DOI: 10.1016/j.epsl.2020.116444
论文题名: Isotopic and textural analysis of giant unmelted micrometeorites – identification of new material from intensely altered 16O-poor water-rich asteroids
作者: Suttle M.D. ; Dionnet Z. ; Franchi I. ; Folco L. ; Gibson J. ; Greenwood R.C. ; Rotundi A. ; King A. ; Russell S.S.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 546 语种: 英语
中文关键词: carbonaceous chondrites
; micrometeorites
; O-isotopes
; water-to-rock ratio
英文关键词: Asteroids
; Hydration
; Isotopes
; Mixing
; Textures
; Aqueous alteration
; Carbonaceous chondrite parent bodies
; Isotope compositions
; Isotopic composition
; Micro computer tomographies
; Ordinary chondrites
; Textural analysis
; Thermal metamorphism
; Meteorites
; asteroid
; identification method
; isotopic analysis
; isotopic fractionation
; isotopic ratio
; micrometeorite
; ordinary chondrite
; oxygen isotope
; parent body
; water
英文摘要: Bulk oxygen isotope data has the potential to match extraterrestrial samples to parent body sources based on distinctive δ18O and Δ17O ratios. We analysed 10 giant (>500 μm) micrometeorites using combined micro-Computer Tomography (μCT) and O-isotope analysis to pair internal textures to inferred parent body groups. We identify three ordinary chondrite particles (L and LL groups), four from CR chondrites and the first micrometeorite from the enstatite chondrite (EH4) group. In addition, two micrometeorites are from hydrated carbonaceous chondrite parent bodies with 16O-poor isotopic compositions and plot above the terrestrial fractionation line. They experienced intense aqueous alteration, contain pseudomorphic chondrules and are petrographically similar to the CM1/CR1 chondrites. These micrometeorites may be members of the newly established CY chondrites and/or derived from the enigmatic “Group 4” micrometeorite population, previously identified by Yada et al., 2005 [GCA, 69:5789-5804], Suavet et al., 2010 [EPSL, 293:313-320] (and others). One of our 16O-poor micrometeorite plots on the same isotopic trendline as the CO, CM and CY chondrites – “the CM mixing line” (with a slope of ∼0.7 and a δ17O intercept of -4.23‰), this implies a close relationship and potentially a genetic link to these hydrated chondrites. If position along the CM mixing line reflects the amount of 16O-poor (heavy) water-ice accreted onto the parent body at formation, then the CY chondrites and these 16O-poor micrometeorites must have accreted at least as much water-ice as CM chondrites but potentially more. In addition, thermal metamorphism could have played a role in further raising the bulk O-isotope compositions through the preferential loss of isotopically light water during phyllosilicate dehydration. The study of micrometeorites provides insights into asteroid belt diversity through the discovery of material not currently sampled by larger meteorites, perhaps as a result of atmospheric entry biases preventing the survival of large blocks of friable hydrated material. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165300
Appears in Collections: 气候变化与战略
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作者单位: Dipartimento di Scienze della Terra, Università di Pisa, Via S. Maria 53, Pisa, 56126, Italy; Planetary Materials Group, Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom; DIST-Università di Napoli “Parthenope”, Centro Direzionale Isola C4, Naples, 80143, Italy; INAF-IAPS, via Fosso del Cavaliere 100, Rome, 00133, Italy; School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom; CISUP, Centro per l'Integrazione della Strumentazione dell'Università di Pisa, Lungarno Pacinotti 43, Pisa, 56126, Italy; Psiche beamline, Synchrotron SOLEIL, Orne des Meurisiers, France
Recommended Citation:
Suttle M.D.,Dionnet Z.,Franchi I.,et al. Isotopic and textural analysis of giant unmelted micrometeorites – identification of new material from intensely altered 16O-poor water-rich asteroids[J]. Earth and Planetary Science Letters,2020-01-01,546