CONICET | Buscador de Institutos y Recursos Humanos

D´Orbigny is an exceptional angrite, and the largest member of this small group of meteorites. The isotopic studies performed in D?Orbigny glasses show that it is an old and unusual matter from the early solar system [1]. It was found in the Buenos Aires province of Argentina (1979) and is peculiar in several aspects, one of them being the abundant presence of glasses, a phase which has not been previously reported from any other angrite [2]. The Cachari achondrite is a monomictic basaltic eucrite found in Argentina (1916), which contains abundant dark glass veins. Isotopic studies undertaken on Cachari bulk indicate an age of 4498 Ma [3], as old as our solar system. The origin of eucrites as well as that of angrites is still an unsettled question. Debates of the igneous [4] or non-igneous [2-5] origin of these rocks are still ongoing. However, there is a general agreement that glasses in eucrites are formed by impact processes on the eucrite parent body. This belief is based on the fact that the major element chemical compositions of glasses are similar to those of their respective bulk host rock. Nevertheless, recent studies that compare the trace element contents in glasses from eucrites with those from other achondritic meteorites, proposed a different and new hypothesis on the origin of glasses and the role of silicate liquids in meteorites [6]. Here we report on the Mössbauer features of glasses in these two achondritic meteorites in an attempt to contribute to the understanding of their possible origin(s). Samples: The glass samples used for this investigation are: In the D?Orbigny rock, glasses belong to the Glass Patches population as defined by [2]. They occur in open spaces and were separated under a binocular microscope . From Cachari, glasses cannot be separate by hand thus a double polish thin section of a glass?filled fracture was specially prepared for this study.

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