Mossbauer studies on impactites from Lonar impact crater

Abstract

Iron mineralogy has been studied using Mossbauer spectroscopy on eight glassy impactite samples from different parts of the Lonar Crater Rim Region. Distinct changes are observed when compared to the host basaltic samples. Significant amount of Fe sup(3+) phase is observed in the impactite samples whereas this phase is known to be almost absent in the basalt. Besides this we have a strong Fe sup(2+) doublet showing up corresponding to the main iron-containing mineral. The Mossbauer results are very similar to those with glasses from Ries crater which is also believed to have formed by meteoritic impact but on nonbasaltic rock bed. Besides the glassy samples, we also study some spherules found in the crater region and some fine glassy particles on the surfaces of melt impact bombs. These contain a good amount of magnetically ordered phase, most likely nanosize hematite. Interestingly, part of it is strongly attracted by amagnet and part of it is not. But both parts show a significantly strong six-line component corresponding to hematite.