-I.,et al."Chronology of serpentinization: Paleomagnetic evidence for 20 Ma serpentinization of the Oeyama ophiolite, Wakasa, Southwest Japan".Earth and Planetary Science Letters 554(2021).