气候变化领域集成服务门户(CCPortal): Dual polarity directions in basaltic-andesitic dykes - reversal record or self-reversed magnetization?

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DOI	10.1111/j.1365-246X.2012.05543.x
	Dual polarity directions in basaltic-andesitic dykes - reversal record or self-reversed magnetization?
	Liebke, U.; Appel, E.; Neumann, U.; Ding, L.
通讯作者	Liebke, U (通讯作者)
发表日期	2012
ISSN	0956-540X
EISSN	1365-246X
起始页码	887
结束页码	899
卷号	190 期号:2
英文摘要	Rock magnetic analyses were performed on basaltic-andesitic dyke samples from the Lhasa Block, which were previously used for palaeomagnetic investigations of the IndiaAsia collision. The aim of the study is to prove whether antipodal directions separated in these samples represent different polarities of the Earth's magnetic field or a self-reversal magnetization. Reflected light microscopy, domain pattern observations and energy dispersive X-ray analyses revealed two generations of titanomagnetite (TM) grains, one consisting of large-sized (similar to 20 mu m to more than 100 mu m) and inhomogeneous Ti-poor TM, and another with small (smaller than similar to 10 mu m) and rather homogeneous Ti-rich TM grains. Partial thermoremant magnetization experiments and reflected light microscopy show that magnetostatic or superexchange interaction between these two phases is unlikely. Temperature dependence of saturation magnetization and low-temperature curves of isothermal remanent magnetization disprove a possible N-type behaviour of the samples. A self-reversal due to ionic reordering can be ruled out as it requires a high degree of oxidation of the Ti-rich TMs, which was not observed. In summary, a self-reversal magnetization is very unlikely in the studied dyke samples, and therefore the observed antipodal directions most probably represent a record of different polarity epochs of the Earth's magnetic field. This conclusion implies that the time of remanence acquisition in the studied dykes was sufficiently long to average out paleosecular variation, supporting the significance and reliability of the palaeomagnetic results.
关键词	SOUTHERN TIBET REMANENT MAGNETIZATION PALEOMAGNETIC DATA DOMAIN STATE MAGNETITE TITANOMAGNETITES TEMPERATURE TI ANISOTROPY COLLISION
英文关键词	Paleomagnetism applied to tectonics; Reversals: process, timescale, magnetostratigraphy; Rock and mineral magnetism
语种	英语
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:000306279100012
来源期刊	GEOPHYSICAL JOURNAL INTERNATIONAL
来源机构	中国科学院青藏高原研究所
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/257997
推荐引用方式 GB/T 7714	Liebke, U.,Appel, E.,Neumann, U.,et al. Dual polarity directions in basaltic-andesitic dykes - reversal record or self-reversed magnetization?[J]. 中国科学院青藏高原研究所,2012,190(2).
APA	Liebke, U.,Appel, E.,Neumann, U.,&Ding, L..(2012).Dual polarity directions in basaltic-andesitic dykes - reversal record or self-reversed magnetization?.GEOPHYSICAL JOURNAL INTERNATIONAL,190(2).
MLA	Liebke, U.,et al."Dual polarity directions in basaltic-andesitic dykes - reversal record or self-reversed magnetization?".GEOPHYSICAL JOURNAL INTERNATIONAL 190.2(2012).