High resolution microscopy and Raman Spectroscopic studies on the Freshest Mukundpura Meteorite, Rajasthan, India: Presence of nanodiamonds.

Authors:

Dornadula CHANDRASEKHARAM, Ummethala Govind, Tripathi RAJENDRA PRASAD, Amir Hossein TAVABI, Sairam Krishna MALLADI, Dunin-Borkowski RAFAL, Dixit AMBESH

Keywords:

Meteorite, Mukundpura, Nanodiamond, Raman Spectroscopy, TEM, Iridium anomaly, pentlandite, Mass extinction.

Abstract:

Carbonaceous Chondrites have special significance in the stellar evolution and in particular in the evolution of life on earth. The carbonaceous meteorite that fell in Mukundpura village, Jaipur, Ra￾jasthan on 6th June 2017 is one such rare CM2 (Carbonaceous Chondrite) carbonaceous meteorite. We carried out high resolution scanning and transmission electron microscopic (SEM and TEM) studies on typical thin sections, showing abundant grains of iridium (Ir), pentlandite (NiS), and more interestingly crystalline carbon (C). These crystallite carbon grains resemble nanodiamond like signature in the freshest Mukundpura meteorite. The high-resolution Raman spectroscopicme￾asurements are carried out on the crystalline carbon grains, showing well resolved three distinct 
peaks with a vibrational mode at 1315 cm-1, with the onset of a weak vibrational mode at 1150 cm-1, substantiating the observation of nanocrystalline diamond in Mukundpura meteorite. The broad peak centered at 1360 cm-1 and 1575 cm-1 (as an average), suggest the presence of graphitic carbon as well together with apparent presence of nanocrystalline diamond. The average size of nanocrys￾talline diamond is ~ 3-5 nm. High iridium content in this meteorite supports the meteoric impact related iridium anomaly in geological stratigraphic boundaries (e.g. Cretaceous-Tertiary boundary) that has caused mass extinction of flora and fauna.

DOI:

10.19111/bulletinofmre.1795402