Thermal effects of scanning electron microscopy on He diffusion in apatite: Implications for (U-Th)/He dating

doi:10.1016/j.chemgeo.2013.03.001

	Thermal effects of scanning electron microscopy on He diffusion in apatite: Implications for (U-Th)/He dating
	Shan, Jingnan 1,2; Min, Kyoungwon 2; Nouiri, Abdelkader 3
刊名	CHEMICAL GEOLOGY
	2013-05-08
卷号	345 页码:113-118
关键词	Scanning electron microscope (SEM) (U-Th)/He dating Durango apatite Temperature rise He diffusion
ISSN号	0009-2541
DOI	10.1016/j.chemgeo.2013.03.001
文献子类	Article
英文摘要	In order to investigate potential diffusive loss of He from apatites during SEM analysis, we performed (1) single-grain (U-Th)/He dating for 47 Durango apatite fragments (from <90 mu m to 150-250 mu m) which were previously examined using SEM under different analytical conditions, and (2) electron-matter interaction simulation combined with diffusion modeling. The determined (U-Th)/He ages are internally consistent within their errors, and indistinguishable from the reported Ar-40/Ar-39 ages of 31.44 +/- 0.18 (2 sigma) Ma and the apatite (U-Th)/He ages of 31.02 +/- 1.01 Ma (Standard Deviation; McDowell et al., 2005). The results from the electron-matter interaction simulation suggest that "temperature rise" (Delta T = temperature increase during electron bombardment) peaks within a very thin layer at the outermost of the hypothetical apatite grain, and falls below similar to 50 K within a depth of 0.3 mu m from the surface. Based on the simulated Delta T profile combined with available He diffusion parameters, the fractional loss of He (f(He)) was calculated for different apatite grain dimensions. The numerical simulation supports that the He loss from apatite grains of typical physical dimensions is negligible (<1%) under regular SEM operating conditions. The direct measurements of (U-Th)/He ages for SEM-treated apatites, as well as diffusion simulation using the electron-matter interaction model, indicate that SEM spot analysis or extensive chemical mapping prior to apatite (U-Th)/He dating does not cause any meaningful diffusive He loss for most of the apatite samples. (c) 2013 Elsevier B.V. All rights reserved,
WOS关键词	HELIUM DIFFUSION ; AR-40/AR-39 AGES ; RADIOGENIC HE-4 ; AR DIFFUSION ; TEMPERATURE ; BEAM ; THERMOCHRONOMETRY ; FLUORAPATITE ; METEORITE ; DURANGO
WOS研究方向	Geochemistry & Geophysics
语种	英语
出版者	ELSEVIER SCIENCE BV
WOS记录号	WOS:000319642400009
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/87340]
专题	中国科学院地质与地球物理研究所
通讯作者	Min, Kyoungwon
作者单位	1.Chinese Acad Sci, Inst Geol & Geophys, Beijing 100029, Peoples R China 2.Univ Florida, Dept Geol Sci, Gainesville, FL 32611 USA 3.Univ Oum El Bouaghi, Dept Mat Sci, Oum El Bouaghi 04000, Algeria
推荐引用方式 GB/T 7714	Shan, Jingnan,Min, Kyoungwon,Nouiri, Abdelkader. Thermal effects of scanning electron microscopy on He diffusion in apatite: Implications for (U-Th)/He dating[J]. CHEMICAL GEOLOGY,2013,345:113-118.
APA	Shan, Jingnan,Min, Kyoungwon,&Nouiri, Abdelkader.(2013).Thermal effects of scanning electron microscopy on He diffusion in apatite: Implications for (U-Th)/He dating.CHEMICAL GEOLOGY,345,113-118.
MLA	Shan, Jingnan,et al."Thermal effects of scanning electron microscopy on He diffusion in apatite: Implications for (U-Th)/He dating".CHEMICAL GEOLOGY 345(2013):113-118.