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DOI	10.1016/j.epsl.2020.116560
	An eruption chronometer based on experimentally determined H-Li and H-Na diffusion in quartz applied to the Bishop Tuff
	Jollands M.C.; Ellis B.; Tollan P.M.E.; Müntener O.
发表日期	2020
ISSN	0012821X
卷号	551
英文摘要	The diffusion of hydrogen in natural hydrothermal quartz crystals was studied between 657–956 °C at atmospheric pressure and various oxygen fugacity (fO2) conditions. Single crystals of OH-bearing quartz were dehydrated in the presence of Li or Na-enriched powders to induce Li-H or Na-H exchange, with the resulting diffusion profiles measured by both Fourier transform infrared (FTIR) spectroscopy and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Diffusion parallel to [0001], i.e. the crystallographic c-axis, is described by: [Formula presented] where log10D is the base 10 logarithm of the diffusion coefficient, R is the gas constant and T is the temperature in kelvins, and uncertainties are 1 σ. Diffusion is not affected by (fO2) in this system. Diffusion perpendicular to [0001] is consistently slower, but quantitative constraints cannot be obtained from our data given experimental limitations. This diffusivity is primarily associated with H+-Li+ (or H+-Na+, Na+-Li+) exchange, where the H+ and Li+ are charge-balanced by tetrahedrally-coordinated Al3+. A faster mechanism may also exist where the monovalent cations are charge balanced by excess oxygen. The final defect population, as imaged by FTIR spectroscopy and LA-ICP-MS, likely results from a combination of diffusion and inter-site rearrangement of the monovalent cations. Regardless of such complexities, the determined Arrhenius relationship should be applicable for natural volcanic quartz crystals from the Bishop Tuff, California, wherein H+ is associated with Al3+, and H loss from quartz preceding and/or accompanying the eruption is charge-balanced by Li-gain, without Al movement. Li and H profiles from an example quartz crystal suggest that it experienced eruption/cooling timescales of just 16 minutes to 2.4 hours, showing the considerable promise of using frozen H diffusion profiles in quartz to extract timescales and thus elucidate the last moments of such explosive silicic eruptions. © 2020 The Author(s)
关键词	diffusion hydrogen nominally anhydrous minerals quartz volcanic timescales
英文关键词	Atmospheric pressure; Diffusion; Fourier transform infrared spectroscopy; Inductively coupled plasma mass spectrometry; Ion exchange; Laser ablation; Lithium; Lithium metallography; Mass spectrometers; Oxygen; Positive ions; Quartz; Sodium metallography; Arrhenius relationship; Defect population; Diffusion profiles; FTIR spectroscopy; Laser ablation inductively coupled plasma mass spectrometries (LA ICP MS); Monovalent cations; Oxygen fugacity; Quartz crystal; Sodium compounds; crystal structure; diffusion; FTIR spectroscopy; hydrogen; inductively coupled plasma method; timescale; volcanic eruption
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/202685
作者单位	Institute of Earth Sciences, University of Lausanne, Géopolis building, Lausanne, 1015, Switzerland; Lamont-Doherty Earth Observatory, Columbia University, 61 Rt 9W, Palisades, NY 10964, United States; Institute of Geochemistry and Petrology, ETH Zurich, NW Clausiusstrasse 25, Zurich, 8092, Switzerland; Institute of Geology, University of Bern, Baltzerstrasse 1+3, Bern, 3012, Switzerland
推荐引用方式 GB/T 7714	Jollands M.C.,Ellis B.,Tollan P.M.E.,et al. An eruption chronometer based on experimentally determined H-Li and H-Na diffusion in quartz applied to the Bishop Tuff[J],2020,551.
APA	Jollands M.C.,Ellis B.,Tollan P.M.E.,&Müntener O..(2020).An eruption chronometer based on experimentally determined H-Li and H-Na diffusion in quartz applied to the Bishop Tuff.Earth and Planetary Science Letters,551.
MLA	Jollands M.C.,et al."An eruption chronometer based on experimentally determined H-Li and H-Na diffusion in quartz applied to the Bishop Tuff".Earth and Planetary Science Letters 551(2020).