Premium
A study of the observed shift in the peak position of olivine Raman spectra as a result of shock induced by hypervelocity impacts
Author(s) -
Harriss Kathryn H.,
Burchell M. J.
Publication year - 2016
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/maps.12660
Subject(s) - olivine , raman spectroscopy , hypervelocity , meteorite , spectral line , shock (circulatory) , mantle (geology) , foil method , geology , materials science , ambient pressure , mineralogy , analytical chemistry (journal) , thermodynamics , chemistry , physics , geochemistry , composite material , optics , astrobiology , medicine , chromatography , astronomy
Kuebler et al. (2006) identified variations in olivine Raman spectra based on the composition of individual olivine grains, leading to identification of olivine composition from Raman spectra alone. However, shock on a crystal lattice has since been shown to result in a structural change to the original material, which produces a shift in the Raman spectra of olivine grains compared with the original unshocked olivine (Foster et al. 2013). This suggests that the use of the compositional calculations from the Raman spectra, reported in Kuebler et al. (2006), may provide an incorrect compositional value for material that has experienced shock. Here, we have investigated the effect of impact speed (and hence peak shock pressure) on the shift in the Raman spectra for San Carlos olivine (Fo 91 ) impacting Al foil. Powdered San Carlos olivine (grain size 1–10 μm) was fired at a range of impact speeds from 0.6 to 6.1 km s −1 (peak shock pressures 5–86 GP a) at Al foil to simulate capture over a wide range of peak shock pressures. A permanent change in the Raman spectra was found to be observed only for impact speeds greater than ~5 km s −1 . The process that causes the shift is most likely linked to an increase in the peak pressure produced by the impact, but only after a minimum shock pressure associated with the speed at which the effect is first observed (here 65–86 GP a). At speeds around 6 km s −1 (peak shock pressures ~86 GP a), the shift in Raman peak positions is in a similar direction (red shift) to that observed by Foster et al. (2013) but of twice the magnitude.