DOI: 10.1016/j.epsl.2020.116560
论文题名: An eruption chronometer based on experimentally determined H-Li and H-Na diffusion in quartz applied to the Bishop Tuff
作者: Jollands M.C. ; Ellis B. ; Tollan P.M.E. ; Müntener O.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 551 语种: 英语
中文关键词: 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
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) Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165063
Appears in Collections: 气候变化与战略
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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
Recommended Citation:
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]. Earth and Planetary Science Letters,2020-01-01,551