High Shock Pressure Metamorphism Induced Transformations of Olivine and Feldspar in Natun Balijan L4 Chondrite: Evidence from Micro-Raman, Infrared Spectroscopy, X-ray Diffraction and Electron Microprobe Analysis

Abstract

For the first time, the presence of olivine-ringwoodite and plagioclase-maskelynite transformations is reported in Natun Balijan L4 chondrite determined by micro-Raman and infrared spectroscopic techniques with mineral phases characterised by electron microprobe analysis. Micro-Raman spectra reveal trace of ringwoodite, which is independently confirmed with the powder X-ray diffraction analysis. Full width at half maximum data of Raman spectrum reveals structural disordered olivine and pyroxene. The nature of infrared peaks at 639 and 724 cm^–1 depicts the presence of maskelynite. Observed maskelynite Raman band at 509 and 581 cm^–1 are used to estimate the shock stage of Natun Balijan L4 chondrite as at least S5. The impact metamorphism with a shock pressure of at least 40 GPa is estimated.