气候变化领域集成服务门户(CCPortal): Decrypting Magnetic Fabrics (AMS, AARM, AIRM) Through the Analysis of Mineral Shape Fabrics and Distribution Anisotropy

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DOI	10.1029/2021JB021895
	Decrypting Magnetic Fabrics (AMS, AARM, AIRM) Through the Analysis of Mineral Shape Fabrics and Distribution Anisotropy
	Mattsson T.; Petri B.; Almqvist B.; McCarthy W.; Burchardt S.; Palma J.O.; Hammer Ø.; Galland O.
发表日期	2021
ISSN	21699313
卷号	126 期号:6
英文摘要	Anisotropy of magnetic susceptibility (AMS) and anisotropy of magnetic remanence (AARM and AIRM) are efficient and versatile techniques to indirectly determine rock fabrics. Yet, deciphering the source of a magnetic fabric remains a crucial and challenging step, notably in the presence of ferrimagnetic phases. Here we use X-ray micro-computed tomography to directly compare mineral shape-preferred orientation and spatial distribution fabrics to AMS, AARM and AIRM fabrics from five hypabyssal trachyandesite samples. Magnetite grains in the trachyandesite are euhedral with a mean aspect ratio of 1.44 (0.24 s.d., long/short axis), and >50% of the magnetite grains occur in clusters, and they are therefore prone to interact magnetically. Amphibole grains are prolate with magnetite in breakdown rims. We identified three components of the petrofabric that influence the AMS of the analyzed samples: The magnetite and the amphibole shape fabrics and the magnetite distribution anisotropy. Depending on their relative strength, orientation and shape, these three components interfere either constructively or destructively to produce the AMS fabric. If the three components are coaxial, the result is a relatively strongly anisotropic AMS fabric (P' = 1.079). If shape fabrics and/or magnetite distribution anisotropy are non-coaxial, the resulting AMS is weakly anisotropic (P' = 1.012). This study thus reports quantitative petrofabric data that show the effect of magnetite distribution anisotropy on magnetic fabrics in igneous rocks, which has so far only been predicted by experimental and theoretical models. Our results have first-order implications for the interpretation of petrofabrics using magnetic methods. © 2021. The Authors.
英文关键词	AARM; AMS; distribution anisotropy; microXCT
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187068
作者单位	Department of Geological Sciences, Stockholm University, Stockholm, Sweden; School of Earth and Environmental Sciences, University of St. Andrews, United Kingdom; Department of Earth Sciences, Uppsala University, Uppsala, Sweden; Université de Strasbourg, CNRS, ITES UMR 7063, Strasbourg, France; Subsecretaría de Minería Provincia de Buenos Aires, Argentina; Facultad de Ciencias Naturales y Museo, Unviersidad Nacional de La Plata, Buenos Aires, Argentina; Natural History Museum, University of Oslo, Oslo, Norway; Department of Geosciences, Physics of Geological Processes, The NJORD Centre, University of Oslo, Oslo, Norway
推荐引用方式 GB/T 7714	Mattsson T.,Petri B.,Almqvist B.,et al. Decrypting Magnetic Fabrics (AMS, AARM, AIRM) Through the Analysis of Mineral Shape Fabrics and Distribution Anisotropy[J],2021,126(6).
APA	Mattsson T..,Petri B..,Almqvist B..,McCarthy W..,Burchardt S..,...&Galland O..(2021).Decrypting Magnetic Fabrics (AMS, AARM, AIRM) Through the Analysis of Mineral Shape Fabrics and Distribution Anisotropy.Journal of Geophysical Research: Solid Earth,126(6).
MLA	Mattsson T.,et al."Decrypting Magnetic Fabrics (AMS, AARM, AIRM) Through the Analysis of Mineral Shape Fabrics and Distribution Anisotropy".Journal of Geophysical Research: Solid Earth 126.6(2021).