DOI: 10.1016/j.epsl.2020.116237
论文题名: Intracrystalline site preference of oxygen isotopes in goethite: A single-mineral paleothermometer
作者: Miller H.B.D. ; Farley K.A. ; Vasconcelos P.M. ; Mostert A. ; Eiler J.M.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 539 语种: 英语
中文关键词: geochronology
; goethite
; iron oxide
; oxygen isotopes
; paleoclimate
; weathering
英文关键词: Geochronology
; Hematite
; Hydrogen bonds
; Iron oxides
; Isotopes
; Oxygen
; Temperature distribution
; Uncertainty analysis
; Weathering
; Environmental conditions
; Formation temperature
; goethite
; Oxygen isotope composition
; Oxygen isotopes
; Paleoclimates
; Temperature dependence
; Temperature dependent
; Crystal structure
; chemical weathering
; crystal chemistry
; crystal structure
; experimental mineralogy
; formation mechanism
; geochronology
; goethite
; iron oxide
; isotopic composition
; oxygen isotope
; paleoclimate
; paleotemperature
; temperature profile
; thermometry
英文摘要: The crystal structure of goethite, FeO(OH), has two distinct oxygen sites, one with exclusively Fe-O bonds, the other with bonds to both iron and hydrogen. We developed a method to assess the oxygen isotope contrast between these sites by measuring both the bulk goethite and the oxygen released in the conversion of goethite to hematite. The method involves collecting the water released by dehydroxylation, fluorinating that population of extracted atoms, and measuring the resulting oxygen isotope composition (extracted δO18). Then, on a separate aliquot, all structural oxygen is fluorinated and measured (bulk δO18). Using synthetic goethite precipitates grown under controlled environmental conditions, we found significant temperature-dependent fractionation, εbulk-extracted=(5.51±0.26)×(106/T2)−(44.5±2.8); T in Kelvin). This intracrystalline fractionation forms the basis of a single-phase paleothermometer with an estimated uncertainty of ∼2-3°C. The temperature dependence appears to be independent of the isotopic composition of the parent fluid from which the goethite formed and the pH of that fluid. This intracrystalline thermometer can be used to simultaneously determine the formation temperature of a goethite and the isotopic composition of the water from which it formed. Natural goethites analyzed with this technique yield geologically reasonable formation temperatures of between 15 and 41°C. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165165
Appears in Collections: 气候变化与战略
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作者单位: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, United States; School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, United States; School of Earth Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
Recommended Citation:
Miller H.B.D.,Farley K.A.,Vasconcelos P.M.,et al. Intracrystalline site preference of oxygen isotopes in goethite: A single-mineral paleothermometer[J]. Earth and Planetary Science Letters,2020-01-01,539