Raman spectroscopic study of four Spanish shocked ordinary chondrites: Cañellas, Olmedilla de Alarcón, Reliegos and Olivenza

Abstract

Shock metamorphism in chondritic parent bodies produces typical textures, visible under the microscope, which are a consequence of structural deformation of the crystals. Such deformations can be studied with Raman spectroscopy. The vibrational characteristics of olivines and pyroxenes, structurally deformed by weak-to-moderate shock metamorphism, have been determined on four Spanish ordinary chondrites (Cañellas, Olmedilla de Alarcón, Reliegos and Olivenza). Such deformations would affect, in principle, the band positions and widths of the Raman spectra peaks. The measured band positions and relative intensities are consistent with chemical composition for olivines and pyroxenes, but show little influence on the degree of shock. However, the full spectral band width of the silicate internal modes shows some dependence on the impact grade, which could be attributed to inhomogeneous effects produced by the impacts.