Experimental reassessment of the Shaw paleointensity method using laboratory-induced thermal remanent magnetization

doi:10.1029/2001JB000620

	Experimental reassessment of the Shaw paleointensity method using laboratory-induced thermal remanent magnetization
	Pan, YX ; Shaw, J ; Zhu, RX ; Hill, MJ
刊名	JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
	2002-07-01
卷号	107 期号:B7
关键词	paleointensity thermal remanent magnetization Shaw method rock magnetic checks
ISSN号	2169-9313
DOI	10.1029/2001JB000620
文献子类	Article
英文摘要	[1] Artificial thermoremanent magnetization imposed on natural basalt samples was used to check the reliability of Shaw's palaeointensity method [Shaw, 1974; Kono, 1978; Rolph and Shaw, 1985] and to give an indication of the accuracy of paleointensity determinations. First, thermal remanence was induced in all samples (50 in total) in a known field (50 +/- 0.1 muT). This remanence was regarded as the "original'' natural remanent magnetization ("NRM''). The samples were divided in to three subsets (A, B, and C) and intensity experiments were performed. Each subset of samples used different thermal remanent magnetization (TRM) acquisition parameters. Rock-magnetic properties on 14 representative subsamples were also measured both before and after the TRM acquisition steps to monitor possible magnetochemical alteration. It has been demonstrated that intensity estimates by the Shaw method give values close to the expected value (50 +/- 5muT) in all three sets of basalt samples. The modified method with Rolph and Shaw [1985] correction, i.e., using ratios of anhysteretic remanent magnetization given before the TRM step (ARM(1)) and after (ARM(2)), is proved to be a powerful approach to correct the TRM capacity changes that result from magnetochemical alteration. This is especially so for sample set C, where the samples were heated up to 700 degreesC and then were held at this temperature for 40 min during TRM acquisition. After correction, 45% of set C samples gave acceptable results. However, some samples with strong magnetochemical alteration sometimes invalidated the ARM(1)/ARM(2) ratio correction and gave wrong intensity estimates. Monitoring rock magnetic properties is therefore very important when applying the Shaw method.
WOS关键词	ALTERNATING-FIELD DEMAGNETIZATION ; ANHYSTERETIC REMANENCE ; GRAIN-SIZE ; DEPENDENCE ; THELLIER ; THERMOREMANENCE ; INTENSITY ; MICROWAVE ; MAGNITUDE ; BASALTS
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	AMER GEOPHYSICAL UNION
WOS记录号	WOS:000178991900022
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/77393]
专题	中国科学院地质与地球物理研究所
通讯作者	Pan, YX
作者单位	1.Chinese Acad Sci, Inst Geol & Geophys, Beijing 100101, Peoples R China 2.Univ Liverpool, Geomagnetism Lab, Liverpool L69 7ZE, Merseyside, England
推荐引用方式 GB/T 7714	Pan, YX,Shaw, J,Zhu, RX,et al. Experimental reassessment of the Shaw paleointensity method using laboratory-induced thermal remanent magnetization[J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,2002,107(B7).
APA	Pan, YX,Shaw, J,Zhu, RX,&Hill, MJ.(2002).Experimental reassessment of the Shaw paleointensity method using laboratory-induced thermal remanent magnetization.JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,107(B7).
MLA	Pan, YX,et al."Experimental reassessment of the Shaw paleointensity method using laboratory-induced thermal remanent magnetization".JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 107.B7(2002).