An unusual occurrence of coesite at the Lonar crater,India |
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| Authors: | Steven J Jaret Brian L Phillips David T King Jr Tim D Glotch Zia Rahman Shawn P Wright |
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| Institution: | 1. Department of Geosciences, Stony Brook University, Stony Brook, New York, USA;2. Department of Geosciences, Auburn University, Auburn, Alabama, USA;3. Jacobs—NASA Johnson Space Center, Houston, Texas, USA;4. Planetary Science Institute, Tucson, Arizona, USA |
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| Abstract: | Coesite has been identified within ejected blocks of shocked basalt at Lonar crater, India. This is the first report of coesite from the Lonar crater. Coesite occurs within SiO2 glass as distinct ~30 μm spherical aggregates of “granular coesite” identifiable both with optical petrography and with micro‐Raman spectroscopy. The coesite+glass occurs only within former silica amygdules, which is also the first report of high‐pressure polymorphs forming from a shocked secondary mineral. Detailed petrography and NMR spectroscopy suggest that the coesite crystallized directly from a localized SiO2 melt, as the result of complex interactions between the shock wave and these vesicle fillings. |
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