Evidence of the impacting body of the Ries crater — the discovery of Fe-Cr-Ni veinlets below the crater bottom |
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Authors: | Ahmed El Goresy E.C.T. Chao |
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Affiliation: | Max-Planck-Institut für Kernphysik, Heidelberg Federal Republic of Germany;U.S. Geological Survey, Mailstop 929, Reston, Va. 22092, USA |
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Abstract: | Fe-Cr-Ni particles and veinlets have been discovered in the top 15 m of the compressed zone with abundant shatter cones below the bottom of the Ries crater. The metallic particles are less than a few microns across. They occur in various minerals along healed intergranular and locally in intragranular microfractures in quartz diorite, amphibolite and chloritized granite of the basement crystalline rocks.The particles consist of major Fe, Cr, and Ni with minor Si and Ca. Origin due to contamination is absolutely ruled out. We believe that these Fe-Cr-Ni particles are probably condensed from the vaporized impacting body which produced the Ries crater. These particles were injected with high velocity into microfractures near the top of the compressed zone, implanted in and across various minerals before these microfractures were resealed. The presence of Si and Ca as well as the fact that the Cr content is nearly twice that of Ni, led us to conclude that the Ries impacting body is very likely not an iron meteorite but a stony meteorite. |
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